Classification of underground structures. Foreign Experience: Urban Underground Projects Urban Underground Structures

1. 
   City underground complexes

1. Principles of organization of urban elevated construction in super-large, largest and large cities 1

World and domestic practices indicate a significant urban planning effect of using underground space: the underground space of the largest city can contain up to 70% of the total volume of garages, up to 80% of warehouses, up to 50% of archives and storage facilities, up to 35% of institutions, research institutes, universities and others. Underground transport and engineering communications are the only real means to radically solve urban transport and communal problems. At the same time, the large-scale development of underground space requires the attraction of large funds, therefore, when planning underground construction in the largest cities of the Russian Federation, the following requirements must be met:

Rigid linkage with the master plan for the development of the city;

Rational use of urban land resources;

Phased development of underground space;

Ensuring maximum interaction of "new" facilities with existing aboveground and underground structures,

In super-large and largest cities, it is advisable:

Creation of a developed multifunctional space in the form of a stepped or flat stylobate platform - below zero with maximum preservation of the natural landscape;

Formation of a multifunctional underground space organized for public and transport services to the population in the most stressful areas of the city with a critical transport and pedestrian situation;

Associated construction of underground structures above the distillation tunnels and shallow stations or next to them with the development of multifunctional vestibule zones and metropolitan centers;

Construction of combined urban backbone networks in through multifunctional communication collectors with the creation of service and repair nodes.

Urban underground development should be organized according to a multi-tiered principle.

In the first tier, at a depth of up to 15 m, common walk-through and semi-passage collectors of engineering communications, pedestrian crossings, traffic interchanges, tunnels, shallow subway structures, three-, five-story underground complexes for various production and auxiliary purposes, motor transport facilities, social and service infrastructure.

In the second tier, at a depth of up to 30÷40 m, it is advisable to locate transport tunnels, railway entries, interchange nodes, multi-tiered parking garages, main engineering communication tunnels with related facilities for their maintenance, large warehouses and tanks,

In the third tier, at a depth of more than 30÷40 m, deep underground lines, transit transport tunnels, treatment facilities, pumping stations, energy facilities, underground enterprises with a specific technological regime, hazardous industries, warehouses of toxic materials should be located.

^ 2. Enlarged classification of urban underground complexes

Urban underground structures should be divided into two groups.

First group includes facilities designed to directly serve the population and ensure the comfort of living in the city. This group includes the subway, motor transport tunnels and interchanges, underground garages and parking lots, under-street crossings, engineering networks, administrative, cultural, commercial, and sports complexes.

^ K second group should include industrial facilities that ensure, first of all, environmental and industrial safety and rational use of urban areas: sewer pumping stations, various types of treatment facilities, waste collection and waste processing enterprises, industrial enterprises or individual facilities of industrial enterprises, warehouses and storage facilities, including including the storage of especially hazardous materials and substances, the construction of the city energy complex, etc.

^ 3. Underground complexes for servicing and ensuring the comfort of living for the population

3.1. City road tunnels and interchanges

Basic concepts

Tunnel - an extended underground structure designed to pass vehicles moving along adjacent or opposite lanes in one direction.

denouement - an underground structure designed to allow vehicles to pass in various directions.

Tunnel overpass - a structure for the passage of vehicles under embankments or roads.

3.2. Trends in the development of urban transport communications at several levels

The main directions of design solutions and fundamental approaches to the design of underground transport communications in super-large and largest cities are as follows.

1. Tunnels and underground junctions are intended for a sharp increase or equalization of the throughput of urban highways in dense urban areas. The experience of Moscow has shown that the creation of a system of underground transport communications at the nodes of the main highways has tripled their throughput.

2. The construction of transport tunnels is mainly determined by the need to organize highways of continuous traffic. Underground interchanges provide a rational crossing of traffic flows at different levels, exclude vehicles from stopping at traffic lights, and increase traffic safety.

3. Comparison of construction options for surface and underground highways indicates a number of advantages of the latter:

Reducing the allotted territories by 4-5 times; preservation of urban development;

Ability to transit significant traffic flows;

Ease of organization of movement at different levels;

Complete separation of traffic and pedestrian flows;

Protection from adverse weather conditions that worsen traffic conditions;

High degree of preservation of the urban landscape;

Improvement of the ecological situation.

The listed advantages of motor transport tunnels and underground junctions are reduced in peripheral urban areas.

4. Tunnels and underground interchanges should be arranged, as a rule, in the central zones of cities in the most loaded directions and sections. At the same time, it should be noted that the construction of a successive series of underground interchanges with a short closed part and long entry-exit ramps (sloping workings connecting the tunnel with the earth's surface) makes it difficult for cars to move and significantly worsens the operating conditions of adjacent roads and streets.

5. It is necessary to provide in the future the possibility of creating a complete system of off-street underground highways, which should organically fit into tunnels and underground interchanges that solve priority transport problems.

6. For the purpose of the planned development of the underground motor transport network, up to the creation of an underground off-street system, it is necessary to include reserve territories in the general plan for the development of the city for connecting underground structures with the surface, as well as for locating facilities that ensure future construction and operation. Reserve territories can be used before the start of construction to accommodate temporary facilities intended to serve the population.

8. The current design of tunnels and underground interchanges should proceed from a differentiated approach. In residential area 2, it is advisable to provide a specialized under-street network intended for the movement of passenger cars, and use full-size structures for transit cargo flows.

9. Consideration should be given to the prospects for the development of underground transport networks in connection with the increasing value of urban land and the intensive development of tunneling technology.

10. When designing underground routes, it is necessary to take into account the “wall effect”, the proximity of oncoming flows, the absence of roadsides, deterioration in visibility conditions, increased noise levels, an increase in aerodynamic resistance to vehicle traffic (up to 15%), and artificial ventilation.

11. It is advisable to provide for the straightening of the routes, taking into account the free and undeveloped territories, the traffic load of the streets and the area of ​​​​the routes and the nature of the building.

12. Placement of entry-exit ramps should ensure such a distribution of traffic flows from the tunnel, which would not complicate successful movement.

^ Classification of urban transport tunnels and interchanges

Tunnels and underground junctions distinguish between:

by depth: shallow and deep;

according to construction method: constructed by open, underground and combined methods;

according to the nature of the location relative to the earth's surface:

Plain tunnels (with inclined entrances-exits - ramps);

Mountain tunnels (constructed in cities with hilly or mountainous terrain and equipped with horizontal entrances and exits - adits);

Underwater tunnels;

Viaduct tunnels (under embankments);

by type of entry and exit:

- with galleries entrances-exits;

inclined ramps;

Spiral ramps;

Combined ramps;

by bandwidth and number of lanes: 3

- single-lane;

Two-way;

Three-lane;

Multiband;

by the number of tiers of movement:

- single-tier;

Bunk;

Multi-tiered;

according to the shape of the outline of the cross section:

- rectangular;

Vaulted (with direct, with direct and reverse vaults);

Circular;

Elliptical, etc.;

by type of lining(in view of the mountain support):

With monolithic reinforced concrete or concrete lining;

Prefabricated reinforced concrete lining;

Tubing finishes;

block linings;

Spray-concrete finishes;

Anchor finishes;

Combined finishes;

Without lining (in strong and stable rocks);

With roads of the first category;

according to the dimensions of the approach of buildings:

- full-size (for the passage of all types of transport);

Small-sized (for the passage of cars).

^ The main elements of the tunnels

The main elements of the tunnels are:

The tunnel itself

Entrances-exits (ramps, galleries);

Portals;

Turn pads, equipment niches and safety pockets;

Sidewalks and curbs, dividing strips;

Drainage complex;

Ventilation complex;

Security systems, including emergency evacuation systems for drivers;

Service workings and cameras;

Construction workings.

Characteristic sections of full-sized road tunnels are shown in Fig..3, 4. Sketch sections of reduced-size tunnels are shown in Fig..5.

A typical design of a frame made of precast concrete is shown in Fig..6.

Structural schemes of portals, turnaround areas and niches of road tunnels are shown in Fig..7,.8.

Figure 9 shows an example of a road tunnel.

Basic principles of tunnel tracing

In accordance with the trends in the development of urban transport communications, the planned routing of road tunnels should be carried out taking into account the following principles:

Tunnels and interchanges should be arranged in the central zones of cities in the most loaded directions;

It is necessary to create extended tunnels that provide simultaneous decoupling of several transport hubs, with intermediate ramps every 1.5÷2.5 km;

It is necessary to provide for the possibility of further development of underground highways (continuation of built or connection of additional tunnels);

It is advisable to provide for the direction of the routes, taking into account the free undeveloped territory, the traffic load of the streets, and the nature of the development. The minimum radius of curves in the plan must be at least 250 m;

The placement of entrance-exit ramps should ensure such a distribution of traffic flows from the tunnel and into the tunnel, which would not complicate the traffic.

Basic requirements for high-altitude tracing of tunnels:

The maximum longitudinal slope should not exceed 0.04; in difficult conditions, with a tunnel length of up to 500 m, the slope can be increased to 0.06;

The minimum longitudinal slope should be 0.003;

Altitude radii at a speed of 60 km/h should be equal:

For a convex curve - 6000 m;

For a concave curve - 1500 m.

The length of the entrance-exit ramps of full-size tunnels and interchanges (one of the main factors determining the possibility of building underground transport communications in dense urban areas) with standard slopes and transitional vertical curves at a speed of 60 km/h is shown in Table. 1.4.1. Similar data for tunnels and interchanges of reduced size are given in Table. 1.4.2.

The limiting minimum length of entry-exit ramps of tunnels of reduced size, assigned according to the experience of foreign transport construction, in difficult topographic and engineering-geological conditions with a non-standard longitudinal slope of 0.1 is given in Table. 1.4.3.

^ Table 1.4.1

Length of ramps for full tunnels

Table 4.2

^ Reduced tunnel ramp length

Table 4.3

^ Minimum ramp length for reduced gauge tunnels

Note. Movement speed - 40 km / h;

The minimum radius of a convex curve is 400 m;

The minimum radius of the concave curve is 200 m.

The depth of tunnels and underground junctions is related to the features of the relief, the nature of development, the location of existing underground structures and the method of construction. In the presence of a free territory or in a favorable transport situation, the technical and economic advantages of an open construction method are undeniable. Meanwhile, in the central zones of the largest cities, the possibilities for implementing an open construction method are limited, therefore, one should focus on an underground or combined method (combining open and closed laying of underground vehicles).

An example of planned and vertical tracing is shown in fig. 1.4.10.

Tunnel ventilation

The tunnels are ventilated naturally and artificially.

Natural ventilation is allowed with a tunnel length of up to 150 m. With a tunnel length of 150 m to 2 km, longitudinal, longitudinal-jet, transverse and combined artificial ventilation schemes are used (Fig. 1.4.11). At the same time, air is supplied and exhausted through portals, shafts or in a combined way.

The ventilation system must ensure the safe operation of the tunnel in the following modes:

A - normal - non-stop traffic is carried out at the maximum permitted speed at an intensity corresponding to the rush hour;

B - slow - non-stop traffic is carried out at a speed of less than 20 km / h;

B - traffic jam - when vehicles stop with running engines for up to 15 minutes.

As a rule, the tunnel is equipped with ventilation compartments located in the upper or lower part of the section. The section of the tunnel with two upper ventilation compartments is shown in fig. 1.4.12.

The cost of ventilation during operation is up to 25÷38% of the total cost of the tunnel.

Drainage and waterproofing in tunnels

The water inflow in the tunnels is formed from groundwater leakage through the lining, washing water, fire extinguishing water.

Drainage in short overcoats up to 300 m long is carried out along the slope of one sign by gravity. In longer tunnels, water flows along slopes with different signs to a sump pumping station located in the lowest part of the tunnel. On slopes, water is transported in trays or collectors, and it is cleaned from suspensions in settling tanks-water collectors and from oil products in gas and oil traps. After cleaning, the water is fed through the bypass pipes to the sump, then it is pumped out through the pressure pipeline directly to the storm drains of the city sewerage.

The effluents coming from the ramps should not enter the drainage system of the tunnel, therefore, independent drainage systems with local treatment facilities are arranged in the portal sections of the tunnel. Ramp sections of city roads should be arranged in such a way as to prevent flood and storm water from entering the tunnels.

