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;

Impossibility of location on the construction site of 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.

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.

Maintaining the operational properties of existing buildings. 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. This:

Excerpt in the immediate vicinity of the building excavation for new construction;

Vibration from those located in close proximity construction machines and mechanisms.

Their reduction to acceptable levels is achieved by the implementation of special engineering measures.

Strengthening foundations and foundations. Before the beginning earthworks necessary

to strengthen the bases and foundations of existing structures and urban

infrastructure located in close proximity to the construction site.

Strengthening the structures of the bases and foundations should ensure the static balance of the building for the period of the excavated pit until the erection of the supporting structures of the underground part of the new building.

Measures to strengthen the bases and foundations are divided, depending on the impact on the supporting frame and adjacent bases, into permanent and temporary. Permanent solutions include those solutions, in the implementation of which the strengthening of the structure becomes an integral part of the structure under construction.

Before the start of earthworks, sheet piling is arranged along the entire perimeter of the pit (Fig. 26.2). Target

sheet piling to prevent slipping and collapse of soil masses located outside the construction site.

In areas where existing structures are directly adjacent to the boundary of the construction site, it is necessary to carry out measures to strengthen their underground structures. To do this, wells are drilled passing through the body of the location, their characteristics are length, diameter, class of the existing foundation, and concrete is injected into them under pressure. The number of piles, mesbeton - is determined by calculation.

At the end of the construction of the underground part of the building, sheet piling is usually removed from the ground, it can be reused. Therefore, the installation of sheet piling can be attributed to temporary measures to strengthen the foundations. Unlike sheet piles, bored-injection piles remain in the body of reinforced foundations even after the completion of new construction. The construction of the underground part of the building can also be attributed to permanent measures by means of the implementation of the previously discussed “wall in the ground” in detail. However, as noted, the "wall in the ground" is a rather complex and expensive engineering structure, and its construction is economically feasible only in cases of large-scale or unique construction.

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 foundations 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 are most commonly used Constructive decisions: "wall in the ground", sheet piling, strengthening of foundations and basement walls of existing buildings, strengthening of foundation soils by injection methods;

The development of pits and the construction of foundations in bursts - 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.

Protection of the ecological environment. The impacts of the facility under construction on the surrounding buildings and infrastructure are mainly as follows:

Noise effect accompanying any construction process;

Dynamic impact of working machines and mechanisms;

Release to the atmosphere a large number dust particles of fine and medium fractions;

Production of a huge amount of construction and household waste;

Increased discharge of wastewater into existing and reconstructed city networks, as well as to the soil;

Violation of the usual transport schemes due to the restriction, and sometimes a complete ban on traffic on the streets on which construction is carried out.

To reduce the noise level at the construction site, the foremen are required to use noise-reducing techniques and equipment at the stage of passing the state examination, that is, in the process of agreeing on the main technical and technological solutions. For example, when carrying out piling and sheet piling, the use of screw-dried piles or driving piles into drilled wells is a mandatory requirement. As lifting and concrete-feeding machines, equipment with lower noise characteristics is recommended with equal overall technical capabilities. Pneumatic jackhammers that cause a special noise effect are replaced by electro-mechanical ones. A temporary restriction is introduced on the conduct of all types of work at the construction site, with a special allocation of the permitted period for the most noisy work, such as installation, welding, concrete, etc.

Approximately in the same vein, measures are being taken to reduce the dynamic impact of operating machines and mechanisms. In addition to introducing restrictions on the use of certain means of mechanization, measures are being developed for the installation of technical structures aimed at reducing dynamic loads on soils and foundations. To do this, in the areas of installation of cranes, concrete feeders and other machines that cause dynamic effects, damping (forced vibration damping) engineering structures are installed, which significantly reduce the spread of dynamic vibrations to the surrounding bases and soils, and, consequently, to the existing buildings.

