Dismantling works are characterized by a relatively large estimated cost and high labor intensity. An analysis of the estimates of the facilities where the overhaul was carried out shows that the cost of dismantling works is 3.1-10% total cost, labor intensity - 13 ... 36%. The most time-consuming work requiring a lot of manual labor is cleaning and transportation of materials from disassembly and construction waste.

Therefore, the organization of dismantling works has its own specifics and technological sequence. This is necessary for all engineers and technicians who are involved in the operation, reconstruction, current and major overhauls.
Dismantling of building structures and engineering equipment, as a rule, is carried out by contractors according to pre-developed and approved work projects (PPR). For buildings and structures that are technically complex or disassembled for the first time, PPR can be developed by the design organization.

Dismantling is prohibited without approved documentation.
The basis for the development of PPR is a floor-by-floor inventory plan (or a floor plan made according to the results of measurement work), a building or structure survey card and a situational plan of underground communications. PPR, both for a building or structure separately, and for an object as a whole, is developed in accordance with the requirement normative documents... It is approved by the chief engineer of the contractor and agreed with the customer's occupational safety engineer.
K PPR in mandatory a certificate with the seal and signature of the chief engineer must be attached stating that all engineering communications (water supply, sewerage, heating, etc.) are disconnected from the building or structure. Without such a certificate, the PPR is invalid.

Dismantling of building structures and engineering equipment is a complex technological process, consisting of two periods: preparatory and basic.
Before the start of the preparatory period, the contractor must receive all design and estimate documentation: working drawings, estimate, PPR, situational plan of underground utilities and work order for dismantling works. All engineering personnel, foremen and workers must be familiar with the documentation and safe work practices. During this period, all tenants and service personnel must be evicted.

During the preparatory period, the following work is carried out:

• inspection of buildings and structures to be dismantled;
• studying and agreeing on the conditions for performing work;
• development of technology for dismantling works;
• checking the disconnection of engineering networks located in buildings and structures;
• preparation of access roads:
• delivery and installation of scaffolding, scaffolds, garbage chutes, bunkers and other equipment for dismantling structures and engineering equipment and removing materials;
• delivery and installation of lifting equipment;
• preparation of equipment for temporary fastening of structures during dismantling works;
• laying and connection of temporary engineering networks.

The main period or the actual dismantling work includes three stages:

• at the first stage, the structures are dismantled by separating their individual elements from each other; removal of separated elements and their inspection, sorting and stacking; destruction, loosening of monolithic concrete, reinforced concrete and stone structures.
• at the second stage, materials are sorted after dismantling structures and engineering equipment, loading and transporting them to places for reuse or to a landfill.
• at the third stage, the front is being prepared for the subsequent construction and installation work.

The main task of dismantling works is to remove worn-out building structures and their elements, engineering equipment units, as well as to create the necessary work front for the installation of new structures and equipment. Dismantling works should be carried out within one grip (for example, between staircases, etc.). At the same time, it is necessary to strictly observe the technological sequence of dismantling structures and equipment, ensuring safe working conditions and maximizing the preservation of materials from disassembly, as well as structures adjacent to those being disassembled.
The installation of new structures can be started only after the completion of the entire complex of dismantling works at the capture.

The technology of dismantling works for stone buildings and structures has specific features depending on the accepted scheme of work and the type of machines and mechanisms used. In this case, work can be performed according to two schemes:

• The first scheme provides for the dismantling of structures from top to bottom - roofing, roof, ceilings, etc. The supply and removal of materials is carried out from above into the well, as a rule, using lifting and transport mechanisms (tower cranes, movable cranes, etc.).
• according to the second scheme, the roof is preserved during its selective repair. The supply and removal of materials is carried out through the window openings. In this case, lifting mechanisms (lifts, etc.) are used as vehicles, and all construction and installation work is performed manually.

In the process of dismantling buildings, work is carried out on dismantling, dismantling, partial and complete destruction of structures.

Dismantling of a building structure is a mechanized process of removing it intact using lifting, rigging and vehicles. In the process of dismantling the structures, partial destruction of individual fastening and connecting elements is performed.

Dismantling of a building structure is a process of its partial destruction with the aim of dividing it into separate elements and with their subsequent removal.

Dismantling and disassembly of structures can be carried out element by element and in enlarged blocks.

Dismantling by enlarged blocks has a number of advantages over element-by-element disassembly, in particular, the terms of work are reduced, their labor intensity is reduced by 1.5 ... 2 times, the safety of work and the culture of production are increased.

In special cases, the entire above-ground part of buildings and structures can be dismantled (administrative and amenity one-story buildings, high chimneys, power transmission line supports, etc.). In this case, the dismantled part of the building or structure is freed from connections with the foundations and, as a whole, is moved to another place or with the help of special Vehicle transported outside the developed construction site.

Dismantling of building structures is performed, as a rule, in the process of their replacement. At the same time, work on dismantling of the replaced and installation of new structures is carried out in most cases with the same assembly machines, which allows us to consider the mechanization of dismantling and assembly work as a single complex process.

The element-by-element disassembly of building structures is carried out manually or using manual machines in order to maximize the yield of materials for their reuse. Disassembly is carried out manually, as a rule, decorative, wooden and small metal structures... Disassembly of brick and rubble concrete structures is carried out manually only with a small amount of work and in those cases when other methods cannot be used for some reason.

The disassembly method using manual machines is rather laborious and expensive. Due to the formation of noise, dust and vibrations, this method should be used if it is impossible to use more efficient methods of disassembly (dismantling).