On fig. 1.4.13 shows typical elements of the drainage system of a road tunnel.

Along with drainage, measures to ensure the waterproofness of linings are mandatory, including the use of waterproof materials, injection sealing of host rocks, waterproofing (painting, coating, glued - roll and film - metal insulation, capillary impregnation, sealants).

Features of the waterproofing device are determined by natural conditions (properties of host rocks), the method of tunnel construction and the type of lining.

Monolithic concrete and reinforced concrete linings are protected by external waterproofing (Fig. 1.4.14, but), applied over a leveling layer of sprayed concrete. In weak water-saturated rocks, internal waterproofing is arranged with a supporting reinforced concrete casing (Fig. 1 BUT. 14.6). In highly watered rocks, internal metal insulation is used (Fig. 1.4.14.e).

Precast concrete linings are sealed at the seams between blocks or tubing and at bolted joints with special sealants or elastic gaskets. The seams in the linings between cast iron tubings, as a rule, are “chased” with lead wire or leaded cord.

It is advisable to perform waterproofing of tunnel linings constructed in an open way outside the object, for example, by coating the structure with penetron, aquatron, etc. capillary impregnations.

In places where the tunnel lining adjoins the chambers and in areas where the lining can move, it is necessary to provide for expansion joints filled with elastic waterproofing mastic and protected by compensating diaphragms.

^ Tunnel lighting

Road tunnels must have round-the-clock lighting that provides clear visibility of moving vehicles, light signals and signs.

The ratio of the highest brightness of the road surface to its lowest value should not exceed 3:1. The minimum illumination at the tunnel portal should be at least 750 lux. An adaptation area is being arranged in the portal area: to reduce the negative effect at the entrance to the tunnel, sun screens and reflective lining of the ramp and portal walls are installed.

^ Traffic safety systems

• 
  fire protection (fire pipeline, automatic fire extinguishing systems, smoke protection and smoke removal);
• 
  control over the dimensions of the transport, and the car that has not passed the control must change the direction of movement before entering the tunnel);
• 
  arrangement of platforms for turning vehicles in sections of 250 - 300 m and safety pockets;
• 
  arrangement of emergency exits, pedestrian sidewalks and safety lanes 1 m wide when separating oncoming flows and 0.4 m from the side opposite the sidewalk;
• 
  a communication and warning system, a telemetric system for monitoring movement, monitoring the operation of drainage, ventilation, the content of harmful substances in the atmosphere, and lighting;
• 
  protection against unauthorized access to closed premises;
• 
  a system for monitoring the operation of automated systems that ensure the accident-free and safe operation of the tunnel.

Tunnel opening called a system for providing access to construction workings (faces). In the conditions of urban development, opening systems are used through ramp sections, through shafts, and a combined system - through ramp sections and shafts. Opening schemes that implement these systems are shown in fig. 1.4.15. In urban mountain tunnels, adits and combinations of adits with trunks are used for opening.

^ 1.4.3.2. Underground garages and car parks Basic concepts

underground garage - a facility designed for long-term and short-term storage of vehicles, as well as for their repair and maintenance.

Underground parking (parking) - building for short-term storage of vehicles.

The growth in the number of residents of our cities and the level of their needs for housing, recreation and life is constantly growing. The city is forced to go into the sky, develop peripherally and go deeper, deeper and deeper into the ground.

A strategic innovative approach to the implementation of projects for the development of the underground space of a modern city is a topical answer to the question of a completely new understanding of a comfortable environment.

Introduction

In the process of natural development of any systems - technical, industrial and urban, a barrier arises, which is simply impossible to overcome with the help of a simple quantitative accumulation of traditional technological methods.

A classic example is usually cited as the problem of the power barrier in aviation, when a further increase in speed and flight altitude - these critical indicators of technical progress - proved impossible on piston-engined aircraft. This barrier was successfully overcome by the transition of the aircraft industry to jet propulsion.

Today, in the field of urban planning, in the course of solving social, transport and environmental problems, the so-called "barrier of space and technology".

Currently, the area of ​​the earth's surface occupied by housing, industrial, economic and socio-cultural facilities, transport, energy and other types of engineering communications is more than 4% of the entire land surface. The building area in some European countries already reaches 15 or even 20 percent of their total territory.

The squares, avenues and streets of cities are filled with "hordes" of cars, the number of which is growing exponentially, requiring the expansion of the roadway and the number of parking spaces.

The development of new territories inevitably leads to a reduction in forest land and a decrease in the area of ​​land suitable for agricultural production.

The lack of land in cities, and especially in megacities, encourages urban planners around the world to look for additional ways to develop territories.

World experience shows that in urban planning it is necessary to abandon the old form of design - flat building of urban areas according to the principle "one to one" with independently executed engineering infrastructure.

Time and circumstances dictate the need to move from horizontal to vertical zoning of urban space, which is able to ensure the formation of a comfortable residential and industrial environment, based on the deep-spatial organization of the entire system of objects, as an integral organism, including the housing stock, and all the necessary social and industrial and engineering infrastructure created at the underground level. In modern urban science, this process is called "complex development of underground urban space."

Underground city space - this is the space under the daylight surface used to expand the living environment of citizens, implement the priorities of environmental and economic well-being and sustainable development, create conditions for people's life in extreme circumstances.

Engaged in the study of underground urban space, the formation of a strategy for its innovative development and development of a scientific discipline called "underground urbanism".

The purpose of this article is to acquaint readers with the current problems of innovative development of underground urban space, as well as with the main theoretical components of underground urbanism and modern experience in solving problems encountered in domestic and foreign practice. The author's task was not to cover the issues of metro construction, since this specific type of transport construction is well covered in the media.

Fundamentals of the concept of underground urbanism

Underground urbanism or underground urbanism, underground urbanization (underground urbanistics) is the area of ​​architecture and urban planning, associated with the integrated use of the underground space of cities and other settlements, which meets the requirements of urban aesthetics, social hygiene, as well as technical and economic feasibility.

The main goal of underground urbanism is to provide optimal working conditions, life, recreation and movement of the mountain population, increase the area of ​​open green spaces on the surface, and form a healthy, comfortable and aesthetically attractive mountain environment.

The development of underground urbanism is strongly influenced by various factors, such as:

• environmental and technical characteristics (groundwater, soil and rocks);
• knowledge of underground features and existing ideas about underground space, as well as information databases;
• architectural representations and organization of urban space;
• legalization and administrative possibilities, features of land ownership, regulation of land use, environmental protection and constructive possibilities;
• economic factors (land value, costs between above-ground and underground construction), the full cycle of use of the structure and external factors;
• psycho-sociological aspects of human behavior in the underground space.

The main challenge is to use these opportunities in a way that maximizes the benefits of the environment, society and the economy. Technically, this problem is intractable, but can be successfully implemented if the tasks are socially and politically acceptable, economically feasible, beneficial and legal.

The systematic use of underground space is carried out in conjunction with surface planning and development, with various types and types of existing underground structures, and taking into account the subsequent stages of the city's development.

This requires the development of special sections in the master plans of cities and in projects of detailed planning and development.

The degree of use of underground space, the technique and technology of conducting work depend on the size of the city, the nature and content of historically developed and prospective development, the concentration of the daily population in various parts of the city, the estimated level of motorization, natural and climatic, engineering and geological and other conditions.

In accordance with this, in the general plan of the city and the detailed planning project, zones are distinguished with varying degrees and sequence of use of underground space.

World experience shows that at the present stage, the strategy for solving complex socio-economic and urban planning problems is carried out through the formation of the spatial structure of cities through the creation of multi-level and multi-functional urban formations with maximum vertical development, with the integrated use of underground space according to a single urban planning plan, linked to the general city ​​development plan.

The need for the construction of underground facilities for various purposes and the tasks of innovative development of underground infrastructure require effective cooperation between scientists and specialists representing various areas in geomechanics and geotechnics, urban planning and architecture, which inevitably contributes to the rapprochement and mutual enrichment of specialists from various fields and various scientific schools.

At the same time, a change in the general strategy of urban planning is planned: to replace the centralized development scheme with the highest density (both on the surface and underground) in the center of the urban agglomeration, it is proposed to disperse the bulk of the volume of multi-storey ground construction (with a relatively less dense underground) in the suburbs.

With such a construction concept, the problem of a systematic approach to the development of underground space at a depth of 20-50 m becomes especially relevant. Currently, it is used only for transport and utility networks and dispersed objects of various purposes, relatively shallow.

A small digression into the history of the origin of underground urbanism

The bowels of the earth have always harbored something terrible, in fact, like other spaces unknown to man. These fears come from the depths of centuries. However, humanity, fighting for its existence, was forced to "to step on the throat" fear of underground space

It is known that the first habitation of man was a cave. She protected him from bad weather, protected him from predators, kept him warm and calm. With the help of simple devices, a person dug, scratched and scraped it out in breadth and depth. Sometimes the caves formed a whole settlement.

From ancient times to the present day, underground cities have been preserved, the largest of which are located in the Turkish region of Cappadocia. Excavations have shown that up to 100 thousand people supposedly lived in a complex system of underground premises. This twilight world with its own special culture was founded by the first Christians, hiding from the persecution of the Roman pagans.

One of the underground cities - Kaymakli stretched for 19 km and consisted of 8-10 levels, where there were living quarters, warehouses, churches, monasteries, pedestrian corridors and cemeteries. Archaeologists who excavated the city in the 60s were amazed at the perfection of the system of ventilation tunnels 70-80 m long, shafts and pipes, which allowed not only to supply clean air to such a depth, but also to control its humidity and temperature.

In the 16th century, Leonardo da Vinci proposed to arrange streets at different levels for a separate movement of "seniors" and ordinary people. And only now this experience accumulated by mankind can be appreciated and used.

However, large-scale urban underground construction began only in the second half of the 19th century. This was facilitated by the emergence and development of rail transport. From the 20-30s. The intensive development of road transport has presented architects and engineers with the difficult task of improving traffic capacity, increasing the speed of transport, and at the same time creating a safe and comfortable intersection of human and traffic flows.

Thus began the construction of underground railways (metro) and road tunnels. Transport began to go underground, and not only for its operation.

In the 40s. large-scale construction of underground garages and parking lots for vehicles began. From the 60s. tunnels were built already for pedestrians, over time they began to be saturated with trading functions in order to bring people closer to their usual comfortable environment.

Brief information about the modern underground urban economy andgeneral principles for the classification of underground structures

The modern system of the underground urban economy includes engineering and transport underground structures, trade and public catering enterprises, entertainment, administrative and sports buildings and structures, public utilities and storage facilities, industrial facilities and engineering equipment.

Engineering and transport facilities include pedestrian, road and railway tunnels, tunnels and subway and light rail stations, parking lots and garages, separate premises and station devices.

Underground trading and public catering establishments include trading floors and ancillary premises of cafe-buffets, canteens, snack bars and restaurants, trade kiosks, shops, separate sections of department stores, shopping centers and markets.

Underground entertainment, administrative and sports buildings and structures consist of cinemas, exhibition and dance halls, separate rooms of theaters and circuses, meeting rooms and conference rooms, book depositories, archive rooms, museum storerooms, shooting ranges, billiards, swimming pools and sports clubs .

Public utilities and storage facilities located underground, these are reception points, ateliers and consumer service factories, hairdressers, baths and showers, mechanical laundries, food and manufactured goods warehouses, vegetable stores, refrigerators, pawnshops, tanks for liquids and gases, warehouses of fuels and lubricants and other materials.

Industrial and energy facilities located underground include individual laboratories, workshops and production facilities (especially those that require careful protection from dust, noise, vibration, temperature changes and other external influences), thermal and hydroelectric power plants, industrial warehouses and storage.

Almost all urban engineering equipment - pipelines (water supply, sewerage, heat supply, gas supply), drains and storm drains, cables for various purposes - are underground networks. More and more transformer substations, ventilation chambers, boiler and boiler houses, gas distribution stations, treatment and water intake facilities, common network collectors are located in the urban underground space.

Underground structures are very diverse. They can be classified by purpose, location in the city, according to the space-planning scheme, laying depth, number of tiers, etc.

