Underground electrical communications. About underground communications

Underground engineering communications- these are linear structures used to transport liquids and gases, transfer energy and information. Distinguish the following types underground structures: pipelines, cable lines and collectors.

Pipelines there are gravity and pressure.

Gravity pipelines remove contaminated wastewater to treatment facilities (industrial and domestic sewerage), atmospheric waters into reservoirs (storm sewers) and groundwater to lower their level (drainage).

Pressure pipelines transport liquid and gas products under pressure. They are divided into water supply (household, drinking, fire-fighting, industrial), heating (water and steam), gas pipeline (high, medium and low pressure), as well as special-purpose pipelines (air, gas, oil, acid, fuel oil and etc.).

Cable lines are divided into high and low voltage power cables and are used for electric transport and lighting; on low-current networks - for telephone, telegraph communications, radio broadcasting, television, signaling, etc.

Collectors designed for combined laying engineering communications for various purposes (usually - water supply, heating, power cables and communications).

In progress geodetic works associated with underground engineering structures, the following should be considered:

- underground utilities, as a rule, are located no closer than 2-3 m from the foundations of buildings and structures; cables - no closer than 0.5 m. The minimum distance between communications for various purposes in plan and in height is 0.5-1.0 m;

- the permissible errors of the planned survey of all types of communications are approximately the same: 0.10-0.15 m. The accuracy of the survey of the altitude position depends on the requirements for compliance with the design marks and slopes. In gravity pipelines, the error of marks is allowed no more than 5-10 mm, in pressure pipelines - 30 mm, in the rest - 50 mm;

- bends and tie-ins of gravity networks are equipped with wells;

- on driveways, underground communications should be practically parallel to the red building lines;

- inputs to buildings of water supply systems, heating systems and gas pipelines are arranged, as a rule, at right angles to the contour of the building;

- the diameters of pipes of gravity communications and heating systems can change in the wells, increasing in the direction from the buildings being serviced to the collector (main). The diameters of pressure pipes can sometimes change their value in the interwell span, but the direction of increasing the diameters is the same as for gravity networks;

- voltage of current in cable lines can change at transformer substations;

- underground communications should not have breaks;

- external signs of underground engineering communications can be structures and devices located directly on pipelines and cable lines, buildings and engineering complexes technologically necessary for the functioning of networks of a certain purpose, micro-changes in the relief, vegetation cover and soil temperature caused by the presence of underground structures.

Underground communications of the city are the most important element of engineering equipment and landscaping, which meets the necessary sanitary and hygienic requirements and provides high level amenities for the population. As underground communications of settlements, networks of water supply (hot and cold), water disposal of domestic, industrial and atmospheric polluted water, drainage (storm sewer), drainage, gasification, power supply, signaling, special purposes, as well as radiotelephone and telegraph communication networks, new types (pneumatic mail and waste disposal), etc.

Engineering networks of settlements are designed as an integrated system that unites all overground, surface and underground networks, taking into account their development for the billing period. Underground networks are laid mainly under streets and roads. For this, in the transverse profiles of streets and roads, places are provided for laying networks: on the strip between the red line and the building line, cable networks(power, communications, signaling and dispatching networks); under the sidewalks there are heating networks or pass-through collectors; on the dividing lines - water supply, gas pipeline and household sewerage. If the width of the streets is more than 60 m within the red line, the water supply and sewerage networks are laid on both sides of the streets. When reconstructing carriageways of streets and roads, usually the networks located under them are transferred under the dividing strips and sidewalks. An exception may be gravity-flowing networks of household and storm sewers.

The specific length of networks depends on the density housing stock, and, consequently, on the number of storeys of the building. With an increase in the density of the housing stock from 1900 m2 / ha (with 2-storey buildings) to 4000 m2 / ha (with 9-storey buildings), the total relative length of the networks decreases 2.6 times.