The methods of destruction of building structures and monolithic massifs are distinguished depending on the means used: semi-mechanized (using pneumatic and electric manual machines); mechanized (using machines and mechanisms of shock and splitting action, tractors, bulldozers, jib cranes and excavators in combination with various attachments for interchangeable equipment in the form of ball and wedge hammers, pneumatic and hydraulic hammers, etc., concrete breakers and rock breakers, hydraulic wedge and cylindrical splitters); explosive (drilling and hydro-explosive - with the use of drilling rigs, perforators, explosives and blasting agents); electrohydraulic (using installations of the electrohydraulic effect); with the use of mixtures expanding during hardening (Table 16.1).

The following methods are used to separate structures during disassembly and to arrange openings and holes in various structures: mechanical drilling, drilling and cutting using hand-held drilling machines and machines with carbide and diamond core drills, drilling rigs and perforators, machines and machine tools with diamond cutting discs, hydraulic attachments and installations for cutting pile heads, electric furrow-doders; oxy-fuel and thermal cutting (oxygen lance, gas-jet powder-oxygen lance, powder-oxygen cutter, jet-jet burner, thermal drill); electric arc, plasma and laser cutting (electric arc melting machines, plasma and laser cutting), water jet cutting (water jet machines).

The semi-mechanized method is used to destroy monolithic concrete, reinforced concrete and brick vaulted ceilings, as well as other monolithic concrete structures of a small volume. Due to the difficulty and high cost works, its application is limited.

The mechanized method is used: for the destruction of vaulted brick, concrete and reinforced concrete floors (using wedge-hammers on an excavator, crane); brick walls and partitions (using hammer balls); concrete bases (with concrete breakers, impact rippers, hydraulic and pneumatic hammers from hydraulic excavators); concrete and brick structures (hydraulic and pneumatic hammers, hydraulic splitters).

The explosive method during the reconstruction of industrial buildings is used for the destruction of stone, reinforced concrete and metal structures, for the collapse of elements of old buildings and structures on their base or in a given direction. When carrying out blasting operations.

measures should be taken to protect against the effects of an air blast wave, the scattering of pieces of exploded material and the effects of gases, which significantly increases the labor intensity and terms of work.

Table 16.1. Methods of destruction of structures of buildings and structures using various machines and mechanisms

When choosing methods for disassembling and destroying building structures, the yield of recyclable materials is taken into account. The choice of one or another method of disassembly and destruction should be justified in each specific case by technical and economic calculations. In fig. 16.1 shows a sequence diagram for the development of organizational solutions for the dismantling of buildings, taking into account the reuse of structures and materials.

Rice. 16.1. Structural destruction process organization diagram:

Stage I- preparation; Stage II- destruction; Stage III- removal of debris; Stage IV- usage

Before starting work on disassembly, it is necessary to outline the places of separation of structures in accordance with the element-wise scheme of their removal, to install temporary fastenings of structures, as well as to arrange temporary fences, flooring and protective canopies.

Initially, they dismantle technological and special equipment, instrumentation, electrical and low-current networks.

Dismantling is carried out, as a rule, from top to bottom in the following order: 1) technological structures (pipelines, utilities, masts, supports, shelves for equipment, lifts); 2) horizontal enclosing structures (floors, roofing), vertical (gates, doors, windows, stained-glass windows and bearing external and internal walls); 3) special structures (stairs, observation decks, ramps, mines, galleries, railways); 4) horizontal supporting structures (lanterns, roof and floor slabs, trusses, beams, girders, crane beams); vertical (walls, columns, stoics); 5) tunnels, basements, foundations.

One-story buildings are disassembled in a sequential manner, including element-by-element disassembly of structures throughout the building; complex, in which the building is dismantled section by section, as well as combined. Multi-storey buildings should be disassembled floor by floor in separate sections or along the entire length of the building.

Dismantling the electrical network should begin by removing the shades, cartridges, switches, sockets, shields, etc., then proceed to dismantle the wiring. The removed wires should be flattened and coiled.

When disassembling, utility lines and equipment should be dismembered using electric or gas cutting. Unsuitable cast-iron pipelines are dismantled without capping the socket, their joints can be broken with a hammer. All removed elements of engineering equipment (sinks, wash basins, bathtubs, toilets, flushing cisterns, heating devices of central heating systems, water taps, etc.) must be sorted with selection of those fit for further use.

The roof is usually disassembled in two stages: first, the roof covering, and then the main load-bearing elements of the roof. The roll roof structure containing the insulation is removed simultaneously with the insulation, the work should be carried out in the transverse direction, starting from the highest elevation of the roof. As a tool, you can use light crowbars, bayonet or shovels. The material to be disassembled should be lowered by means of taps in buckets or special boxes or along closed chutes. It is recommended to tear off the roof covering made of rolled materials without insulation from the solid base with a steel spatula, and cut off its section along the slope with scissors.

Roofs made of piece small materials are disassembled element by element in the reverse order of their arrangement. With careful disassembly, up to 80 ... 85% of the material can be saved.

During reconstruction multi-storey buildings often it is necessary to disassemble interfloor ceilings, which are usually of monolithic reinforced concrete (flat or ribbed), of bricks in the form of vaults or made of metal beams with wood or concrete filling. Steel floors are less common.

The initial data for the development of PPR (work production projects) are the results of the survey and measurements (in the absence of drawings of buildings' structures).

Overlapping on metal beams with brick filling in the form of vaults is most expedient to disassemble across in relation to the blocks, in sections up to 2 m wide and length according to the size of the overlap (Fig. 16.2).

If for some reason it is impossible to disassemble the floor across, it is disassembled along the area bounded by two adjacent beams, however, before disassembly, special spacers should be installed between the beams. Spacers can be made of logs with a diameter of 16 ... 18 cm, they are installed every 2 ... 3 m along the length of the beams.

Work on the dismantling of vaulted brick floors
should be carried out only from working decks made of planks on stitching strips laid along the floor beams. The decks are 60 ... 80 cm wide.

