10. Installation of concrete and reinforced concrete pipes
Installation of pipe elements is carried out in accordance with the layout schemes in the working drawings, taking into account geometric tolerances in the dimensions of the elements
It is necessary to mount concrete and reinforced concrete pipes from the outlet head to the input head. With portal heads, the portal wall of the outlet head is first mounted, after which the slope wings are mounted. Next, the pipe sections are installed, and then the portal wall and sloped wings of the inlet head. If the project provides for the priority installation of heads, then the installation of links can be performed in any direction.
After the link is installed in the design position, the sling loops that interfere with the installation of the next link and the insulation device must be cut flush with the concrete surface.
It is not allowed to cut the hinges with a chisel or bend them in order to avoid chipping of the concrete and difficulties during installation, because. bent hinges prevent the installation of links in the design position.
When installing cylindrical links on prefabricated patterned blocks, the links are installed on wooden (non-removable) wedges, while providing the design gap for laying the cement-sand mortar using metal funnels for filling joints and metal screws.
Pipes should be lowered into the trench with jib cranes, pipe layers or gantry cranes.
To determine the crane boom L when laying pipes in a trench with slopes, it is recommended to use the following formula:
where a is the distance b from the axis of the pipe to the edge of the trench, m (for a trench with vertical walls, the value a should be taken equal to the depth of the trench plus half the width of the trench along the bottom; c is the distance from the edge of the trench to the outriggers of the crane, m (b is taken equal to 0 .7-1.0 m); c - distance from the outriggers to the axis of rotation of the crane, m.
11. Installation of sections of corrugated metal pipes
Before installing sections of a corrugated metal pipe, a special bed is cut out from granular materials in the foundation cushion, the dimensions of which must meet the requirements. The cutting of the bed should be done with a motor grader equipped with a profiled knife, or with a rough excavator, followed by manual finishing according to the template. The template can be made from sheet steel, boards or plywood. The radius of the curved edge of the template must be equal to the radius of the pipe along the center line of the corrugations.
The template should be installed on two wooden guide beams laid on both sides of the longitudinal axis of the pipe strictly along the level, taking into account the formation of the building rise of the pipe tray. By moving the template along the bars and cutting out the soil, a bed is created, into which the corrugated pipe is then installed. Deviations of the profile of the soil bed from the template should not exceed 2-3 cm.
Figure 7 - Scheme of installing a template for cutting a soil bed in the zero layer
1 - template; 2- wooden bars; 3 - zero layer; 4 - the level of the top of the pillow (should not exceed the lower mark of the soil bed)
After the pipe is installed in the design position, soil is poured into the gaps between the surface of the lower part of the pipe and the soil bed. The soil is compacted using manual wooden bayonets with a diameter of not more than 8 cm, and additional soil is added to the lower quarters (until the pipe is covered with soil of at least 120 °) with compaction by manual electric rammers and backing. Electric rammers and vibrocompactors compact the soil at a distance of 5 cm and further away from the crests of the corrugations. The soil in the corrugations is compacted with bayonets.
Further, the zero layer directly near the pipe should be additionally compacted by a machine with a vibro-impact working body in one or two passes of the machine along the pipe walls. In the case of using pneumatic rollers for soil compaction, additional compaction of the zero layer near the pipe walls should be carried out with manual electric rammers.
If the pipe is installed on a flat base, then after that soil should be poured into the lower quarters of the pipe with compaction by manual electric rammers and bayonet until the pipe is covered with soil by at least 120 °. The subsequent compaction of the soil near the pipe is carried out in the same way as with a profiled bed.
Depending on local conditions, it is necessary to mount the pipe with overlap bolted joints at the construction site from sections pre-assembled from individual elements on polygons, or from individual elements.
In all cases where it is possible to deliver pipe sections to the facility by vehicles or tractors and install them with a crane, especially in areas with a calculated minimum outdoor temperature below minus 40 ° C, the method of installation from sections should be the main one. At the same time, it is recommended to install pipes “from wheels”, setting the sections immediately to the design position after lifting from vehicles.
The length of the sections should be assigned based on the given design lengths of the culverts. In this regard, it is possible to use sections of various lengths on one structure. When assigning the lengths of pipe sections, it is necessary to take into account the capabilities of the available vehicles for transporting structures to the construction site. In intermediate sections, the number of links must be odd. The length of the sections is recommended to take no more than 10 m.
Pipe assembly should be carried out in accordance with the wiring diagram available in the project for the production of works. The installation scheme should provide for: the order of installation of corrugated elements during assembly and combination of sections, the procedure for transporting sections, the procedure for installing bolts, the scheme of special ties and scaffolds for fastening pipes with a diameter of more than 2 m in cross section during assembly.
When installing pipes, a set of tools should be used: socket wrenches, crowbars, hooks with rings, electric or pneumatic wrenches, hammers.
The set of bolts supplied to the construction site should include 10 mounting bolts, 75 mm long, of the same diameter as the service bolts. These bolts should be used to temporarily tie corrugated sheets and should not remain in the structure.
The project for the production of works should take into account the peculiarities of installing metal structures in the design position, depending on the upper outline of the pillow under the pipe. With a foundation planned without a bed, it is allowed to install the pipe side by side (parallel to the design axis of the structure) and then roll it into the design position. With a profiled base bed, the pipe should be installed with a crane.
All elements of the pipe structure, materials, tools and equipment must be brought to the construction site before the pipe is assembled. When installing pipes "from wheels", only individual elements are delivered to unite the section.
The installation of pipes with monolithic or prefabricated heads should begin with the assembly of the foundation part of the lower head, followed by the laying of the metal structures of the structure (sections, elements) and the completion of the heads.
Before starting work, you should check the presence of markings, reject the elements, straighten the bent places with a wooden hammer and lay out the elements and boxes with fasteners along the axis of the pipe.
When rejecting elements and fasteners, the marking of elements, geometric dimensions of elements and fasteners, quality protective coating.
On each corrugated sheet, on its inner surface, near the second row of holes for the longitudinal joint on the first convex corrugation, the steel grade, the element and the stamp of the quality control department of the plant and the factory inspector of Glavmostroy should be indicated. The brand of the element conditionally indicates the diameter of the pipe and the thickness of the sheet. Each package of corrugated elements must be labeled with the element brand, steel grade, element thickness, pipe diameter, manufacturer and year of manufacture. The geometric dimensions of structural elements and fasteners must meet the requirements of the project and this Instruction.
The surface of the zinc protective coating of pipes should not have visible cracks, nicks, sags on the mating surfaces and places not covered with zinc. The use of elements with the specified defects is not allowed. Defects in the protective coating are eliminated by the manufacturer.
Before installing the elements, in order to ensure the necessary clearance in the bolt holes, it is necessary to melt the excess of retained bituminous mastic in them in advance using mandrels of a standard diameter heated to a temperature of plus 130 ° C.
The contact surfaces of the elements and fasteners must be cleaned of dirt and foreign particles.
First, it is necessary to assemble the links in a vertical position (the elements are installed on the edge) with a limited number of bolts (3-4 bolts) in the middle of the longitudinal joints. In this case, one end of the element must be on the outer surface of the link, and the other on the inner. In the second row of the longitudinal joint, there should be no holes on the outer crests of the waves (Figures 9 and 10).
In properly assembled pipe sections, all element grades must be visible. Then the links must be sequentially installed in a horizontal position on wooden beams laid along the pipe sections so that the longitudinal joints in them are at the same level, and the location of the overlap of the elements in the connected links is exactly the same.
The links are combined into a section by standard elements. When installing these elements at the junction of three sheets, contact of two sheets included in one link is not allowed. Therefore, each connecting element with one end is inserted into the gap between the elements of previously assembled links A and B.