Urban underground communications are constantly evolving and represent a complex system - an important part of the urban "organism". Underground networks are subdivided into transit, trunk and distribution (distribution) networks.

Transit utilities include underground communications that pass through the city, but are not used in the city, for example, a gas pipeline, an oil pipeline running from the field to other settlements.

The main networks of the city belong to the main ones, through which the main types of carriers in the city are supplied or taken off, designed for a large number of consumers. They are usually placed in the direction of the main transport highways cities.

Distribution (distribution) networks include communications that branch off from the backbone networks and are brought directly to houses.

When designing the main routes of underground utilities, they are made rectilinear, parallel to the axis or red line of the street, placed on one side of the street without crossing it. Underground networks should not be located one above the other, with the exception of sections at intersections and branches, where intersections are provided in accordance with the norms in different levels... The most expedient is the location of underground utilities under the green zone of the street and sidewalks, but it is often necessary to use also part of the space under the carriageway of the streets.

In case of reconstruction and expansion of communications in the integrated design, reserve sections are provided in the underground space of streets.

In the conditions of urban development and during the reconstruction of existing enterprises, where underground communications are located in significant volumes (water supply, sewerage, drains, heat and cable networks), the laying of new and replacement of old underground networks in an open way is difficult. An open way of laying communications under railway and tram tracks, city streets with heavy traffic is almost impossible. In this regard, for last years open and closed methods of laying communications began to be widely used. The closed method allows to reduce the volume of earthworks by 60-80% and to carry out construction in winter conditions without large increases in prices. With the closed method, it is possible to develop the soil and lay communications using shield penetration, punching, puncture and horizontal drilling. Underground also includes buried in the ground. underground structures, such as pumping stations for water intake and pumping, underground storage facilities, warehouses and tunnels.

The complex process of setting up tunnels consists of laying out tunnel routes, strengthening foundations near located buildings, erecting a vertical shaft of the route for lowering and lifting tunneling shields, workers, lifting soil from the tunnel, supplying materials to the tunnel to ensure ventilation, drainage

About 70% of the population of Russia now lives in cities with more than 100 thousand people. At the same time, the tendency of the consistent inclusion of rural settlements in the urban line is clearly progressing.

A significant factor in ensuring social progress is reliably functioning underground communications of the city, which provide its population with communications and the Internet, water, electricity, gas, heating, and sewerage.

They are extremely saturated and branched. Their characteristic structural components are manifolds, pipelines and low and high voltage cables. In addition to settlements, enterprises and organizations also have their own engineering support structures.

It is noteworthy that book value communication facilities sometimes exceed a third of all overground buildings. Its development and systematic improvement can stimulate or, conversely, restrain the development of megalopolises.

The existing urban development, on the other hand, also affects the acceptable construction methods. engineering networks and communications. Nowadays, most of them are laid in a closed way without preliminary trenching.

Definition and concept of communications (PC)

Thus, the underground functionally provide the population with electricity and heat supply, water supply and drainage, communications, signaling and the Internet. Their main veins are most often placed under street and road routes.

Thus, the structural elements of the PC are:

• Steel, ceramic, concrete, polyethylene, asbestos-cement pipelines. They are laid, guided by hydraulic calculations. They are pressure (water -, gas -, oil pipelines) and gravity (drainage, sewerage, water drainage).
• High and low voltage power supply cable communications.
• Cable communications, signaling.

Classification of underground utilities

According to the method of providing services, PCs are subdivided into transit, trunk, and distribution. The first pass through the city to the others settlements(gas and oil pipelines). The second are the main supply channels for the entire city or metropolitan areas, while the third directly bring services to homes.

By depth, the networks are subdivided into those laid down to the boundary of freezing of the soil and below it (SNiP 2.05.02.85).

In turn, water and heat supply schemes are subdivided into those with forced and natural circulation, with lower and upper distribution, with associated water movement and dead-end, two- and one-pipe.

Underground power supply and communication schemes consist of cable shafts, switchgears and substations.