With regard to the tasks of underground urban planning, the classification “by purpose” is most often used. In accordance with it, all underground structures are subdivided depending on the time a person spends at the facility:

• duty-shift stay up to 24 hours
• long stay up to 3 - 4 hours;
• temporary stay up to 1.5 - 2 hours;
• short-term stays no more than 5 - 10 minutes;
• premises and structures without the presence of people.

Underground urbanism and the practice of using underground space in modern conditions.

The innovators of underground urban planning are Canada, Japan and Finland.

in Canada in 1997. an entire underground city was built - RATH. It is enough for residents to leave the house and go downstairs - and they will get to work without obstacles. There is no need for winter clothes and a car.

Montreal has the largest "underground city" (La ville souterraine) an area of ​​12 million square meters. m. Promoted by the mayor's office as one of the local curiosities, the city is interesting not only for its size. The designers proved that below you can place not only what you want to hide from your eyes - pipes, warehouses. IN la ville there is almost everything you need for life: shopping centers, hotels, banks, museums, universities, metro, railway interchanges, a bus station and other entertainment and business infrastructure facilities.

Japan is home to the country's largest underground city, Yaesu. It houses 250 restaurants, shops and other service facilities. According to statistics, Yaesu is visited every month by 8 to 10 million people.

In Beijing, in accordance with a program approved by the city government, in five years all transport from the surface will be removed underground - people will be able to move freely along the streets, relax in parks, and breathe fresh air.

In the intensive construction of underground structures, the state, the professional urban planning community and developers see one of the most promising areas for the development of Russian cities.

Underground urbanism is seen as the key to solving the many problems plaguing all of the country's major cities, where increasing building density is exacerbated by the rapid growth of the car fleet and the inevitable disruption of public transport.

The construction in 1997 near the walls of the Kremlin, on the site of Manezhnaya Square, of the Okhotny Ryad shopping and entertainment complex, located mainly below ground level, was a peculiar beginning of a new urban planning era in Moscow. In a multi-tiered underground complex with an area of ​​​​about 70 thousand square meters. m. housed a variety of objects: the archaeological museum and offices, a shopping center and bars, cafes, restaurants, parking lots and garages. In fact, a small underground city appeared.

Immediately began the development of adjacent underground spaces under Tverskaya Street and Bolshaya Dmitrovka, as well as the construction of a giant ground-underground complex "Moscow-City" on an underdeveloped section of the bank of the Moskva River in the Krasnaya Presnya region.

This is where the architects' fantasy came into play: the project provides for the construction of not only stations for two new metro lines, but also multi-storey underground garages and a monorail station that should connect the complex with Sheremetyevo International Airport. Time, however, has made its own adjustments to these plans, but it is already indicative " swing depth", which with a creak, but acquires real features.

Development of underground potential as the main way to sustainable development of the city.

It is no secret that our Russian cities are often expanding chaotically, carelessly and rapidly, without any effective control.

The consequences of such anarchic sprawl are, for example, increased traffic congestion and consequent levels of air pollution, lack of green spaces or difficult water supply, which is incompatible with the concept of sustainable development.

The development of underground space makes it possible to effectively use such functions as transport interchanges, shopping centers, theaters, and catering facilities. This, in turn, should lead to greater compactness of cities, ensuring the sustainable development of the city and will create a favorable environment for life as a result of free ground space for recreation and social activity, green fields and residential areas.

In large cities with a high population density, the possibility of saving and rational use of the urban area in the design of underground spaces is especially valuable.

The exploitation of the underground potential will make it possible to use space more efficiently, make the traffic system more mobile, which will lead to a reduction in the amount of harmful emissions and noise levels and, as a result, to renewal and improvement of the quality of life in the metropolis. At the same time, the length of underground communications and the cost of socially useful time are reduced, and the quality of transport services to the population is improving. It becomes possible to save energy resources due to lower heat losses of underground buildings and the absence of sharp temperature fluctuations, depending on the change of seasons.

Free space is not the only resource of underground construction. In order to achieve sustainable development, groundwater, geomaterials and geothermal energy should also be optimally used.

Despite the fact that the transition from the surface to the depth has been underway for a long time and more and more urban underground resources are being exploited, this is happening, unfortunately, without real planning.

Management of the potential of underground space is necessary for the rational use of resources and the prevention of possible irreversible consequences of chaotic development.

Underground construction in modern city

The choice of zones for the most active construction of underground structures is determined by urban planning and functional requirements and the feasibility of using certain sections and zones of the city.

It should be noted that sanitary-hygienic and psycho-physiological requirements establish normalized stay of people underground - no more than 4 hours, but a number of significant advantages almost completely compensate for this limitation, namely:

• underground structures can be designed under existing buildings, roads, communications and even riverbeds;
• the construction is not affected by elevation changes, problems of insolation or shading of neighboring existing facilities, the impact of external factors;
• only underground space allows you to lay the shortest paths for transport.

Underground structures are provided with a complex engineering system, which includes: constant and reliable artificial lighting; ventilation with continuous supply and exhaust ventilation, a system of sound alerts; systems for maintaining humidity and temperature.

The following factors have a significant impact on the organization of the architectural and spatial environment of underground structures:

• natural conditions and the nature of the historically developed urban environment;
• the presence of already existing, previously laid communications and foundations of neighboring buildings, which, as a rule, will form a single interconnected system with new underground facilities.

When studying natural factors to determine the nature of the site and its natural features, detailed engineering-geological and hydrogeological studies are necessarily carried out, engineering-geological maps and profiles are drawn up.

The construction of underground facilities at a shallow depth is usually carried out in an open way, while deep facilities are built in a closed way. During the construction of underground facilities, dewatering, soil stabilization, waterproofing of facilities are carried out, structures designed for rock pressure are used.

The main emphasis in the creation of underground structures in Moscow is on the technical and economic advantages of closed driving and tunnel construction. The main thing is that there is almost no need to dig pits, fence large areas, block streets, disrupting the rhythm of the already intense traffic.

There is no need for demolition of buildings, re-laying of underground utilities, restoration of road surfaces and green spaces. Invisibly for the townspeople, another important level of the city is gradually being created for a richer and more fulfilling life in an overpopulated metropolis.

Environmental benefits of underground structures

Within the city, underground structures can be located almost everywhere, with minimal impact on the natural landscape and the environment. They are reliably protected from the direct impact of climatic factors: rain and snow, heat and cold, wind and sun. Underground structures are distinguished by increased vibration resistance and acoustic insulation. And, finally, they are quite well protected from the effects of seismic explosive waves and penetrating radiation, which ensures their invulnerability from weapons of mass destruction.

Energy Efficient Aspects of Underground Structures

One of the most economical solutions is the underground placement of warehouses and refrigerators. So, with an underground location, the cost of building warehouse buildings is 4 times lower, operating costs are 10.6 times less than with ground placement.

The cost of construction of refrigerators with underground placement is 3.3, and operating costs are 11.6 times lower than with ground location. These data were obtained by comparing similar large refrigerators built in Kansas City and Sao Paulo (USA).

When assessing energy costs, both refrigerators were turned off, which caused an increase in the temperature in the above-ground refrigerator by 0.6 °C per hour, and in the underground refrigerator by 0.6 °C per day. Much better thermal insulation and heat capacity of the environment allow not only saving electricity, but also connecting underground refrigerators to the power grid, bypassing the peak of electricity consumption, and reducing the capacity of underground refrigeration plants.

preliminary conclusion

In recent decades, there has been a significant increase in underground construction for various purposes and its multifunctional use. This was facilitated by the reduction in the cost of underground construction. If earlier the cost of underground work was several times higher than ground work, today, due to the improvement of equipment and technology of underground work, their cost is in many cases slightly more expensive than ground work, especially in built-up areas.

Economic efficiency of underground urbanization

The effectiveness of underground urbanization consists of socio-economic, engineering, economic and urban planning components.

When identifying the effectiveness of objects located in the underground space, can be divided into three groups.

1. The efficiency of placing transport communications and structures underground is determined on the basis of: saving urban areas at the expense of space for the construction of both the objects themselves and the protective zones attached to them; increasing the turnover of vehicles; reducing travel times; cargo delivery; reducing the number of stops, saving energy resources; maximum safety of the existing ground building; improving the sanitary and hygienic state of the terrestrial environment.

2. The effectiveness of placing underground entertainment facilities, trade and public catering enterprises, as well as a number of public utility facilities is determined on the basis of: saving the territory, as well as maintaining ground buildings when located in the existing parts of the city; saving time of the population due to the approach of service objects to the consumer, along the way of his movement (passing service); increasing the size of trade turnover and profits of trade enterprises, public catering and cultural and entertainment enterprises due to their convenient location in areas of intensive congestion of pedestrians and passengers - potential visitors to the listed service facilities.

3. The efficiency of placing underground storage facilities, industrial buildings and structures, communal facilities, individual transport facilities, engineering equipment facilities is determined on the basis of: saving urban areas; reducing the length of engineering communications by placing structures and facilities in the center of loads; improving the sanitary and hygienic state of the urban environment, economic benefits due to a compact planning solution.

Thus, based on the integrated use of the underground space of the city, efficiency is considered in various areas:

• socio-economic - saving time by the population, reducing traffic fatigue, improving the sanitary and hygienic living conditions of the population, pedestrian safety;
• urban planning - the right choice of functional and construction zoning of territories, solving transport problems, increasing the area of ​​green spaces and water spaces;
• engineering and economic - accelerating the turnover of vehicles, increasing the speed of all types of transport, saving fuel, reducing the cost of developing engineering equipment, increasing the profitability of service enterprises, concentrating construction, reducing its time and ensuring the complexity of development, saving operating costs, reducing the size of the alienation of agricultural lands.

The total economic effect is calculated for each type of facility, taking into account the economy of the territory, the preservation of the existing development and the operating conditions of underground structures: savings in transport costs, transport time, growth in trading profits, etc.

Factors that increase the cost of using underground space include: geological and engineering-geological conditions, the complexity of engineering and design solutions for underground structures, constraint in the production of work in the existing building blocks. Underground construction causes additional volumes of earthworks, strengthening of load-bearing and enclosing structures, complication of works on waterproofing of objects, complication of sanitary equipment.

At the same time, underground construction makes it possible to reduce the cost of foundations, roofing, and to abandon a number of structural elements of above-ground buildings, such as external window blocks, internal drains, facade decoration, etc.

In addition to the above results, the expediency of the underground execution of a number of structures is determined by the specific requirements for the operation of the objects themselves. When designing facilities in the underground space, favorable operational factors should be taken into account, such as non-susceptibility to climatic influences; relative stability of air temperature and humidity starting from a depth of 5-8 m. etc.).

Such positive characteristics of underground structures as increased vibration resistance and acoustic insulation compared to surface structures are also used. The advantage of the underground solution for a number of industries and workshops is the ability of the floor bases to carry increased loads from heavy technological equipment.

Conclusion

The growth of volumes and scales of effective development and development of underground urban space is observed today throughout the world. It is associated with the ever-increasing concentration of the population in these cities and the continuous growth of the number of car parks, which give rise to almost all the most acute modern urban problems - territorial, transport, environmental, energy.

Innovative use of underground urbanism methods and settings proved to be the only way to improve and adapt the transport system to the growth of the largest cities without significant changes in the traditional planning structure and development.

The principles of vertical zoning of urban space have been scientifically defined and formulated.

The levels closest to the surface of the earth (up to the mark - 4 m) are reserved for pedestrians, continuous passenger transport, parking lots, local distribution networks. Levels from - 4 m to - 20 m are used for subway routes and shallow motor transport tunnels, multi-level underground garages, warehouses, reservoirs and main collectors. Levels at a mark from - 15 m to - 40 m are intended for deep rail transport routes, including urban railways.

In recent decades, an increase in the volume and scale of underground construction has also been observed in the most significant cities of Russia. Large underground complexes for various purposes, transport and communication tunnels, underground parking lots and garages, production and storage facilities are being built, the length of metro lines is growing.

Deeper, deeper and deeper into the bowels of the earth, scientists, urban planners and we, modest construction practitioners, strive to penetrate and master them. In the modern world, where science offers innovative solutions, where there are unique technologies, and where there are highly professional specialists, any “barriers of space and technology” will be successfully overcome!