Figure 8 - The sequence of assembling a pipe section from individual links
a- the magnitude of the shift of the longitudinal joints,
1–9 - the order of installation of elements when combining links BUT and B
Figure 9 - The layout of the bolts of the longitudinal joint:
1 ,2 - respectively the 1st and 2nd rows of bolts of the inner sheet
Figure 10 - Scheme of connecting two sections with connecting elements:
1 ,2, 3 - numbers and sequence of installation of connecting elements;
A, B- ends of connected sections; a- the value of the shift step of the longitudinal joints
Longitudinal joints in the links should be placed with ligation - mutual shift by an amount a, equal to one - four steps of the holes of the transverse joints. The shift value for each individual pipe is assumed to be constant.
When installing connecting elements (assembling sections and combining them), bolts in the amount of 3-4 pcs. should be baited first in the middle parts of the longitudinal and transverse joints. The rest are installed after combining the required number of links into a section. The last bolts are placed at the junction of the three elements.
Bolts should be tightened with IE-3101 electric wrenches or IP-3103 pneumatic wrenches, as well as socket and box wrenches.
It is allowed to use other electric wrenches of small mass (2-3 kg), providing a tightening torque of 15-20 kgf × m.
When tightening the bolts, it is necessary to monitor the correct position of the plano-convex and plano-concave washers.
When assembling pipe sections, bolts in longitudinal joints should be placed at a distance of at least 15 cm from the ends of the end links of the section. The bolts installed in the end links should not be tightened, which facilitates the installation of standard elements with their insertion into the gaps of the longitudinal joints between the elements of the end links.
Before starting work, it is necessary to prepare elements intended for connecting sections, fasteners, and also deliver the necessary tools and equipment.
Installation of the pipe should be carried out on a planned base or side by side (near the design axis of the pipe). Sections are laid on wooden bars for unhindered setting of bolts in the lower part.
Sections in the design position, as a rule, should be installed by a crane. When slinging sections, measures must be taken to exclude the possibility of damage to the protective coating. Slings are placed at a distance of a quarter of the length of the section from their ends.
The sections should be combined according to the scheme shown in Figure 10. First, the ends of the sections are installed with a truck crane so that the longitudinal joints are located at the same level, then the connecting elements are installed.
Before starting the installation of the pipe, all preparatory work must be completed.
If there is no flat area at the pipe construction site near the prepared base, then light wooden scaffolding should be prepared for pipe assembly, placing them near the design axis of the pipe.
According to the first scheme, the pipe should be built up with standard elements gradually (the numbers show the sequence of their installation). The elements are carried and held in the required position by special hooks. Centering holes in the elements for installing bolts is carried out by mandrels, inserting them into the holes located next to the holes into which the bolt is inserted. When installing elements in places where three sheets overlap, contact between two sheets included in one link is not allowed. Assembly should be carried out with the installation of a minimum number of bolts: first, 2-3 bolts are placed in the middle sections of the longitudinal and transverse joints, after which a screed is made at the junctions of the three elements with long mounting bolts, which are then replaced with ordinary ones. After bolting in a link of elements 11 and 12 continue assembling the next section of the pipe, and in a link of elements 5 and 6 install and tighten all bolts.
According to the second scheme, first lay out the lower elements for the entire length of the pipe, combining them with bolts in the middle part. Then two other link elements are installed through one link (see figure 3.5, numbers in brackets). Next, the remaining elements of the missing links are sequentially mounted, completing the installation by setting and tightening all the bolts.
Between the link in which all the bolts are tightened and the link being assembled, there must be at least three links with baited bolts.
When installing pipes at a construction site, pre-assembly of the links and their subsequent joining can also be carried out. For pipes with a diameter of 2 m or more, this assembly technology is preferred.
The links are assembled on a specially prepared site with wooden deck in close proximity to the pipeline under construction. The assembled links are installed by a crane on the base, placing wooden bars under each link and orienting them along the pipe (after installing and tightening all the bolts, the bars are removed from under the pipe).
Figure 11 - Mounting diagram of the pipe (end view):
a- the magnitude of the shift of the longitudinal joints;
1–12 - the order of installation of elements when assembling a pipe
When assembling pipes with a diameter of more than 2 m, the project must provide for portable scaffolding for installers. For pipes with a diameter of 3 m, scaffolds are arranged inside the pipe with a height of 1.3 m and a plan size of 2 × 2 m, as well as external scaffolds (two sets) with a height of 1.5 m and a plan size of 1 × 2 m; when assembling pipes with a diameter of 2 m, scaffolds are arranged with a height of 0.5-0.8 m.
Fringing corners are installed when the bolts located at a distance of 0.3-0.5 m from the ends are not tightened in the longitudinal joints of the end sections of the pipe.
Acceptance of the installed pipe must be documented.
Concrete and reinforced concrete pipes are laid on a natural or artificial base. The joints of pressure pipes (bell or socket) are sealed with rubber sealing rings, and non-pressure (bell or seam) - with a resin or bituminous strand, asbestos-cement or cement lock, as well as asphalt mastic. Before laying pipes in a trench, they, like couplings, are subjected to an external inspection during acceptance to identify defects and check dimensions.
Concrete and reinforced concrete pipes are laid out along the trench in various ways (perpendicular to the trench, at an angle, etc.), the choice of which depends on the type and load capacity of the erection cranes used.
Installation of pressure pipelines. Pressure pipelines are mounted from socket and smooth reinforced concrete pressure pipes on coupling joints, which diversifies the technology of their laying.
Installation of pipelines from socket pipes is carried out in the following sequence: delivery of pipes and laying them out along the trench, feeding them to the installation site, preparing the end of the pipe and installing a rubber ring on it; introducing it together with the ring into the socket of the previously laid pipe; giving the laid pipe the design position - final sealing of the joint; preliminary testing of the finished unfilled section of the pipeline (and for pipes of large diameters, only butt joints); backfilling of this area; his final test.
The installation of pipes is carried out by jib cranes, and the pipes from the berm of the trench are fed with sockets forward along the installation and always against the flow of liquid. Before laying the first pipe, a concrete stop is installed at the beginning of the route, which ensures a stable position for the first two or three pipes when they are connected into a socket. The recommended layout of mechanisms, assembly workers and pipe layout during pipeline installation is shown in fig. 4, a. When laying the pipe, first, according to the template, the depth of its insertion into the socket of the laid pipe is marked on its smooth end. Having installed the crane in the middle of the pipe being laid and slinging it with a semi-automatic grip (Fig. 4, d, c, e) or using slings or a traverse, the pipe is fed into the trench (Fig. 4, e, f).
Fig.4 - The main working operations during the installation of a pipeline from reinforced concrete socket pipes: a - general scheme organization of work (T -1, T -2, T -3, T -4, T -5 - jobs for pipelayers); b - marking the smooth (sleeve) end of the pipe with a template; a, d - slinging the pipe and lowering it into the trench with the help of a tong grip; e - the introduction of the smooth end of the pipe into the socket; e - reconciliation of the position of the pipe in the plan according to the landmarks; g - pipe centering; h - inventory pole with a plumb line; and - tension device; 1 - pipes; 2 - crane; 3 - trench; 4 - tick grip; 5 -- laid socket pipe; 6 - stacked pipe; 7 - pits; 8 - stairs; 9 - fixed sights; 10 -- portable (running) sight; 11 - inventory poles; 12 -- tension screw; 13 - beam; 14 - thrust; 15 - spacer
At a height of 0.5 m from its bottom, the lowering of the pipe is stopped and a rubber ring is put on its smooth end, after which it is led into the socket of the previously laid pipe and lowered onto the prepared base. Wherein Special attention centering of the spigot end of the introduced pipe with a rubber ring relative to the lead-in chamfer of the socket of the previously laid pipe.
To align the position of the pipe being laid, a running sight is supported on its tray and then it is ensured that the top of this sight is on the common line of sight with two fixed sights on the cast-offs (Fig. 4, f, g). After aligning the pipe vertically, the grip is removed from it, the crane is released to install the next pipe and proceed to align the position of the pipe in the plan. For this purpose, inventory poles are installed along the plumb line (Fig. 4, h): one of them is at the end of the pipe being laid, and the other is at the previously laid one. According to the fixed pole installed in the well or on the mounted section of the pipeline, the correct laying of the pipe in the plan is checked (Fig. 4, e). If necessary, it is shifted in the right direction.
