Main Directorate for Housing and Civil Construction in Moscow
GLAVMOSSTROY under the MOSCOW CITY EXECUTIVE COMMITTEE
TECHNICAL MANAGEMENT
TEMPORARY TECHNICAL INSTRUCTIONS
FOR LAYING REINFORCED CONCRETE PIPES
LARGE DIAMETERS (1.0-2.5 m) FOR
NON-PRESSURE SEWER CHANNELS
AND WATER COLLECTORS
VSN-27-61
Moscow - 1962
“Temporary technical instructions for laying reinforced concrete pipes of large diameters (1.0-2.5 m) for free-flow sewer canals and drainage collectors” were developed by the laboratory of road, bridge and underground construction of NIIMosstroi (laboratory head L. Akselrod, researchers V. Sakharov and G. Moshchevitin) and agreed with the Road and Bridge Construction Department of Glavmosstroy, the Water Supply and Sewerage Department and the Improvement Department of the Executive Committee of the Moscow City Council.
I. GENERAL PROVISIONS
1. These Temporary Technical Instructions are an addition to the “Technical Rules for Design, Construction and Acceptance into Operation sewer pipes pipelines in Moscow" (TPK-1-57) and provide rules for the construction of free-flow sewer and drainage pipelines from reinforced concrete pipes with a diameter of 1.0 to 2.5. They are mandatory for all construction organizations of Glavmosstroy.
2. Pipes for the construction of drainage and sewer collectors must meet the requirements of the current GOST 6482-53 and technical specifications approved by Glavmospromstroymaterials.
3. At the construction site, pipes are accepted according to factory documents, as well as by external inspection by persons authorized for these purposes.
The plant must submit a passport in the established form for each pipe. The following markings must be clearly marked on the inner and outer surfaces of each pipe with indelible paint: pipe brand, date of manufacture, name of the manufacturer, quality control stamp.
Pipes must be rejected if they do not meet current specifications.
Particular attention should be paid to the inadmissibility of:
a) kinks and cracks passing through the entire thickness of the wall of the pipe barrel or socket;
b) at the ends of pipes there are more than two rings more than 5 cm long along the generatrix or circumference of the pipe;
c) the conchoidal structure of concrete, indicating its insufficient density;
d) the presence of protruding or exposed reinforcement from the concrete.
Pipes without markings and passports are not allowed to be accepted.
4. Before laying pipes, gouges and other minor defects that do not interfere with the use of pipes must be repaired with cement mortar by the installation organization.
5. All construction and installation work on pipe laying is carried out in accordance with the requirements " Technical instructions for the production and acceptance of work on the installation of external water supply and sewerage pipelines" (SN-161-61), instructions of the "Safety Rules for Construction installation work"Gosstroy of the USSR (1958), "Instructions on safety precautions during underground work" Glavmosstroy (1958).
Geodetic work when laying out the route and installing pipes should be carried out only with proven tools that have passports and certificates of the date of the last inspection.
II. TRENCH DEVELOPMENT
6. Development and acceptance of trenches and pits must be carried out in accordance with technical rules production of excavation and drilling and blasting works (SNiP, part III), as well as these Technical Instructions.
7. The width of the trench along the bottom for pipes with a diameter of 1 m with a trench depth of up to 3 m (with and without fastening) is taken equal to the outer diameter plus 1.0 m*; with a depth of more than 3 m and fastening the walls of the trench for each meter of depth, 0.2 m is added to the width of the trench. The width of the trench along the bottom for pipes with a diameter of more than 1.0 m is taken according to the instructions of SN-161-61, § 34 equal to the outer diameter plus 1.5 m.
If it is necessary to install drainage trays or special drainage devices, complex artificial foundations for pipelines, as well as the presence of underground structures near the trench, the width of the trenches is determined by the design.
_________________
* According to SN-49-59, part IV, volume 1, chapter IV-B-1, paragraph 76.