Cylindrical brick vaults are dismantled in separate sections 0.8 ... 1 m wide from the end walls from the middle of the arc to the supports simultaneously from both sides. The last middle section is brought down by undercutting the base of the supports.

Rice. 16.2. Dismantling vaults between steel beams:

I ... VI- the order of disassembling the vaults; a - arrangement of wooden struts between steel beams; b - disassembly of vaults with transverse sections, 1 - wooden spacer; 2 - brick vault; 3 - transverse section of disassembly; 4 - steel beam; 5 - vault on the beam

Closed, cross, domed and sail arches are disassembled into circular zones 250 mm wide from the center (lock) to the heels (Fig. 16.3).

In the presence of through cracks and the loss of individual bricks, the vaults, depending on the nature of the cracks and the degree of development of deformations, collapse, expanding the cracks, or disassemble them in parts. For dismantling brick vaulted and monolithic reinforced concrete floors, pneumatic and electric jackhammers should be used.

Brick walls of old buildings, stacked with lime mortar, are usually easily disassembled along the planes of individual bricks. Therefore, the bulk of the bricks can be reused. However, when disassembling such brickwork, a significant amount of dust is generated.

Dismantling brickwork on cement-lime mortars requires much more effort. In this case, the brick and mortar break into large blocks and it is almost impossible to separate the brick from the mortar. In these cases, hand-held machines should be used for disassembly.

Rice. 16.3. Disassembly diagram of cylindrical (i), closed (b) and cross (e) vaults:

I...Vii- sequence of disassembly in sections - 1 - support wall - 2 - heel of the vault;

3 - start of disassembly; 4 - end wall

Brick walls are usually taken from the scaffolding. Inventory tubular scaffolds are often used, which are attached to the dismantled wall in accordance with a typical project for the use of these scaffolds. For this, for example, anchors are screwed into wooden plugs, driven into the nests pre-punched with a bolt, or inventory plug anchors are used. The order of installation and the sequence of their disassembly should be set out in the PPR.

Brick walls in the cramped conditions of an existing workshop are dismantled in rows, usually by hand using crowbars, light sledgehammers, wedges and picks, or in a semi-mechanized way using jackhammers. All other methods in most cases are unacceptable. Depending on the strength of the masonry, the thickness of the wall and the tool used, disassembly is carried out to a height of two or three rows.

All work on the destruction of old walls on each floor must begin after the complete dismantling of the floor structures under this floor and the implementation of measures to ensure the safety of workers in the building.

One of the methods allowing large areas to dismantle internal and external walls was applied at one of the reconstructed objects in Moscow. The method eliminates the widespread piece-by-piece dismantling of the building due to the collapse of wall sections on the overlap of the underlying floor. The calculation of floors under the load from the fall of wall sections allows you to determine the size of the floor that can withstand the fall of elements weighing up to 4 tons onto it.

Rice. 16.4. Wall disassembly diagram:

a- dismemberment of walls into blocks; b- dismantling of the walls by the "roll on the shield" method; 1 - shield; 2 - winch; 3 - cable

According to these calculations, in order to evenly distribute the load on the floor (Fig. 16.4) from the falling brick block, a shield is made with a frame made of a rolled profile with a receiving hopper installed on it using clamps. From the bunker, the fragments of structures are reloaded by a tower crane into a vehicle. The building is broken up into conquests. At the first grip, the lintel part of the wall is cut off from the wall. On the second, after dismantling the lintels, the walls are divided into blocks. On the third grip, the block is undercut at the level of the overlap and collapsed.

Before overturning the block, a receiving board is placed on the carefully cleaned section of the overlap in the place of its fall. Then a specially made clamp with a cable from a winch installed on the ceiling with a pulling force of 45 tons is attached to the block. When the winch is turned on, the block falls into the receiving hopper of the shield and by a tower crane, it is fed into the motor transport.

Installation of structures

Erection and dismantling of building structures of reconstructed industrial, civil and residential buildings is carried out by various methods. The choice of the method and method for its implementation is mainly determined by the amount of work, the degree of constraint on the construction site, the conditions for combining assembly with other types of construction and assembly work, the completeness of the supply of structures, the range of available assembly cranes, structural solutions of buildings, the technical condition of dismantled structures and nodal connections of buildings , established terms of reconstruction.

The conditions of the construction site of the reconstructed object should facilitate the most efficient use of assembly kits and limit the influence of constraint parameters on the operational performance of the driving machines. For this purpose, in the pre-installation period, in accordance with the reconstruction project, the demolition and relocation of all outdoor facilities and networks must be fully completed.

The level of organization and rates of dismantling works in many cases determine the technology and rates of erection of building structures.

The main material for the manufacture of prefabricated structures intended for the reconstruction of residential, public and industrial buildings is; reinforced concrete.

TO prefabricated reinforced concrete structures used in the reconstruction of buildings and structures are subject to a number of specific requirements:

the need to articulate new structural elements with old ones, which ensures their joint, work, restoration of broken spatial connections, strength, rigidity and stability of both individual structures and the building as a whole at all stages of reconstruction;

the impossibility of arranging extended supports in existing walls for the installation of new structures due to the danger of collapse;

limiting the mass and geometrical dimensions of prefabricated reinforced concrete structures and assembly blocks after enlargement assembly based on the conditions of fitting the assembly machines of the corresponding carrying capacities and the optimal passability of the structures during their assembly.

An increase in the carrying capacity of machines with limited working areas and, consequently, the size of machines, an increase in the level of mobility, versatility and maneuverability make it possible to use more industrial structures for the reconstruction of residential buildings, to carry out their installation in enlarged blocks.

