In feng shui and in general in China, water is considered the primary element, the basis of all life...
General provisions
When erecting buildings and structures in conditions of dense urban development, a number of factors arise, the observance of which ensures the quality and durability of not only the directly erected objects, but also the structures surrounding them:
The need to ensure the maintenance of the operational properties of objects located in the immediate vicinity of the development spot;
the impossibility of locating on the construction site a full range of household and engineering structures, machines and mechanisms;
development of special constructive and technological measures aimed at optimizing the process of building an object;
development of technical and technological measures aimed at protecting the ecological environment of the facility and existing buildings.
The peculiarity of the factors listed above lies in the fact that for many of them today there is no normative base, which comprehensively considers them in relation to the processes of building construction.
Problems that arise in the very first months of construction associated with the formation of cracks in the walls, floors and ceilings of existing buildings can lead not only to financial losses, but also lead to the closure of construction. The same consequences may arise from the impossibility of ensuring engineering and sanitary requirements for the arrangement construction site. In order to develop solutions that allow not only high-quality construction of a building, but also ensure a stable balance of both the nearby development and the urban environment as a whole, we will consider in more detail the problems that arise during the construction of buildings in dense urban areas.
Specific features of the building plan
The limited space allocated for the construction site prevents the full development of the construction site. At the same time, there is a whole range of mandatory measures, without which the construction will be immediately suspended by the regulatory authorities. These include fire fighting and safety measures. Mandatory is the presence of evacuation passages (exits) on the construction site, prepared for the use of fire hydrants, emergency fire fighting equipment; restrictive cast-off or fencing around the pit, signs of work areas at the construction site, sheds over pedestrian areas located along the construction site.
In cases of a limited area of the building site outside the construction site, the following may be located:
Administrative and amenity premises;
canteens and sanitary facilities;
reinforcing, carpentry and locksmith shops and workshops;
open and closed warehouses;
cranes, concrete pumps and other construction machines.
Administrative and amenity, storage facilities, production shops and workshops(Fig. 26.1). The location of certain premises within the construction site can be difficult due to the lack of space required by the standards, and attempts to find technical solutions for the placement of temporary structures, such as increasing their number of storeys, complicating the configuration in accordance with the configuration of the building site, lead to significant technical difficulties. and cost of the project.
Rice. 26.1. Placement of a residential camp outside the construction site:
1 - construction site; 2 - open and closed warehouses; 3 - administrative and amenity premises
In some cases, the site is so limited in size that no technical solutions allow placing auxiliary premises within its boundaries. At the same time, there are organizational and technological solutions that allow these premises to be placed outside the building site without significant damage to the building construction process. In this case, the economic, organizational and technological feasibility of placing certain premises on the territory of the construction site and outside it is considered.
Administrative and amenity premises, taken out of the construction site, may be located in existing buildings or in newly erected amenity camps. Prior to the start of construction, a search is carried out for buildings in which it is possible to place amenity premises for the period of construction, or a plot of land on which it is possible to build a residential town. The requirements for search objects are as follows:
Location as close as possible to the construction site;
availability at the facility of the possibility of connecting to the networks of urban infrastructure - heat supply, electricity, water supply and sewerage;
the minimum cost of renting premises or land.
Having chosen a room or plot of land, an administrative and amenity camp is located there, if possible, close in size to the requirements of sanitary standards. If the camp is located in the immediate vicinity of the construction site, then the staff independently gets to their jobs and back. In some cases, if it is impossible to locate the camp in the immediate vicinity of the site, the staff is delivered to and from the site by buses.
The removal of canteens and sanitary facilities from the site is associated not only with the lack of necessary space, but also with the difficulties that arise at the first stages of construction with connection to city networks. However, the availability of toilets is necessary from the first day of construction, therefore, from the very beginning of the deployment of the construction site, biological toilet cubicles for personnel should be installed there. Canteens, showers and toilet rooms must be provided for in the leased areas deployed near the facility and in buildings.
Delivery of products and equipment on time. The absence of reinforcing, carpentry and metalwork shops and workshops makes it difficult to manufacture products and elements of building structures, such as fittings prepared to size, reinforcing cages, elements of load-bearing metal structures, joinery and metalwork elements. To solve this problem, all of the above elements are brought to the construction site in a form prepared for use. They are manufactured at our own production facilities located outside the construction site, or at specialized enterprises for special orders. They are delivered to the site in accordance with delivery schedules, on exactly the agreed days and hours. At the construction site, they are unloaded and delivered to the place of work, i.e., their installation is carried out directly "from the wheels". Failure to meet the deadlines for the delivery of any product can lead to a disruption in the schedule for the construction of the entire structure. Therefore, when working “from wheels”, the role of dispatching services of construction and installation organizations, which control the development of delivery schedules and their subsequent implementation, increases.
The impossibility of placing open and closed storage facilities on the territory of the construction site leads to the need, firstly, to carry out a large amount of installation work “from wheels”, and secondly, especially for expensive imported equipment, to create intermediate storage facilities. As a rule, plumbing, electrical and elevator equipment, sometimes window blocks, doors, and various finishing materials are delivered to such premises located on the territory of their own production bases or rented in the immediate vicinity of the construction site. As they are in demand at the construction site, products and materials are delivered from the warehouse and mounted directly from Vehicle.
In some cases, the supplier undertakes to deliver the requested equipment directly to the construction site within the agreed period, in the same way as suppliers of products and structures do. Some problems in the supply of imported equipment are related to the fact that delivery from abroad and the implementation of customs procedures are quite difficult to normalize in time and it is almost impossible to accurately indicate the day and hour when the equipment will be delivered to the site. In this case, the equipment is ordered in advance, 2...3 weeks before the required date and before installation, it is stored in the supplier's warehouse. In the presence of a large number Such suppliers eliminate the need for intermediate storage facilities, but at the same time, all participants in the construction process are within very tight time limits established by work schedules and equipment delivery.
Location of cranes and large construction machines. A big problem in conditions of dense urban development is the placement of large-sized construction machines and cranes directly on the site. Cranes and concrete pumps must be located on the construction site or in its immediate vicinity. This is due to the technical capabilities of the equipment - the maximum outreach of the crane boom or the concrete pump feeder. However, in most cases, there are previously constructed buildings and structures around the construction site and the placement of large tower cranes next to them, installation of crane runways is impossible. In this case, easy-mounted tower cranes without crane runways are used, which require a crane area of up to 9 m2, heavy-duty self-propelled cranes or self-elevating cranes installed directly in the building site.