Finally, using a tensioner (Fig. 4, i), the smooth end of the pipe is inserted into the socket of the previously laid one, while monitoring the uniformity of rolling the rubber ring into the socket slot. ; a gap must be left between them (for which marking is done), and for pipes with a diameter of up to 1000 mm - 15 mm, and for pipes of large diameters - 20 mm. Having connected the pipes, remove the tensioner and knock the pipe from the sides with soil to a height of 1/4 of its diameter with its layer-by-layer compaction with manual rammers.
Fig.5 - Methods for mounting bell-shaped pressure reinforced concrete pipes and devices used for this: 1 - laid and laid pipe; 2 - half collar; 3 - rubber ring; 4 - cable; 5.6 - thrust and working beams; 7 - tension screw; 8 - friction-ratchet device; 9 - hinge clamp; 10 - adjusting screws; 11,12 - support and movable fortifications; 13 - ratchet; 14 - concrete stop; 15 - hydraulic cylinders; 16 - oil pipeline; 17 - pump; 18 - pipe-laying crane; 19 - bell; 20 - lever winch; 21 - blocks; 22 - cable to the winch; 23 - thrust beam; 24 - bulldozer or tractor; 25 - excavator bucket; 26.29 - removable and repair clamps; 27 - support clip; 28 - pusher; 30 - repair rubber ring; 31 - bolts; 32 - traverse; 33 - levers; 34 - plate; 35 - clamping pads; 36 - gripper for pipes; 37 - hook
When installing pipelines from socketed reinforced concrete pipes, the most time-consuming operation is the introduction of the sleeve end of the pipe with a rubber ring into the previously laid socket. To facilitate it, various devices, devices and mechanisms are used. In particular, two-three-cable external tensioners are used (Fig. 5, a, b), rack and pinion hydraulic jacks(Fig. 5, c), internal tensioners, lever and gear winches (Fig. 5, d, e), bulldozers and excavators (Fig. 5, f, g).
For the installation of pipes with a diameter of 500, 700, 900 mm, a universal hydraulic device is also used (Fig. 5, i), which is fixed on the pipe, and then lowered into the trench with it. After checking the accuracy of centering the pipe and the correct location of the rubber ring, the pipe is joined to the pipeline under the action of the stroke of the hydraulic cylinder.
When choosing a pipe installation method, take into account the presence necessary equipment and mechanisms, as well as the conditions for the construction of the pipeline. Installation of pipes using a bulldozer (Fig. 5, e) can be carried out if the bulldozer is used when planning (cleaning) the bottom of the trench, i.e. when these two operations are combined. Installation of pipes with a diameter of 1000--1200 mm in trenches with a bottom width of 2.2 m is carried out using a D-159B bulldozer (Fig. 6). For the installation of pipes of small diameters (up to 500 mm), the Tsentrospetsstroy trust manufactured a small-sized bulldozer based on the T-548 tractor with a blade width of 1.25 m. tensioner recommended for pipes with a diameter of 800 mm or more.
Fig.6 - Installation of reinforced concrete pipes with a diameter of 1000-1200 mm using a bulldozer: 1, 2 - laid and stacked pipes; 3 - bulldozer D -159 B; 4 -- assembly crane (E-652 B); 5 -- pipe layout
The installation of the pipeline using an excavator bucket (see Fig. 5, g) is carried out when laying pipes in water-saturated soils or in cramped urban construction conditions, when the trench is torn off as the pipes are laid, and the excavator located nearby is used to install them by turning the bucket.
Applied means of mechanization of the installation of reinforced concrete and concrete pipelines depend mainly on the type of butt joint and pipe diameter. The type of butt joint determines the technical requirements for the installation equipment, and the diameter of the pipes and the dimensions of the trench determine the possible layouts of the installation equipment and the flow diagrams of the installation work resulting from this.
The main technical requirements for equipment for mounting pipes on rubber sealing rings are: ensuring the alignment of the pipes and creating the necessary axial force for their joining. When installing pipes with a socket-screw connection, it is additionally necessary to ensure that the pipe being laid is screwed into the previously laid pipe. For the installation of pipes with caulking of butt joints, mechanized compaction of fibrous materials in the socket gap should be provided.
The installation of concrete and reinforced concrete pipes is currently carried out mainly in two technological schemes. In the first case, attachments are used to the pipe-laying crane to perform all operations: capturing the pipe on the berm and lowering it to the bottom of the trench, centering the pipe being laid to the laid section of the pipeline and joining the pipes. The second scheme provides for the performance of centering and docking operations by a base machine moving along the bottom of the trench with the appropriate equipment. Each of these schemes has its own areas of application, due to the length and diameter of the pipes and the width of the trench.
Existing methods of installation of reinforced concrete pipes (especially large diameters of 1000, 1200 mm) do not provide accurate alignment during installation of the laid and previously laid pipes. Usually, the laid pipe is supported on weight by a lifting mechanism, and a longitudinal force is created by another mechanism (tractor, excavator), which ensures that the smooth end is inserted into the socket of the laid pipe. At the same time, as experience shows, it is very difficult to provide the same annular gap between the surface of the smooth end of the pipe and the inner surface of the socket at the joint, due to which the rubber ring located in this gap is not clamped uniformly along the perimeter of the pipes. Therefore, the rubber ring does not roll evenly as it enters the socket, and sometimes twists, which is unacceptable. It is also difficult to provide the necessary clearance at the joint between the pipes, since the pipes are shifted until they touch in the socket, often without any control.
Fig.7 - Scheme hinged device for installation of reinforced concrete pipes on rubber sealing rings (a), attachments for installation of pipes with a socket-screw connection (b) and a trench machine for installation of socket pipes (c): 1 - stop - clamp; 2 - pipe clamps; 3, 9 - hydraulic cylinders; 4 - traverse; 5 - bracket; 6 -- guide sleeve; 7 - stock; 8 - a pipe previously laid; 10 - captures; 11 - stacked pipe; 12 -- wedge retainer; 13 - frame; 14 -- rotation drive and axial pipe feed; 15 -- roller grips; 16 - capture of a previously laid pipe; 17 -- pipe pusher cross beam on a horizontal frame; 18 - clamshell bucket of a pit digger; 19 -- inclined boom pit digger; 20 -- plow spoon digger; 21 -- road seals; 22 - bed; 23 - pit; 24 -- window for skipping the bucket into the face; 25 -- passive side diffuser; 26 -- dump
Attached equipment for mechanized installation of reinforced concrete pipes, eliminating these shortcomings, was developed by the Tula Polytechnic Institute together with the Tula-Spetsstroy trust and other organizations. Such attachments (Fig. 7, a) for the installation of reinforced concrete pressure pipes on rubber sealing rings are structurally made in the form of a load carrier beam with suspension to the hook of the pipe-laying crane. On the beam there are two grippers of the stacked pipe, a gripper of the previously laid pipe and a horizontal feed drive of the stacked pipe. The device has simple design and reliable in operation.
The hydraulic drive is carried out from the hydraulic system of the pipe-laying crane and is designed for pressure up to 10 MPa. At the same time, the force in the docking hydraulic cylinder reaches 95,000 N. Due to the large difference in the mass of pipes of different diameters, four options for such attachments have been developed: for pipes with a diameter of 500; 600 and 700; 800 and 1000; 1200-1400 mm, and changeover from one diameter to another in each variant is carried out using replaceable parts. The mass of attachments for pipes with a diameter of 1200 mm, shown in fig. 19.9, a, is 900 kg.
For the installation of pipes with a diameter of 900 mm, the Yaroslavl Institute of PTIOMES developed attachments for the pipe-laying crane TG-124. Its length is 5600, width and height are 1640 mm. weight 940 kg.
To mechanize the installation of reinforced concrete pressure pipes with a steel core of the RTNS type, attachments have been developed, including a fixed and a movable frame. A hydraulic cylinder is installed in the fixed frame, the rod of which is connected to a cam rod, which acts on all mechanisms of the equipment when the rod moves. An emphasis-grab is rigidly fixed on the movable frame, behind which there is a mechanism with a tong grip.