During reconstruction public buildings erection of building structures can be complicated not only by the cramped construction site, the internal layout of the facility, but also by the large size of building structures, the relatively high mark of their design position, and a significant mass of structural elements.

Depending on the degree of wear of building structures, the sequence of their dismantling, the volume and order of their reinforcement, the number of interfloor floors to be replaced and the assembly machines used during the reconstruction of multi-storey buildings, the structures are installed horizontally (floor by floor) or vertically (to the entire height of a certain span).

Floor-to-floor installation is advisable to carry out with a slight change of interfloor floors, a relatively small amount of work to strengthen the columns and girders used for installation with cranes "in the window" and suspended monorail or rope systems.

The installation of structures horizontally corresponds to a comprehensive method of organizing installation work, and vertically - to a differentiated one.

When assembling structures horizontally, the technological break required for the acquisition of concrete in the joints, prefabricated monolithic structures, reinforcement elements of sufficient strength is provided, allowing installation work to begin on the next floor.

For vertical mounting, preference should be given to welded joints by means of embedded parts. For temporary fixing of frame elements or reinforcement, special conductors, clamps, etc. are used.

If the reconstruction project provides for a significant amount of work to strengthen the existing columns and girders on all floors of the building using monolithic concreting, then the installation of structures begins after the completion of these works and the acquisition of concrete in the lower reinforced structures of sufficient strength.

In the process of strengthening existing structures and installing new ones, portable assembly platforms, inventory scaffolds are used, and hinged metal stairs are used for welding embedded parts.

When performing assembly and dismantling works at reconstructed industrial facilities, all assembly methods known in new construction are used. At the same time, the individuality of the space-planning solutions of the reconstructed buildings, the diversity of external and internal constraints, the need to combine work with the main activity of the enterprise and with related construction and installation works, the technological structure of work that differs from new construction and other factors impose a number of restrictions on the possibility of using those or other methods.

To replace columns inside existing industrial buildings, the method of dismantling the columns by turning around the hinge using winches is often used (Figure 16.5). In this method, the pavement structures are first supported on temporarily arranged supports. After that, by oxy-fuel cutting, the support units of the trusses are disconnected from the embedded parts of the column being removed.

Rice. 16.5. Dismantling of reinforced concrete columns:

a - by turning around the hinge; b - winches; 1 - dismantled column; 2 - temporary support; 3 - pulley block; 4 - support table; 5 - swivel joint; 6 - safety rope; 7 - crane girder; 8 - pull rope: 9 - scale cells; 10 - crossbar for fastening the cargo chain hoist; 11- branch blocks

The pivot joint is fixed on the dismantled column, which ensures its stability after the destruction of the column section near the foundation. Then, two movable blocks of pulley blocks are fixed on the column, one on the upper part, the other below the center of gravity of the column. After cutting the concrete of the head (at least 600 mm) and the bottom of the column between the pivot hinge clips (at least 400 mm) and cutting off the bearing reinforcement, the column is lowered by switching on the chain hoist attached to the upper part. Another pulley block comes into operation only after the column is tilted 30 ° to the horizon.

Reinforced concrete columns are dismantled with winches in the case when work inside existing workshops is carried out without dismantling the pavement structures, and the structures of the main frame allow fixing the used rigging and take on additional loads arising from the dismantling of the column and crane beams.

It is advisable to mount intrashop partitions in cramped conditions with a crane with a telescopic tower-boom equipment. This method is used in workshops with a roof truss bottom height of up to 15.6 m in places accessible for a crane.

In places inaccessible for the approach and placement of jib cranes, it is recommended to dismantle and mount crane beams using electric winches and pulley blocks.

Small-sized beams are replaced with heavy crane beams of a larger span while increasing the existing column spacing. Such a replacement is carried out using self-propelled jib cranes and most often winches and chain hoists, the fixed blocks of which are fixed on the supporting structures of the frame.

Crane rails can be replaced with self-propelled jib cranes if their placement inside the existing workshop does not cause great difficulties. If it is impossible to pass and place the boom self-propelled cranes, electric winches are used to replace the rails (if the supporting structures are capable of taking additional installation loads).

In fig. 16.6 shows an example of replacing crane girders through windows arranged by disassembling the Outer wall panels.

Lantern structures of one-story industrial buildings are dismantled using various means of mechanization, including the use of cable, roof jib or gantry cranes.

It is recommended to disassemble the lanterns with a cable crane if the length of the workshop is up to 400 m and the weight of the mounted elements is up to 1.5 tons.

It is possible to dismantle the skylight structures when replacing them using roof jib cranes. This achieves a reduction in the terms of work. During the paired operation of the cranes, the first one performs dismantling and the second one - installation work.

Rice. 16.6. Replacement of crane beams in the operating chain through window openings

Depending on the specific conditions and the nature of the work performed to replace the coating, various types of lifting and transport installation mechanisms are used: cable cranes (stationary and mobile), bridge-type installers or bridge cranes (for dismantling and installation in large blocks), roof cranes (gantry and jib ), bridge boom, self-propelled boom and tower cranes. The last three types can work on the extreme spans, and the rest of the mechanisms - on the extreme and middle spans. In some cases, you can use a helicopter.

It is possible to disassemble the coatings of one-story buildings when production is stopped using self-propelled jib cranes moving along the span axis, or special cranes mounted on overhead cranes.

When disassembling and replacing the coating without stopping production, work is carried out section by section in separate areas. In this case, disassembly should be combined with the installation of new structures.

It is advisable to carry out a complete replacement of the coating of the reconstructed workshops in large spatial blocks with a large internal constraint of the workshop. For this purpose, bridge-type installers or technological bridge cranes are used. At one of the ends of the reconstructed span, there must be a free area sufficient for the installation of a self-propelled jib or tower crane, as well as for storage and pre-assembly of structures.