The emission of dust particles of small and medium fractions into the atmosphere is the most difficult parameter to control. The maximum amount of dusty particles is emitted into

atmosphere mainly during finishing work, such as puttying and painting. Therefore, by ensuring the supply of the largest number of pre-painted products and equipment to the construction site, it is possible to minimize the implementation of these processes in construction conditions, and, consequently, reduce harmful emissions into the atmosphere. In addition, in processes associated with mechanical impact on erected reinforced concrete and stone structures, such as drilling, gouging, adjusting sizes, etc., it is recommended to moisten the treated surfaces with plenty of water before and during work. This leads to the deposition of dusty particles on horizontal surfaces, followed by their removal from the site along with construction debris.

From the very beginning of the construction of the facility, a huge amount of construction and household waste accumulates, which can lead to pollution of nearby areas. Therefore, it is necessary to establish a clear system for the collection and removal of construction and household waste from the facility. On the territory of the construction site, separate containers are installed for construction waste, including for handed over waste, such as scrap metal, broken glass, and household waste. As you fill

containers are taken to city dumps or collection points.

An increase in the discharge of water, storm and fecal sewage during construction is a serious environmental problem, since at the time of the start of work, the existing capacities of the city networks are insufficient, resulting in unauthorized discharge of associated effluents into the environment. To prevent this, it is necessary to ensure an organized flow from the construction site at the stage of preparatory work; reconstruct, according to the issued specifications for the periods of construction and operation of the constructed building, existing city networks; tie the wheel washing areas to storm sewer networks; establish areas on the construction site in which it is allowed

use water, sewerage for domestic and industrial needs. In the process of work, prohibit any discharge of water on the construction site outside the established zones.

In conditions of dense urban development, new construction is carried out, as a rule, along existing transport routes, and sometimes even crossing them, thereby violating the existing system of habitual transport patterns. This leads not only to the complication of traffic, but also to the formation of truncated traffic flows, traffic jams, additional exhaust of harmful gases from Vehicle and, consequently, the deterioration of the ecological situation in the city. Therefore, when agreeing on the construction plan, together with the traffic safety authorities, they develop schemes for the rational movement of vehicles around the construction site for the period of construction. Around the building site, standard road signs are installed that prescribe driveways, detours and stopping zones for road users, and, if necessary, additional pedestrian crossings - traffic lights.

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Introduction

foundation engineering survey

With a wide variety of engineering and geological conditions of construction sites, in many cases the construction of new buildings on sites with dense buildings leads to deformations and sometimes destruction of nearby existing buildings. Therefore, the main goal in the performance of work is to ensure the reliability of existing buildings during the construction of new buildings of any design on built-up sites with various engineering-geological and hydrogeological conditions. Features of the design of foundations and foundations for new buildings and the development of measures to maintain the reliability of existing buildings in conditions of dense development require careful consideration and consideration of the characteristics of the designed buildings and possible designs of their foundations, as well as the technical characteristics and condition of the structures of existing buildings.

To ensure the safety and possibility of normal operation of facilities located in the zone of influence of new construction, it is necessary, in addition to making reliable design design decisions, to provide for the implementation of special technological measures.

When erecting buildings near those existing in conditions of dense urban development, it is necessary to monitor the state of the building under construction and the surrounding buildings and the environment both during construction and during operation.

The implementation of these decisions and measures does not exclude the possibility of damage to the structural elements of existing buildings, and therefore additional work may be required with the inclusion of the costs of these works in terms of actual volumes in the estimate for the construction of a new or reconstructed building.

Basic concepts and classification of foundations

The foundation (lat. Fundamentum) is a supporting structure, part of a building, structure, which perceives all loads from overlying structures and distributes them over the base.