- © M.N. Shuplik, 2014

ULC 622.25/26(075.8)

M.N. Shuplik

ANALYSIS OF SPECIAL METHODS OF CONSTRUCTION OF UNDERGROUND STRUCTURES IN URBAN CONDITIONS

The features of the construction of underground structures in complex hydrogeological conditions of dense urban development are considered. The methods of construction with the help of protecting supports, with the use of dewatering, artificial freezing of soils, jet grouting, as well as with the help of preliminary plugging of soils are analyzed. For each of the considered methods, the areas of their effective application and prospects for use in urban underground construction are shown. Key words: construction of underground structures, enclosing linings, dewatering, artificial freezing of soils, jet grouting, plugging of soils.

The rapid development of modern cities, the continuous growth of their population and occupied territories, as well as the high rates of social and scientific and technological progress, sharply raise the question of the systematic, effective development of the underground space of the largest cities and the placement of objects of various purposes in this space. Studies show that in the next five years alone, over 600 km of tunnels for various purposes, more than 200 social and cultural facilities, as well as other underground structures that ensure the normal functioning of cities, will be built in the underground space of large cities.

The Concept of Comprehensive Socio-Economic Development of Moscow until 2015, approved by the Government of Moscow, which is based on the economic and social development of the region as a single complex, provides for a 2.5-3-fold increase in labor productivity in the manufacturing sector. by increasing the technical level, by one third - by improving the organization

labor and production. It is planned to widely use modern technologies, flexible automated systems and robotics, deepen specialization and develop intersectoral industries. The introduction of scientific and technical developments is designed to significantly reduce the energy intensity and material consumption of production, to reduce the time for creating and mastering new equipment and technology by 3-4 times.

It should be emphasized that the development of underground space will be carried out with increased attention to environmental issues, saving water and energy resources, while a strict resource-saving policy will be pursued.

The choice of method and technology for the production of works in the construction of urban underground structures largely depends on a whole complex of interrelated factors. The depth of the structure is of the greatest importance. So, when building utility tunnels at a depth exceeding 6-7 m, from an economic point of view, it is advisable to switch to closed tunneling methods using tunneling shields. At the same time, with increasing depth, the probability of drilling in unfavorable hydrogeological conditions sharply increases. For example, below are the averaged results of the analysis of hydrogeological conditions for the city of Moscow, from which it can be seen that, starting from a depth of 20 m, the construction of underground facilities is carried out, as a rule, in flooded soils.

Deep - Unstable soils (sandy), % Stable soils (clayey), %

watered non-watered watered non-watered

10 28 28,25 20 23,75

15 52,5 14,5 20,25 6,75

20 61,37 3,29 33,6 1,8

Analyzing the hydrogeological conditions of underground construction in other large cities of Russia, it can be stated that in about 20% of cases underground structures are being built or will be built in difficult mining and geological conditions, characterized by unstable soils with low filtration coefficients, often with pressure groundwater.

In Moscow, such conditions account for approximately 24% of the total volume of underground construction. Under these conditions, the construction of underground structures requires the use of special methods of work.

In recent years, due to the intensive introduction of modern shields and micro-panel complexes, builders increasingly began to say that with their introduction, the role and importance of special methods in urban underground construction is not as acute as it was before. Indeed, over the past 10 years, shields with hydraulic and soil loads, micro-panel complexes, punching installations have been introduced into the practice of building tunnels for various purposes, with the help of which it is possible to build underground facilities in the most difficult hydrogeological conditions with a water pressure of up to 40 m. All this is true. But the use of modern shield complexes requires a large amount of preparatory work for the construction of shafts, chambers, technological waste, which is almost impossible to perform without the use of special methods. Thus, with the use of modern panel complexes, it is possible to build tunnels at a speed of 70-200 meters per month. But due to preparatory and final drilling operations, the speed advantages of such complexes are lost, especially if the tunnels are of short length, which, by the way, is typical for urban underground construction, where the length of utility tunnels from assembly to dismantling chambers ranges from 30 to 150 meters.

Very often there are problems associated with the sinking of failures between tunnels during the construction of transport tunnels. The tunnels themselves pass without any problems at sufficiently high speeds, and the time spent on sinking failures in difficult hydrogeological conditions sometimes exceeds the time spent on tunneling.

Let us dwell on the analysis of the most used special methods in urban underground construction. It should be noted that a special method of construction means the implementation of an additional set of measures, impacts that are carried out in advance of the start of mining operations in non-cohesive, weakly stable aquifers or in strong fractured and aquiferous rocks. Such activities

allow you to create safe, comfortable conditions for excavation of rock and the construction of temporary or permanent lining without violating the integrity of the surrounding massif and affecting underground utilities that fall into the construction zone.

Depending on the nature of the impact on aquifers, the duration of the measures, as well as the type of equipment used to perform the work, special methods in urban underground construction can be divided into three groups, providing:

the use of temporary or permanent fencing supports without changing the physical and mechanical properties of the host rocks;

temporary change in the physical and mechanical properties of rocks for the period of work on the construction of an underground structure

fixing of rocks for the period of construction and operation of an underground structure.

Let's consider them in more detail.

Special methods for the construction of urban underground structures with the use of temporary or permanent fencing without changing the physical and mechanical properties of the host rocks.

When using special methods of the first group, before the start of mining and construction work, a protective lining is erected along the contour of the future underground structure, under the protection of which excavation is carried out in the future, and sometimes the erection of a permanent lining.

Depending on the material and design, the fencing supports can be made of: individual sheet pile elements immersed in the ground to the estimated depth (sheet piling); from closed monolithic or prefabricated shells, made of a material with sufficient strength, they are immersed under the action of their own weight as the soil inside the shell is developed (lowering supports); from monolithic or prefabricated reinforced concrete in narrow trenches, torn off along the perimeter of an underground structure to its entire depth, as a rule, to an aquiclude (wall in the ground).

Of the listed special methods of the first group, the wall in the ground in various technological designs finds the greatest application in the practice of urban construction.

The construction of underground structures using the wall-in-soil method consists in the fact that, first, a trench 0.4-1.5 m wide is torn off along the contour to the entire depth of the structure. . A thixotropic clay solution, having a low viscosity and high claying ability, penetrates into the soil and clogs the walls of the trench, forming a thin (0.5-30 mm) and rather dense and durable crust on their surface. The presence of such a clay cake prevents excessive filtration of the clay solution into the soil massif and keeps the trench wall from collapsing. The clay cake is also a kind of screen that ensures the transfer of static and dynamic pressure of the clay solution to the ground. For the stability of the trench walls, it is necessary that the pressure of the clay solution exceed the pressure of the soil and water. From this condition, the required density of the clay solution is found, which usually ranges from 1.05-1.2 g/cm3. After excavating the trench to the design depth, the clay solution is replaced with permanent lining. Under the protection of the erected walls, in the future, the development of the soil inside the structure is carried out.

Permanent support along the contour of an underground structure with this method can be made of monolithic reinforced concrete or precast concrete. In recent years, the construction of the wall in the ground around the perimeter is often made of piles joined together (secant piles).

As experience has shown, the use of the wall-in-soil method is most effective in difficult hydrogeological conditions in the presence of a high level of groundwater and an aquiclude at a practically achievable depth.

The currently used equipment makes it possible to erect walls in the ground up to a depth of 70 m. In Russia, a wall in the ground was erected to a maximum depth of 38 m. As experience has shown, with a wall depth in the ground of less than 8 m, the use of the method usually does not provide significant technical and economic advantages and does not occur in construction practice. When determining the depth of the wall in the ground, one should take into account the need for its deepening into the aquiclude. The depth value is taken equal to: in dense

rock 0.5-1 m, in marl and dense clay 0.75-1.5 m, in plastic loam and clay 1.5-2 m.

The use of a wall in the ground is limited in the presence of soils containing solid inclusions of natural or man-made origin (large boulders, fragments of concrete structures, masonry, etc.). In such cases, when developing a trench, it is necessary to use equipment equipped with milling equipment, for example, Casagrande, Bauer, TONE Boring.

The use of clamshell equipment, which removes large inclusions, can lead to deformation of the trench wall, a drop in the level of thixotropic mortar and deformations of the surrounding massif and nearby buildings.

The use of the considered method is difficult in the presence of flowing silts, quicksand, occurring near the surface of the earth.

It is difficult to apply the method in soils with high filtration coefficients (high speeds of groundwater movement), in which there are large leakages of the clay solution, excluding the possibility of screen formation on the walls of the trench. Difficulties also arise in the presence of pressure water with a pressure exceeding the hydraulic pressure in the trench, as a result of which the trench works like a drain.

Assessing the method under consideration, it should be noted that with the right technology for its implementation, it most fully meets the requirements for safe construction in dense urban areas. With its help, you can build underground facilities in the immediate vicinity of buildings, structures and underground utilities. In principle, a wall in the ground can be erected at a distance exceeding 0.4 m from existing buildings and structures, preventing deformations and displacement of soils to a depth of 60 m.

An analysis of the production experience of using a wall in the ground in Russia shows that, due to non-compliance with the technical regulations for construction, objects built using the method in question, in most cases, had serious defects.

The most common defect is the inconsistency of individual gates (piles) in depth. So, during the construction of a wall in the ground, no depth exceeding 18 m, in 90% of cases, the structures had inconsistencies in depth and, as a result, water leaks, followed by

soil removal. The reason for this situation is the lack in some cases of modern technical means of controlling the verticality in the process of excavation of soil from trenches, the failure to take into account real hydrogeological conditions during the construction process, low qualifications and performing discipline.

The weak point of the wall in the ground are the joints, especially non-working ones, formed using pipes. Such joints do not hold water well and are a source of soil removal into the structure as it is erected. True, in recent years, to reduce the flow of water through the seams, special seam structures and materials (stopsol, waterstop, etc.)

Problems often arise when excavating soil from inside the structure. Due to poor-quality fastening of structures, unacceptable deformations occur, and sometimes their stability is lost.

To ensure the stability of the walls in the ground with a pit depth of more than 4-6 m, it is necessary to use their fastening with expansion or anchor structures.

The advantages of spacer systems over anchor systems include the following: their installation is simpler, cheaper and does not require special technology and special equipment, they can be reused. Therefore, where possible, spacer systems should be preferred.

The use of anchor fastening of the enclosing structures of pits instead of spacer systems in many cases provides a number of technical and economic advantages, the most important of which are:

There are no restrictions on the width of the pit;

The front of soil development in the pit is expanding with construction equipment;

There are no interferences during the installation of structures of the structure;

There is no need to relocate spacer elements;

The use, where possible, of one-sided fastening of the excavation fence;

A significant technical and economic effect is achieved in subsequent technological operations for the construction of an underground structure (earthworks, installation of building structures), which ensures a significant reduction in construction time.

Anchors can be installed in all soils, except for weak ones (fluid clays, silts, peaty soils and peat, subsiding soils).

In those cases, where possible, it is advisable to strive to abandon the fastening of the excavation fence with temporary spacer structures or anchor fastenings and switch to “top-down” and “up-down” underground structures construction methods, in which interfloor floors. The development of soil in the pit in this case is carried out under the protection of floors and is carried out by small-sized excavators and conventional bulldozers. The issuance of soil - with the help of a clamshell excavator through the mounting holes in the ceilings.

These construction methods are the most sparing in relation to the nearby existing buildings, providing minimal settlements of existing buildings and structures in comparison with other methods of fixing pits.

The up-down construction method involves the construction of buildings with several underground floors by simultaneously constructing floors up and down from the ground level with a wall-in-soil excavation enclosure, which often serves as the wall of the underground part of the building. Construction according to the "up-down" scheme begins with the installation of trench "walls in the ground" along the perimeter of the structure and intermediate drilling supports (columns). Trench walls and drill strings serve as supports for future topside structures. Then the open excavation of the soil begins on the first underground tier, and in parallel with the grips, a ceiling is erected above the first floor (at ground level). When the concrete floor reaches 75% strength at ground level, a tower crane is permanently installed on it in a specially reinforced zone. When the floor concrete reaches 100% strength, the construction of the structures of the ground floors begins and, at the same time, the construction of the second and subsequent underground floors is carried out.

The second in the group in terms of volumes of application in urban underground construction is the method of construction using sheet piles. The method has long been proven, and consists in the fact that before the start of excavation along the contour of the future underground structure, a temporary sheet piling consisting of separate sheet pile elements is immersed tightly to each other to the full thickness of unstable soils. A set of sheet piles driven around the entire perimeter of an underground structure is called a settlement. The sheet piling must be waterproof, durable and not deform when immersed; should be buried in the aquiclude at least 1-1.5 m and protrude 1-2 m above the aquifer.