For the installation of reinforced concrete non-pressure pipes with a socket-screw connection, special attachments have been developed (Fig. 7, b), which consists of a frame, roller grippers of the pipe being laid, and a gripper of the previously laid pipe. Stops are rigidly attached to the frame, mating with the socket and the sleeve part of the laid pipe.
With a pipe-laying crane, the attachments are brought to the pipe to be laid and fixed in roller grips. Then the attachment with the pipe is moved and lowered into the trench, brought to the previously laid pipe, which is fixed with a grip. With the help of a rotation drive and axial feed, the pipe to be laid is screwed into the socket of the previously laid pipe.
For mechanized caulking of socket pipes with fibrous materials, a special device is used, which contains a removable caulking unit, consisting of caulking in the form of petals, attached to a three-section roller wheel rigidly fixed on a three-section body. The case rotates on rollers of three-section capture. To carry out caulking, a removable assembly is installed on attachments. Before mounting on the pipe in front of the petals, a strand of hemp or other fibrous material. After lowering into the trench with the help of hydraulic cylinders, the end of the pipe is inserted to the required distance into the socket of the previously laid one. The hydraulic motor is turned on, the petals begin to rotate, at the same time they are progressively introduced into the socket slot and the fibrous material is caulked with a rotational movement.
Trust Spetstyazhtransstroy has developed a device for mechanized sealing of joints in large-diameter socket pipes. In this device, the embossing sleeve is equipped with vibration exciters, which ensures an improved quality of pressing the fibrous material into the socket slot of the pipes to be connected.
The structural diagram of a special trench machine for the installation of socket pipes is shown in fig. 7, c. The machine includes a basic tractor with a pipe pushing transverse beam suspended in front of it and a plow spoon digger and a pit digger placed on opposite end sides, made in the form of a longitudinally inclined boom and a clamshell bucket freely suspended from its head.
The main requirements for the quality of the installation of reinforced concrete pipelines: during the docking process, it is necessary to check the uniformity of the placement of the rubber ring and its rolling. If a backlog is observed in some part of the circumference, it is necessary to “powder” the ring with cement in this place, to exclude further uneven rolling of the ring.
Rings in the gap of socket and socket joints must be compressed by 40-50% of the thickness of their sections. They must not be twisted. In case of violation of the tightness (water tightness) of the joints, they are repaired, for which additional rubber rings or their segments are installed on defective place using a special removable clamp (see Fig. 5, h).
Installation of pipelines with coupling butt joints. After centering and checking the correct laying of pipes along the cord, plumb line and sight at the ends of the pipes to be connected, markings are made with risks that determine the initial position of the rubber rings, distances a and b. When installing pipes, the coupling is installed in starting position so that its end face on the working side coincides with the risk applied on the pipe. The rubber ring is placed near the working ring of the coupling, which is then inserted into the conical slot of the coupling flush with its end using a caulk. At the same time, another rubber ring is put on the second pipe, placing it at a distance b from its end.
Further, with the help of mounting devices, the coupling is advanced towards the pipe to be joined with simultaneous rolling of the first rubber ring. Upon reaching the coupling on the second pipe, risks b from its end, a second rubber ring is introduced into the coupling slot, which ensures the necessary final position of the rubber rings in the joint and its water tightness. The sequence of installation of pipe joints using collarless and single collar couplings is shown in fig. eight.
The distance a, b and their fixing the final position of the coupling and rubber rings of the distance c, d, e are given in Table. one.
Non-pressure socket and socket pipes are connected with a gap between the smooth end of the pipe and the socket surface equal to 10 and 15 mm for pipes with a diameter of 700 and more than 700 mm, respectively. The installation of non-pressure pipelines from socket and socket pipes with sealing with rubber rings is carried out by the same methods as pressure ones. The joints are sealed with a hemp strand by caulking the bell to half its depth with two or three turns of tarred or bituminized hemp strand with an asbestos-cement mixture casserole (30% asbestos, 70% cement).
Installation of a pipeline from seam free-flow pipes is associated with the need to seal seam joints. Joints of pipes with a diameter of more than 1000 mm are sealed around the entire perimeter with a hemp strand and rubbed with a 1: 1 cement mortar with a device outside the belt from this solution.
Installation of pipes with a crane using a mounting bracket is carried out in the following sequence: mark the position of the pipe on the base; sling the pipe and lower it into the trench; lay the pipe on the base and verify its position; caulked with a resin strand and sealed with cement mortar; wrap joint reinforcing mesh and monolithic it. The joints of pipes with a diameter of 2000-4000 mm, laid on a concrete and reinforced concrete base, are sealed with shotcrete along the reinforcing mesh.
Fig.8 - Installation of pipe joints using collarless (a) and single collar (b) couplings: I - the first stage of installation and the initial position of the first rubber ring; II - the second stage and the initial position of the second rubber ring; III -- final position of the coupling and rubber rings in the mounted joint
Table 1. Distances when marking the position of the coupling and rubber rings before installation (a, b) and from the ends of the coupling to the rubber rings in the mounted joint (c, d, e) - see fig. 9
|
Distances, mm, from the end to the mark at the end of the pipe |
Distance from rubber ring |
||||
|
without a collar, but |
with collar, b |
from the end of the coupling from the side |
to its initial position, d |
||
|
working, in |
non-working, g |
||||
|
Reinforced concrete: previously tense with metal shell |
|||||
|
Asbestos cement: without shoulder |
CENTRAL INSTITUTE REGULATORY
RESEARCH AND SCIENTIFIC AND TECHNICAL
INFORMATION"ORGTRANSSTROY"
MINISTRIES OF TRANSPORT CONSTRUCTION
DEVICE ASSEMBLY
REINFORCED CONCRETE CULVER
DIAMETER 1 m UNDER THE ROAD
I. SCOPE
The technological map was developed taking into account progressive methods of organizing construction and work production, as well as methods of scientific organization of labor and is intended for use in the development of a project for the production of work and the organization of work and labor at the facility.
The technological map provides for the construction of a single-point prefabricated reinforced concrete pipe with a diameter of 1 m, length 26.28 m under the road (with an embankment height of 4 to 7 m).
The design of the pipe was adopted according to the "Standard design (501 Zh-5) of prefabricated unified concrete culvert pipes for iron and highways» Glavtransproekt, approved by order of the Ministry of Railways and the Ministry of Transport and Construction of July 8, 1966 No. , Inv. No. 101/1.
The pipe is assembled from precast concrete elements:
foundation - from curved blocks laid on crushed stone preparation;
pipe body - from links with a length of 1 m;
caps with postcards - from separate blocks.
Strengthening of the channel at the heads in the technological map is not provided.
In all cases of using the technological map, it is necessary to link it to the local conditions of work.
II. MANUFACTURING PROCESS INSTRUCTIONS
Pipe construction works include:
preparation of the construction site;
marking works;
acceptance and placement of equipment, materials and structures at the construction site;
excavation for the foundation of the pipe and head;
crushed stone preparation device;
installation, foundation blocks, heads and pipe links;
filling the sinuses of the pit with soil;
concreting trays within the heads;
waterproofing works;
backfilling the pipe with soil.
Site preparation
The site in the pipeline construction zone (at a distance of at least 10 m in each direction from the axis of the pipe) are planned by a bulldozer with slopes that ensure the flow of water from the pipe.
At the outlet head, the natural channel is cleared, and at the input head, at a distance of at least 1.5 m from the contour of the pit, they block the channel with soil and arrange a bypass ditch or embankment of the construction site. These measures should ensure the complete removal of surface water from the pit.
For the delivery of equipment, concrete blocks and materials, a bulldozer clears and plans access roads that provide free passage along the ring traffic pattern.
Marking work
The position of the pipe is determined by the road design. The design organization must fix in kind and hand over to the contractors, according to the act, the point of intersection of the road axis with the longitudinal axis of the pipe, the longitudinal axis of the pipe, fixed with four outrigger stakes (Fig.), as well as the high-altitude benchmark.