Foundations are classified:

According to the material: from natural materials (wood, rubble stone) and from artificial materials (rubber concrete, prefabricated or monolithic concrete, reinforced concrete);

By shape: the optimal cross-sectional shape of rigid foundations is a trapezoid, where the pressure distribution angle is usually taken: for rubble and rubble concrete - 27--33 °, concrete - 45 °. In practice, these foundations, taking into account the needs of the calculated width of the sole, can be rectangular and stepped. Pillow blocks are rectangular or trapezoidal;

According to the method of construction, the foundations are prefabricated and monolithic;

According to the structural solution - tape, columnar, pile, solid;

According to the nature of the static work, the foundations are: rigid, working only in compression, and flexible, the structures of which are designed to absorb tensile forces. The first type includes all foundations, except for reinforced concrete. Flexible reinforced concrete foundations are able to absorb tensile forces;

According to the depth of laying: shallow foundations (up to 5 m) and deep foundations (more than 5 m). The minimum depth of foundations for heated buildings is taken for external walls not less than the freezing depth plus 100-200 mm and not less than 0.7 m; under internal walls not less than 0.5 m.

Features of engineering surveys

Engineering surveys for the design of new buildings next to existing ones provide not only the study of the engineering and geological conditions of the construction site of a new building, but also the receipt of the necessary data to check the effect of a new building on the settlements of existing ones, to design measures to reduce the effect of a new building on deformations of existing ones, as well as for designing, if necessary, strengthening the bases and foundations of existing buildings.

The terms of reference for the survey are drawn up after inspection by a representative design organization existing buildings located next to the new one, in order to visually assess the condition of the supporting structures of buildings (both outside and inside) and clarify survey requirements.

IN terms of reference for surveys, the characteristics of the new building and the characteristics of adjacent buildings in operation (number of storeys, design, type of foundation, type and depth of foundations, year of construction, level of responsibility, geotechnical category, etc.) are given. Information on the available survey materials for these buildings (survey organization, year of survey, numbers of archival files) and information on the technical condition of building structures based on the results of previous surveys, as well as a preliminary visual survey, are indicated. The tasks of surveys, expanded due to the presence of nearby buildings, are given.

The volume and composition of the technical survey of above-ground and underground structures of existing buildings are established taking into account the preliminary survey of the building.

The collection and analysis of archival survey materials of specialized organizations is carried out not only for the site of new construction, but also for nearby existing buildings. Gather planning information engineering training and improvement of the site, documents for the production of earthworks. In the conditions of the existing development, special attention is paid to the identification of underground structures and engineering networks (collectors, communications, etc.).

Based on a comparison of new survey materials with archival data, changes in engineering-geological and hydrogeological conditions that have occurred over the period of operation of existing buildings are established.

Mining workings and sounding points are located not only within the new site, but also in close proximity to existing buildings. Shafts are provided near the foundations of existing buildings to examine the structures of the foundations and foundation soils.

In areas of historical development, the presence and location of existing and existing underground structures, basements, foundations of demolished buildings, wells, reservoirs, underground workings, etc.

The depth of drilling and sounding is assigned not only based on the type and depth of the foundations of the new building, but also taking into account the type and depth of the foundations of existing buildings. When choosing a sounding method in conditions of dense residential development, preference is given to static sounding.

The program of engineering and geological surveys in the areas of development of adverse processes and phenomena provides for the performance of stationary observations by specialized organizations in order to study the dynamics of their development, as well as to establish the areas of their manifestation and depths of intensive development, confinement to geomorphological elements, landforms and lithological types of soils, conditions and causes of occurrence, forms of manifestation and development.

Special studies of soils are carried out to assess possible changes in their properties due to these processes.

During construction unique structures, structures of increased economic, social and environmental risk (I level of responsibility), as well as in the presence of difficult engineering-geological conditions (geotechnical category III), it is economically feasible to increase the volume of engineering-geological and hydrogeological surveys by 40-60%, against the recommended normative documents, and this increase is carried out mainly due to mine workings and the determination of soil characteristics by field methods. When performing these works, specialized organizations are involved.

For structures with an increased level of responsibility, observations of precipitation are organized from the moment of laying their foundations.

Technical report (conclusion) on engineering surveys compiled in accordance with SNiP 11-02-96. Additionally given:

- information about archival survey materials for adjacent buildings and analysis of the correspondence of new survey materials to archival data;

- characterization of engineering-geological strata, physical and mechanical properties of soils and hydrogeological conditions of the foundations of existing buildings;

- forecast of the possible impact of the construction of a new building on the deformation of existing ones;

- information on the presence and condition of underground water-bearing and other communications.