The foundation slab is mounted using a mobile crane, then it is installed tower crane. As the structures located above the foundation slab are erected, the crane can be lifted and installed on the mounted ceilings. Sometimes the crane remains on the foundation slab until the end of the construction of the building, so in the ceilings around the crane there are unconcreted sections with reinforcement outlets. The dimensions of these sections are determined based on the dimensions of the most horizontally extended part of the crane. After completion of work, the crane is dismantled, removing it in sections. Unconcreted floor zones, reaching 10 ... 20 m2 each, are concreted starting from the bottom. Concrete is laid using self-propelled heavy-duty cranes.
During construction in conditions of dense urban development, a number of factors arise, the observance of which ensures the quality and durability of not only the directly erected objects, but also the structures surrounding them. These factors include:
the need to operate facilities located in the immediate vicinity of the development spot;
the impossibility of locating on the construction site the entire complex of construction infrastructure provided by the technology for the production of works (household and engineering structures, machines and mechanisms);
the need to develop technical and technological measures aimed at protecting the ecological environment of the facility and existing buildings.
The limited space allocated for construction prevents the full deployment of the construction site.
At the same time, there is a whole range of mandatory measures, without which the construction will be suspended by the regulatory authorities. These include fire prevention measures and ensuring labor protection and safety precautions for construction and installation works:
availability of evacuation passages on the construction site;
prepared for use fire hydrants and emergency fire fighting equipment;
fencing of the construction site and hazardous areas (pit, erection stationary crane, structure warehouses);
canopies over pedestrian areas adjacent to the construction site.
In cases of a limited area of the building site outside the construction site may be located: administrative and amenity premises; canteens and sanitary facilities; reinforcing, carpentry and locksmith shops and workshops; open and closed warehouses. When organizing a construction plan, it is advisable to provide for these purposes restorative territories, by agreement with their owners. To limit storage space, you can organize:
assembly of building structures from wheels,
use the most enlarged elements,
apply advanced construction technologies tested in similar conditions.
Sometimes intermediate storage sites are organized as close as possible to the facility under construction. In this case, the required materials and products are delivered to the facility as needed and placed in the area of use. The use of intermediate warehouses imposes strict requirements on the participants in the construction industry (including suppliers and customers) for the implementation of work schedules and the delivery of technological equipment.
Administrative and amenity premises, taken out of the construction site, can be located in existing buildings or in newly erected towns, as close as possible to the construction site. The areas used must meet regulatory requirements according to the minimum sanitary and hygienic standards per worker. Delivery of workers to the facility is carried out by the customer service.
A serious problem in conditions of dense urban development is the placement of large construction machines and cranes directly on the site. Cranes and concrete pumps must be located on the construction site or in its immediate vicinity. However, in the immediate vicinity of them there are previously constructed buildings and structures that prevent the movement of the boom of a crane or concrete pump, or it is not possible to lay crane tracks. In this case, easily mounted stationary-type cranes (self-elevating) are used on a relatively small foundation or (for concrete work) concrete-laying complexes are used, associated with the vertical supply of the concrete mixture inside the building and its subsequent distribution on the tier by manipulators various types. At process design we must strive to make the most of the experience of building in similar conditions and modern mechanization.
Maintaining the operational properties of the existing building.
Buildings located in close proximity to a development site may be subject to a number of impacts arising from the construction of a new building. These impacts include: excavation of the pit in the immediate vicinity of the building and vibration from construction machines and mechanisms located in the immediate vicinity.
The first group of defects arises from changes in the static characteristics of the bases. The removal of soil near the foundations of buildings leads to a change in the force field around them. Therefore, the creation of a constructive balance allows you to compensate for the resulting impacts.
The second group of defects is a consequence of the dynamic effects of operating construction machines and mechanisms. Their reduction to acceptable levels is achieved by the implementation of special engineering measures.
Specific measures aimed at maintaining the operational properties of the existing building are developed in the projects for the production of works. These include:
strengthening of bases and foundations, which should ensure the static balance of the building for the period of the open excavation until the erection of the supporting structures of the basement of the new building and backfilling of the sinuses of the excavation. The following design solutions are most often used: "wall in the ground", sheet piling, reinforcement of foundations and basement walls of existing buildings, strengthening of foundation soils by injection methods;
development of pits and construction of foundations in stages - this allows you to reduce the consumption of temporary retaining structures;
selection of machines and mechanisms with minimal dynamic characteristics;
vibration isolation of the soil mass adjacent to existing buildings and structures.
In construction, conditions that lead to a decrease in labor productivity and work, causing unproductive actions and maneuvers of the machines and mechanisms used, creating any inconvenience in transporting, storing and supplying building structures and materials, are called cramped construction conditions.
These conditions are created when working near ground structures, overhead power lines, underground utilities, trees, etc. During the reconstruction and overhaul of buildings and structures, when working at existing industrial enterprises, additional difficulties arise. Various territorial restrictions not only reduce the productivity of construction machines and mechanisms, but also often make their use impossible. As a result, all this leads to a sharp increase in manual labor, an increase in labor costs and, as a result, to an increase in the duration of construction and its rise in price.
Works near existing buildings and structures are carried out taking into account:
Special measures to ensure the safety of existing buildings;
Measures to monitor existing and under construction buildings and the underground space adjacent to them;
Implementation of measures for the engineering protection of the surrounding buildings, including, if necessary, fixing the foundation soils and strengthening existing buildings and structures;
Prevention of damage to existing communications;
Compliance with traffic safety.
Taking into account all the difficulties of construction or reconstruction in conditions of dense urban development, special measures are being developed to increase the reliability of organizational and technological solutions, prevent deformations, and ensure the strength and stability of existing buildings, structures and structures. Also, during construction (reconstruction), the state of structures is continuously monitored (installation of beacons, reference surveys, strengthening of existing structures, etc.).
In the construction organization project, organizational and technological schemes for the construction (reconstruction) of urban development objects are developed, providing for the sequence of construction of buildings and structures and measures to ensure the safety of the construction of new structures and the safety of existing objects. They are also trying to reduce the number of temporary buildings and structures under construction by using permanent facilities for the needs of the construction site.
During construction in the immediate vicinity of the operated subway structures and other underground structures, the use of the impact pile driving method is determined in accordance with applicable standards. When using vibro-immersed piles, the need for their trial immersion is taken into account in order to exclude unacceptable vibrations of the structures of buildings and structures surrounding the construction site.