Measurements along the axis of the pipe outline the contour of the pit and mark it with pegs.
At a distance of 1 m from the boundaries of the pit, they arrange a cast-off of boards or beams (Fig.) and designate on it the longitudinal axis of the pipe and the position of the heads, openings, sections of the foundation.
The cast-off, if possible, should be buried in the ground to protect it from damage by a bulldozer or excavator.
The sequence of installation of blocks and pipe links
|
Crane parking |
Mounting number |
Marne element (block No.) |
block weight, t |
The maximum reach of an arrow, m |
|
|
Installation of outlet head blocks (portal and openings) |
|||||
|
Device for gravel-sand preparation for the outlet head |
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|
Laying the foundation block |
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|
Installation of conical link and pipe links |
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|
Laying patterned foundation blocks |
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|
Installation of pipe sections |
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|
Pattern block laying |
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|
Installation of pipe sections |
|||||
|
Installation of inlet head blocks |
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|
Gravel-sand preparation device for the inlet head |
|||||
|
Installation of molded foundation blocks |
|||||
|
Installation of pipe links and conical link |
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Installers 4 size. - 1 and 3 bits. - 1 accept blocks and links and install them with the help of braces and crowbars in the design position.
Installer 3rd category inspects and cleans blocks and links, slings them for feeding into the pit. Installer 2nd category fills the vertical seams of the patterned foundation blocks with sand-cement mortar before installing the links. After installing and unfastening the head blocks, the link in full force performs work to fill the space behind the portal block and the base for the trays with a gravel-sand mixture.
Before installing the last pipe links, the fitter 2 raz. proceeds to pour cement mortar under the pipe links using a flat funnel (see Fig. rice.). He finishes work immediately after installing the last pipe links. Then he moves on to another pipe.
The working links of the insulators, working two at each head, concrete the trays at the output and input heads. The concrete mixture is delivered by dump trucks and unloaded for sand and gravel preparation, spread with shovels in an even layer and compacted with a surface vibrator. The surface of freshly laid concrete is smoothed with floats and covered with sand. Immediately after the installation of the trays, the workers of the link fall asleep simultaneously on both sides of the sinus of the pit. The soil is pushed by a D-271 bulldozer, in hard-to-reach places they are thrown up manually, and then they are evenly distributed with shovels in the sinuses of the pit and compacted with S-690 electric rammers. The section of insulators also performs work on sealing the seams between the links and head blocks, gluing and coating waterproofing of the pipe, as well as backfilling the pipe with soil to a height of 0.5 m.
Two waterproofers 3 and 2 razr. they make bundles from tow, dip them in bitumen and caulk the seams between the links. Then they proceed to caulking the seams from the inside with cement mortar with jointing. They work from the middle of the pipe to the edges, placing light portable circles under the upper part of each seam (see Fig.), supporting the solution in the seam.
Following them are two waterproofers 4 and 2 pit. arrange pasting insulation of seams. To do this, one cuts bituminized fabric panels into strips 25 wide. cm, at this time, another worker brings the mastic, pours hot bituminous mastic onto the joint with a thin stream from a scoop with a drainer, and both stick the bituminized fabric.
The same link arranges coating insulation using a spray unit or an asphalt distributor.
Backfilling of the pipe with soil is carried out by the entire link using an E-302 excavator equipped with a grab. Workers compact the soil in layers with S-690 electric rammers.
At the beginning of the shift (or at the beginning of work with a small amount of work), the machine operators are obliged to check the readiness of the machines for work, eliminate minor malfunctions, refuel the machine with fuel and water, operate the machine during work, and at the end of the shift (or work) clean the machine and inform mechanics about the noticed shortcomings. The crane operator must check and test the rigging and mounting equipment before starting work.
V. CALCULATION OF LABOR COSTS FOR THE CONSTRUCTION OF A PREPARED CULVER WITH A HOLE 1 m, LONG 26.28 m
|
Code of rates and prices |
Description of works |
The composition of the link |
unit of measurement |
Scope of work |
Norm of time, man-hour |
Price, rub.-kop. |
Standard time for the full scope of work, man-hour |
The cost of labor costs for the full scope of work, rub.-kop. |
|
|
BUT. Preparatory work |
|||||||||
|
ENiR, 2-1-24, No. 6a |
Layout of the construction site with a bulldozer in 3 passes on one track |
Machinist 5th grade - one |
100m 2 |
||||||
|
By the time |
Breakdown of the structure with the removal of axes and the device of the cast-off |
2 bits - one |
man-hour |
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|
Reception of tools, fixtures and equipment and their installation, construction site lighting |
Structural assemblers: 3 cuts. - one 1 bit - one |
man-hour |
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|
ENiR, 4-4-92, No. 1 |
Unloading and sorting head blocks |
Crane driver 6 years - one Structural assemblers: 4 cuts. - one 3 bits - one |
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|
ENiR, 4-4-92, No. 3 |
Unloading and sorting of pattern blocks |
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|
ENiR, 4-4-92, No. 6 |
Unloading and sorting of pipe sections |
Crane driver 6 years - one Structural assemblers: 4 cuts. - one 3 bits - one |
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|
Total |
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|
B. Earthworks a) Digging a pit |
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|
ENiR, 2-1-15, tab. 2, No. 56+d |
The development of the soil of the II group by the bulldozer D-271 (when moving it up to 20 m) |
Machinist 5th grade - one |
100m 3 |
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|
ENiR, 2-1-10A, tab. 3, no. 3z |
Group II soil excavation with an E-302 backhoe |
Machinist 4th grade - one |
100m 3 |
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|
ENiR, 2-1-15, tab. 2, No. 56+d, approx. 3, K = 0.85 |
Moving soil of group II by bulldozer D-271 at a distance of 20 m |
Machinist 5th grade - one |
100m 3 |
||||||
|
ENiR, 2-1-31, tab. 2, No. 1e, approx. 3a, K = 1.2 |
Refinement of soil of group II in the pit manually after its development by an excavator and a bulldozer |
Digger 2 bit. - one |
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|
ENiR, 2-1-46, No. 26, K = 1.2 according to 2-1-31, approx. 3b |
Cleaning the bottom of the pit in soils of group II manually with cutting off irregularities, filling in recesses with soil compaction, checking the planned surface according to the template |
Digger 2 bit. - one |
100m 2 |
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|
b) Backfilling of the sinuses of the pit and pipe |
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|
ENiR, 2-1-15, tab. 2, No. 56+d, approx. 3, K = 0.85 |
Moving soil of group II by bulldozer D-271 at a distance of 20 m |
Machinist 5th grade - one |
100 m 3 |
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|
ENiR, 2-1-44, tab. 1, no. 26 |
Backfilling the sinuses of the pit with soil manually with tamping |
Excavators: 2 raz. - one 1 bit - one |
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|
As applied to ENiR, 2-1-45, tab. 3, no. 2a, K = 1.2 |
Compaction of soil of group II with electric rammers after backfilling in layers of 15 cm |
Digger 3 bit. - one |
100m 2 |
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|
ENiR, 2-1-12, tab. 3, No. 1v |
Backfilling the pipe with soil to a height of 0.5 m E-302 excavator equipped with a clamshell bucket |
Excavator driver 5 years - one |
100m 3 |
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|
As applied to ENiR, 2-1-45, tab. 3, no. 1a, K = 1.2 |
Compacting the soil with electric tampers when backfilling the pipe with layers 20 thick cm (66m 3 : 0,2m = 330m 2) |
Digger 3 bit. - one |
100m 2 |
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|
Total |
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|
Total earthworks |
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|
B. The device of two heads |
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|
ENiR, 4-4-88, No. 56 |
Device for gravel-sand preparation for bevels and head trays in layers of 15 cm (11,8: 0,15 = 79m 2) |
3 bits - one 2 bits - one |
100m 2 |
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|
ENiR, 4-4-88, No. 4A |
Device for crushed stone preparation with a thickness of 0.1 m(1,2: 0,1 = 12m 2) |
100m 2 |
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|
ENiR, 4-4-91, tab. 2, no. 1b |
Crane installation of pattern blocks No. 24 weighing 1.5 tons |