Characteristics of the designed buildings

For construction in conditions of dense development, the design of buildings and structures for housing, civil and industrial purposes, above-ground and underground complexes is carried out. These buildings and structures can be designed with and without buried rooms.

The location conditions of the designed building or structure are determined not only by its architectural and economic significance, but also by the technical characteristics and methods of work.

The main technical characteristics of the designed buildings are given in tables 3.1, 3.2 and 3.3. An approximate scope of various types of foundations, depending on the loads transferred to the foundation soils, as well as on the features of the sites allocated for construction, and the specifics of the construction site, are given in tables 3.4 and 3.5.

Depending on the existing historical development, the designed buildings can directly adjoin the existing building or be located at some distance from it.

The height (number of storeys) of the designed building is dictated by:

The architecture of the existing building;

Mutual influence with the existing development;

operational requirements.

The technical characteristics of the load-bearing structures of the designed buildings (according to the existing design and construction experience) are given in tables 3.1, 3.2 and 3.3.

Table 3.1 Main characteristics of residential buildings

	Names	Specifications
	Purpose	Residential buildings
	Floors, fl.
	Type of supporting structures	Iron bet. panels, frame, brick walls	reinforced concrete panels, frame
	Step of load-bearing structures, m
	Basement	usually there is
	Availability of underground facilities	may have
	Foundation type	tape, pile	tape, slab, pile	tape, slab, pile, combined slab-pile
	SNiP 2.02.01-83*)	Relates sediment difference
		average draft, cm

Table 3.2 Main characteristics of public buildings

	Names	Specifications
	Purpose	Public buildings
	Floors, fl.
	Type of supporting structures	frameless from monolithic or precast concrete	frame made of monolithic reinforced concrete	mixed frame made of monolithic reinforced concrete
	Step of load-bearing structures, m
	Basement	usually there is
	Availability of underground facilities	usually there is
	Quantity floors of underground premises., fl.
	Foundation type	tape, pile, slab	tape, slab, pile, combined, slab-pile
	Limit deformations of the bases (according to Appendix 4 SNiP 2.02.01-83*)	relative sediment difference
		average draft, cm

Table 3.3 Main characteristics of industrial buildings

	Names	Specifications
	Floors, floor			underground up to 4 floors
	Approximate level of loads on foundations, kN
	Type of supporting structures	monolithic reinforced concrete or steel columns	monolithic reinforced concrete walls or frame
	Step of load-bearing structures, m
	Basement	May be	usually there is
	Availability of underground facilities		May be	the whole building is underground
	Number of floors of the underground room, fl.
	Foundation type	monolithic columnar, pile	monolithic columnar, slab, pile	monolithic tape, slab, pile
	Limit deformations of the bases (according to Appendix 4 SNiP 2.02.01-83*)	relative sediment difference
		average draft, cm

Structure Floor. in construction for 1996-2000

Proc. acc. Building by floor.

Note. ur. pressure under fund., kPa

Foundation type

Naturally. basis

Pile foundations

Reinforced concrete foundations

Piles from sandstone. seal mixtures

Piles Buroinek.

Piles borezavinch.

Piles scoring.

Piles borenab.

Combined Swainop.

	Features of the sites allocated for construction, specifics of the construction object	Foundation type
		On nature. basis	Pile foundations
		Iron. fundamental	Piles made of sand.. compact.. mixtures	Piles buroin.	Piles borer..	Driving piles	Piles borenab.	Combined Swainop.
	Builds. in newly allocated territories
	Builds. on the territory after their prev.. inzh. prepared
	Construction on free or free. territories in the zone of existing development
	Recon. buildings with rev. (partial or complete) its const.
	Reconstruction of architectural monuments

Underground premises of the designed buildings are classified:

By number of floors and depth (from 1 to 4 floors, depth 3-12m or more);

In terms of size in plan (under the entire building, under part of the building, larger than the size of the building);

By technological purpose;

According to the method of installation (in an open pit, in a temporary or permanent enclosure, using enclosing structures as load-bearing structures).