8. In the soil natural humidity trenches are dug with slopes or with fastening walls.
The steepness of the slopes of trenches developed without fastenings must correspond to the data given in.
Table 1
9. Trenches up to 3 m deep must, as a rule, be secured, guided by the instructions of the current technical conditions (“Instructions for safety precautions during underground work”, appendix 4, published by NIIMosstroy, 1958), and those with a depth of more than 3 m - for individual projects.
When designing fastening structures, it is necessary to provide for the possibility of pulling pipes along trenches.
10. When developing trenches with an excavator, “shortfall” of soil is allowed to a depth of no more than 0.2 m; “overkill” is, as a rule, not allowed.
In case of “overkill,” a layer of sand is added to the bottom of the trench up to the design mark. The degree of sand compaction must be at least 0.95.
11. Clean the bottom of the trench to the design marks, as well as dig pits for socket and seam butt joints immediately before laying pipes.
The dimensions of the pits for installation of pipe joints are as follows: length 1.1 m, width D + 1.1 m and depth 0.4 m,
where D - outside diameter bell or fold.
After laying the pipes, the pits are filled with sand and compacted. The compaction coefficient must be at least 0.95
12. Soil dumps are usually placed on one side of the trench at a distance of at least 0.5 m from the edge.
13. Trenches must be protected from flooding and erosion by surface water by dumps of soil on the upland side, appropriate planning of the adjacent territory, and, in necessary cases, upland drainage ditches, protective embankments, etc.
14. Development of trenches below the horizon groundwater should be carried out after an artificial decrease in the groundwater level.
15. Artificial water lowering when digging a trench should ensure the removal of water during execution next works: preparation of natural or artificial foundation for pipelines, cleaning of trenches and pits, laying pipelines, sealing butt joints, testing pipelines (if trenches are not backfilled), backfilling trenches.
16. Drainage from trenches must be organized in such a way that the foundation soils are not loosened by the ascending flow of groundwater.
17. In heaving, silty, clayey and loamy soils, the bottom of the trench should be protected from freezing before laying pipes and immediately after laying or testing.
To reduce the depth of soil freezing at objects planned for construction in winter, it is necessary to plow the soil according to the dimensions of the trench in the fall (no later than October 15).
To protect the base from freezing, laid pipes must be immediately covered with soil to a height of at least 0.5 m above their top, and the ends of the pipes and wells must be covered with wooden shields.
Note. In dry sandy and gravelly soils, the bottom of the trench may not need to be protected from freezing.
18. When digging trenches in plastic clays, as well as in water-saturated soils with low water levels, measures must be taken to prevent soil subsidence outside the trenches due to the removal or slumping of soil. It is necessary to monitor subsidence of structures and buildings located near the pipeline route.
Subsidences of the ground surface outside the trench anchorage should not exceed 0.5% of its depth, while their spread to the sides of the trench should not be more than a value equal to the depth of the trench.
III. DESIGN OF BASES FOR PIPES
19. In sandy soils, the construction of a soil bed in the shape of a pipe at the bottom of the trench (type I) is made according to a template. The surface of the bed profile is cleared of stones. Laying pipes on a waterlogged soil base is not allowed.
20. When installing sand base in clayey and loamy soils, the thickness of the sand layer under the pipe should be at least 10 cm (type II).
TypeI
Rice. 1. Construction of a soil bed in the shape of a pipe at the bottom of the trench:
type I - in sandy soils; type II - in clay and loamy soils
21. Monolithic and prefabricated concrete and reinforced concrete foundations for pipes are made in accordance with the requirements of the project.
IV. STORAGE AND TRANSPORTATION OF PIPES ON CONSTRUCTION SITE
22. Reinforced concrete pipes must be laid out along the pipeline route within the range of the crane carrying out installation, at a distance of at least 3 m from the edge of the trench
23. If it is impossible to unload pipes along the route, they are stored in an on-site warehouse separately by diameter and manufacturer's grade.