When working on the construction of pits, decompaction of soils under the foundations of existing buildings is not allowed and the properties of foundation soils are preserved in pits, excavations and other workings intended for the construction of foundations and other structures. The fastening of the walls of the excavations depends on their size and depth, the physical and mechanical characteristics of the soil, etc. Excavation and construction work can be carried out in the following ways:
Beams made of piles, steel pipes and beams and fences in between;
In the form of walls constructed using metal sheet piles, screwed, bored piles, flat "walls in the ground" both prefabricated and monolithic.
As a rule, without special justification, it is not recommended to use ground anchors for fixing pits. More preferable is the use of structures "wall in the ground" and the choice of technology for the construction of underground parts of buildings and structures using the "top-down" method.
For the safe performance of construction and installation work with the help of cranes, hazardous working areas associated with the operation of the crane are limited on the construction site. Limitation methods working area crane:
Arrow reach limitation;
Limiting the movement of the crane;
Lift height limitation.
To increase safety during crane operation in cramped conditions, a number of systems have been developed that automatically limit the crane operating area. These systems limit the movement of the crane, its boom and load within specified limits horizontally and vertically. When the mechanism is dangerously close to the existing limit of the prohibition, these systems give warning signals. If the crane operator does not take the necessary measures, they automatically block the corresponding mechanisms of the crane, stopping their movement.
In conditions of dense urban development, temporary access roads at construction sites are performed according to dead-end or through schemes. The volume of warehousing sites and storage facilities is calculated for short-term storage of a stock of necessary materials, semi-finished products, parts and products delivered to the construction site in special containers. During construction, such methods are used as the installation of building structures from vehicles, the use of the most enlarged elements, the use of advanced building technologies tested in similar conditions.
If it is impossible to locate the necessary equipment, engineering structures, machines and mechanisms on the construction site, administrative and amenity premises, canteens and sanitary facilities, reinforcement, carpentry and locksmith shops and workshops, open and closed warehouses may be located outside the construction site.
It is not allowed to store on the construction site materials shipped in bulk, as well as long products (structures, rolled metal, timber).
In order to reduce the occupied territory as much as possible, temporary engineering communications are raised on supports to a height that ensures unhindered passage of construction equipment under them, or they are laid in trenches. Also, when the crane is operating in the security zone of the overhead power line, it is necessary to de-energize it. If it is impossible to relieve stress, it is allowed to carry out work, subject to the following requirements set forth in.
These measures make it possible to increase the reliability and safety of organizational and technological solutions used in construction (reconstruction) in dense urban areas. This is relevant and one of the most important areas in modern construction.
Bibliography:
- Asaul A.N., Kazakov Yu.N., Ipanov V.I. Reconstruction and restoration of real estate objects. Textbook edited by Doctor of Economics, Professor A.N. Asaula. - St. Petersburg: Humanistics, 2005. - 288s.
- On approval of the rules for the preparation and production of earthworks, arrangement and maintenance of construction sites in the city of Moscow. Decree of the Government of Moscow No. 857-PP of December 7, 2004 - 126s.
- Pogodin D.A., Ermolaev A.I. The main problems arising in the construction or reconstruction of residential buildings in conditions of dense urban development // Actual issues of modern construction of industrial regions of Russia: Proceedings of the All-Russian Scientific and Practical Conference with International Participation. / Sib. state industry un-t; under the general editorship of I.V. Zorya, A.Yu. Stolboushkina, A.A. Olennikov. - Novokuznetsk: Ed. Center SibGIU, 2016. - 339 p.
- Pogodin D.A., Kozlov V.A. On the problems of reconstruction of residential buildings in cramped conditions // Effective building structures: theory and practice: collection of articles of the XIV International Scientific and Technical Conference. - Penza: Privolzhsky House of Knowledge, 2014. - P. 105 - 108.
- Roytman, V.M. Labor safety at the objects of urban construction and economy when using cranes and lifts / V.M. Roitman, N.P. Umnyakova, O.I. Chernyshev. - Moscow: Gostekhizdat, 2007. - 176 p.
- SNiP 12-03-2001. Labor safety in construction. Part I General requirements/ FGU TsOTS Gosstroy of Russia.- M.: Stroyizdat, 2001.
V.A.Usanov, General Director;
A.L. Khlopotin, Chief Engineer;
R.M. Yunusov, ex-director,
JSC "Lyubertskaya heating network", Lyubertsy
Introduction
Lyubertsy Heating Network was founded on October 1, 1969. At that time, the enterprise included 20 boiler houses with an installed capacity of 121.6 Gcal/h, which served only 152 people. To date, OJSC "Lyubertskaya Teploset" is an organization that employs more than 500 people. It has 28 boiler houses with an installed capacity of 325 Gcal/h, 64 central heating stations, 6 ITPs and about 170 km of networks in 2-pipe terms. Thermal networks operate according to temperature schedules: 150-70 ° C, with a cutoff at 130 ° C, and 95-70 ° C. The annual volume of heat sales is more than one million Gcal.
Lyubertsy, being the fifth largest city in the Moscow region and the first in terms of population density, is located so close to Moscow that it is sometimes difficult to understand where one city ends and another begins. Such a neighborhood with a multi-million dollar capital imposes a number of features in terms of the work and interaction of all engineering services, and difficulties cannot be avoided. There are several large ground intercity transport hubs (including the railway that divided the city into two parts), and local engineering communications are adjacent to the capital, which, being laid almost in the center of Lyubertsy, provide heat, water and electricity to remote areas of Moscow ( an example of this is the main heat pipeline Du 400, owned by the Moscow Heating Network Company). Naturally, the production strategy of the enterprise JSC "Lyubertskaya Teploset" must be built taking into account these factors.
Back in the mid-eighties, when the demand for thermal energy increased in the city, the possibility of reconstructing the heat supply system of some districts with their connection to the Moscow central heating system was considered. In 1986, an agreement was concluded with OAO Mosenergo, OAO MOEK, and others on the allocation of thermal capacities for the enterprise, and for almost 20 years we have been working under an agreement on mutual cooperation with the prefecture of the South-Eastern District of the capital. This turned out to be the most economically rational solution compared to the construction of new sources. The possibility of obtaining thermal energy from Moscow power generating enterprises helped eliminate a number of small, unprofitable boiler houses: during this period, 26 obsolete and obsolete facilities were decommissioned, which had worked for 40-50 years. Since 2009, another 15 central heating stations and ITPs have been switched to the Moscow Central Heating System, and such events are planned to be carried out in the future.