With a variety of engineering and geological conditions of the sites, as well as a difference in the structures and structures used, as a rule, columnar, tape and slab foundations on a natural or artificially fixed base and pile foundations from bored, screwed, crushed, driven, bored and other piles.

The choice of the type of foundations is carried out depending on the engineering-geological and hydro-geological conditions of the construction site, the location of the building being designed, the depth of the underground room, the condition of the structures and foundations of existing buildings near which construction is planned to be carried out.

Characteristics of protected buildings and foundations

Protection of existing buildings (including bases and foundations) during the construction of new ones is carried out in the following cases:

The location of the existing building in the zone of influence of the new building;

Erection of recessed premises that affect the deformation of the existing building;

When performing the device of foundations using special types works (freezing, injections, etc.);

If necessary, perform construction dewatering.

Protected buildings are characterized by:

historical significance;

Technological purpose;

Dimensions (dimensions);

Age (service life);

Type and condition of load-bearing structures;

Type and dimensions of underground facilities;

Type and condition of foundations;

Geological and hydrogeological conditions of the bases.

By age, protected buildings are divided into:

Historical (over 100 years old);

Monuments of architecture regardless of age;

Old (age 50-100 years);

Modern (age 10-50 years).

General technical characteristics of buildings near which construction works and which are subject to pre-protection are shown in Table 4.1.

Table 4.1 Specifications of existing buildings to be protected

	Names	Specifications
	Building age	19th century and earlier	late 19th - mid 20th centuries	end of the 20th century
	Purpose	Residential and civil buildings
	Floors, floor
	Approximate pressure level under foundations, kPa
	Type of supporting structures	wooden, stone, brick walls	brick, reinforced concrete walls, columns, steel structures
	Step of load-bearing structures, m
	Basement	cellars, cellars	cellars, technical undergrounds
	Availability of underground facilities		were in commercial buildings	were in various buildings
	Quantity floors of the underground
	Foundation type	rubble, rubble concrete, brick, pile, wooden piles	rubble, rubble-concrete, brick, piles, wooden piles, reinforced concrete, strip and free-standing, slab, piles made of reinforced concrete driven and bored piles	reinforced concrete, tape and separate, cast, piled from reinforced concrete. driving and borenab. piles, "slotted", by the method of "wall in the ground"
	Previous deformation of the bases according to adj. 4 SNiP 2.02.01-83")	relative sediment difference
		Avg. draft, cm

The assessment of protected buildings is based on consideration of:

Archival design and survey materials and executive delivery documentation;

Field survey results.

To ensure the operational suitability of existing buildings and structures near which new construction is planned, it is advisable to use the following basic methods of their protection and work performance, including:

Foundations on natural foundations: reinforcement of foundations, increase in the bearing area, installation of cross bands or foundation slabs, reinforcement of the foundation slab, reinforcement with piles various kinds(bored injection, bored, compound indented, driven);

Pile foundations: reinforcement (repair) of piles, installation of additional piles with widened grillages, changing the design of the pile foundation by transferring load-bearing structures to additional piles with a significantly higher bearing capacity, installing cross strips or a solid reinforced concrete slab on pile foundations, widening grillages, strengthening the body grillages;

Enclosing structures (picking, sheet pile, walls in the ground of various designs and methods for their manufacture);

Preliminary fixation of soils different ways(cementing, tarring, drilling mixing method, etc.) in the interface zones of the reconstructed and new structures;

The use of constructive solutions that do not create additional impacts on existing structures (console type solutions with piles, the use of pressed and screwed pile structures).