The USSR has accumulated extensive experience in the use of helicopters in the reconstruction of buildings and structures. So, when choosing possible methods of mounting and dismantling the structures of the cupola spark arrestors at the Kharkov Tractor Plant, preference was given to the installation using a MI-10K helicopter. During the reconstruction process, the spark arresters were dismantled in blocks, the mass of which corresponded to the carrying capacity of the helicopter. Considering that each spark arrester was divided into two blocks, 16 lifts were performed in the process of dismantling and installation work (Fig. 16.7).

When reconstructing multi-storey buildings, when structures weighing up to 3 tons are used, depending on the width, installation can be carried out by a tower crane moving from one side of the building, from both sides or along the central axis.

Rice. 16.7, Replacement of cupola spark arrestors using a MI-10K helicopter

When erecting heavy structures and a slight constraint on the site, it is possible to use two tower cranes.

With a low frame height, installation work is carried out by automobile, pneumatic-wheel and crawler cranes.

During the reconstruction of buildings of great height, when a significant number of small elements are used, the installation can be carried out by a crane-mast, which can be moved upward as the underlying structures are reinforced and installed.

In the practice of reconstruction of multi-storey buildings, self-lifting tower cranes are often used for the installation of building structures.

In the absence of overhead cranes or the impossibility of their use, the coating elements are mounted using a mechanism consisting of a crane part of an automobile crane installed on a running platform, moving along driving beams laid on the upper chords of roof trusses and shifted in the course of work.

This scheme is used when using cranes with a lifting capacity of 7.5 ... 16 tons.

The simplest lifting devices are used for single hoists, as well as in very cramped conditions, when the use of assembly cranes is economically impractical or technically impossible. These include assembly masts, portable assembly booms, mast cranes, winches, jacks, assembly beams, overhead cranes, monorail installations. Using the simplest mechanisms, individual columns are replaced inside the workshop with preliminary hanging of the adjoining load-bearing structures of the coating, that is, by re-supporting the trusses on temporary stands; replacement of wall panels, crane girders and crane tracks in places inaccessible to the approach and placement of assembly cranes; strengthening the structures of the existing workshop.

In the context of the reconstruction of industrial enterprises, bridge cranes can be used with high efficiency at full or partial stoppage of production. The scope of their application will expand if they install lifting equipment and equipment for tower cranes - a full-revolving boom, a tower and clips with radial brackets on which undercarriages are installed (Fig.16.8, a). The use of such bridge jib cranes allows you to solve all issues related to both dismantling and installation of all structural elements of the building. Replaceable equipment is installed on the overhead crane in the end end cell of the span, where the cover is preliminarily dismantled with a self-propelled jib crane installed outside the dimensions of the workshop.

Along the span with a bridge-boom crane, when moving away from oneself, they dismantle the structures of the old coating, crane beams and columns, while moving the crane "towards itself", all new structures of the building frame are mounted. The use of such cranes provides a significant increase in labor productivity.

Mechanical assembly shops of machine-building enterprises are characterized by the presence of clearly defined transport zones. However, their width is insufficient for the installation and movement of self-propelled jib cranes in the span. Under these conditions, it is possible to use a converted tower crane moving along one line of the track laid in the transport area. Its stability is ensured by a rigid articulation with an overhead crane (Fig.16.8, b).

In existing workshops, bridge cranes can also be used to mechanize work when replacing and straightening crane beams and rails. To do this, they need to be equipped with a pivoting boom attached to the main beam or mounted on the crane's cargo trolley (Fig. 16.8, c).

Improvement of assembly cranes for reconstruction conditions in combination with the improvement of means of small-scale mechanization reduces the costs of manual labor, comprehensively solves the problem of mechanization of work and contributes to a significant increase in labor productivity.

The variety of space-planning and design solutions, a wide range of works determine the variety of organizational and technological solutions in the context of reconstruction. Therefore, one of the main tasks in the field of further increasing the efficiency of work during reconstruction is the development of typified technological schemes for the production of work and the creation on their basis of a set of unified assembly tools and devices.

Rice. 16.8. Variants of using overhead cranes for assembly and dismantling works:

1 - full revolving boom; 2-tower; 3 - clip: 4 - brackets with undercarriage; 5 - winch; 6 - electric bridge crane; 7 - self-propelled bridge; 8 - converted tower crane; 9 - mounting boom

16.5. Concrete work during reconstruction

For the organization of concrete work in the conditions of reconstruction, in the development of PPR, in addition to the initial data used in new construction, it is necessary to take into account: information about the sources of obtaining concrete mixture, formwork and reinforcing blanks, data on the modes of work in existing workshops, indicating the time of stopping production and the number of shifts work per day, information on the use of the enterprise's resources (external and internal transport, electricity, water, compressed air) and an indication of the places of possible connection, as well as other information reflecting the peculiarities of local conditions.

The PPR should contain instructions for linking the production of concrete work (installation of formwork and reinforcement, transportation and compaction concrete mix) with the functioning of an operating enterprise.

The volume of work is especially great during the reconstruction of foundations for a new technological equipment, which most often requires reconstruction (restructuring, strengthening, replacement) or the construction of new foundations in the cramped conditions of existing production. These foundations, as a rule, are complex both in design and in outline in plan, especially for the equipment of rolling and open-hearth shops, blooming units, turbine units, forging and pressing equipment, ball mills of mining and processing plants. The volumes of monolithic concrete and reinforced concrete in foundations and their nomenclature differ significantly depending on the industry.

The choice of the method for the production of concrete works depends on the production conditions, the tightness of the construction site, the depth and construction of existing foundations, soil conditions, the height of the room, the width of the span, the pitch of the columns, the availability of concreting sites.