Pipes with a diameter of up to 1.7 m inclusive are allowed to be stored in stacks of no more than two rows, and each pipe must be placed on wooden supports. Pipes with a diameter of over 1.7 m are stored in a vertical position.
24. It is allowed to transport pipes along the route by cars or on drags with tractors.
Do not drag or roll pipes.
25. Pipes with a diameter of up to 1.7 m inclusive should be transported horizontally. The ends of the pipes during transportation should not hang down more than 0.5 m. Pipes with a diameter of over 1.7 m (up to 2.5 m) are transported in a vertical position.
V. PIPE LAYING
26. The pipes are laid on the base provided by the project, cleared of collapsed soil and drained.
Note. Pipes should be laid in accordance with the factory marks that fix the position of the tray and shelyg.
27. Drag the pipes to the installation site and lower them into the trench is resolved with a cable strapped in the middle with outside pipes, or using special gripping devices.
28. Pipes should be lowered into the trench using jib cranes, pipe layers or gantry cranes.
Rice. 2.
29. To determine the reach of the crane boom () when laying pipes in a trench with slopes, it is recommended to use the following formula:
L = a + b + c,
where L is the boom radius in m;
a is the distance in m from the axis of the pipeline to the edge of the trench. For a trench with vertical walls, the value “a” should be taken equal to the depth of the trenches plus half the width of the trench along the bottom;
b - the distance from the edge of the trench to the outriggers of the crane (“b” is taken equal to 0.7-1.0 m);
c - the distance from the outriggers to the axis of rotation of the crane, taken for:
crane K-51 - 1.4 m
crane K-102 - 2.8 m
crane K-252 - 3.85 m
Note. Reference data on the weight of pipes is given in. The lifting capacity of cranes and pipe layers available at Glavmosstroy in 1962 is given in.
30. Pipes, as a rule, should be laid from bottom to top along the slope with the sockets forward, and the smooth end of the pipe should be inserted into the socket of the already laid one, and the crest of the seam pipes into the groove of the laid pipe.
31. Before joining, the internal and external surfaces of the ends of the pipes must be cleared of ice, snow, dirt and sagging of mortar and concrete.
Pipes in a straight section must be centered so that at any point along the perimeter the width of the socket gap is at least 10 mm, and the gap between the smooth ends and the thrust part of the socket is no more than 15 mm.
VI. SEALING JOINTS
32. The sealing of pipe joints should be carried out with a lag of at least 2-3 pipes from the installation site.
33. Sealing the joints of socketed reinforced concrete pipes for sewerage should begin with caulking the socket to half its depth with outside pipes with two turns of tarred rope or strand, followed by embossing with a moistened asbestos-cement mixture from the end of the socket. WITH inside pipe socket close up cement mortar( , a) composition 1:3.
When sealing the joints of socketed reinforced concrete pipes for drains, first caulk the annular gap to half its depth with tarred rope or strand. On the inside and outside of the pipes, the gaps are sealed and rubbed with cement mortar of composition 1:3 (by weight) without caulking (, b). The internal surface of the seal must be flat and smooth.
34. The pipes are caulked from the outside with tarred rope (GOST 483-55). This operation can be performed with pneumatic coining hammers R-1, R-2 and R-3 or manually (using a hammer and a hammer weighing 0.5-1.0 kg).
35. The sockets are sealed with asbestos-cement mixture in layers no more than 20 mm thick with caulking of each layer separately. The asbestos-cement mixture can be compacted using a pneumatic caulking hammer R-1 or manually, starting from the bottom of the pipe. The socket is filled with asbestos cement flush with the end.
Rice. 3. Pipe joints:
a - sewer; b - drainage; 1 - caulking with tarred rope or strand; 2 and 5 - sealing with cement mortar on the inside of the pipe; 3 - sealing with asbestos-cement mixture on the outside of the pipe; 4 - sealing with cement mortar from the outside of the pipe
Composition of asbestos-cement mixture (by weight):
asbestos fiber not lower than grade IV - 25-30%;
Portland cement grade not lower than 400 - 70-75%.