Methods for assessing the impact of the construction of new buildings on nearby buildings and structures

The main causes of deformations of existing buildings and structures during construction near them can be:

Changes in hydrogeological conditions, including flooding associated with the barrage effect during underground construction, or lowering the level of groundwater;

An increase in vertical stresses in the foundation under the foundations of existing buildings caused by construction near them;

The device of pits or change of planning marks;

Technological factors, such as dynamic impacts, the impact of all types of piles, deep foundations and enclosing structures of excavations, the impact of injection anchors, the impact of special types of work (freezing, injection, etc.);

Negative processes in the soil mass associated with the implementation of geotechnical works (suffusion processes, formation of quicksand, etc.).

The degree of influence of the construction of new buildings on nearby buildings and structures, as a rule, is largely determined by the technology of work and the quality of construction.

Methods for assessing the impact of construction on nearby buildings and structures are focused on strict compliance with all technological requirements for the production of works. Technological deviations can lead to a significantly greater impact of construction on existing development.

When performing calculations of the foundations of existing buildings and structures affected by new construction, changes in the physical and mechanical properties of soils and hydrogeological conditions in the process of neighboring construction are taken into account, including taking into account seasonal freezing and thawing of the soil mass.

The calculation of foundations and foundations of existing buildings according to the I group of limit states is performed in the following cases:

Pit devices near buildings;

Devices for workings and trenches (including those under the protection of thixotropic solutions) near buildings;

Reduction of planning marks near the outer walls of buildings;

Changes in pore pressures in the soil mass during the unfinished process of consolidation;

Transferring additional loads and impacts to existing foundations.

The purpose of the calculation for the I group of limit states is to ensure the strength and stability of the foundations, to prevent shifting or overturning of the existing foundations.

In the case of using piles or sheet piling during construction and vibro-immersion, the load-bearing structures of the existing building closest to the immersed elements are checked for dynamic strength.

The calculation of the foundations of existing buildings or structures according to the II group of limit states is performed in all cases if they are located in the zone of influence of new construction.

The calculation of additional deformations of the foundations of buildings and structures affected by new construction is carried out from the conditions of joint operation of the structure and the foundation.

The choice of the method of arranging the foundations and foundations of a new building

When erecting a new building closely adjacent to an existing one, the minimum distance between the edges of the new and existing foundation is set during design, depending on the method of excavation and the depth of the pit, the design of the foundations and the dividing wall.

The design, dimensions and mutual placement of the foundations of a new building, arranged near existing buildings, are assigned taking into account the development of additional uneven deformations of the foundations of existing buildings and the formation of distortions of the supporting structures of these buildings (foundations, walls, ceilings, etc.) caused by additional settlement.

If the project of a new building does not provide for the support of its structures on the structures of an existing building, a sedimentary seam is arranged between the new building and the existing one.

Sedimentary seams are designed and made in such a way that the width of the seam ensures the separate movement of new and old buildings during the entire period of their operation.

If it is necessary to lay the foundations of a new building in an unsupported pit below the foundation level of the existing one, the permissible difference in elevations is determined.

Rice. Location of adjacent foundations at different depths

If the magnitude of the deformation of the existing building from the influence of the new building exceeds the maximum permissible values, then measures are taken to reduce the impact of the settlement of the new building on the existing one. These measures include:

The use of pit fasteners;

Dividing wall device;

Transfer of pressure from the new building to the layers of dense underlying soils through the use of deep supports or piles of various designs;

Strengthening the foundation soils of buildings by various technological means (chemical fixing, reinforcement, ramming of crushed stone, etc.).

As a dividing wall can be used:

Sheet pile;

A series of screwed steel pipes with wire winding (drilled pile);

Wall of piles, including bored, bored and pressed;

A row of driven piles;

- "wall in the ground."

The question of the type of wall is decided on the basis of a technical and economic comparison of the options or capabilities of the contractor.

The rigidity and depth of the sealing of the dividing wall, and if it also serves as a pit enclosure, determined by the calculation, or structural measures (installation of anchors, struts, spacers with emphasis on the previously erected structures of the new building, etc.) should ensure the limitation of horizontal displacements in foundation of an existing building.

The calculation is made of the depth of embedment of the dividing wall into stronger soil layers or into soil layers located below the compressible thickness of the base of the designed foundation.