This does not mean that their own sources are completely closed. On a city scale, the share of purchased thermal energy is only 25%, so the systematic reconstruction of boiler houses and central heating centers is an integral part of the company's development programs.
Organizational events
In any case, before developing enterprise development programs, you need to see where this development will go. In the late 1990s, the depreciation of heating networks was more than 60%, equipment - more than 40%, depreciation of the fleet of special equipment - 100%. In addition, I had to work in difficult financial conditions, when, due to accumulated debts, gas was turned off for the entire summer period, and salaries had to wait for several months.
As a preventive measure, in 2006 the first investment program was adopted, which was supported by the Lyubertsy district administration, an energy saving plan was developed and leasing schemes were used for the supply of equipment, according to which equipment was first purchased, and then mutual settlements were made. The plan included the installation of metering devices, the replacement of gas meters with new ones with an electronic corrector, a diagnostic service was organized to conduct an express analysis of gas combustion modes in boilers; in 2009, thermal aerial photography of heating networks was carried out.
Around the same time, as part of the implementation of the Federal Law "On Energy Saving", a heat carrier metering system was organized both at its facilities - boiler houses, central heating stations, and the problem of providing budgetary organizations with metering devices - about 70 social facilities was solved. To equip their facilities with metering devices, they used their own capabilities, and equipped social facilities with the help of budget funds. This made it possible to monitor: the implementation of temperature schedules, the hydraulic regime of networks, to check the quantity and quality of the supplied thermal energy. The introduction of metering devices gives a very good economic effect, and the dispatching accounting system allows not only collecting, storing and processing data from metering devices, but also monitoring their condition in real time.
Work was also carried out on the installation of metering devices. cold water, going to the needs of hot water supply (about 100 objects), and a metering system was organized jointly with OJSC "Lyubertsy Vodokanal" to maintain the regulatory requirements for the temperature regime of hot water supply.
The installation of meters made it possible to solve problems with the hydraulic regime in secondary networks, because if on our side the hydraulics are observed through the installed pumping groups, then the management companies (MC) thought about why typical houses have different heat consumption, and residents are pushing the UK to carry out repair and adjustments at home.
Again, the meters played a double role: on the one hand, it’s good that the consumer himself saw that his system was not working properly and forced the UK to move, and on the other hand, the talk of the town is the notorious heating of water and an increase in enterprise costs.
The fact is that at one time a number of houses and networks were designed taking into account superheated water with the operation of an elevator. When the new sanitary norms, then there was a problem with the heat supply of buildings where elevator units are installed, because in order to maintain the temperature of hot water at the point of water intake at the level of 60 ° C, it was necessary to raise the lower temperature of the supplied coolant above 70 ° C, and, consequently, to revise all schedules, but at the same time there were enormous overflows in the off-season. I wanted to get away from such a scheme where technical capabilities allowed, "closing" the network circuit.
To switch to an independent system and a single hydraulic regime, taking into account heating networks, risers in houses that were laid with a reduced diameter for superheated water, an accurate hydraulic calculation of the throughput of building heating systems was required. This was done by our specialists, after which the elevator units were dismantled and the transition to an independent heat supply scheme for buildings through the central heating center was carried out. Thus, the operation of heating networks throughout the northern part of the city was optimized.
In 2010, the company introduced an internal energy audit system. The start was a third-party energy survey, which allowed us to identify problem areas and shortcomings in the work. Of course, this survey was not a panacea for solving all the accumulated technical and organizational problems, but it became a launching pad for the start of effective management of technological processes for the production and distribution of thermal energy.
First of all, unprofitable objects were identified, inefficient heat engineering equipment, which does not allow the proper use of incoming resources. Again, a clear understanding of the depth of this unprofitability was necessary: which boiler houses are completely unpromising, and in which something else can be done to make it profitable: increase capacity, carry out some kind of reconstruction, train staff competently (a paradox, but sometimes this was sufficient). Promising and profitable directions were also determined here.
Generally speaking, this A complex approach allowed us only in 2010 to reduce gas consumption by 4.7% and reduce electricity consumption by 7%.
The results of the energy survey at the first stage did not offer ready-made solutions, but made it possible to really look at those things that had been done wrong in their time.
First of all, we paid attention to the main sources of thermal energy, such as a large quarterly boiler house No. 201 on the northern side of the city, which has been operating since 1978. In 2000, its reconstruction was carried out at the expense of the regional budget with an increase in capacity in connection with the upcoming a sports complex with a swimming pool and a huge shopping and entertainment center. The boiler house, with an installed capacity of 62 Gcal/h, initially had three KVGM-20 hot water boilers (to cover the heating load and hot water supply) and two E 1.0/0.9 steam boilers for own needs (deaeration and reserve fuel oil facilities).
The municipal contract for the reconstruction, concluded with a certain military organization, provided for the complete dismantling of the steam group and the installation of two DE-16/24 boilers with their own deaerator and steam pipeline. In addition, the project included the installation of three steam turbine generators with a capacity of 600 kW each to generate electricity.
This project, despite a number of our comments, passed all the approvals, a building permit was received. In technical terms, this was implemented as follows: according to the project, steam with a pressure of 11 kgf / cm 2 at the outlet of the boiler comes to the turbine, expands, does work and, with residual pressure, is sent to the heat exchanger to heat the network water.
Synchronization with the city's power grids was also implied, because the ignition of the boilers was provided for by the city's electricity, and then, when the boiler room entered the generation mode, it had to completely switch to self-sufficiency with a power load. Synchronization of the generator with the network was provided by a specialized automation system, the control unit of which was located in a separate panel.
At the same time, the power consumption of the boiler house is on average about 400 kW. The power margin has been calculated taking into account the maximum energy consumption, for example, the short-term operation of two fans connected in parallel when switching from one to another, or a similar need to switch from one pump to another. Unfortunately, at full load, these steam generators could not even reach 360 kW, possibly due to technical flaws - the serial numbers on them were 001, 002, 003.
In addition, the disadvantage of the project was the installation of a VFD on the network pumps in front of the boiler. The idea of the designers was to use the soft starter and the frequency converter of the mains pump to adjust the hydraulic mode. But when designing, it was not taken into account that the process of adjusting the operating mode of the boiler depends not only on its operating pressure, but also on the flow of water, and the safety automation is set to a critical decrease in these parameters. Therefore, with the declared scheme, as soon as the frequency converter starts to lower the output frequency (voltage), the boiler's AB is activated. Subsequently, we abandoned the use of a frequency converter according to the project, but left a soft start on all four pumps.