The most labor-intensive and expensive are formwork, the production of which takes 40% of the total labor costs and more than 17% of the cost of work.

The use of fixed formwork in the erection of monolithic structures in existing workshops allows to reduce the volume and scope of work, reconstruction time, reduce labor and machine intensity, and also makes it possible to maximize the combination of processes. In this case, instead of the usual formwork, prefabricated shell slabs (reinforced concrete or reinforced cement) are used. They are mounted instead of the concrete cover provided by the project and left in the body of the structure after concreting. When using fixed formwork made of reinforced cement or reinforced concrete slabs, a certain saving of materials is achieved, since there is no need to make special formwork forms, the labor intensity of work is reduced, since there is no need to remove the formwork of structures.

The concrete mixture is supplied to the formwork of foundations mainly by concrete pumps and pneumatic blowers, concrete pavers, dump trucks from concrete carrier racks and mobile bridges, belt conveyors.

The advantage of concrete pumps and pneumatic blowers is high productivity, which allows you to perform large volumes of work and ensure the supply of concrete mixture to any point of the foundation, regardless of its complexity and configuration. The effectiveness of this factor is especially noticeable when combining work and performing them in cramped conditions. At the same time, the labor intensity and the cost of work on laying the concrete mixture are reduced by 25 ... 30% compared to its supply by cranes.

As practice shows, in conditions of reconstruction, the method of conveying concrete mixture to the place of laying with the help of belt conveyors and conveyors is more effective than others. It allows you to provide greater productivity with less labor intensity compared, for example, with the supply of a mixture by cranes, to create any route of the transport highway, which is important when organizing work in the cramped conditions of an existing production. For concreting freestanding foundations and columns during in-shop reconstruction, it is also convenient to use a forklift equipped with a vibrating hopper.

Monolithic reinforced concrete structures, which in terms of labor intensity, successfully compete with prefabricated floor solutions, are widely used in the reconstruction of residential and public buildings. The following types of structures are used: flat floor slabs with support along the contour or on both sides (in buildings with a span of up to 6 m); ribbed (ribs up) and hollow ceilings (for buildings with a span of more than 6 m); ribbed on existing metal

Dismantling of buildings and structures is one of the most laborious construction processes. Its complexity increases several times if the work is carried out in a dense urban environment. In general, dismantlingis the division of an object into elements and their further removal from the construction site. At the same time, the technology is selected taking into account the material, shape, weight, dilapidation, location and other features of outdated structures and their surroundings.

Element disassembly

The most gentle and at the same time the most time consuming method. It implies the use of manual labor and the appropriate tools - a sledgehammer, crowbar, jackhammer, etc. It is advisable in small areas, as well as if the dismantled elements are planned to be used in the future for reconstruction or when .

Directional blast

The fastest and effective method demolition of large structures located away from residential buildings and busy areas. It is strictly regulated by law, requires high professionalism from performers and permits to work with explosives.

Mechanized demolition

The most popular way in densely built-up conditions - using special equipment: hydraulic hammers, hydraulic shears, excavators with an extended boom. Differs in high efficiency and speed of work, affordable cost.

Diamond cutting

In the case when it is necessary to remove structures without dust and vibration, equipment with a diamond cutting part is used. At the same time, it is possible to cut reinforced concrete and brick structures with maximum accuracy, cutting off parts and sawing openings. The main disadvantage of this method is the high cost of using the equipment.

Hydraulic wedging

To quickly and cleanly dismantle stone and reinforced concrete structures with a thickness of up to 1.5 m, the use of an expanding hydraulic wedge allows. It is installed in special holes and, under the influence of a hydraulic pressure build-up system, is expanded with an effort of 200-300 tons, breaking concrete in the desired direction without noise and dust.

AlfaStroy specialists have extensive experience in dismantling works of varying complexity. We provide a full range of services, from pre-project inspection of the facility to garbage collection after completion of work, choosing in each case the most economical and efficient technologiesdismantling.

Modern dismantling of walls, partitions and entire structures in a building is a high-tech process that includes two stages:

• Preparatory.
• Basic.

At the preparatory stage, the contractor must receive from the customer full package project documentation and drawings, which should also include a prepared working estimate, a plan of underground utilities, PPR and a signed order for dismantling work. All engineering and construction personnel involved in dismantling work must be familiarized with the documentation. It is also required to conduct a safety briefing during such work.

What is included in the preparatory period for dismantling

• Thorough inspection of the premises intended for dismantling;
• Careful study terms of reference, formulating the conditions for the performance of such work;
• Selection and development of technologies for dismantling works at a specific site;
• Disconnection of all existing utilities in the dismantling area;
• Equipping the place of work with special scaffolding, bunkers, construction hoses, garbage chutes, scaffolds and other equipment necessary for dismantling. It is also necessary to establish a system for removing construction waste from the facility.
• Selection of equipment for temporary fastening of the necessary working structures;
• Installation and safe connection of temporary utilities to the place of work.

Stages of the main period

• Dismantling of individual structures and elements that are not connected to each other. Elements that are not connected to each other are removed, sorted and stored in a special way. The destruction and subsequent loosening of monolithic structures, which are made of reinforced concrete or natural stone, are also carried out;
• Sorting of materials and building elements remaining from dismantling, equipment of engineering and other communications, subsequent storage and transportation to the place specified by the customer;
• Preparing the site for subsequent installation construction works.

In the course of dismantling, old unusable structures, utilities and other structural elements are removed, the further use of which has become impossible for technical reasons.

During the dismantling work, the personnel must create a place for the installation of new structures or utilities and other equipment. Only after the complete completion of dismantling works will it be possible to start installing new elements and new equipment.