PC design

The underground utilities plan is an important and mandatory component of any complex construction project... Typically, communications in order to avoid excessive mechanical stress are located outside the areas of pressure on the ground of buildings.

In the plan of the PC, the ways of laying are necessarily reflected. Let's consider their options.

With a separate method, one or another communication is supplied to the construction object individually. The timing of its construction is also individual, independent of the laying of other PCs. This is an outdated method because in a busy urban environment excavation repairing one communication can damage another. It is used nowadays in a narrowly targeted manner, in cases of revision of existing PCs.

The combined method involves the location of several communications at the same time in one trench. It is used in conditions of limited funding and a critical need for specific PCs.

The most common and promising in terms of mass development is the collector method (CM), in which various PCs are placed in a standard common collector. This method greatly simplifies the repair and operation of a PC. However, the collection method cannot be called universal. It is impossible to combine sewerage, pressure water supply in one collector with other communications.

The collector itself is a concrete box. It can be of different heights. Height and half-height (up to one and a half meters) requires ventilation. In the box itself, a temperature regime of 5 to 30 degrees Celsius is observed.

Security requirement in building a PC

Errors in the construction of underground communications lead to accidents, injuries, fires, breakdowns of devices and equipment powered from them (STO 36554501-008-2007). When building a PC in mandatory the geological and hydrogeological properties of soils should be taken into account, as well as the possible seasonal dynamics of their change should be predicted.

Electrical equipment used for laying trenches and pipes must be explosion-proof. Tunnels and mines in the areas of electric welding works for the time of their execution are obligatorily provided with a local hood.

The stay of workers - laying in pipelines is permissible if the diameter of the structure exceeds 1.2 meters, and the length is no more than 40 m. For a pipe length of more than 10 m, forced ventilation is provided from 10 cubic meters / hour.

In terms of time, the stay of workers in the pipeline is limited to one hour with breaks of 0.5 hours.

Typical PC construction

Modern construction underground communications are carried out in accordance with the location of city streets, terrain, large users of services. The cross-section of streets that are being built or renovated is taken into account.

In this case, cable networks are laid along roads and streets. Moreover, main communications run along the main streets, while residential neighborhoods are equipped with receiving and distributing PCs powered by them.

Pass-through collectors and heat pipes are located under the sidewalks. At the borders of the sidewalk and streets, they will equip a sewerage system, a gas pipeline, and a water supply.

Modern PC Laying Methods

The laying of underground utilities is now more and more often performed trenchless. This method allows you to bend around terrain obstacles with high precision and time efficiency.

The first trenchless method begins with pilot drilling using a drill rod to bypass obstacles along the bottom edge. The drilled hole is then enlarged with a reamer.

The second is based on the use of a self-propelled tunneling mechanism called a shield. The latter is placed in a specially opened starting pit, and then put into action. He punches a channel in the ground up to the finishing pit, which was also previously opened for him.

The third is also performed between the channels, but at a smaller distance and with the help of a pipe horizontally driven by a pneumatic punch.

PCs often form an intersection with each other, underground utilities in this case are separated from each other vertically according to the requirements of SNiP II-89-80, see table 1.

Table 1. Standard distances during PC construction to roads, building foundations, etc.

PC detection problem

Modern urban construction, carried out in areas with already existing buildings, presupposes a preliminary search for underground utilities. It is carried out using specialized equipment. The most often used is a locator of underground utilities. He determines the configuration of the PC, the depth of location and even the location of damage, the location of its individual veins, hidden communications.

Neglecting such a search is fraught with PC crashes. Aspiration of the individual construction organizations to save money by not paying certified firms for the services of determining third-party communications in the area of ​​earth construction, often leads to accidents and, as a result, to a forced increase in the costs of eliminating them.

About PC shooting

Survey of underground utilities is advisable if there is no primary executive documentation for them, (i.e., documentation that is produced directly in the process of their construction). It is important for tying PCs to new infrastructure.