It is advisable to use sheet piling under the following conditions: the thickness of unstable soils is from 5 to 12 m; the depth of unstable soils is not more than 20 m from the surface; the presence of an aquiclude with a thickness of at least 3 m below unstable soils; the absence in the geological section of boulders and solid inclusions more than 20 cm in diameter; groundwater pressure up to 12 m.

An analysis of the experience in the construction of urban underground structures shows that sheet piling has been successfully used for many years in the construction of chambers for underground utilities, mine shafts, pumping stations, shallow subway tunnels and other underground structures near buildings, underground utilities.

The disadvantage of the technology of building underground facilities using sheet piling is that mechanical hammers are often used to drive sheet piles, which adversely affect nearby buildings and structures. To eliminate this shortcoming, in recent years, sheet piles have been immersed using vibratory hammers. It is obvious that in the coming years sheet piling, due to its simplicity and reliability, will not lose its attractiveness and will be used in urban underground construction for many years to come.

A construction technology that has been successfully used for decades and belongs to the first group of special methods is the construction of urban underground facilities using the lowering method.

The construction of underground facilities by the lowering method consists in the fact that on the site prepared for construction, the walls (structure) of the future underground structure are initially erected, which are equipped with a cutting shoe in the lower part. Subsequently, soil is removed in the inner contour of the underground structure. As the soil is excavated, the structure of the future underground facility is immersed in the array until it reaches the design depth.

Such a method in the technical literature is often called the method of a sinking well or submersible support, depending on the type and purpose of the structure being built.

According to their purpose, drop structures can be divided into two types: drop wells for the installation of critical buildings and structures and drop underground structures for placing process equipment and service premises (water intake and sewer pumping stations, warehouses and storage facilities for various purposes). The dimensions of the sinkholes are usually small - up to 4 m in diameter. The diving depth reaches 130 m.

Lowering underground structures in shape are made round or rectangular in large sizes up to 60 m in diameter and up to 250x50 m in plan. However, the depth of immersion of such underground structures does not exceed 60 m.

The drop method in urban underground construction is used quite often. To expand the scope of its application, the lowering of underground structures is mostly carried out in the so-called thixotropic jacket. The essence of the lowering method in a thixotropic jacket is the use of a thixotropic clay solution, which is used to fill the cavity between the outer surface of the structure and the ground, which significantly reduces lateral friction and ensures the stability of the soil walls. A cavity 10-15 cm wide, which is filled with a clay solution, is created due to a protrusion on the knife part of the lowering structure.

It should be noted that in recent years the lowering method has been gradually replaced by other special methods and, in particular, by a wall in the ground. Despite this, the lowering method, due to its simplicity, low cost, reliability and a large amount of work experience, will be used for many years to come in the construction of urban underground facilities in dense urban areas.

Special methods in which a temporary change in the physical and mechanical properties of rocks is carried out for the period of work on the construction of an underground structure

Special methods for the construction of urban underground structures with temporarily changing properties include: artificial freezing of rocks; dewatering; tunneling under compressed air (caisson).

Artificial freezing of rocks

The method consists in the fact that prior to the start of mining and construction works along the contour of the underground structure, a system of wells equipped with freezing columns is drilled every 0.8-2 m. A refrigerant (usually an aqueous solution of calcium chloride) is pumped through the freezing wells with negative temperatures (brine freezing).

As a result of the constant circulation of the coolant in the freezing columns, the water in the rock freezes and ice-rock cylinders gradually form around each column, which later merge into a single ice-rock enclosure. As a result of the transition of water into ice and a decrease in temperature, frozen rocks sharply change their original physical and mechanical properties (strength, adhesion, etc.), which makes it possible to start mining operations when the ice wall reaches the design dimensions.

In this case, the ice barrier plays the role of a temporary watertight enclosing lining, providing safe conditions for the production of mining and construction works.

The ice barrier is kept frozen until the construction of the underground structure is completed. After the construction of the structure, the ice-rock barrier is eliminated.

In addition to brine freezing, non-brine methods are also used in the practice of urban underground construction (freezing with liquid nitrogen, freezing with the use of solid carbon dioxide).

It should be noted that the method of freezing rocks is one of the leading special methods in world practice.

The method was widely used in Germany, Japan, Poland, Canada, Great Britain and other countries.

The method of freezing rocks is universal. It is successfully used for sinking shafts in both fractured and loose aquifers under conditions of groundwater filtration. Freezing can be carried out at almost any depth. The method of freezing still remains the most reliable and universal special method both in dense urban areas and in mining industries.

Artificial freezing of soils has become widespread due to the fact that this method is quite well developed technically. Powerful drilling equipment, high-performance stationary and mobile freezing stations have been created. The freezing method also has a good scientific basis. Theoretical and experimental studies have been carried out on the study of non-stationary heat transfer processes in a rock mass, freezing columns, refrigeration equipment, solid data on the thermal and mechanical properties of frozen rocks have been accumulated, engineering methods for calculating the design of ice barriers and refrigeration equipment have been developed. Resource-saving, machine-free technologies for soil freezing using solid carbon dioxide (dry ice) as a refrigerant are proposed.

In order to further improve the method, a new design and installation technology for screw-free freezing columns was proposed and justified at Moscow State Mining University. This technology is indispensable for freezing soils at shallow depths (up to 25 m), as well as for freezing soils between transport tunnels, since it does not involve drilling and installation of freezing wells, which leads to a sharp acceleration of installation work, a decrease in the metal intensity of the method, reducing the time and, as a result, the cost of freezing.

Despite the above, over the past 10 years, the volume of construction of underground structures using the freezing method has unreasonably sharply decreased. There are several reasons for this situation.

Firstly, it is believed that the method is very expensive, although serious studies on this subject comparing the technical and economic

nomic indicators with other alternative methods were not carried out.

Secondly, in recent years, in the practice of urban construction, when excavating shafts, chambers and other objects that require the use of a temporary waterproofing curtain, where artificial freezing of soils can be reliably and successfully used, massive enclosing structures (a wall in the ground in various designs, jet grouting, lowering support). Their presence in soils in most cases leads to a violation of the hydrogeological regime of groundwater movement, the occurrence of barrage effects and other negative consequences.

When artificial freezing is used, after the excavation of the working and the freezing station is turned off, the soil massif is thawed naturally in 2-4 months or artificially within 1-1.5 months, and the natural hydrogeological situation is restored in the work area.

Thirdly, one of the reasons for the decrease in freezing volumes is the lack of mobile mobile stations. The existing park of PHS-100 stations is physically and morally obsolete and needs to be replaced with more modern refrigeration units.

The Moscow State Mining University (MGGU) is continuously working on improving the freezing method and making it cheaper. In recent years, new resource-saving freezing methods have been substantiated and developed and successfully tested in relation to urban conditions using solid carbon dioxide, which make it possible to abandon freezing stations and create ice-ground enclosures of design dimensions in 5-10 days instead of 30-70 days with brine freezing

At present, research work is underway at Moscow State University for the further improvement of the brine-free freezing method. Combined freezing methods have been substantiated and developed, in which the coolant can be cooled by solid carbon dioxide to temperatures from -20 to -60 degrees in special evaporators. This method allows you to create design dimensions in a short time (5-10 days)

ice-ground fencing with a sharp reduction in material, energy and cost costs compared to the traditionally used brine method.

The second direction of research is the search for reserves to reduce material and cost costs during freezing of soils by improving the processes of drilling and installation of freezing columns and the time of formation of an ice-soil fence of design dimensions, each of which takes from 35 to 40% of the total freezing time.

The conducted studies have shown that resource saving and intensification of the process of soil freezing in urban conditions can be achieved by switching, where it is technically possible, to the design of freezing columns of a new type with screw winding of reinforcement around its perimeter for the entire length, excluding the use of drilling operations during its installation. . Pilot experiments have shown that the proposed design of the column of a new type is efficient, allows them to be screwed to a predetermined depth.

The application of the results of the studies performed contributes to the further improvement of the technology of artificial freezing of soils in urban conditions and will reduce material and cost costs.

Dewatering

Dewatering is used for temporary (for the period of construction) reduction of hydrostatic pressure (levels) of groundwater in order to create more favorable and safe conditions for mining and construction work.

The task of dewatering is to appropriately create and maintain the required zone of drained soils for the period of construction of an underground structure, which makes it possible to carry out mining operations in relatively favorable conditions.

The choice of the dewatering method depends on: the properties and conditions of the soil occurrence, groundwater supply conditions, water permeability (filtration coefficient) of the drained soils, the size of the drained zone in the soils, the thickness of the aquifer, the characteristics of the technical means of dewatering.

The most widely used surface method of dewatering. However, depending on the type and location

dewatering devices use a linear dewatering scheme - dewatering devices are arranged in a row in a straight line; contour - when they are located along the contour enveloping the structure; ring, when the contour of the location of water-reducing devices is closed; longline - when water-reducing devices are located on several ledges along the depth of the pit.

Depending on the method of dewatering, the following technical means are used. For shallow surface and underground dewatering, light wellpoints (PIU), ejector wellpoints (EI), vacuum (UVV) and downhole dewatering (UZVM) installations are used. For deep surface dewatering, dewatering and water-absorbing wells and powerful pumps are used. For an approximate choice of means of dewatering, table is recommended. one.

The method of dewatering is by far the most common special method for the construction of urban underground structures due to its simplicity, efficiency, extensive application experience and low cost compared to other special methods.

In recent years, an opinion has not been justified about the catastrophic consequences of artificial dewatering, which causes additional soil precipitation and the associated deformations of adjacent buildings. To avoid the problem associated with the possible consequences of sedimentation from dewatering, it seems to many designers only if the enclosing structure is built to the full thickness of the aquifer, which is completely wrong. This situation is caused by the fact that at present there are no reliable theoretical studies of the effect of the process of dewatering on the precipitation of the earth's surface due to the complexity of describing the processes occurring in the massif during dehydration. Computer modeling methods are still used in limited volumes and are not available to many designers.

An analysis of the experience of dewatering in urban conditions shows that precipitation of the earth's surface during its implementation does occur, as a rule, smoothly over the area and their magnitude depends mainly on: filter design, depth and time

Soils Filtration coefficient Kf, m/day Value of groundwater level decrease, m

up to 5 up to 20 over 20

Sandy loam, silty sands 0.2-0.7 Installations EVVU, UVV, LIU, EI Longline installations, LIU, EI, EVVU Wells with submersible pumps and additional vacuuming

Sands: fine medium coarse 1-10 10-25 25-50 Light wellpoints

Single-tier Multi-tier, ejector wellpoints The same

Coarse sands, gravel-sheets Gravel soil More than 50 Pumping water from a well with centrifugal pumps Pumping water from a well with submersible pumps The same

Multi-layered strata of rocks of different permeability 0.005-200 Determined depending on specific geological and hydrogeological conditions

dewatering. The time and depth of dewatering have the greatest influence on surface precipitation.

For example, at depths of dewatering of more than 10 m by dewatering wells for a month or more, the amount of sediment can reach 50-70 mm, and when dewatering by vacuum installations for 10-20 days, precipitation sometimes does not appear at all or fluctuates within 1-5 mm and only with their long-term use (50-70 days) can precipitation reach 10-15 mm.

In this regard, in the most critical cases, when water drawdown is carried out in conditions of dense urban development, in order to predict possible precipitation, it is necessary to carry out computer modeling taking into account hydrogeological conditions, work technology and the duration of the water drawdown process.

Special methods in which the fixing of rock pores is carried out for the period of construction and operation of a semi-ground structure

The most common special methods of this group used in urban underground construction include: rock cementing, soil silicification, chemical fixing, jet grouting (sometimes called jet grouting).

Cementation. The essence of cementation lies in the fact that before the start of mining and construction work, wells are drilled along the perimeter of the structure, and sometimes throughout its entire area, and cement mortar is injected into them under pressure. The solution, spreading to a certain distance from the well, fills the voids and cracks in the rocks. After the solution hardens, the water resistance of the rock mass is significantly reduced, which makes it possible to build underground structures inside the fixed rocks in the absence or with a slight influx of water into the face.