Dismantling is subject to expensive good quality floor coverings, engineering equipment in working order, other equipment such as ovens, built-in furniture and lighting fixtures.

The main stages of dismantling floors of various types

Plank floors

Dismantling plank floors begins with removing the skirting boards. After that, remove the boards. You need to start work from the site farthest from the front door. If you intend to use the floorboards a second time, then you must not violate the scheme of laying the boards. To preserve it, each board is marked with special symbols. After removing the logs, the inventory wooden floorings installed on the floor slabs are also removed.

Parquet

Parquet floors are also disassembled. The ridges and dowels of the parquet floor must be marked very carefully so that it is easier to reassemble the floor covering later.

Dismantling of panelboard parquet starts from the place of open fastening. In the event that the fastening is made with screws, then you must first unscrew the fasteners. If the parquet floor consists of independent parquet rivets, then the parsing of the covering starts from the middle row. In this case, the base of the boards is disassembled according to the scheme for disassembling the plank floors.

Removing linoleum begins with dismantling metal or plastic thresholds. Then the linoleum sheet is torn off the floor and rolled into a roll.

Screed removal

Dismantling of the old screed is carried out in the event of its complete or partial destruction. Also, removal occurs if the old screed is uneven and does not respond modern standards noise insulation. To remove the concrete layer from the floor, use special pneumatic concrete hammers, grinders, various types of hammer drills and other impact tools.

In this case, it is very important not to touch the electrical wiring laid in the building. According to modern building technologies used in the construction of residential buildings, the electrical wiring for the lower floor is laid under the screed of the upper floor. Usually they are hidden in corrugation or HDPE insulation. Before starting dismantling in such places, it is required to carefully study the construction documentation and find a place for laying the electrical wiring.

Dismantling windows

The removal of old window blocks should start with the sashes. They must be removed together with the vents. Before removing the structure, they are torn off with a nail puller from the window frame or the screws are unscrewed. It all depends on the state of the window structure and the type of fasteners.

Glass and devices installed on them, such as air conditioners, are removed from the window frames. For removal, special portable workbenches are used, on which it is convenient to work. The removed glass is stored in a vertical position in specially prepared boxes that protect the glass from damage.

After the dismantling of the window sashes is completed, the workers proceed to the removal of the slopes. Before that, old plaster is knocked down from them. Only after that they begin to remove the window sills.

The leaning window block remaining in the window opening is squeezed out of the fasteners with a crowbar and tilted inward, carefully laying it on the floor.

If the window openings laid with bricks are dismantled, then the work begins with the dismantling of the internal masonry. This is a complex monotonous process that requires a lot of physical effort from the staff. Before disassembling the window unit itself, it is necessary to establish the degree of its suitability for reuse. If the block becomes unusable completely, it should be destroyed.

Dismantling doors

Dismantling the door frame begins with dismantling the fittings and glass from the door leaf. After the complete removal of all these elements, the door leaf itself is removed from the hinges. Before dismantling it, the door trims are removed from the inside.

After that, the door frame must be unfastened using boards or special strips. 2 boards are driven into the box at a 45 degree inclination into the upper corners of the box. The third board is installed horizontally at the bottom of the door frame.

With the help of a crowbar or a nailer, the box, after being unfastened, is separated from the wall and pulled out of the doorway. If necessary, you can remove the trims from the outside of the doorway.

When carrying out dismantling in old houses, as well as when dismantling metal and polymer window structures, special recommendations must be followed. In this case, special gas cutting and cutting machines are used. They should be delivered to the work site prior to dismantling.

The last stage of dismantling work is the removal of debris and dust from a window or doorway. All construction waste is placed in bags and carried away from the premises.

Dismantling of internal partitions

In building technologies, it is customary to distinguish two types of interior partitions: load-bearing and non-load-bearing. Non-bearing structures are made of thin concrete slabs, gas silicate or tongue-and-groove elements. Such partitions are disassembled in parts and stored on the floor.

Before starting to dismantle the internal partitions in the room, it is necessary to glue the windows.

Dismantling the load-bearing partitions must be done carefully. The condition of the entire structure of the building will depend on this. Often, to create arches or when expanding a doorway, the bearing partition is partially dismantled. In this case, it is imperative to strengthen load-bearing wall... A complete dismantling of load-bearing partitions is never done.

At the beginning of dismantling works of load-bearing partitions, it is necessary to check the general condition of the building and obtain permission to carry out dismantling works from the city's architectural committee.

Partial dismantling is carried out using a grinder, with which an opening of the required size is cut. All figures should be given in the project document, which guides the workers. Metal corners are inserted between the enlarged opening, which are welded at the joints. The same is done with back side walls.

After strengthening the bearing wall, the pieces are crushed with a perforator or grinder in the allocated area. Work should be done from top to bottom. To protect and strengthen the metal corners, after making the opening under the arch, an injection of the weld is made and the corners are painted. For the injection of the seam, the wall is slit between the horizontal and vertical overlap, and the working solution is poured into the resulting opening.

For the safety and security of the ceilings of the lower floors, boards are placed in the places of dismantling. This will prevent the weight of the falling concrete structures from breaking the ceiling joint on the lower floor.

Dismantling of partitions is carried out only after the dismantling of utilities has been carried out. Before dismantling the load-bearing partitions, the structure should be inspected again.

Disassembly of non-load-bearing partitions made of blocks

If there is a doorway in such a partition, dismantling should begin from the top of the doorway. First, you should embroider the joint between the ceiling and the wall. Only after that start knocking out blocks. Pi it is necessary to move along the masonry - horizontally or like a ladder. This will ensure the safety of the worker.

Non-load-bearing reinforced concrete panels can also be dismantled from the top. In this case, to cut the reinforcement of reinforced concrete partitions, you need to use a grinder.