Scheme for the calculation of the dividing wall

The dividing wall runs along the entire line of adjoining the foundation of the new building to the existing one and on each side goes beyond the existing building in terms of at least 1/4 of the compressible thickness.

The project for the production of earthworks (PPR) and works on the installation of foundations for new buildings being erected next to existing ones is being developed in accordance with the requirements of SNiP 3.02.01-87 " Earthworks, bases and foundations.

In the case of a direct junction of the pit to the foundations of existing buildings, the methods of excavation and dismantling of old foundations, if any, are selected in accordance with the stress state of the base of the existing foundations. It does not apply:

Ball or wedge - a hammer for crushing frozen soil and old foundations to be dismantled;

Explosive way;

Excavator with bucket type "Dragline";

Powerful hydraulic impact mechanisms.

When constructing foundations near existing buildings:

Minimize the time of work in construction pits;

Do not allow storage building materials in the immediate vicinity of the existing foundations and on the edge of the pit;

When immersing a metal or wooden sheet pile, to reduce friction forces, the sheet pile locks are filled with crumpled plastic clay, a solution of thixotropic bentonite clay, polymer and other lubricants.

The admissibility of using driven piles near existing buildings should be established only on the basis of the results of instrumental measurements of vibrations during test pile driving with the participation of specialized organizations to determine the level of vibration exposure and its compliance with regulatory restrictions. Particular attention is paid to the danger of dynamic effects during pile driving in the following cases:

Buildings whose base deformations are in the process of stabilization;

There are cracks in the load-bearing structures of buildings with an opening of more than 3 mm;

At the base of the foundations lie weak soils (silt, organo-mineral and organic soils, water-saturated loose sands, etc.);

Unique buildings, including architectural and historical monuments, for which, according to the operating conditions, increased requirements are established to limit the level of vibration exposure.

Dive Prefabs reinforced concrete piles and metal sheet piling next to existing buildings is made with heavy hammers with a low drop height of the shock part according to the instructions of VSN 490-87. The ratio of the weight of the impact part of the hammer to the weight of the swan is at least 5:1 and the use of leader holes is preferable. On the adjoining site, one row of piles closest to the existing building, which is the screen, should be loaded first.

When performing work on the construction of a new building next to the existing one, as well as in cases of dismantling old buildings, the following are not allowed:

Violations of the structure of the bearing layers of the base and loss of slope stability during excavation of pits, trenches, etc.;

Filtration destruction of the base;

Technological vibration impact;

Freezing of soils of the base of an existing building from the side of an open pit.

Development of environmental protection projects

Measures to protect the surrounding buildings, their constructive solutions, methods of work and their volumes are directly related to the decisions made on the newly constructed building. Design decisions for the construction of a new building and the protection of the surrounding buildings are made on the basis of an analysis of their interaction. For achievement optimal solution the development of projects for the protection of buildings located in the zone of influence of a newly constructed building is carried out as part of the project of a newly constructed building. The Neighborhood Protection Project is part of this project.

The environmental protection project is carried out by specialized organizations that have the appropriate licenses to carry out such work.

The zone of influence of a newly constructed building on the existing development is established by the general designer with the involvement of specialized and scientific organizations and is determined taking into account:

Stock materials of engineering and geological surveys in the construction area;

The results of the survey of the existing building before the start of construction;

Report on engineering and geological surveys for new construction;

The presence of negative geological processes (karst, suffusion processes, gas release, landslide processes, etc.), predictive data on changes in the level of groundwater.

The foundation structures of the new building and the magnitude of the loads on the foundations under them;

Methods for the production of work on the construction of a newly constructed building: the use of lowering the level of groundwater, driving piles, sheet piles, deep excavation, the design of fastening the walls (slopes) of the excavation, anchoring, etc.