Water should be added to the prepared and mixed mixture in an amount of 10-12% of the weight of the dry asbestos-cement mixture by spraying (the mixture should be of such humidity that it does not crumble after squeezing in the hand).
In winter, when sealing sockets with asbestos cement, the following rules must be observed:
a) when negative temperatures air, the dry asbestos-cement mixture should be mixed with dry fine-crystalline snow or crushed ice in an amount of 10-12% of the weight of the mixture. Before mixing, the mixture of cement and asbestos must be cooled to outside temperature and mixed with snow with a wooden shovel;
b) when the air temperature is close to zero, the asbestos-cement mixture in a warm room must be cured cold water. When mixing outdoors, use water at a temperature of 50-60°.
36. From the inside of the pipe, the seams are sealed after backfilling the pipeline with soil. IN winter time one of the following hardening accelerators is added to the cement mortar: calcium chloride - 3% by weight of water; sodium chloride - 5% by weight of water, liquid glass - 4-5% by weight of cement. The cement must have a grade of at least 400.
37. After caulking, asbestos-cement joints should be covered with burlap and moistened for 1-2 days.
38. Seam joints of pipes are sealed as follows:
a) with gaps of 15-20 mm, the joint on the inside of the pipe is caulked with an asbestos-cement mixture (30% asbestos-cement chips, 70% Portland cement grade 400 and 10-12% water by weight of the dry mixture), and on the outside it is sealed with cement mortar;
b) with gaps of 20 mm and above, the joints are sealed from the outside of the pipe with a reinforced concrete coupling, and from the inside - with a cement-sand mortar of 1:3 composition.
VII. FILLING THE TRENCHES
39. Trenches are backfilled in accordance with the “Technical rules for the construction of embankments and backfilling of trenches in Moscow” (approved by the decision of the Executive Committee of the Moscow City Council dated December 22, 1958 No. 70/50).
40. Depending on the location in relation to the roadway, the trenches are filled:
a) within the carriageway of existing, under construction and reconstructed city roads - to the full height with sand, the degree of compaction of which should not be lower than a coefficient of 0.98;
b) outside the carriageway of city roads, in courtyard areas, on lawns and squares (unless there are special instructions in the project) “sinuses” - with sand up to half the pipe, and the rest of the trench - with local soils. The degree of sand compaction when filling the “sinuses” should be no lower than a coefficient of 0.95.
41. When backfilling trenches, it is necessary to take measures to prevent displacement and damage to pipes by the dumped soil. It is possible to dump soil into a trench with a bulldozer only after tamping the “sinks” of the pipelines and filling the pipes with soil to a height of 20-25 cm above the top of the pipe.
The “sinuses” are filled with sand in layers and each layer is compacted with flat hand tampers, vibrators and other mechanisms that ensure the safety of the pipes from damage. Compaction of subsequent layers of soil must be mechanized.
Self-propelled rollers with smooth rollers and vibrating machines can be used to compact the surface layer of soil.
Note. For rollers and vibrating machines, the height of filling with sand or soil above the top of the pipe must be at least 1 m. For other compaction machines minimum height the backfill above the top of the pipe must be installed by the design organization.
42. The hydraulic method of soil compaction by flooding trenches with water or alluvium can be used for sandy soils. With this method of work, it must be ensured that water is removed from the trench. If it is impossible to ensure water drainage from the trench, the use of the hydraulic method is prohibited.
43. Dismantling of trench fastenings during backfilling is carried out with the obligatory adoption of measures against soil collapse.
Note. If dismantling the fastenings can lead to damage to the pipeline, settlement of buildings and structures located nearby, or is dangerous to the lives of workers, then backfilling the trenches is allowed without dismantling the fastenings. The need to leave fastenings in the ground must be documented in a document.
44. B winter conditions trenches are backfilled depending on the area where the trench is located:
a) within the carriageway of city roads - with melted sand with compaction to the entire height of the trench;
b) outside the roadway - with melted sand compacted to a height of 0.5 m from the top of the pipes. The upper part of the trench is covered with local soil, unless there are special instructions in the project.