Crane driver 6 years - one Structural assemblers: 4 cuts. - one 3 bits - 2 |
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|
ENiR, 4-4-94, No. 2b |
Installation by a crane of conical links No. 27 weighing 1.3 tons |
Crane driver 6 years - one 3 bits - 2 |
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|
ENiR, 4-4-93, No. 1 |
Installation of a portal wall weighing 3 tons by a crane of block No. 35 |
Crane driver 6 years - one Structural assemblers: 4 cuts. - 2 3 bits - 2 |
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|
ENiR, 4-4-93, No. 5 |
Installation by crane of blocks No. 39p, l of sloping wings weighing 3.1 tons |
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|
ENiR, 4-4-99, No. 1 |
Caulking of seams of links with portal walls of tow impregnated with bitumen |
Structural assemblers: 4 cuts. - one 3 bits - one |
1m seam |
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|
ENiR, 4-4-99, No. 3 |
Joint isolation device |
3 bits - one |
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|
ENiR, 4-4-99, No. 2 |
Sealing of joints between the conical link and the portal wall of the head with cement mortar |
Structural assemblers: 4 cuts. - one |
1m seam |
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|
ENiR, 4-4-97, No. 2 |
Caulking of vertical seams between the blocks of the portal wall and the sloping wings of the head |
1m seam |
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|
ENiR, 4-4-97, No. 4 |
Filling vertical joints between head blocks with cement mortar |
Structural assemblers: 4 category - 1 3 bits - one |
1m seam |
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|
ENiR, 4-4-97, No. 7 |
Jointing of seams between head blocks |
Structural assemblers: 4 cuts. - one 3 bits - one |
1m seam |
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|
ENiR, 4-4-101, No. 1 |
Coating insulation device |
Waterproofers: 3 cuts. - 2 |
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|
Total for 2 heads |
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|
D. Installation of links and pipes and arrangement of foundations |
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|
a) 2.01 m section |
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|
ENiR, 4-4-88, No. 4a |
Device for crushed stone preparation with a layer thickness of 0.1 m |
Road workers: 4 resp. - one 3 bits - one 2 bits - one |
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|
ENiR, 4-4-91, No. 1b, tab. 2 |
Laying by crane of pattern block No. 4 of the foundation of the pipe body weighing 1.9 tons |
Crane driver 6 years - one Structural assemblers: 4 cuts. - one 3 bits - 2 |
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|
ENiR, 4-4-94, No. 2b |
Crane installation of pipe sections weighing 1.1 tons |
Crane driver 6 years - one Structural assemblers: 4 cuts. - 2 3 bits - 2 |
|||||||
|
ENiR, 4-4-99 No. 1 |
Structural assemblers: 4 cuts. - one 3 bits - one |
1m seam |
|||||||
|
ENiR, 4-4-99, No. 3 |
Joint insulation device |
Waterproofers: 4 cuts. - one 3 bits - one |
1m seam |
||||||
|
ENiR, 4-4-101, No. 1 |
|||||||||
|
ENiR, 4-4-99, No. 2 |
1m seam |
||||||||
|
Total per section |
|||||||||
|
Total for 2 sections |
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|
b) 3.02 m section |
|||||||||
|
ENiR, 4-4-88, No. 4a |
Device for crushed stone preparation with a layer thickness of 0.1 m |
Road workers: 4 resp. - one 3 bits - one 2 bits - one |
|||||||
|
ENiR, 4-4-91, tab. 2, no. 16 |
Laying by crane of pattern block No. 5 of the foundation of the pipe body weighing 1.4 t |
Crane driver 6 years - one Structural assemblers: 4 cuts. - one 3 bits - 2 |
|||||||
|
ENiR, 4-4-94, No. 26 |
Crane laying pipe sections weighing 1.1 t |
Crane driver 6 years - one Structural assemblers: 4 cuts. - 2 3 bits - 2 |
|||||||
|
ENiR, 4-4-99, No. 3 |
The device of pasting insulation of the joint |
Waterproofers: 4 cuts. - one 3 bits - one |
1m seam |
||||||
|
ENiR, 4-4-99, No. 1 |
Caulking seams of pipe links with tow impregnated with bitumen |
Structural assemblers: 4 cuts. - one 3 bits - one |
1m seam |
||||||
|
ENiR, 4-4-101, No. 1 |
Coating waterproofing device |
Waterproofers 3 razr. - 2 |
|||||||
|
ENiR, 4-4-99, No. 2 |
Sealing joints with cement mortar |
Structural assembler 4 size. - one |
1m seam |
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|
Total |
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|
Total for 5 sections |
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|
Total for 7 pipe sections |
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|
D. The device of trays at the heads |
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|
ENiR, 4-4-98 |
Concreting of trays at the input and output heads with a thickness of 20 cm |
Concrete workers: 4 bits. - one 3 bits - 2 |
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|
ENiR, 17-31, No. 1 + 3 |
Fresh Concrete Care |
Road worker 1 resp. - one |
100m 2 |
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|
Total |
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|
Total per pipe |
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|
Including: for the work of link No. 1 (I cycle) №№ 1 - 10, 17; 29; 36 |
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|
Tapered links #27 |
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|
Round links No. 13 |
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|
Portal Wall Blocks No. 35 |
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|
Blocks of sloping walls No. 39l and No. 39p |
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|
Concrete mix M-150 |
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|
Cement mortar M-150 |
Excavator equipped with backhoe and grab |
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|
Bulldozer |
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|
mobile power station |
|||||||||
|
Mobile spray unit |
|||||||||
|
surface vibrator |
|||||||||
|
Electric rammers |
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|
Digging shovels LKO-1 |
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|
Picking shovels LP-1 |
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|
Carpentry axes |
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|
Portable circles |
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|
Cross saw |
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|
Level length 1 m |
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|
Roulette RS-20 |
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|
Steel skins |
TsNIIS Mintransstroy |
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|
flat funnels |
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|
Steel caulks |
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|
Water tank |
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|
Container for bituminous varnish |
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|
Reiki for leveling |
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|
Trowels (trowels) |
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Reducing labor costs and increasing the output of workers is achieved through the use of improved tools and devices, in reducing the loss of working time - by performing process operations by a flow-dissected method.
The composition and sequence of work processes during the laying of pipelines largely depend on the type of pipes used (metal or non-metallic), as well as on the conditions for their laying (in cramped urban or field conditions, on flat or rough terrain, with or without natural and artificial barriers and etc.). When laying, for example, main pipelines from steel pipes the main workflows are performed in the following sequence:
During the construction of conduits and collectors in urban areas, where along the laying route there is a large number of various structures (wells, chambers), as well as crossings under roads, the composition and sequence of work will be different. The composition and sequence of work processes during the laying of pipelines from various pipes. However, the leading work processes in any case are the laying of pipes or their sections and lashes in the design position and their connection into a continuous pipeline line.
In winter, measures are taken to minimize the freezing of the soil and protect temporary roads and entrances from drifts. When laying pipelines on fertile lands, perform additional work for cutting and moving for storage in a special dump of a fertile humus layer for subsequent restoration (reclamation) of land.
The pipeline route is broken up on the ground before the start of earthworks. The position of its axis is fixed with signs that allow you to quickly and accurately perform layout work. When laying out the route, it is necessary to install temporary benchmarks along it, connected by leveling moves with permanent ones, fix and tie the staking axes and vertices of the angles of rotation of the route to permanent objects (buildings, structures) or to poles installed on the route. Further, it should be noted on the surface of the intersection of the pipeline route with existing underground utilities and the location of the wells. The layout of the route is drawn up by an act with an appendix to it of a statement of benchmarks, turning angles and bindings. Prior to the start of earthworks, a working layout of trenches and pits for wells and chambers is checked. During earthworks, all marking and geodetic signs must be preserved.