Such jobs are most in demand in large cities, where their density is highest. Survey of underground communications is a core area of ​​work of specialized electrical measuring laboratories that exist at organizations involved in pipe and cable laying.

The proper level of their implementation allows you to determine not only the direction and depth of the entire communication route as a whole, but also each of its segments separately.

Its essential elements are essential functional parts of each type of PC:

• pipe and water supply (valves, hydrants, angles of rotation, plungers, pipe diameter);
• cable networks (transformers, switchgears);
• sewerage systems (pumping stations, overflow and inspection wells);
• gutters (overflow and water outlets);
• drains (perforated pipes);
• gas pipelines (main and distribution sections, shut-off valves, pressure regulators, condensate collectors);
• heat supply networks (compensators, chambers with valves, condensation devices).

High accuracy of PC shooting is ensured by the competent use of high-precision equipment for PC diagnostics, specialized software,

A locator of underground utilities, a cable detector, a metal detector, a multiscanner allow diagnosing a PC with a high accuracy of identifying all their structural elements. In passive shooting mode, it is possible with sufficient accuracy to determine communications located at a depth of 2.5 m.

However, the rich structure of communications, especially if they are located from each other, as well as their significant depth (up to 10 m), significantly complicates a more detailed search for underground communications. In this case, the active detection mode is practiced. Around the investigated cable or pipe, an electromagnetic field is initiated with a special generator, and by measuring it, the required characteristics of the PC are determined.

PC repair

It is obvious that the existing underground communications are subject to overhaul and reconstruction only by organizations and enterprises that have the appropriate permits, within the timeframes approved in the consolidated plans of municipal communal management structures. Every year, by November 30, the operating enterprises submit their plans for such work to the city administration of housing and communal services for coordination and accounting.

If in the course of such work it is necessary to violate the integrity of the lawns, to remove the roadway, then permits from the local government are required. When redeveloping existing PCs in connection with the construction of new facilities, their re-equipment is carried out by the general contractor according to the project. Each specific PC repair project must be agreed by the general contractor with all business entities whose underground communications are located in the work area.

To obtain it, the customer submits the following package of documentation:

• a letter agreed with the municipal authorities;
• project of work and plan of the PC route;
• guarantee of restoration of the road surface;
• confirmation of the availability of equipment and materials necessary for the repair;
• order to appoint a person responsible for the repair.

The customer also pays for the lease of the repair area, after which he receives a permit.

If, while performing work, the contractor discovers a PC that is not specified in the project, he is obliged to stop work and notify the customer. He, in turn, calls the employees of the project company, who draw up an act on this matter and formulate an official decision.

In case of damage to the PC, the architecture management, with the participation of all interested parties, draws up an act and makes a decision on compensation for the damage. The culprit is determined, and the terms of elimination are set.

PC service

PC maintenance is carried out for the purpose of safe and uninterrupted supply of the population and business with electricity, water, gas, communication services, drainage, sewerage, etc. This task is complicated by the visual inaccessibility of communication routes. Thus, the operation of a PC is reduced to their preventive maintenance and current repair.

The goal of preventive maintenance is to identify possible damage resulting in leaks and other supply disruptions. The first part of it is the inspection and measurement of basic indicators directly on the external elements of communications (transformers, switchgears, inspection chambers, condensation devices). However, the basic indicators are the pressure of water and gas, the voltage of electricity. The frequency of the inspection is determined by the organizations that supply utility services to consumers, it is finally approved by their higher management bodies.

Description of one of the types of service

For the main gas pipeline, route maps are created with hydraulic locks and condensate traps applied to them. In the latter, condensate is pumped out using motor pumps. Only certified specialists are allowed to perform such work. Safety measures prohibit the use of open fire and smoking is strictly prohibited.

To find out the operating modes of gas pipelines at least twice during the period of maximum winter and minimum summer load, the pressure in them is measured.