VIII. ACCEPTANCE OF PIPELINES
45. Preliminary acceptance of non-pressure pipelines for drains and sewerage must be accompanied by:
a) acceptance hidden work with drawing up an act;
b) a thorough inspection of the laid pipes from the inside,
c) checking the straightness of the pipeline in the area between two adjacent wells;
d) instrumental check of the tray marks in the wells:
e) visually checking the tightness of butt joints and pipe-to-well connections.
46. The height of individual “stagnant” places, detected by a test run of water, should not exceed 20 mm for pipes with a diameter of 1.0 to 2.5 m inclusive.
47. The deviation of the pipe axis from the straight line between two adjacent wells should not exceed 20 cm at an interval of 100 m.
48. The deviation of the marks of trays in wells from the design ones should not exceed ±5 mm.
49. Sewage pipelines are checked for leaks.
In dry soils, pipelines are tested for water leakage by filling the well with water from the upstream side of the site. For high wells, the filling height should be at least 4 m above the shell.
Water leakage should not exceed the values specified in. The test can be carried out when the pipes are completely or partially filled with soil. The minimum backfill height must be at least half the diameter of the pipe.
In wet soils, pipelines are tested for water inflow at the natural groundwater level. When the groundwater level above the shelyga is 2 m, the flow should not exceed the values specified in.
table 2
ANNEX 1
Assortment of large diameter reinforced concrete pipes manufactured by the Glavmospromstroymaterials department (as of 1962)
|
Manufacturing plant |
Interior nominal diameter, mm |
Inner actual diameter, mm |
Pipe type |
Wall thickness, mm |
Length, mm |
Connection type |
Pipe weight, t |
Note |
|
Moscow plant of reinforced concrete pipes (Filevsky) |
Normal strength |
|||||||
|
Increased strength |
||||||||
|
Normal strength |
Bells |
|||||||
|
Normal strength |
Bells |
|||||||
|
Normal strength |
Bells |
|||||||
|
Increased strength |
Bells |
|||||||
|
Normal strength |
To be released in 1962 |
|||||||
|
Normal strength |
To be released in 1962 |
|||||||
|
Normal strength |
||||||||
|
Normal strength |
Note. Addresses:
Moscow plant of reinforced concrete pipes - Moscow, G-87, Beregovoy proezd, building 2, tel. G 9-31-23.
Concrete concrete products No. 15 - Moscow, Zh-88, St. Ostapovskoe highway, house 83, tel. ZH 2-56-04.
Concrete concrete products No. 13 - Moscow, B-319, Otsevsky proezd, building 9a, tel. D 7-59-16.
Normal strength pipes are intended to be laid to a depth of 4 m above the top of the pipe, high strength pipes - 6 m above the top of the pipe.
APPENDIX 2
Loading capacity of cranes depending on boom radius
|
Name of mechanisms |
Maximum boom reach, m |
Boom radius, m |
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|
Crane lifting capacity (in support jacks), t |
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|
A. Truck cranes with a lifting capacity of 5 tons (K-51, K-52) |
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|
B. Pneumatic wheel cranes: |
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|
with a lifting capacity of 10 tons (K-102, K-104, Lorraine, Orton) |
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|
with a lifting capacity of 25 tons (K-252, K-255) |
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|
B. Crawler cranes: |
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|
with a lifting capacity of 15 tons (E-753, E-754, E-801, E-1004, Harni Shveter) |
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|
with a lifting capacity of 20 t (E-1252, E-1254) |
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|
G. Pipelayer T-L-3 |
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|
Tractor S-80 |
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The technology for installing external pipelines largely depends on their purpose and type of laying, the material of the pipes, their diameter, wall thickness, length of the pipes, the presence of ready-made insulation on them and its type (or lack thereof), as well as on the provision of construction installations elements (pipe sections, strands) and other conditions.