To break down the pipeline route by profile, i.e. in terms of height, they use cast-offs with sights installed at the locations of the wells and at the tops of the turning angles. The transfer to nature of the design axis of the pipeline, as well as its linear and angular elements, is carried out from the layout drawing. Each turn of the route is tied to three local objects, points of the center base or to points fixing the red building lines. The beginning and end of the route, all its turning points, wells and chambers are brought to the area. When laying pipelines in trenches, a detailed breakdown is performed based on the design longitudinal profile of the route and layout drawings. It begins with the transfer to the bottom of the wells of the design marks of the bottom of the trays in two adjacent wells, the centers of which are determined using a plumb line. The edges of the pits of the wells are broken from their centers, setting aside on both sides of the longitudinal axis of the trench half the design width of the pit of the well, taking into account the slopes, and fixed with pegs. Similarly, on straight sections of the trench, the longitudinal axis is fixed with pickets and points every 5 + 10 m. Then, from this axis, the distances to the left and right edges of the trench are perpendicularly laid and marked with pegs. Since the pegs are often destroyed when digging trenches and pits, the position of the main and auxiliary axes is fixed with the help of wooden castings (Fig. 1, a). The longitudinal axis of the trench is transferred with the help of a theodolite installed above the leading sign, fixed on a cast-off and marked with a horizontal shelf 3 (see Fig. 1, a). A permanent visor 4, made in the form of the letter T from the slats, is installed and nailed (sewn) onto the shelf 3 and nailed (sewn). From the longitudinal axis of the trench, auxiliary axes are broken on the cast-off and the number of the well, the diameter of the pipes being laid and the name of the axes are written with paint. The direction of the longitudinal axis of the trench is determined using a steel wire stretched through the axis marks on the toes and a plumb line. The design slope of the trench bottom is checked using a running (portable) sight (Fig. 1, c, d) 2.5 long; 3 and 4 m, also made in the letters T. Its length is taken such that when its heel is installed on the bottom of the trench, the upper edge of the crossbar rises above the ground by at least 1 m. Permanent sights above two adjacent wells are installed at such a height that the plane drawn through their vertical faces is parallel to the bottom of the trench in compliance with the design slope. It will be provided if the top of the running sight installed at any point in the trench coincides with the plane of sight. An example of calculating the top of permanent sights with a gravity pipeline slope of 0.008 and a distance between wells of 45 m is shown in Fig. 1, b. Under these conditions, the difference in the marks of the tops of the visors will be 0.427 m. The visors are also used to control the depth of the trench, preventing enumeration.
Fig.1. Breakdown of trenches of pipelines a - cast-off with a permanent (sewn-on) sight; b - scheme for calculating constant sights; c - portable (running) sight with a ledge-shoe; g - the same without a ledge; 1 - pillars; 2 - board; 3 - shelf; 4 - permanent sight
Before laying the pipeline, check the depth and slopes of the bottom of the trench, the steepness of the slopes. If the trench has fasteners, then check the correctness of their installation. The necessary conditions for the reliable operation of the pipeline are its laying at the design level with its tight support on the bottom of the trench, as well as the safety of the pipes and their insulation during laying. Therefore, great attention is paid to the preparation of trenches for laying pipes. When laying pipelines in urban areas, the trench is often crossed by various communications (pipelines, cables). If they are below the pipeline under construction, then this does not complicate its laying, and if they are higher, then it is necessary to take measures to enclose them in special boxes with reliable fastening. Pits in trenches for sealing socket and socket butt joints, as well as welding pipe joints, are torn off for pipes with a diameter of up to 300 mm immediately before they are laid, and for pipes of large diameters - 1 hour 2 days before they are laid.
Underground pipelines are laid on natural or artificial foundations. Concrete, reinforced concrete, ceramic, asbestos-cement, plastic, as well as metal pipes. When laying reinforced concrete pipes of large diameters (1.5 + 3.5 m), the following requirements are observed: sandy soils the bed for pipes should cover at least 1/4 of the surface of the pipe, and in clay and rocky - the pipes are laid on sand cushion at least 100 mm thick with careful sealing. Artificial foundations for pipelines are arranged in weak, dry, as well as in water-saturated soils that cannot serve as a reliable natural foundation.
The quality control of pipes is usually carried out twice - at the manufacturing plant and directly on the route, before they are laid in the trench. At the plant, the quality of pipes is checked according to the established methodology, sometimes with their testing. On the route, almost all incoming pipes are subject to inspection and verification of their quality. This is extremely necessary, because if at least a few or even one low-quality pipe is used during the installation of a pipeline, especially a pressure one, breaks and accidents will occur at the place of their installation. Eliminating them is often very difficult, because it will require stopping the operation of the conduit and digging trenches.
On the route, incoming pipes are accepted according to the documents (certificates, passports) of manufacturers, confirming their quality. However, defects can occur in pipes due to improper loading, transportation and unloading. Therefore, before laying pipes in a trench, they are carefully inspected, their actual quality is checked, and if serious and faulty defects are found, they are rejected.
It is not allowed to lay pipes with cracks, chipped edges and sockets, large deviations of their circumference, i.e. with "ovality", and other serious defects. The surface of rubber cuffs and rings used for pipe joints should be smooth, free of cracks, bubbles, foreign inclusions and other defects that reduce their performance.
Pipes are lowered into the trench in most cases with the help of cranes, as well as special lifting devices. Only light pipes (small diameters) are lowered manually using soft ropes, towels and other devices. Dumping pipes into a trench is strictly prohibited.
Lowering pipes and sections into a trench or to the bottom of a channel is a rather laborious process. It is comparatively easier to lower pipes into a trench with gentle slopes without fasteners, the lowering efficiency depends only on right choice pipe laying schemes and type of erection crane. It is more difficult to lower pipes into trenches with vertical walls, especially in the presence of fasteners with cross braces. At the same time, pipes are laid with sequential removal and installation of spacers. All this slows down and complicates the process of laying pipes, increases its labor intensity and lengthens the construction period. This process can be somewhat accelerated and secured by using large-sized fasteners with vertical shields, horizontal girders and spacer frames located every 3 + 3.5 m (Fig. 2).
Pipe laying in a given direction and slope between two adjacent wells is carried out using portable sights, beacon pins or using a level. Running sights (see Fig. 1, c, d) are used when cleaning the bottom of the trench to the design mark. When laying the pressure pipeline on the cleaned bottom of the trench, the top of the pipes is leveled, for which purpose sights without protrusions at the bottom are used, installed on the top of the pipes. Therefore, the length of such a sight is reduced by the value of the outer diameter of the pipes (see Fig. 1, d).
For laying gravity sewer pipes along a given slope, a running sight is used, which has a ledge attached at a right angle at the bottom of the heel (see Fig. 1, c). When laying pipes, the protrusion sight is installed vertically on the pipe tray (Fig. 4).
The technology of installation of external pipelines largely depends on their purpose and type of laying, pipe material, their diameter, wall thickness, pipe length, the presence of ready-made insulation on them and its type (or lack of it), as well as on the provision of construction with installation elements (pipe sections, lashes) and other conditions.
Installation of pipelines from any type of pipes (or their sections) is associated with the need to connect them into a continuous thread. Pipelines on the route are assembled (mounted) from individual elements (pipes) of relatively short length, and therefore a large number of joints have to be sealed or welded. This slows down and increases the cost of laying pipelines. Somewhat facilitates the laying of pipelines by preliminary enlargement of pipes into links or sections of two or three or more pipes.
The laying of pipelines consists in the installation and assembly of assembly units on the route - pipes (or their sections, lashes), fittings, compensators and fittings - in the design position. At the same time, the larger the mounting unit, the fewer mounting joints and the easier it is to assemble pipelines. The nodes are completed and tested, as well as covered with a layer of insulation or painted at pipe procurement bases. The industrial technology of laying pipelines provides for the centralized procurement of mounting elements and assemblies, their delivery to ready-made on the track preliminary training grounds and supporting structures to laying, on-precise assembly of pipelines.