The way out of this situation was understandable, but this meant another change in the technological scheme of the boiler house, for which documentary confirmation is required. When the conducted energy audit officially showed the direction of development of the technological re-equipment of the boiler house, we legally began to prepare for a new reconstruction and the opportunity to get rid of unnecessary steam generators.
As a result of the dismantling of turbogenerators and the reconstruction of automated process control systems for steam boilers, the possibility of their simultaneous operation was realized and the heat output increased.
In 2006, it was decided to gradually change the water heating group using the budget funds allocated at that time. The replacement of KVGM-20 boilers was justified by the fact that, since the standard period of their operation has ended, it is necessary to obtain an annual expert opinion and permission for further operation, because. experts, being reinsured, set the minimum period - 1 year. Given the annual cost of repairs and expertise, this decision was justified. At the same time, no reconstruction of the building was required: the equipment was chosen to be similar, with installation at the same sites. The first two boilers were brought disassembled, so there were no problems during installation: the pipe part, the replacement of collectors was carried out right on the spot, after which the lining was made. All work was carried out only in the summer, the boiler room remained in operation.
But a year later, I had to tinker with the third boiler. It was delivered assembled. They did not dare to cut, because then the dimensions could be violated during assembly. I had to measure with tape measures all the distances of the building structures of the boiler shop literally to the millimeter. It turned out that the boiler could pass through the window opening if the brickwork was slightly dismantled from below, but “back to back”. They made a flooring like a railway skating rink and early in the morning, as soon as it dawned (so that the boiler did not shake with the wind), they carefully pulled it up and rolled it inside with a winch. The rest was a matter of technique.
The next stage was the reconstruction of the reserve fuel economy (RTH) with the replacement of fuel oil with diesel fuel. The fact is that a dead-end fuel oil pipeline was originally designed in the boiler room, which did not provide for a system for collecting and returning condensate formed during its heating with steam, there was no storm sewer on the territory of the boiler room, and a system for cleaning condensate from fuel oil impurities. Therefore, the extremely time-consuming and dirty process of switching to liquid fuel, coupled with the listed shortcomings of the fuel supply scheme, led to significant costs for the maintenance of RTX and large losses of thermal energy and coolant. Several Yet important points In favor of diesel fuel, the choice was influenced by its longer shelf life and problems with the disposal of viscous residues of fuel oil. As a result, after receiving all the relevant permits for the conversion of RTH, a new container with a volume of 400 m 3 for diesel fuel was delivered to the territory of the boiler house (Fig. 1), where superheated water is used as a heat carrier if it is necessary to heat it. Accordingly, for this purpose, the boiler equipment was modernized, replacing the burners.
Rice. 1. Reserve fuel economy of boiler house No. 201.
As soon as steam began to be used only on deaerators, we approached the main thing - the transfer of steam boilers to a water-heating mode. This was done to simplify the thermal scheme of the boiler house and get rid of steam-water heat exchangers, which made it possible to increase the available pressure at the distant central heating network from 0.4 to 12 m while maintaining the existing pumping group.
Rice. 2. Storage tank (former atmospheric deaerator).
Due to the fact that the old atmospheric deaerator ceased to function due to the lack of steam, a new, vacuum, accumulative type was installed, with a volume of 25 m 3, but the atmospheric deaerator was kept as a storage tank (Fig. 2). In the event of a leak above the standard value, it is possible to replenish the losses of network water until the location of the damage is detected. While the vacuum deaerator is under warranty service, therefore, in case of violations in the mode or malfunctions, specialists of the service group are called to debug. So problems with the operation of equipment in this moment no. The TOVP system remained the same - 2-stage Na-cationization.
Of course, all these activities were not carried out in one year, but based on financial capabilities and quite systematically.
After the reconstruction, the available capacity of the boiler house increased to 84 Gcal/h. The ongoing changes in this boiler house are legal, all the necessary permits from Rostekhnadzor have been received.
I would like to note that the replacement of equipment, the modernization of sources is almost always carried out without the withdrawal of boiler houses from production - the reconstruction takes place at an existing facility.
Rice. 3. Boiler room No. 203 after reconstruction.
So it was at the small boiler house No. 203, in the area of which it was planned to build a residential complex. The design load presented by the developer showed that the capacity of the boiler house is not enough (9 boilers ZIO-60, with a capacity of 0.8 Gcal / h). The layout of the district did not allow to locate a new boiler house in the development area, it was also impossible to attach an additional room for new boilers in the old one, because. the facility is located on a federal site. Then a decision was made on the reconstruction, which began with the dismantling of part of the boilers and auxiliary equipment, leaving at the possible minimum - for the needs of hot water supply during the non-heating period. At the same time, dismantling of old equipment, demolition of boilers, installation of a new multi-stem chimney was carried out when the boiler house was operating in normal mode. As a result, we still had to make a small extension, where we placed the central heating station with plate heaters, as well as premises for personnel. And in the main building, next to the four remaining old boilers, which were kept in reserve, three Russian-made fire-tube boilers were installed (Fig. 3), with imported burners, with a capacity of 4.3 Gcal each; network pumps with optimized flow path, with VFD; installation of continuous HVP with a productivity of 7 m 3 / h. All equipment operates in automatic mode depending on the specified parameters. Results:
■ the installed capacity was increased from 7.2 to 12.9 Gcal/h - without increasing the gas limit (+3.2 Gcal/h - reserve);
■ an independent heat supply scheme was implemented;
■ increased efficiency from 82 to 92%;
■ optimized fuel consumption: specific gas consumption decreased from 176.97 to 155.28 kg/Gcal;
■ reduced specific power consumption by 5%;
■ reduced costs for TOVP;
■ reduced operating costs by 20%;
■ improved working conditions for service personnel.
The project was implemented on the terms of co-financing with the developer.