Cementation should be used: in strong fractured rocks with a crack size of at least 0.1 mm, a specific water absorption of more than 0.05 l / s and a groundwater flow rate of less than 600 m / day; in gravel-pebble rocks with a grain size of more than 2 mm, provided that the pores between the grains are free from clay or sand particles; in coarse-grained sands with a grain diameter of more than 0.8 mm.

Here I would like to draw attention to the conditions for the use of cementation. The fact is that in practice, when performing construction work, cement mortars are often injected into the soil, not paying attention to their granulometric composition. In this case, the method in any soil conditions is called cementation. In the event that the cement mortar is injected into finely dispersed soils with a particle diameter of less than 0.8 mm, the solidity of the fixed array will not work and water will flow through the treated array during mining operations. In this situation, when the cement mortar is injected into finely dispersed soil due to the pressure of the mortar, the massif is hydraulically fractured, artificial cracks are formed, along which the mortar sometimes flows for considerable distances from the place of work. In this case, it is wrong to talk about strengthening the array. In the best case, there is a partial compaction of the soil. If work is carried out near existing communications (operating sewers, drainage systems, basements, etc.), then as a result of such work, cement mortar can penetrate into them and disable or damage them.

To expand the area of ​​effective use of cementation in fine soils, it is necessary to switch to the use of cements of finer grinding or special colloidal cements (such as Microdur).

Silicization and chemical fixation of soils

Silicization is based on the injection of inorganic high molecular weight compounds of silicate solutions of liquid glass and their derivatives into the soil mass, which, in combination with a coagulant, form a silicic acid gel that cements the soil particles. In the practice of urban underground construction, two-solution and one-solution methods of silicification are used.

In the two-solution method of silicification through perforated pipes (injectors) immersed in the soil to a given depth, solutions of sodium silicate and co-agulant_calcium chloride are pumped in turn. The silicic acid gel formed as a result of mixing solutions gives the soil strength and water resistance. The two-solution silicification method is used to strengthen sands with a filtration coefficient

2-8 m/day, in which the speed of groundwater movement is less than 5 m/day, and the pH of groundwater is less than 9.

With a one-solution method of silicification, one gel-forming solution is pumped into the soil, prepared from a mixture of sodium silicate with a coagulant (monophosphoric, hydrofluorosilicic acids or sodium aluminate). When these solutions are mixed, the formation of a silicic acid gel occurs at a given time, depending on the amount of coagulant. The soil fixed on the basis of sodium silicate and fluorosilicic acid has a compressive strength of 2-5 MPa. The one-solution silicification method is used to fix sandy soils with a filtration coefficient from 0.5 to 50 m/day. Groundwater movement speed is not more than 8 m/day, groundwater pH is less than 7.

Analyzing the experience of applying the silicification method, it should be noted that the method is constantly being improved and is increasingly used in the practice of urban underground construction. There are several reasons for this situation: the simplicity of the technology, the availability and cheapness of consumables, and complete environmental safety. Given these advantages, the silicification method will be in demand in urban underground construction for many years to come.

During the chemical fixation of rocks (tarring), aqueous solutions of high-molecular organic compounds (resins) with the addition of coagulants (oxalic, hydrochloric acids) are injected into the massif. As a result of chemical reactions occurring in the rock mass, resins pass from a liquid to a solid state. As a result, the rocks are hardened, their water resistance decreases and strength increases, which creates favorable conditions for mining operations.

The resinization method can be used in fractured hard rocks, separate-grained and even porous rocks with a filtration coefficient from 0.5 to 50 m/day, while the minimum particle size of a non-cohesive mass is 0.01-0.05 mm.

Quite a few chemical solutions for fixing soils were produced and tested in Russia, but urea-formaldehyde (carbamide) resin with various hardeners turned out to be the most acceptable by all criteria. This resin is easily soluble in water, has a low viscosity, and cures at a low temperature.

tour, and most importantly, it is produced by the domestic industry in large volumes and, at its price, is quite affordable for wide use. The disadvantage of this resin is some toxicity due to the release of free formaldehyde at the time of the development of a fixed array, so its use is justified where there are no people during the operation of an underground structure.

In foreign practice, resins of various compositions and properties, including polyurethane foam, are also used to fix soils. In the practice of urban underground construction, such resins are used in extremely limited volumes due to their high cost. In somewhat large volumes, resins from foreign companies are used in the practice of repairing underground structures.

Summarizing the existing experience of chemical fixing, it should be noted that resinization is used in various areas of construction, including in the practice of urban underground construction. However, the volumes of application of the method are still gradually falling and today, despite the effectiveness of the method, they are episodic. This is due to the fact that the resins produced by the domestic industry do not fully meet environmental requirements, and foreign formulations sold on the market are expensive.

Jet grouting

Jet grouting technology has been used in Russia relatively recently (the experience of its application is less than 10 years) and is based on the use of the energy of a high-pressure jet of cement mortar for destruction and simultaneous mixing of soil with cement mortar. After hardening of the solution, a new material is formed - soil cement, which has sufficient strength and deformation characteristics for mining and construction work.

There are three main types of technology.

Single component technology (jet 1). In this case, the destruction of the soil is carried out with a jet of cement mortar. The injection pressure of the solution is 40-60 MPa. In the process of erosion of the soil, it is mixed with the cement mortar. After hardening, a new material is formed - soil cement, which, compared with the original soil, has increased strength,

deformation and impervious characteristics. The jet 1 technology is the simplest in execution, requires a minimum set of equipment, however, the diameter of the resulting columns is also the smallest in comparison with other technology options. So, for example, in clays, the diameter of the columns does not exceed 0.6 m, in loams and sandy loams it is 0.7-0.8 m, in sands it reaches 1.0 m.

Two-component technology (jet 2). In this embodiment, compressed air energy is used to increase the length of the water-cement jet. For separate supply of cement mortar and compressed air to the monitor, double concentric hollow rods are used. Cement mortar is supplied through the inner rods, and compressed air is supplied through the outer rods. The monitor also has a more complex design, including a nozzle for water-cement mortar and an additional annular nozzle for forming an air jacket surrounding the main jet.

The air jacket that protects the water-cement jet sharply reduces the resistance of the environment along the side surface of the jet and thereby increases its destructive effect. The injection pressure of the cement slurry corresponds to jet 1 technology. The air pressure should be at least 0.5 MPa, the flow rate is 7-10 m/h.

The diameter of the columns obtained by this technology reaches 1.2 m in clays, 1.5 m in loams and sandy loams, and 2.0 m in sandy soil.

Three-component technology (jet 3). This option differs from the previous ones in that the water-air jet is used exclusively for soil erosion and the formation of cavities in it, which are subsequently filled with cement mortar. The advantage of this option is to obtain columns from pure cement mortar. The disadvantages include the complexity of the technological scheme, which requires the use of triple rods for separate supply of water, compressed air and cement mortar, as well as additional technological equipment - a compressor and a grouting pump.

In table. 2 shows the main technological parameters of the considered varieties of jet grouting technology. For all considered variants of jet grouting, the cement consumption varies in the range of 350-700 kg/m3.

Compared to traditional injection soil stabilization technologies, jet grouting makes it possible to strengthen almost the entire range of soils - from gravel deposits to fine clays and silts.

The technology of jet grouting of soils has an extremely wide area of ​​practical application, primarily in urban underground construction in the construction of motor transport and utility tunnels, chambers, pits and other underground structures of various purposes. The technology allows you to work in cramped conditions - in basements, near existing buildings, on slopes, etc. In this case, only a small-sized drilling rig is installed at the facility, and the entire injection complex is located at a more convenient remote site.

The method is widely used in solving problems associated with the installation of piles, but not so much in the field of new construction, but in the reconstruction of existing buildings, as well as in the repair of emergency foundations.

The technology of jet grouting has proven itself very successfully in the construction of impervious curtains. Moreover, unlike the field of installation of vertical curtains, where the technology of jet grouting of soils competes with other technologies of underground construction, in the field of installation of horizontal curtains, this technology is practically a “monopoly”, allowing you to create a layer of artificial aquiclude in the bottoms of pits with high reliability.

An important advantage of the technology is the absence of shock loads during the production process. It is this advantage that makes the technology indispensable in conditions of dense urban development, when it is necessary to perform work without negative impact on the foundations of closely located buildings and structures.

It should be noted that the jet grouting used in Russia, in terms of a number of its characteristics, differs significantly from the technology widely used in many industrialized countries by many construction companies. This is explained by the economic and historical specifics of Russia's development. Taking into account the indicated objective circumstances, the experience of using

table 2

The main parameters of the technology of jet grouting of soils

Technology Options Option

№ 1 № 2 № 3

Pressure Water MPa PRG PRG 300-500

Cement mortar MPa 400-600 400-600 40-60

Compressed air MPa not used 8-12 8-12

Water l/min PRG PRG 70-100

Consumption Cement slurry l/min 60-150 100-150 150-250

Compressed air M3/h not used 6-18 6-18

Number of nozzles Water pcs. PWG(1) PWG(1) 1-2

Cement mortar pcs. 2-6 1-2 1

Nozzle diameter Water mm PRG PRG

(1,6-2,4) (1,6-2,4) 1,8-2,5

Cement mortar mm 1.6-3.0 2.0-4.0 3.5-6.0

Monitor rotation speed rpm 10-30 10-30 10-30

Time to raise the monitor by 4 cm s 8-15 10-20 15-25

Column diameter Sandy soil m 0.6-1.0 1.0-2.0 1.5-2.5

Clay soil m 0.5-1.0 1.0-1.5 1.0-2.0

Note. PRG - preliminary erosion of the soil.

of foreign imported equipment and technologies by Russian specialists is still limited and, apparently, has limited prospects for expansion in the foreseeable future. In this regard, given the prospects of the method, scientific and design organizations need to make every effort to further improve the method in terms of testing the technology parameters and developing cheaper domestic equipment.

BIBLIOGRAPHY

1. Shuplik M.N., Plokhikh V.A., Nikiforov K.P., Kiselev V.N. Perspective technologies of soil freezing in underground construction // Underground space of the world. - 2001. - No. 4. - S. 28-40.

2. Shuplik M.N., Korchak A.V., Nikitushkin A.V., Nikitushkin P.A. A device for freezing soils in the construction of underground structures. Utility model patent No. 84869 dated March 17, 2009.

3. 3. Broid I.I. Jet geotechnology. - M.: Publishing House of the Association of Construction Universities, 2004. - 448 p.

4. 4. Malinin A.G. Jet grouting of soils. - Perm: Presstime, 2007. - 168 p. ESH

Shuplik Mikhail Nikolaevich - Doctor of Technical Sciences, Professor of the Department of Construction of Underground Structures and Mines, Moscow State Mining University, [email protected]

5. Urban underground structures of shallow construction, erected by a closed method Introduction

Structures and technologies for the construction of urban shallow underground structures (multi-purpose complexes, underground garages and parking lots, communication tunnels, pedestrian crossings) must meet the following basic requirements:

Ensure the stability of the walls of workings in the process of sinking and operation of the structure;

Perceive loads and impacts from rock pressure or the thickness of the overlying soil and land transport;

Ensure the waterproofing of linings or their waterproofing;

Provide mechanized excavation and construction of lining;

Ensure that disruptions to surface conditions for vehicular and pedestrian traffic are minimized;

Exclude, if possible, the use of dewatering, which can cause sedimentation of the soil surface, ground and underground facilities;

Ensure the safety of the surrounding mountain range and closely located ground and underground facilities;

Ensure high penetration rates, reduce material consumption, labor intensity and construction time;

Ensure compliance with environmental, health and fire regulations.

The construction of shallow underground structures should be based on the use of industrial technologies using modern tunneling equipment, monolithic or prefabricated reinforced concrete lining structures, comprehensive mechanization of all major processes and specialization of certain types of work, and the introduction of new building materials into the production of works.

At the same time, the entire complex of the underground structure should be built in unified design and technological solutions, mutually linked to each other.

5.1. Mining methods of work

5.1.2. The existing main methods of performing work on the construction of a mine working can be divided into three groups:

The first group includes methods in which the section of the working is completely freed from the rock, using options for a fully open section (flow and annular options), continuous slaughter, stepped slaughter, central adit, underwater section, lower and upper ledges, after which in the development of a full section build walls and vault lining;

The second group includes methods when the calotte is first opened and fixed, in which a vault is erected, based directly on the rock, using two-barrel, one-barrel and advanced calotte penetration options);

In the third group of methods, the walls of the lining are built in adits, after which the calotte is opened, in which a vault is erected, based on the walls (support core method).