Installation of pipelines from any types of pipes (or their sections) involves the need to connect them into a continuous thread. Pipelines on the route are assembled (mounted) from individual elements (pipes) of a 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. The laying of pipelines is somewhat facilitated by the preliminary enlargement of pipes into links or sections of two or three and more pipes
Laying pipelines involves installing and assembling assembly units along the route - pipes (or their sections, strands), fittings, compensators and fittings - into the design position. Moreover, the larger the assembly unit, the fewer assembly joints and the easier the assembly of pipelines. The units are assembled and tested, and also covered with a layer of insulation or painted at pipe procurement bases. Industrial technology for laying pipelines provides for centralized procurement mounting elements and units, delivering them to finished form to the track, preliminary preparation reasons and supporting structures for laying, precise assembly of pipelines.
The composition and sequence of work processes when laying pipelines depend on the type of pipes used (metallic and non-metallic), as well as on the conditions of their installation (in cramped urban or field conditions, on flat or rough terrain, in the presence or absence of natural or artificial barriers, etc.).
Work when laying pipelines is usually carried out in several stages, performed sequentially: checking the quality of pipes; lowering pipes into the trench; centering and laying them in a given direction and slope, securing the pipes in place; sealing joints and checking their quality; testing and acceptance.
Checking the quality of pipes is usually carried out twice - at the manufacturer (according to an established method, sometimes with testing them on a stand) and directly on the route before laying them in a trench. On the route, almost all incoming pipes are subject to inspection and quality control. This is extremely necessary, because when installing a pipeline, especially a pressure one, using at least several or even one low-quality pipe will lead to ruptures and accidents at the place where they are laid. It is very difficult to eliminate them, since this requires stopping the operation of the water pipeline and digging trenches. In case of accidents on water pipelines made of socketed cast iron or reinforced concrete pipes, replacing a low-quality pipe is very difficult. If in such cases it is impossible to correct the defects of a low-quality pipe in the trench, you have to destroy it (which is also not easy) and remove it, and in its place lay an “insert”, most often made of 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 documents (certificates, passports) of the manufacturing plants, confirming their quality. However, defects may occur in pipes due to improper loading, transportation and unloading. Therefore, before laying in a trench, pipes are carefully inspected, their actual quality is checked and rejected if serious and irreparable defects are detected. 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 making pipe joints must be smooth, without cracks, bubbles, foreign inclusions or defects that reduce their performance properties.
The pipes are lowered into the trench using 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 throw pipes into a trench. It is relatively easy to lower pipes into a trench with gentle slopes without fastenings; the efficiency of lowering depends only on the right choice pipe laying diagrams and type of installation crane. It is more difficult to lower pipes into a trench if there are fasteners with transverse struts. In this case, the pipes are laid with sequential removal and installation of spacers. All this slows down and complicates the pipe laying process, increases its labor intensity and lengthens the construction period. To speed up and secure this process, large-sized fastenings with vertical panels, horizontal purlins 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 in two threads. First, pipelayers, using a crane, lay the pipe on the bottom of the trench and continue to work on final alignment and temporary fastening, and then installers, using a compressor and pneumatic hammers, caulk the pipe joints. In the second scheme, the process is performed in three threads using two taps. Moreover, one of them lowers the pipe and continues to work with the installer team to align and temporarily secure the pipe, and the second one duplicates all these processes for laying the next pipe (second flow); the third flow of caulking (sealing) pipe joints is carried out as in the first scheme. Light pipes are lowered into trenches with fastenings using small-scale mechanization or manually. Pipes or sections should be lowered in strict compliance with safety regulations.
Laying pipes in a given direction and slope (figure below) between two adjacent wells is carried out mainly using portable (running) sights, beacon pins or using a level. Walking sights are used when cleaning the bottom of a trench to the design mark. When laying a pressure pipeline on the cleaned bottom of a trench, the top of the pipes is leveled (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 amount of the outer diameter of the pipes.