And although at this stage the capacity of the boiler house is calculated with a good margin, the remaining boilers and the old pipe are also planned to be changed over time - the city continues to expand.
circuit solutions
In addition to the ongoing repair work, in 2013, using an electronic model of the heat supply system, a project was developed in such a promising area as the loopback of boiler houses. The difficulty lies in the fact that Lyubertsy is a very scattered and dispersed city, and most importantly, it is divided by a railway track, so large quarterly boiler houses, which have an installed capacity of about 80-90 Gcal / h, cannot be looped back to each other, although this would be ideal option. But it is possible to loop small boiler houses (with an installed capacity of 6-9 Gcal / h) with these large sources for the summer period. As a result of the justification and calculation performed by our specialists, it turned out that some boiler houses can be left in the operation mode of the CHP all year round. At these boiler houses, heat exchange equipment was installed for the heating load, separately for hot water supply, all the necessary pipelines were laid, and some of the previously existing ones were also involved.
The purpose of the activities:
■ stabilization of the heat supply regime;
■ exclusion of emergencies;
■ maintaining the load of hot water supply during a 2-week shutdown of boiler houses for the period of repair;
■ significant fuel economy with good loading of large sources;
■ the economic effect of reducing the number of service personnel (given that the shift of the operator lasts 12 hours, in the small boiler house 1 person/day and 2 people/night are involved in the summer period. In the case when gas equipment disabled, and the boiler room operates in the central heating mode, then two options are considered: either 1 person works. day after three (as a rule, these are seasonal workers who are comfortable working in that
com schedule), or the boiler room, as an object, is included in the central heating bypass system and then the operation of the equipment is controlled in accordance with the bypass schedule);
■ reduction of electricity consumption;
■ Boiler house space optimization: during reconstruction, old shell-and-tube heaters are replaced with lamellar ones, other pumping groups, mostly of vertical type, more compact TOVP equipment are installed.
Of course, when implementing these projects, a very large amount of work has to be done, but the effect is worth it!
Over the past 1.5 years, 5 objects have been looped in this way. In the future, it is planned to transfer all small boiler houses to the central heating mode, and transfer their load to large boiler houses, after unloading them again, for example, by transferring a number of facilities to the Moscow central heating system.
With regard to new sources, the construction of which is necessary in remote areas, now this is most often carried out by the developer. Since the Lyubertsy heating network is a UTO, on the basis of the issued technical conditions for connection, boiler houses built for new areas are transferred to municipal ownership. Incidentally, representatives of construction organizations are also interested in this, as they understand the difficulties they will face in owning and operating such unprofitable facilities. This has become especially relevant recently, when, firstly, the collection of payments has fallen sharply, secondly, the supply of thermal energy has decreased due to warm winters, and thirdly, experience shows that only a small part of the population is settled in the first few years , which means that you will have to pay for all the energy for 5-6 years yourself, and after this period, depreciation will already begin and, therefore, it is necessary to make some financial investments. We, of course, do not mind at all, so the construction of new facilities is carried out only under our control. To this end, the company has created a group of technical supervision, which leads the facility until commissioning.
Based on the accumulated experience, we are trying to issue technical specifications for connection to heating networks with a perspective on the source: taking into account a certain margin of the designed capacity, so that there is variability. Here we also lay the reconstruction of heating networks (if necessary) and also taking into account the possible future load.
Attention - TsTP
In addition to sources, one should not forget about heating points, which are extremely important to maintain in proper technical condition.
Financing of such works is carried out mainly within the framework of investment programs. For example, the implementation of such a program in 2011-2014. allowed to repair a number of objects in different parts of the city.
The dispatching of the central heating substation is also carried out without fail according to the scheme: equipment operation - technological mode - operation parameters - emergency situations. Everything is brought together in a single emergency dispatch center that exercises control and management, which currently covers the central and southern parts of the city. Unfortunately, the creation of a single city dispatch service is problematic due to the railway that separated the north side. A solution is still being sought on how to implement this stage in a complex.
But still, the presence of a control system does not replace visual observation, since it fixes not the cause of the problem, but only the end result, so the bypass system cannot be completely abandoned. For example, with a small leak, when there is no sharp drop in pressure in the network, the control device remains in operation and continues to take readings, but after a day the pump will be in the water and stop. Of course, the lineman's work is hard, especially for older workers - on average, they "run" about 6 km a day, but now young people are being attracted, who cope with the task quite well with the help of a bicycle.
In addition to standard equipment replacement solutions, investors have recently appeared who are interested in our central heating from a commercial point of view. This applies to those objects under which the land is registered as the property of the organization, and the size of the site allows you to build some not very large social facility there: a store, a laundry reception point or a workshop (1-2 floors and an attic - so as not to go to Minstroy). When drawing up the contract, it is stipulated that the investor will dismantle this CHP (under the control of the heating network, of course) together with the building. A new building is being built on the vacant site, which also houses the renovated central heating station. But the most important thing is that all this is done without shutting down: sometimes the building itself is not yet there, and the equipment has already been installed, practically under the open sky (Fig. 4). Last year, according to the described scheme, two central heating stations were reconstructed, now the third one is being completed (finishing work is underway).
Rice. 4. TsTP "under the open sky".
As for pumps, in terms of price-quality ratio, of course, preference is given to well-known brands, the production of which has already been established in Russia. Although today there is an alternative to this equipment - Chinese pumps, similar in their characteristics and much cheaper. From German, for example, they differ only in the inter-flange distance (the Chinese have it less). For testing, such pumps were installed at several sites, where they have proven themselves well. Vertical type pumps are a good layout solution - they fit optimally in size, especially in old walls where space is limited.
Such energy-saving measures as the installation of frequency-pulse converters, which have already become classic, are also being carried out. But here, again, it must be understood that this requires interconnection with the operation of safety automation, as mentioned above. In large quarterly boiler houses, VFDs are installed on all equipment: smoke exhausters, fans, network groups. Smaller VFDs are installed: for cold water - 100% (this is due to the need for guaranteed pressure support, especially during periods of max and min drawdown), also on smoke exhausters and fans - they work very well and allow you to get away from mechanical control of dampers and dampers; on network pumps - as needed. In the central heating station - on pumping groups (depending on power), because this stabilizes the pressure in hot water as well, avoiding unnecessary hydraulic loads and shocks.
Thermal networks: modeling and reality
Replacing dilapidated heating networks is a priority: the organization annually shifts 10-12 km of pipelines with the involvement of contractors. At the moment, the share of dilapidated heating networks in JSC "Lyubertskaya Teploset" has decreased to 30-32%. Over the past five years alone, about 70 km of pipelines have been replaced with pipes with polyurethane foam insulation and a UEC system, and secondary networks are now being reconstructed.