The composition and sequence of work processes when laying pipelines depend on the type of pipes used (metal and non-metallic), as well as on the conditions for their laying (in cramped urban or field conditions, on flat or rough terrain, with or without natural or artificial barriers, etc.).
Work during the laying of pipelines is usually carried out in several stages, performed sequentially: checking the quality of pipes; lowering pipes into a trench; centering and laying them in a given direction and slope, fixing pipes in place; sealing joints with checking their quality; testing and acceptance.
The quality control of pipes is usually carried out twice - at the manufacturing plant (according to the established methodology, sometimes with testing them on the bench) and directly on the route before they are laid in the trench. On the route, almost all incoming pipes are subject to inspection and verification of their quality. This is extremely necessary, because the use of at least a few or even one low-quality pipe during the installation of a pipeline, especially a pressure one, will lead to breaks and accidents at the place of their installation. It is very difficult to eliminate them, since it requires stopping the operation of the conduit and digging trenches. In case of accidents on water conduits made of bell-shaped cast-iron or reinforced concrete pipes, replacing a poor-quality pipe is very difficult. If in such cases it is impossible to correct the defects of a low-quality pipe in the trench, it is necessary to destroy it (which is also not easy) and remove it, and in its place to lay an “insert”, most often from a steel pipe, since it is almost impossible to lay the same socket pipe. If it is possible to correct the defect and put the pipeline into operation, then the “insert” will always be a weak point due to the rapid corrosion of the steel pipe.
On the route, incoming pipes are accepted according to the documents (certificates, passports) of manufacturers confirming their quality. However, defects may occur in pipes due to improper loading, transportation and unloading. Therefore, before laying in a trench, the pipes are carefully inspected, their actual quality is checked and they are rejected if serious and irreparable defects are found. It is not allowed to lay pipes with cracks, chipped edges and sockets, large deviations from the circumference, i.e. with ovality, and other serious defects. The surface of the rubber cuffs and rings used for pipe joints should be smooth, without cracks, bubbles, foreign inclusions and defects that reduce their operational properties.
Pipes are lowered into the trench with the help of cranes, as well as special lifting devices. Only light pipes (small diameters) are lowered manually, using soft ropes, panels, etc. It is strictly forbidden to dump pipes into the trench. It is relatively easy to lower pipes into a trench with gentle slopes without fasteners; the efficiency of lowering depends only on the correct choice of the pipe laying scheme and the type of mounting crane. It is more difficult to lower the pipes into the trench in the presence of fasteners with transverse struts. At the same time, pipes are laid with sequential removal and installation of spacers. All this slows down and complicates the process of laying pipes, increases its labor intensity and lengthens the construction period. To speed up and secure this process, large-sized fasteners with vertical shields, horizontal girders and spacer frames are used, located every 3-3.5 m.
Pipe laying is carried out according to two schemes. In the first scheme, the process is performed by two threads. First, the pipe-layers, using a crane, lay the pipe on the bottom of the trench and continue to work on the final alignment and its temporary fixing, and then the installers, using a compressor and pneumatic hammers, caulk the pipe joints. In the second scheme, the process is performed in three streams using two taps. Moreover, one of them lowers the pipe and continues to work with a link of installers to align and temporarily fix the pipe, and the second duplicates all these processes for laying the next pipe (second stream); the third flow for caulking (sealing) of pipe joints is performed as in the first scheme. Light pipes are lowered into trenches with fasteners with the help of small-scale mechanization or manually. Pipes or sections should be lowered with strict observance of safety rules.
Pipe laying in a given direction and slope (figure below) between two adjacent wells is carried out mainly along portable (running) sights, beacon pins or with the help of a level. Running sights are used when cleaning the bottom of the trench to the design mark. When laying a pressure pipeline on the cleaned bottom of the trench, the top of the pipes is leveled (levelled), for which purpose sights without protrusions below, installed on the top of the pipes, are used. Therefore, the length of such a sight is reduced by the value of the outer diameter of the pipes.
Laying pipes in a given direction and slope
1 - cast-off; 2 - constant sight; 3 - running sight
For laying gravity sewer pipes along a given slope, a running sight is used, which has a ledge glued at a right angle at the bottom of the heel. When laying pipes, the protrusion sight is installed vertically on the pipe tray. The pipe is considered to be laid along a given slope to the design marks if the top of the running gear and two permanent sights are in the same plane visible to the naked eye. The straightness of pipe laying is checked by plumb lines suspended on an axial wire (mooring). After installing cast-offs and half-checks, using a level, determine the marks of the shelves at the ends of the stacked area.
The line connecting the points between the centers of the permanent sights on the cast-offs has the same slope as the slope of the pipeline. This line is called the line of sight. A template with a marked axis of the pipeline is inserted into pipes of large diameters, which facilitates their laying in a given direction. To speed up the work, inventory metal portable cast-off sights are used. For more accurate observance of the design slope of the pipeline tray, a visual method of an inclined beam of a level or a laser beam (sight sight) is used. With the latter method, a laser level is used, which is installed at the beginning of the site.
Gravity-flowing pipelines along a given slope can also be laid using a level. The correctness of laying the pipeline in a given direction and slope is finally checked before filling pipes and wells by leveling the bottom of the pipe and well trays, i.e. perform executive shooting. The difference in marks between the bottom of the wells and the tray at individual points of the pipeline should not differ from the design by more than a construction tolerance. The straightness of the pipeline between the wells is checked using mirrors that reflect the beam along its axis.
Pipes are fixed in place after they are laid, either by powdering with soil, or by using wedges (for example, when laying heavy pipes of large diameters on concrete bases).
Sealing of joints is carried out when installing pressure and non-pressure pipelines from short concrete, reinforced concrete, cast iron, asbestos-cement and ceramic pipes(bell-shaped or smooth on coupling connections). The joints of pressure pipes are usually sealed with rubber rings or cuffs, and gravity pipes - with a tarred strand, asbestos-cement mixture, etc. (picture below). The joints of steel pipes are welded, and plastic pipes are welded or glued.
The tightness and water tightness of the socket joints of cast-iron pipelines are achieved by sealing the socket gap with a hemp tarred or bituminized strand, followed by a lock made of an asbestos-cement mixture that keeps the strand from being squeezed out by hydraulic pressure. Sometimes it is used instead cement mortar and, in exceptional cases, lead. Recently, mastics have been used. When sealing joints with self-sealing rubber cuffs, no locks are required.
Joints of reinforced concrete pipes
a, b - socket; in - folded; 1 - smooth end of the pipe; 2 - asbestos cement; 3 resin strand; 4 - bell; 5 - cement mortar; 6 - rubber rings; 7 - cement mortar or asphalt mastic; 8 - grouting with cement mortar
Seal of socket joints with a strand. A hemp strand is inserted into the bell slot until the bell stops at such a depth that there is room for the lock device. Since the thickness of the bundle from the strand is somewhat greater than the width of the socket gap, it is pushed into the joint with the help of a caulk, with which the bundle is inserted into the annular gap first by hand, and then with strong hammer blows (during hand chasing). During mechanical chasing, the tourniquet is compacted with a pneumatic tool. To create the required tightness of the joint, 2-3 bundles are usually laid in the slot, moreover, so that their overlaps do not coincide along the circumference. After sealing the joint with a strand, an asbestos-cement lock is arranged, laying the asbestos-cement mixture into the gap in layers-rollers (3-4 layers each) and sealing with embossing, applying on them strong blows hammer. The sealed joint is covered for 1-2 days with wet burlap, which creates favorable conditions for setting and hardening of the asbestos-cement mixture.
Sealant mastics are used to seal butt joints of cast-iron socket pipes when laying pressure sewer pipelines with a maximum working pressure of up to 0.5 MPa. Most often, polysulfide sealants are used from sealing and vulcanizing pastes, to which asbestos or rubber crumbs are sometimes added. Mastics-sealants are prepared at the place of work 30-60 minutes before their use. Joints are sealed using syringes with manual or pneumatic extrusion of mastic or pneumatic installations. The sealant is introduced into the socket gap using a nozzle, which is attached to the tip of the syringe or hose of the pneumatic installation.
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