The tightness of these communications is carried out by periodic drilling and casing inspections. For this purpose, a well with a diameter of 20-30 cm is drilled behind each joint of the gas pipeline. The drill is immersed into the depth at a distance of 20 cm, not reaching the gas pipeline. Next, the presence of gas in these wells is checked.

If the soils in which the gas pipelines are laid have increased corrosiveness, then the integrity of the structures is checked at least once every 2 years, with neutral soils, once every 5 years.

Thus, the areas with the highest pressure drops are determined. Most often, the reason for their formation is the sagging of the gas pipeline caused by the violation of the uniformity of the soil. Therefore, simultaneously with the repair of the integrity of the pipe, a thorough tamping of their soil bed is carried out.

PC organizations (enterprises)

The organization's underground communications are designed in a comprehensive manner as part of a single general project together with buildings and structures. PCs are placed in technical strips optimized in terms of area.

Directly on the territories of the enterprises themselves, only overground and ground communications are used.

The pre-factory communications are laid underground. They are housed together in common tunnels. The length of the PCs of the leading industrial enterprises is up to several tens of kilometers. Labor intensity of laying various communications (in percent) is: sewerage - 65%; water supply - 20%; heat pipelines - 7%; gas pipelines - 3.5%, electric and communication cables - 3%; technological pipelines - 1.5%.

Process pipelines can be placed together with a gas pipeline, a heat pipeline, while it is prohibited to place pipelines with explosive and flammable liquids.

Conclusion

The problem of replacing underground communications is now becoming very urgent. Its root cause is systemic flaws. state machinery financing according to the deliberately failed residual principle. Thus, in fact, neglected objective reality: the fact that each project laying of underground utilities assumes specific terms for their replacement, in accordance with the materials of their manufacture and the conditions of occurrence in the ground.

PC replacement should be planned within the framework of state economic policy. Unfortunately, the inconsistent economic function of the state actually prevents the creation of full-fledged and effective funds for regular capital investment.

In this regard, there is a positive world experience. An example to follow is the Norwegian PC system, which is clearly regulated by the direction of the country's budget to the observance of the relevant state standards.

We constantly observe a vicious closed cycle: how, in the absence of such an established economic mechanism, managing monopoly organizations now and then initiate an increase in already overstated tariffs for public Utilities, citing 90% outdated PCs.

Shallow and deep networks. Underground communications of the city are the most important element of engineering equipment and landscaping, meeting the necessary sanitary and hygienic requirements and providing a high level of amenities for the population. Underground communications include networks of hot and cold water supply, gasification, power supply, signaling for special purposes, telephony, radio broadcasting, telegraph, sewerage, drainage (storm sewer), drainage, as well as new types of development (pneumatic mail, garbage disposal), etc. ...

Urban underground communications are constantly evolving, representing a complex and important part of the urban "organism". Underground networks are subdivided into transit, trunk and distribution (distribution) networks.

The entire main network of trunk and transit pipelines, channels and cables is located under the streets of the city. Part of the networks is found under the carriageways of the streets. The laying of new and the reconstruction of existing networks, as well as emergency work on the networks, are accompanied by tearing of the streets, and when the networks are located under the carriageways, they cause violation of the road surface.

Urban underground networks are divided into pipelines, non-passable or semi-passable canals, passable underground gallery tunnels, called common collectors, and cable networks.

There are underground networks: transit, trunk and distribution (distribution). The last of them are located in the territories of microdistricts and quarters. Transit underground networks are characterized by the absence of branches on them. Trunk lines are usually laid under streets.

Transit refers to those underground communications that pass through the city, but are not used in the city, for example, a gas pipeline, an oil pipeline going from the field through this city.

The main networks of the city belong to the main ones, through which the main types of carriers in the city are supplied or taken off, designed for a large number of consumers. They are usually located in the direction of the main transport routes of the city.

Distribution (distribution) networks include those communications that branch off from the main ones and are brought directly to houses.