In preparation for repairs, an annual analysis of work in the winter period is carried out, based on the results of which plans are drawn up for major and current repairs, and equipment replacement.
When planning the reconstruction of pipelines of heat networks, an approach based on system analysis is also used. The overhaul plan includes not only those heating network, the shifting of which is due to their unsatisfactory condition. Sometimes it becomes necessary to shift some section, taking into account the promising steps required to solve an urgent problem, for example, in the case of a loopback of source networks.
The electronic model of the heat supply system, which allows solving many specific issues, is of great help in this. The map contains not only heating networks owned by JSC "Lyubertskaya Teploset", but also other engineering communications with all sizes, so it is possible to track all intersections with third-party services, roadbeds, etc.
Other characteristics and dates of input-output can be found in the PTO, where a specially trained team has been created for technical support and database support. Access to the program is opened from any PC of the enterprise for each employee. Using the electronic map, you can determine the coverage area in the event of emergency situations of a different nature, localize emergency areas, make a switch and work further to eliminate the accident. In addition, the program allows you to simulate the creation of networks of various configurations, for example, loopback or transfer to a closed circuit. And although there is a passport for each section, where all changes are necessarily entered, the electronic map is an ideal tool for modeling heat distribution, hydraulic regime, carrying out all kinds of calculations and planning repairs.
If the electronic model shows that the capacity of the calculated area is insufficient or the hydraulics are broken, then the replacement of pipes is included in the repair plan. If software modeling is not enough, if there is a lack of data, a portable instrument complex-flowmeter is used, with which specialists go to the site, install sensors in a thermal chamber or in a section of a heating network (with preliminary drilling) and measure speed, water flow, etc. parameters needed to refine the calculations.
When transferring pipelines, control is inevitable at all stages of work with the maintenance of all necessary documentation. Even at the time of the tender, a strict selection policy is carried out when choosing a contractor. Despite the information they provide or letters of recommendation, the company conducts an additional check - papers alone cannot be trusted. The technical supervision engineer is responsible for this, he monitors all the actions of the contractor. Current control at work sites is carried out by the head of the operational site - he signs all acts of hidden work, and all demand is from him. Members of the commission for acceptance of work under the contract are also: a specialist of the Operations Department, a heat supervision engineer, a chief engineer and a deputy general director. Much attention is paid to keeping a log of the production of works.
As for the technical part, here, Firstly, input control is required: if, for example, the quality of the pipeline is not satisfied, the delivery is simply canceled. Secondly, until recently, the company has never purchased ready-made pre-insulated pipes. Instead, a solid-drawn steel pipe with an increased wall thickness was purchased, which, after passing the input control, was sent for applying an insulating layer to one of the plants near Moscow. This increases the service life, because even 1 mm of excess pipe thickness plays a significant role. Even taking into account the increased cost of such pipes, the solution is economically justified, because. significantly increases the service life (up to 5 years).
We stopped using welded pipes since the perestroika period, when we encountered low-quality products, and the steel pipe began to break into sharp fragments during operation, like cast iron. Since then, despite a single such case, a thorough incoming inspection of the metal and 100% flaw detection of welds have been carried out.
As soon as pre-insulated pipes began to be used at the enterprise, the organization of the UEC system immediately began, which made it possible to reduce the number of crawlers and optimize the operation of heating networks. If with the dispatching and automation of boiler houses and central heating stations all the advantages are clear, then the installation of the UEC system on pipelines is considered a little more luxury. Although here it is not only a matter of determining the location of the leak. In our case, in the presence of SODK, Moscow heat supply companies do not require hydraulic tests, it is enough for them to take system readings. However, with all our desires, we cannot create a unified dispatch service, a unified control system: firstly, not all networks have yet been transferred, and secondly, as mentioned earlier, it interferes Railway. Therefore, for the time being, the coverage area is the district.
If with the help of contractors the repair of main pipelines is carried out, then the own overhaul team works on the secondary networks (intra-quarter wiring). For obvious reasons, so that the brigade does not stand idle in the winter, its employees are involved in the repairs of the central heating substation, in boiler rooms, in the re-laying of cold water pipelines, etc.
Unfortunately, this year we had to cut the amount of funding due to the strong rise in the cost of materials. In 2014 overhaul was completed for 160 million rubles. Of course, I would like to do even more, but, based on the tariff possibilities, only the most basic is taken.
Organization of the water-chemical regime
Due to the poor quality of the source water, chemical water control is very seriously organized at the enterprise: in addition to the fact that each boiler house has its own chemical laboratory and responsible employees who carry out all the necessary measures to maintain the appropriate water regime, there is a Control Service for technological and water-chemical modes, where there is a laboratory. Once a week, specialists of this service visit all facilities, take tests and check the compliance of entries in the TOVP maintenance logbook. The need for this is confirmed by the fact that deironing stations in the city are not installed everywhere and the water contains a large amount of iron, so the convective surfaces of the boilers are “knocked out” decently, which means that these surfaces have to be washed periodically with “chemistry” or changed.
As water treatment in boiler houses, the Na-cationization system is mainly used. All filters are transferred from plastic caps to stainless steel. Plastic, with all its advantages of working in an aggressive environment, turned out to be extremely inconvenient in operation: on plastic caps, after all, the thread is also plastic - during operation it often breaks even with small pressure drops, after which the cation exchanger ends up in the boiler water, then you have to stop filter, open it and clean it. Naturally, these are additional costs, and the consumption of the reagent increases significantly.
At new facilities for stabilization water treatment (as a measure to prevent the formation of deposits of scale formation and corrosion products), complexones are used. Equipment for anti-scale and anti-corrosion treatment of water was also installed at the central heating station.
Rice. 5. The result of cleaning the DHW plate heaters.
But, unfortunately, in some areas there are still problems with DHW equipment and pipelines due to inadequate quality of raw water: literally 2-3 months after the start of operation of a new heater, and its surface, and polyethylene pipes DHWs are completely clogged with deposits (Fig. 5). The examination showed that the main pollution is iron and silt inclusions. Moreover, before the introduction of new requirements for the temperature of hot water, when heated to 55 ° C, there were fewer such pollution. When the temperature rises to 60 ° C, these fractions are immediately sealed. Therefore, if earlier, according to the PPR schedule, the TO was cleaned once a year, now it has to be opened once a quarter. Moreover, a check of cold tap water at water points among the population did not reveal such inclusions.