5.1.3. Ways of sinking workings and means of mechanization are determined depending on the purpose of the structure, the size and shape of the cross section, engineering and geological conditions, etc., based on the results of a technical and economic comparison of options.

5.1.4. Prior to the start of the main work on the construction of workings, if necessary, it is necessary to carry out the sinking of the advanced adit within the entire section to ensure the drainage of the workings and the drainage of groundwater by gravity, improve its ventilation, organize transport links between the portal sites and clarify engineering and geological conditions.

5.1.5. The continuous slaughter method should be used for driving workings up to 10 m high with a monolithic lining in rocky soils with a strength factor according to Protodyakonov of at least 4. At the same time, temporary fastening of the workings when driving in rocky (unweathered) soils with a strength factor of 12 or more is not required, and when driving rocky weathered and highly fractured soils, the use of temporary lining is mandatory.

5.1.6. The bench method should be used for driving workings with a height of more than 10 m, constructed in rocky soils with a hardness factor of at least 4, and for driving workings with a height of less than 10 m in rocky soils with a hardness factor of 2 to 4. The driving of workings should be carried out mainly with a lower ledge.

5.1.7. The supported vault method can be used in the construction of workings or their sections up to 300 m long in dispersed soils such as hard clays and loams, in cemented coarse and other soils, as well as in rocky soils with a strength factor of 1 to 4, capable of absorbing pressure from the heels of the vault lining, taking into account all the loads acting on the arch. When constructing workings in non-watered soils, the supported vault method should be used mainly according to a single shaft scheme. Workings in water-saturated soils should be built according to a two-barrel scheme.

The upper and lower adits must be connected to each other by dredgers (furnels), as well as inclined posts (bremsbergs).

When driving tunnels by the method of a supported vault, the opening of the calottes should be carried out in separate sections (rings), the length of which is determined depending on the engineering and geological conditions and should not exceed 6.5 m.

5.1.8. The support core method should be used in the construction of workings or their sections up to 300 m long in non-saturated clay soils that are not able to perceive pressure from the lining arch. In this case, the walls are erected in adits, after which the calotte is opened, in which a vault is erected, based on the walls.

When constructing tunnels with a cross section of more than 40 m 2, preliminary driving along the axis of the development of the lower transport adit is allowed.

Side adits for erecting walls during excavation should, if possible, be developed for the entire length of the excavation section being constructed.

5.1.9. The development of soil in the face, depending on engineering and geological conditions, cross-sectional dimensions and the accepted method of penetration, is carried out in the following ways:

When sinking with a continuous face - by drilling and blasting using drilling equipment and soil cleaning with rock-loading machines or excavators;

When sinking by a bench method - the upper ledge by drilling and blasting using self-propelled drilling rigs or mining machines, and the lower ledge - by drilling and blasting using self-propelled drilling rigs and cleaning the soil with excavators or rock loaders;

When sinking the workings in parts (using the methods of a supported arch and a supporting core) - in the calotte and side bars - with jackhammers and pneumatic shovels; in the core - by tunnel excavators or by drilling and blasting with soil cleaning by small-sized rock-loading machines.

5.1.10. Recently, work on the development of soil in the face of workings and removal to the surface of the earth is carried out by modern automated and mechanized means.

Roadheaders with mechanized installation of temporary and permanent supports are of great use.

5.1.11. At present, new more efficient methods of soil development are being created and introduced: hydraulic, pneumatic, electrophysical, chemical, etc.

These methods can be applied alone or in combination with mechanical methods.

5.1.12. The choice of means of mechanization should be made on the basis of the conditions for ensuring the in-line process at the lowest cost and duration of construction.

5.1.13. Soil overruns against the design cross-section of a working in rocky soils in cases of developing workings by drilling and blasting without using the contour blasting method should not exceed the values ​​\u200b\u200bspecified in Table. 5.1 .

In dispersed soils, the overburden of soil against the design section during the development of workings by mechanical means should not exceed 50 mm. In the bottom of a working without a reverse vault and when developing a tray for a reverse vault in dispersed soils, soil sorting is not allowed.

Table 5.1

The method of filling the voids formed from the sorting of soil against the design section should be established by the project for the production of works.

5.1.14. Temporary fastening of workings when driving with a continuous face or a ledge method in rocky soils of fractured, strong and medium strength should be carried out using anchor or sprayed concrete lining or combinations thereof.

The use of arch support as a temporary support is allowed during a feasibility study. In these cases, arched and anchor-arched support may be used in fractured rocky soils with a strength factor of up to 8, as well as in areas with tectonic disturbances.

5.1.15. Sprayed concrete should be used as a temporary support when driving in rocky fractured soils that do not show rock pressure. When driving workings in rocky, fractured and weathered soils that exhibit rock pressure, sprayed concrete reinforced with a metal mesh in combination with anchor bolting should be used.

The number of layers of sprayed concrete is set depending on the engineering and geological conditions and the thickness of the sprayed concrete adopted by the project.

5.1.16. Anchor support should be used for temporary fastening of workings for the period of work before the construction of a permanent lining in rocky fractured soils with a strength factor of 4 or more. In this case, reinforced concrete, polymer concrete or metal anchors are used. The use of anchor bolting in weaker soils should be justified by field studies.

When installing anchor lining in frozen soils using reinforced concrete anchors, solutions should be used in which additives that accelerate setting are introduced, or electrical heating is performed to ensure the hardening of the solutions.

5.1.17. The design of anchors, their number and length are determined by the project, depending on the strength and condition of the soil.

A passport should be drawn up for the anchor support, taking into account the engineering and geological features of each section along the length of the working.

5.1.18. Permissible deviations of the actual position of the anchor lining from the design one should not exceed the following values: distance between anchors - ± 10%; hole size - 5 mm; the angle of inclination of the hole is 10°.

5.1.19. Mining methods of work have been improved in different countries.

1) In Japan, tunneling in hard rock is carried out with drilling a system of slots in the bottom. To do this, along the contour of the tunnel working or directly on the surface of the forehead of the face, unloading slots are arranged, which weaken the massif and facilitate its development by explosive means.

It is expedient to use this technology in hard rocks that maintain the stability of leading cracks for the period of the main mining operations included in the technological cycle.

2) In the People's Republic of China, the method of the central adit is used in rocks. With this method, mining operations are performed with a preliminary sinking of the central pilot tunnel, from which fan holes are drilled. In order to increase the degree of stability of the face and avoid blocking the pilot tunnel with blasted rock, it is necessary to create an advance in the lower part of the face, i.e. arrange a kind of upper ledge, which is achieved by a certain sequence of blasting the upper holes. This technology of drilling and blasting has the following advantages:

Possibility of a detailed study of the geological conditions of work;

Acceleration of drilling and blasting operations by conducting them on a wide front of the pilot adit;

Possibility of selective fixation of soils.

This technology, along with the acceleration of the pace of penetration, allows for the evacuation of rock with a decrease in the cost of mining operations.

3) In foreign practice, using the mining method of work, many underground structures have been built (underground garages and parking lots, underground shelters, storage facilities, etc.).

A characteristic example is a tunnel-type underground garage for 1,500 cars built in a mining way in Salzburg (Austria).

Two tunnels with a length of 136 m are located in parallel in the rocks and are interconnected by breakers (Fig. 5.1 ). Each vaulted tunnel with a span of 16 m and a height of 15 m is designed for 4-tier car storage. On each tier with a height of 2.2 m, a two-sided rectangular arrangement of cars is adopted perpendicular to the axis of the passage; the size of the parking lot is 5×2.3 m, the width of the passage is 6 m. Along the ends of the tunnels, spiral ramps with a diameter of 18 m are arranged for the passage of vehicles from tier to tier.

Tunneling was carried out mainly by drilling and blasting, and partially by a tunnel boring machine with a working body of selective action of the AM-50 type with a capacity of 40 m 3 / h. The lining of the tunnels was built from sprayed concrete.

5.1.20. The most progressive method in the construction of underground structures by mining is the New Austrian method of tunneling (NATM).

The NATM technology for fixing a working is to create a special shotcrete support, held by a rod anchor system, constructed with maximum involvement of the enclosing soil mass in the work (Fig. 5.2 ).

According to this method, a two-layer lining of a closed shape is erected. The primary lining is made of sprayed concrete 10 - 20 cm thick and reinforced with steel arches or anchors, and the secondary lining is made of cast concrete or sprayed concrete 25 - 35 cm thick.

In the construction of tunnels using NATM, ribbed linings made of sprayed concrete, reinforced with lattice arches, turn out to be effective. At the same time, instead of expensive rolled, shaped steel, reinforcing elements from welded reinforcing cages of various cross sections are used.

Using NATM allows you to:

To increase the range of application of the mining method of work in difficult engineering and geological conditions, including in soft soils, in which it is difficult to use the traditional mining method of work;

Increase the bearing capacity of the lining without thickening it by installing reinforcing elements (arches, anchors);

Erect underground structures of almost any shape and cross-sectional size;

To carry out the development of the rock both by drilling and blasting and by mechanized methods using excavators and various tunneling machines;

Combine penetration with special methods of strengthening soils by draining, fixing by injection methods, freezing, etc.;

Provide up to 10% reduction in construction costs compared to other methods.

Fig.5.1. Scheme of an underground garage in Salzburg (Austria)

1 - parking tunnel; 2 - entrance ramp; 3 - exit ramp; 4 - parking places; 5 - driveways; 6 - auxiliary workings; dimensions in meters

Rice. 5.2. Comparison of lining designs performed by mining and new Austrian methods

a) mountain method: 1 - wooden puff; 2 - steel arch; 3 - roshpans; (1, 2, 3 - make up a temporary lining located outside the permanent lining); 4 - concrete or reinforced concrete permanent lining; 5 - reverse arch

b) the new Austrian method: 6 - bearing rock-anchor vault; 7 - anchors; 8 - the outer layer of the sprayed concrete lining with a thickness of 5 - 15 cm (together with the anchors serves as a temporary lining); 9 - inner layer of permanent lining of sprayed concrete or concrete with a thickness of 15 - 35 cm

5.1.21. The main requirement in the construction of underground structures using the NATM method is to monitor the behavior of the soil mass, both in the mine working and on the earth's surface. Collection, evaluation, optical and written indication of observational data are carried out using computer technology and using high-precision mathematical apparatus. The main condition for monitoring is the immediate presentation of the measurement results to the construction site management and technical supervision authorities for urgent action.

5.1.22. The HATM method, due to technical and economic advantages, has become standard in the field of underground construction over the past 10 to 15 years.

In many countries of Western Europe, Asia and America, NATM is enriched with various modifications and is used in almost any engineering-geological conditions and at any depth. Special measures for fixing soils make it possible to apply this method in weak water-saturated soils.

When using NATM, tunneling machines began to be used, for example, "Paurat E 242" and a pliable tubing support with rock compression elements of the "Meiso" type.

5.1.23. Below are examples of the use of NATM in world practice.

1) In Vienna and Copenhagen, NATM built shallow subways with the prevention of precipitation in densely populated areas by injecting hardening solutions into the host rocks and with a water draw of up to 10 m.

Combines of selective action of the firms "Noel", "Alpinist Westfalia" allow, with the new Austrian method, to pass tunnels up to 6.5 m high and up to 7.8 m wide.

2) In the United States, in recent years, NATM technology has been largely modified, retaining the basic principles, but adapting it to the conditions of underground construction in North America.

The modified "North American Technology" is characterized by a more intensive use for the development of rock tunneling machines with a boom working body, which have a fairly high productivity and do not require manual labor. In addition, in the United States, additional drainage and injection fixing of weakly stable soils are often arranged.

3) A slightly modified NATM technology is used in Norway. In fractured rocks, it is used in combination with drilling and blasting, and in soft rocks - with mechanized mining. The main feature of the "Norwegian method" is the fastening of the working with dispersed reinforced sprayed concrete, applied by the "wet" method, and anchors.