Underground networks have different depths. Shallow networks are located in the soil freezing zone. The depth of soil freezing is determined according to SNiP 23-01-99. For Moscow, for example, it is 140 cm.

Shallow networks include networks, the operation of which allows significant cooling: electric low-current and power cables, telephone and telegraph cables, signaling cables, gas pipelines, heating networks. Deep networks include underground utilities that cannot be overcooled: water supply, sewerage, drainage. For underground networks, steel, concrete, reinforced concrete, asbestos-cement, ceramic and polyethylene pipelines can be used.

19. Device vertical layout in difficult terrain.

In conditions of significant differences in the heights of the relief of the territory of the microdistrict, urban planners use a wide range of vertical planning techniques. With their help, they form the planning surface of the microdistrict territory, organize transport and pedestrian traffic between the terraces lying at different levels. In each specific case, one or another method or device of vertical planning is chosen depending on the properties of the soil, geological and hydrological conditions, and the requirements for the territory of the microdistrict.

The simplest element of the vertical planning of the territory when surfaces are mated with a difference in elevation is a slope. Main question when designing - the establishment of its steepness. It is chosen from the conditions of soil stability, prevention of landslides and erosion. It depends on the height of the elevation difference. At a slope height of up to 6 m in stable soils (semi-rocky and similar), the steepness is expressed in a ratio from 1: 1 to 1: 0.5; with soils of medium stability - up to 1: 1.5; with loose soils (fine-grained sands and the like) - 1: 1.5 or less. To protect the slope from erosion by surface waters, trays, ditches, drain pipes buried in the ground are arranged at its bottom. According to them rainwater are directed to the intake grates of the city drain or to the nearest body of water. In addition, the slopes are strengthened by planting green spaces, sowed with herbs with a developed root system, covered with sod, paved with stones, concrete and reinforced concrete slabs. For the same purpose, cement concrete slabs with holes filled with grasses or perennial flowers are used to place slopes. When using green spaces to anchor slopes, it is important to provide them with a vegetative layer of soil.

Slopes of great height (more than 5 m) are sometimes expedient to dissect in height by horizontal surfaces, which are called berms. Berms can be used for walking paths.

Instead of slopes, retaining walls are often arranged. They are made of durable material (stone, concrete, reinforced concrete) that can hold back the pressure of the overlying soil. Retaining walls are calculated in shape and section from the condition of equilibrium of earth masses, the height is determined by the difference in heights.

Retaining walls are made vertical and inclined (slopes 1:10 and 1:12). To prevent the soil of the overlying terrace from being washed away, the upper terrace is provided with drainage system and trays intercepting rain streams. Retaining walls are decorated with stone, rustication and other types of finishes.

For pedestrians, the terraces at different levels are connected by stairs. Ladders are arranged in slopes and breaks of retaining walls with a slope of no more than 1: 3, a riser height of 10 ... 14 cm. The width of the tread of the stairs is not limited. With a slope of less than 1:13 (8%), it is allowed to arrange pedestrian inclined ramps - ramps. Stairs and ramps are arranged taking into account the main directions of the system of transport and pedestrian routes.

On the draft vertical layout, design marks of characteristic points are indicated: at the corners and entrances of buildings, at places where the longitudinal slope changes and at the intersections of red lines of streets by passages, arrows in the street trays indicate the directions and values ​​of the longitudinal slopes (in percent). In these directions, there will be surface water runoff. In addition to the longitudinal slopes of driveways, sidewalks, green areas, as well as areas of microdistricts, for the convenience of drainage of rainwater, transverse slopes are arranged.

The longitudinal and transverse slopes of all platforms and paths have a direction that ensures the flow of water towards the nearest passage.

In the case of difficult terrain with slopes greater than the limit adopted for sites, they are located in recesses, on embankments or partially using a recess and embankment. At the same time, the architectural and planning combination of territories should not deteriorate.