The supposed reason is that not all suppliers have an iron removal station, and therefore the cold water supplied through the 2-pipe system is purified for cold water needs, but not for hot water. And the second problem is dead-end cold water networks, when loopback is provided for in the circuit, the equipment becomes clogged less often.
Now, since according to SanPiN 2.1.4.2496-09 hot water equated to drinking standards, there was a real chance to compete with water supply organizations for quality. Therefore, the enterprise is preparing a preparatory and accumulative base of documentation (with all ongoing analyzes, sediment samples and examinations) in order to be able to put forward reasonable requirements for a water supply organization.
Conclusion
In the conditions of the new economic crisis, when many enterprises are winding down their activities, showing caution, taking a wait-and-see attitude, we do not have such an opportunity - after all, the whole city, its inhabitants depend on our actions. We must work for the future, i.e. prevent incidents, maintain correct hydraulic and temperature regime. Therefore, a new Investment Program for 2015-2018 has now been approved, and there are certain plans regarding ongoing measures to repair and modernize equipment and networks that are waiting to be implemented in the coming years.
CONSTRUCTION OF BUILDINGS AND STRUCTURES UNDER DIFFICULT CONSTRUCTION CONDITIONS
The main advantages of Ethernet technology
1. The main advantage of Ethernet networks, thanks to which they have become so popular, is their cost-effectiveness. To build a network, it is enough to have one network adapter for each computer, plus one physical segment of a coaxial cable of the required length.
2. In addition, fairly simple algorithms for accessing the medium, addressing and transmitting data are implemented in Ethernet networks. The simplicity of the network logic leads to a simplification and, accordingly, a reduction in the cost of network adapters and their drivers. For the same reason, Ethernet network adapters are highly reliable.
3. And, finally, another remarkable property of Ethernet networks is their good extensibility, that is, the ability to connect new nodes.
Other underlying networking technologies such as Token Ring and FDDI, while distinct, share many similarities with Ethernet. First of all, this is the use of regular fixed topologies ("hierarchical star" and "ring"), as well as shared data transmission media. Significant differences between one technology and another are related to the peculiarities of the used method of access to a shared environment. Thus, the differences between Ethernet technology and Token Ring technology are largely determined by the specifics of the media separation methods embedded in them - a random access algorithm in Ethernet and an access method by passing a token in Token Ring.
The construction of buildings and structures has to be carried out in various construction conditions: in large cities and in uninhabited areas; in winter and in hot climates; in difficult geological and hydrological conditions and permafrost. These so-called extreme construction conditions impose certain restrictions on standard work production technologies or require the development of new technological regulations.
Consider some specific construction conditions.
During construction in conditions of dense urban development, a number of factors arise, the observance of which ensures the quality and durability of not only the directly erected objects, but also the surrounding structures. These factors include:
§ the need to operate facilities located in the immediate vicinity of the building site;
§ the impossibility of locating on the construction site the entire complex of construction infrastructure provided for by the technology for the production of works (household and engineering structures, machines and mechanisms);
§ the need to develop technical and technological measures aimed at protecting the ecological environment of the facility and existing buildings.
The limited space allocated for construction prevents the full deployment of the construction site. At the same time, there is a whole range of mandatory measures, without which the construction will be suspended by the regulatory authorities. These include fire prevention measures and ensuring labor protection and safety equipment for construction and installation works:
§ Availability of evacuation passages on the construction site;
§ prepared for use fire hydrants and emergency fire fighting equipment;
§ fencing of the construction site and hazardous areas (pit, erection stationary crane, structure warehouses);
§ canopies over pedestrian areas adjacent to the construction site.
In cases of a limited area of the building site outside the construction site may be located: administrative and amenity premises; canteens and sanitary facilities; reinforcing, carpentry and locksmith shops and workshops; open and closed warehouses. When organizing a construction plan, it is advisable to provide for these purposes restorative territories, by agreement with their owners. To limit storage space, it is possible to organize the installation of building structures from wheels, use the most enlarged elements, and use advanced building technologies tested in similar conditions. Sometimes intermediate storage sites are organized as close as possible to the facility under construction. In this case, the required materials and products are delivered to the facility as needed and placed in the zone of use. The use of intermediate warehouses imposes strict requirements on the participants in the construction industry (including suppliers and customers) for the implementation of work schedules and the delivery of technological equipment.
Administrative and amenity premises, taken out of the construction site, can be located in existing buildings or in newly erected campuses, as close as possible to the construction site. The areas used must meet the regulatory requirements for minimum sanitary and hygienic standards per worker. Delivery of workers to the facility is carried out by the customer service.
A serious problem in conditions of dense urban development is the placement of large construction machines and cranes directly on the site. Cranes and concrete pumps must be located on the construction site or in close proximity to it. However, in the immediate vicinity of them there are previously built buildings and structures that prevent the movement of the boom of a crane or concrete pump, or there is no way to lay crane tracks. In this case, easy-to-mount stationary-type cranes (self-elevating) are used on a relatively small foundation or (for concrete work) concrete-laying complexes are used, associated with the vertical supply of concrete mixture inside the building and its subsequent distribution on the tier by manipulators of various types . In technological design, one should strive to make the most of the experience of building in similar conditions and modern mechanization.
Maintaining the operational properties of the existing building.
Buildings located in close proximity to a development site may be subject to a number of impacts that occur during the construction of a new building. These impacts include: excavation of the pit in the immediate vicinity of the building and vibration from construction machines and mechanisms located in the immediate vicinity.
The first group of defects arises from changes in the static characteristics of the bases. The removal of soil near the foundations of buildings leads to a change in the force field around them. Therefore, the creation of a constructive balance allows you to compensate for the resulting impacts.
The second group of defects is a consequence of the dynamic effects of working construction machines and mechanisms. Their reduction to acceptable levels is achieved by the implementation of special engineering measures.
Specific measures aimed at maintaining the operational properties of the existing development are developed in the projects for the production of works. These include:
§ strengthening of bases and foundations, which should ensure the static balance of the building for the period of the open excavation until the erection of the supporting structures of the basement of the new building and backfilling of the sinuses of the excavation. The following design solutions are most often used: "wall in the ground", sheet piling, reinforcement of foundations and basement walls of existing buildings, strengthening of foundation soils by injection methods;
§ development of pits and construction of foundations in stages - this allows to reduce the consumption of temporary retaining structures;
§ selection of machines and mechanisms with minimal dynamic characteristics;
§ vibration isolation of the soil mass adjacent to existing buildings and structures.