The walls are cleaned of old wallpaper with a special fur roller, which is well moistened with water. With its help, the wallpaper is moistened with water. You need to apply water in several steps so that the old wallpaper is better saturated. After removing the wallpaper layer, you can proceed to remove the old newspaper layer in the same way. Ultimately, completely "bare" walls should remain.

Dismantling of decorative plaster is also done by wetting the wall. After that, the old layer of plaster is removed with a spatula.

IT IS FORBIDDEN!

Begin dismantling without obtaining permission from the regulatory architectural authorities.

The specifics of dismantling work

All work of this type begins only after the complete agreement of all project documentation. Dismantling the floor screed must be done very carefully so as not to disturb the electric cable laid in the floor, which provides ceiling lighting on the lower floors in new buildings. Damage to it will delay construction work and increase its overall cost.

When dismantling the sewer system, the openings of the necks of the sewer risers should be closed.

Checking the quality of the dismantling

Floor slabs must be completely free of old screeds.
The door or window opening must be completely cleaned.
All work must be performed strictly according to the drawn up and confirmed project.
The ceilings must not form cracks after dismantling.

STANDARD TECHNOLOGICAL SCHEMES FOR DISMANTLING THE PRODUCTION CASE
(PROJECT OF WORK PRODUCTION)

Section I... TOTAL INFORMATION

The diagrams are made for the dismantling of the production building T1 in axes 1-7¸ J-N.

The dismantled section of the production building is a one-story frame building with a size of 36´ 24 m in plan, and 10.8 m high inside the building.

The building frame is made of reinforced concrete structures: columns with a height of 10.8 m with a section of 800´ 400 mm spaced in 12 steps´ 18 m; the trusses have a span of 18 m and a height of 3 m; ribbed cover plates, two standard sizes 12´ 3 m and 12 ´ 1.5 m.

Fencing structures - wall panels (height - 1.0; 1.2; 1.8 m) 6 m long and 300 mm thick. Reinforced concrete half-timbered columns, section 300´ 400 mm. In axes 7 ¸ J-M section of the wall thick. 250 mm to mark 6.6 m is made of silicate bricks.

Between the columns in the longitudinal direction at an elevation of 8.0 m there are horizontal ties representing a rigid spatial metal structure. In axes 1, 4, 7¸ J-L vertical braces are located, representing a rigid spatial metal structure.

Inside the case at elevation 7.2 m along the reinforced concrete columns in the longitudinal direction there are metal beams of the bridge crane tracks.

Dismountable section of the T1 housing from the side of the axis 7¸ M-N adjoins the T2 body, and from the axis 7¸ J-N to the body to be dismantled.

To carry out work on dismantling the frame elements, it is planned to use an RDK-250 crawler crane (boom - 25.3 m; rigid jib - 5 m) as a lifting mechanism, and AGP-18.04 aerial platform as a means of paving. It is allowed to use other mechanisms with similar cargo-height characteristics.

It is allowed to start dismantling the production building T1 in axes 1-7 ¸ J-N only after the installation of new vertical braces in the building T1, which are provided by the project instead of the dismantled ones.

The dismantled structures are transported from the grapples to the on-site site for storage by special vehicles (panel trucks, scows).

Section II... TECHNOLOGICAL SEQUENCE OF WORK PERFORMANCE

Install on the roof of the T1 building along axes 1-7 ¸ J, N after dismantling the structures, the protective fence is GOST 12.4.059-89 .

All persons on the construction site are required to wear safety helmets. Employees without protective helmets and other necessary personal protective equipment are not allowed to work.

When performing work using the gas-flame method, the following safety requirements must be met:

Gas cylinders should be stored and used in accordance with the requirements of the rules for the design and safe operation of pressure vessels;

Cylinders must be installed vertically and secured in special racks;

During operation, the distance from the burners (horizontally) to the groups of gas cylinders must be at least 10 m, to gas pipelines and rubber-fabric hoses 3 m, to individual cylinders 5 m;

Gas cylinders must be protected from shocks and direct sunlight;

When storing cylinders in open areas, sheds that protect them from the effects of precipitation and direct sunlight must be made of non-combustible materials;

At the end of the work, gas cylinders should be placed in a place specially designated for storage of cylinders, excluding access to them by unauthorized persons;

Empty cylinders should be stored separately from cylinders filled with gas;

Gas cylinders are allowed to be transported, stored, issued and received only by persons trained in handling them and holding an appropriate certificate.

It is forbidden to keep flammable and flammable materials in the immediate vicinity of the place of work with the use of burners.

Fire-fighting equipment must be kept in good working order. Passages to fire-fighting equipment should always be free and marked with appropriate signs.

When carrying out dismantling works, observe the requirements:

Dismantling of wall panels in / o 1 J-N

Dismantling of frame structures of high-quality 1-4¸ L-N
(roof slabs; horizontal ties; bridge crane beams; half-timbered columns)

Dismantling of the farm in / about 1-4¸ L and columns 1 L

Table of mass of structural elements

	Name	Element weight, t
PS-1.0 ´ 6	Wall panel (1000´ 6000 ´ 300 mm)
PS-1,2 ´ 6	Table of load-gripping devices, equipment, tools Name Unit rev. Qty. 4-branch sling,RD 10-33-93 , 4SK2-10; L = 6.0 m (with equalizing blocks) PCS. 2-branch sling - "- 2SK-12.5; L = 6.0 m Lightweight sling - "- SKK-2.0; L = 2 m SKK-3.2; L = 3 m L = 5 m SKK-5.0; L = 3 m SKK-10; L = 2 m Sledgehammer (light) Hammer Assembly scrap Brush with handle Chisel (elongated) Gas post (for cutting fasteners) set