4) One of the examples of successful implementation of NATM technology for the construction of underground structures is the construction of a three-level underground car park for 345 cars in Landesberg (Germany). Due to the fact that the location of the parking lot is surrounded by architectural monuments and the creation of ground facilities is almost impossible, a closed method of work was adopted.

According to engineering and geological surveys, a 17-meter layer of dense gravel and conglomerate lies on the surface, underlain by a layer of water-resistant clay 3-34 m thick. The groundwater level is located at a depth of 1 m from the earth's surface.

The parking lot is made in the form of an underground working 180 m long, with a span of 18.9 m and a height of 16.4 m (Fig. 5.3 ). The construction of the parking lot was carried out in 6 stages with the development of rock with a backhoe excavator and the fastening of each element of the working (cross-sectional area 20 - 40 m 2) with a layer of sprayed concrete and lattice arches with a step of 0.8 - 1 m. Sprayed concrete was applied along dry technology. The walls of the main working were fixed with 2 layers of sprayed concrete 20 cm thick with two steel meshes. In addition to the main working, a 60-meter walk-through tunnel, 3 lift shafts 30 m deep and an emergency ventilation shaft 37 m deep were built.

Rice. 5.3. Longitudinal section (a) and cross section (b) of an underground car park in Landesberg (Germany)

1 - parking spaces; 2 - lining; 3 - travel; 4 - entry-exit; 5 - emergency exit; (distance in meters)

5) The largest underground sports complex in Norway in the Holmlia region, covering an area of ​​6800 m 2, was built by the mountain method. The main workings of vaulted cross-section, with spans of 15 - 25 m and a height of 8.5 - 13.2 m, were laid at a depth of 16 - 18 m from the earth's surface.

6) An underground complex for a sewage and storm water pumping station was built in Chicago. Vaulted underground workings with a span of 19.2 m, a height of 29.3 m and a length of 83.7 m were constructed by drilling and blasting.

Description of work

The current intensive development of urban underground infrastructure is due to a number of factors. At the present stage of the socio-economic development of mankind, the creation of a favorable environment for life and the sustainable development of cities is largely possible due to the maximum use of the urban potential of underground spaces.

Introduction ………………………………………………………………………….. 3
1. Prerequisites and factors influencing the development of underground space ………………………………………………………….…..…………………….… 5
2. Urban underground structures ………………………………………… 8
Networks of engineering communications ………………………………………….. 11
Transport tunnels …………………………………………………… 12
Pedestrian crossings …………………………………………………… 15
Underground garages ………………………………………………………... 16
Trade and catering enterprises ……………………… 18
Conclusion ……………………………………………………………………. twenty
Literature..…………………………………………………………………… 21
 

Files: 1 file

– industrial and energy facilities

– objects of engineering equipment

In accordance with the conditions of location in the city, the following can be distinguished:

- underground structures located under city streets and squares, high-speed roads, rail transport routes and various kinds of driveways;

- underground structures located under undeveloped areas, including squares and boulevards;

- underground structures and underground parts of buildings located directly under residential, administrative and public buildings or their complexes;

- separate underground structures or parts of structures that are part of developed complexes for engineering and transport purposes, which can be located under city streets, squares and buildings for various purposes.

As the principles of construction and organization of urban underground structures, the author singles out the following: all underground structures should in the future form a single spatio-temporal system; more complex zoning compared to surface buildings, their interconnections in space, the need for communications, taking into account obstacles and topographic and geological conditions, etc.

One of the main problems in the use of urban underground space is that, with a high density of its use, there is a danger that the processes of construction and operation of underground structures will influence each other and surface objects. For urban underground structures, it is not always possible to create a significant surface complex and therefore all the necessary processes must be located underground.

Let us consider in detail the main directions of the use of urban underground space.

Engineering communications networks

Among the underground structures of cities, the engineering communications network (utility networks) is one of the most important. The main engineering communications that provide normal conditions for everyday life in the modern largest city are the following: drinking water supply lines; economic (industrial) water supply lines; household sewerage; storm sewer; gas pipelines; heating pipelines; hot water pipelines; cables and communication lines; electrical lines of various voltages; pneumatic mail pipelines; pipelines for pneumatic removal of debris; fuel lines; traffic control cables; cables of electrified railways; lighting cables, etc.

Sometimes other systems of underground communications can also be found, mainly in industrial and even agricultural enterprises, in particular, kerosene pipelines or milk pipelines.

Underground engineering communications are usually built separately, most often at different times in separate trenches, at different depths from the surface, depending on the nature of the previously laid communications, certain physical properties of the soil, groundwater level, climatic and other conditions.

Cross-sections, throughput, or power of underground utilities are also different. The so-called main pipelines (main cable, large water conduit, main collector, etc.) serve, as a rule, large areas. Distribution pipelines depart from them, which, in turn, branch out again and are laid near the individual buildings and structures they serve and feed them through separate inputs.

Most of the underground utilities, with the exception of domestic and storm sewers, are usually located at a shallow depth - up to 3 m.

Transport tunnels

For transport purposes, tunnels are created: pedestrian, automobile, railway, navigable and subway tunnels. They are carried out to overcome mountains, reservoirs and other obstacles in the places where transport routes pass. Currently, there are sufficiently developed tunneling technologies that make it possible to ensure the stability of these structures to the effects of rock pressure, water inflow and other factors for millennia.

For the largest cities of our country, off-street, mainly underground passenger rail transport is the most promising. Lines of high-speed off-street rail transport in cities can be classified according to the types of vehicles used, according to the concept of the development of routes, according to the nature of operation, depth of laying, space-planning solution of stations, vestibules and other premises.

According to the types of vehicles used, there are subways and high-speed trams, and in some cases - city railways, express (high-speed) subway lines and monorails. Corresponding networks may have underground and semi-underground sections.

Depending on the concept of the development of off-street rail transport, its lines can be traced in the form of one or more diameters (or chords), united by circular or semicircular lines. In cities developing in length, lines of off-street rail transport are laid mainly in the longitudinal, the most loaded direction in terms of transport.

In accordance with the nature of operation, networks of off-street rail transport are distinguished with independent (closed) movement of trains along separate, unrelated lines (in Moscow and Leningrad), with the transition of part of the trains from one line to another (in London and New York) and combined networks.

According to the space-planning solution of the stations, single-platform structures are known - with a central passenger platform of an island type, double-platform - usually with coastal platforms and multi-platform, most often found only in transfer hubs or in underground railway stations.

The features of underground transport facilities are their rigid binding to transport routes, as well as a specific elongated shape. This direction of using underground space is one of the most common and profitable in terms of making a profit.

Transport tunnels in cities are classified according to purpose, length, configuration in terms of traffic organization and design scheme, depth, location in urban areas.

By purpose, tunnels are distinguished for mixed (road and rail) or only road traffic. In foreign practice, there are tunnels designed only for the movement of cars.

In terms of length, transport tunnels are divided into short ones with a length of the tunnel covered part up to 300 m and long ones (more than 300 m) that need forced-exhaust ventilation.

In accordance with the configuration in the plan, rectilinear, curvilinear, branching and mutually intersecting (at different levels) tunnels are distinguished; confluence of traffic flows or their intersection at the same level in transport tunnels is not allowed.

According to the organization of traffic, tunnels for one-way and two-way traffic (in opposite directions) are known, and according to the design scheme - single-span, double-span and multi-span; the number of lanes for safety in the tunnel must be at least two.

Depending on the depth of laying, shallow tunnels (up to 10-15 m deep) are known, usually created with an opening of the surface, and deep-laying tunnels (more than 10-15 m deep), carried out by underground mining methods.

According to the location in the city, tunnels of the usual type are distinguished, laid under streets, driveways, buildings and squares, as well as mountain and underwater.

Transport tunnels can be presented in the form of separate structures, be part of the intersections of city streets and roads developed in plan and profile at several levels, or be elements of multi-level public transport and other complexes for various purposes.

Pedestrian crossings

The need for an off-street, including an underpass, is determined either by the categories of streets and roads intersected, or by the quantitative ratios of pedestrian and vehicle flows. In all those cases when pedestrians are not able to cross the carriageway during permissive traffic signals, one should either reduce the volume of traffic at this node, or find the possibility of arranging a transport intersection at different levels or an off-street crossing.

Pedestrian crossings are classified according to a number of features: in relation to traffic flows and to the surface of the earth; planning scheme; the number of tiers and depth of laying; functional and compositional relationship with urban development; equipment of service establishments; devices for moving pedestrians vertically.

In relation to the flow of urban traffic and to the surface of the earth, pedestrian crossings are divided into street, traced at the level of the carriageway, and off-street, located under the level of the carriageway or above it. Depending on the location relative to the surface of the earth, off-street crossings can be ground, above-ground and underground.

According to the planning scheme, off-street crossings of the following types are distinguished: linear (corridor), single-span or two-span, the simplest type; structures built according to developed planning schemes, including those that are curved in plan; hall (multi-span); structures of combined types, created according to relatively complex schemes.

Underground and semi-underground off-street passages can be designed in one, two or several tiers, both completely isolated by ceilings, and united by a common open space. The constructive and space-planning solution of the underground passage largely determines the depth of its foundation.

In this regard, the following are known: - deep underground structures, the construction of which is carried out by underground methods (without opening the surface); such structures are usually calculated for significant rock pressure from overlying rocks; - shallow underground structures, the construction of which is carried out with the opening of the surface; - closed structures formed by large-area ceilings and devoid of natural light and ventilation, as well as structures partially buried, for example, on relief differences.

Depending on the functional and compositional relationships with urban development, off-street crossings are distinguished, solved in the form of separate structures; crossings built in combination with other transport buildings and structures (intersections of streets and roads at different levels, metro entrances, stations for various purposes, etc.); transitions that are an integral element of public, administrative, residential and other buildings and their complexes.

According to the equipment of crossings by service establishments, crossings intended only for “transit” pedestrian traffic, crossings with separate institutions and associated service devices (phone booths, newspaper and book kiosks, theater ticket offices, etc.), crossings with a developed composition of associated service establishments are known. (trade, consumer services, public catering).

Depending on the devices and mechanisms used to move pedestrians vertically, there are transitions with stair and ramp exits, as well as transitions equipped with various types of escalators or continuous belt lifts.

Underground garages

One of the fastest growing areas of urban underground construction is the construction of underground garages. Even in the most favorable climatic conditions, each car is in motion on average no more than 1-1.5 hours per day (300-400 hours per year). Consequently, each car is parked approximately 22-23 hours a day; this circumstance should be taken into account.

It is necessary to ensure such placement of garages for permanent storage of cars so that the maximum distance from the house to these structures does not exceed 600-800 m, i.e. the time spent on approaching them is not more than 8-10 minutes. Parking lots should be located at a distance of 200-250 m from the dwelling. Only such placement of car storage places eliminates the need to use transport vehicles. Bringing car storage areas closer to home is not only convenient for owners, but also economically justified. Otherwise, for each car, not one, but two places will be required: the first is a permanent one in a permanent garage, about 2-3 km from the house; the second - open parking directly at the dwelling, on the nearest streets, on intra-block passages or utility sites.

In foreign practice, ground-underground garages are often used. For example, in Budapest, on Martinelli Square, a multi-storey office building is combined with a 400-car above-ground and underground ramp-type garage. The garage has eight ground and two underground tiers and was built in a very cramped place. The garage includes a built-in gas station and a semi-underground service station, designed mainly to service "city" cars entering the parking lot, as well as transit cars. For departmental vehicles, a special underground floor has been allocated with independent entry and exit.

Based on the need to save urban territory or preserve the existing nature of development, underground or semi-underground garages and parking lots can be provided for a certain part of the cars. At the same time, sanitary gaps to residential and public buildings are significantly reduced. The dimensions of the gaps in this case are calculated not from the outer walls, but from the places of emission of harmful emissions and noise sources, i.e. from entrances to garages and ventilation shafts. The upper tier (cover) of underground or semi-underground car parks can be used for landscaping or open storage of cars. For example, a one-storey underground garage for 180 cars and 80 motorcycles has been built according to this principle in the Cité-Model residential area in Brussels, along with numerous outdoor car parks with 830 spaces. This garage is connected by underground passages directly to the elevator halls of three large multi-storey residential buildings. The entrance to the garage is separated from the entrances to residential buildings by 20-25 m. In the same area, a separate petrol station and a service station have been built.