The environmental protection project is carried out on the basis of the following initial data:

Design assignments issued by the customer in agreement with the general designer;

Report on engineering-geological, engineering-geodetic surveys;

Report on the results of the survey of existing buildings located in the zone of influence of the newly erected building;

The results of the analysis of the adopted method of constructing a new building and assessing its impact on possible deformations of buildings in the surrounding area for the period of construction and the subsequent period of operation.

Influence of factors negative impact new construction on the existing buildings of the surrounding development is expressed in the appearance of additional uneven deformations of the bases and foundations of existing buildings.

The appearance of these deformations is due to the following main reasons:

Changes in the stress-strain state of the soil in the zone of influence of new foundations on the surrounding buildings;

Changing the hydrogeological regime in the construction area;

Leaks and other negative phenomena in case of damage to underground water-bearing networks.

The factors listed above must be taken into account when designing and erecting a new building.

Monitoring during the construction of buildings near existing

Monitoring at sites where the construction of new buildings is carried out near existing ones in densely built-up conditions is integrated system designed to ensure the reliability of both the building under construction and the surrounding buildings, as well as the preservation environment.

The purpose of monitoring is: to assess the impact of new construction on surrounding buildings and structures, to ensure the reliable construction of a new building, to prevent negative changes in the environment, to develop technical solutions to prevent and eliminate deviations that exceed those provided for in the project, as well as to monitor the implementation of these decisions.

Methods and technical means for monitoring new construction and surrounding development are assigned depending on the level of responsibility of structures, their design features and condition, engineering-geological and hydrogeological conditions of the site, the method of erecting a new building, the density of surrounding development, operating requirements and in accordance with the results of a geotechnical forecast .

Monitoring is carried out according to a specially developed project. The composition, methods and scope of monitoring are established depending on the geotechnical category of objects in accordance with MGSN 2.07-97 by a joint decision of the customer of the new construction and the general designer.

Features of the production of works near existing buildings

To ensure the safety and possibility of normal operation of the objects surrounding the construction site, in addition to making constructive decisions in the production of work near existing buildings, special technological measures are taken, as well as preventing violations of existing drainage systems, waterproofing, etc.

Before starting work, a thorough examination of all buildings and structures located in the zone of influence of the planned construction work should be carried out.

For the production of geotechnical works near existing buildings, they develop technological regulations for their implementation and impose strict control over compliance with all requirements of the project and technological regulations. Control over the implementation of the technological regulations and the quality of the work performed is carried out by the engineering and technical service of the work foreman, checked by a representative of architectural supervision and technical supervision customer.

Conclusion

When performing work on the design and installation of bases and foundations during the construction of buildings near existing ones in dense building conditions, control methods are provided in accordance with SNiP 3.02.01-83 and GOSTs 18321-73 and 16504-81.

List of used literature

1.Telichenko, V.I. Technology for the construction of buildings and structures. Textbook for builders, universities. V.I. Telichenko, O.M. Terentiev, A.A. Lapidus - 2nd ed., Revised and added. - M .: Higher school, 2004. - 446 pp., il;

2.Government of Moscow. Moskomarchitectura. "Recommendations for the design and installation of foundations and foundations for the construction of buildings near existing ones in dense building conditions in the city of Moscow" dated 13.01.99;

3. Wikipedia - a summary encyclopedia [Electronic resource] // http://ru.wikipedia.org/wiki/Foundation.

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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 is imposed on participants construction industry(including suppliers and customers) strict requirements for the implementation of work schedules and 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 cranes of a stationary type (self-elevating) are used on a relatively small foundation or (for concrete work) use concrete-laying complexes associated with vertical supply concrete mix inside the building and its subsequent distribution on the tier by manipulators of 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.

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.

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 inability to provide engineering and sanitary requirements for the arrangement of the 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 household 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, they place an administrative and amenity camp there, if possible, close in size to the requirements sanitary norms. 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 locksmith shops and workshops makes it difficult to manufacture products and elements of building structures, such as fittings prepared to size, reinforcing cages, load-bearing elements metal structures, carpentry and locksmith 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 vehicles.
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. With a large number of such suppliers, there is no 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 a tower crane is installed on it. 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.