Laying pipes in a given direction and slope
1 - cast-off; 2 - constant sight; 3 - sight tracker
To lay gravity sewer pipes along a given slope, a running sight is used, which has a protrusion at the bottom of the heel, glued at a right angle. When laying pipes, the sighting device with its protrusion 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 beam and two permanent sights are in the same plane, visible to the naked eye. The straightness of pipe laying is checked with thread plumbs suspended on an axial wire (mooring). After installing cast-offs and shelves, use a level to determine the marks of the shelves at the ends of the laid 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 makes it easier to lay them in a given direction. To speed up work, use inventory metal portable cast-offs. To more accurately comply with the design slope of the pipeline tray, use the visual method of an inclined beam of a level or laser beam(visor). The latter method uses a laser level, which is installed at the beginning of the site.
Gravity 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 backfilling pipes and wells by leveling the bottom of the pipe trays and wells, i.e. perform executive shooting. The difference in elevations between the bottom of the wells and the tray at individual points of the pipeline should not differ from the design value by more than the construction tolerance. The straightness of the pipeline between the wells is checked using mirrors that reflect the beam along its axis.
The pipes are secured in place after they are laid either by adding soil or using wedges (for example, when laying heavy pipes of large diameters on concrete foundations).
Sealing of joints is carried out when installing pressure and without pressure pipes wires from short concrete, reinforced concrete, cast iron, asbestos-cement and ceramic pipes(socket or smooth on coupling connections). The joints of pressure pipes are usually sealed with rubber rings or cuffs, and gravity pipes - with tarred strands, asbestos-cement mixture, etc. (picture below). The joints of steel pipes are welded, and the joints of plastic pipes are welded or glued.
Tightness and water resistance of socket joints cast iron pipes wires are achieved by sealing the socket gap with tarred or bituminized hemp strand, followed by the installation of a lock made of asbestos-cement mixture, which holds the strand from being squeezed out by hydraulic pressure. Sometimes cement mortar and, in exceptional cases, lead are used instead. Recently, mastic sealants have been used. When sealing joints with self-sealing rubber cuffs No locks are required.
Joints of reinforced concrete pipes
a, b - bell-shaped; c - 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
Sealing socket joints with strands. The hemp strand is inserted into the bell slot until the bell stops to such a depth that there is room left for the lock. Since the thickness of the tow from the strand is slightly greater than the width of the bell slot, it is pushed into the joint using caulk, with which the tow is inserted into the annular gap, first by hand, and then with strong blows of a hammer (for hand-chasing). In mechanical embossing, the tow is compacted using a pneumatic tool. To create the required tightness of the joint, 2-3 strands are usually placed in the gap, and so that their overlaps do not coincide along the circumference. After sealing the joint with a strand, an asbestos-cement lock is installed, laying the asbestos-cement mixture into the gap in layers of rollers (3-4 layers each) and compacting with stampings, striking them hard with a hammer. The sealed joint is covered with damp burlap for 1-2 days, which creates favorable conditions for the asbestos-cement mixture to set and harden.
Sealant mastics are used to seal the butt joints of socketed cast iron pipes when laying pressure sewer pipelines with a maximum operating pressure of up to 0.5 MPa. Most often, polysulfide sealants made from sealing and vulcanizing pastes are used, to which asbestos or rubber crumbs are sometimes added. Mastic-sealants are prepared at the work site 30-60 minutes before their use. The joints are sealed using syringes with manual or pneumatic extrusion of mastic or pneumatic installations. The sealant is introduced into the socket slot using a nozzle, which is attached to the tip of a syringe or hose of a pneumatic installation.
10. Installation of concrete and reinforced concrete pipes
Installation of pipe elements is carried out in accordance with the layout diagrams in the working drawings, taking into account geometric tolerances in the dimensions of the elements
Concrete and reinforced concrete pipes must be installed from the outlet head to the inlet head. With portal heads, the portal wall of the outlet head is first mounted, after which the slope wings are installed. Next, the pipe links are installed, and then the portal wall and the slope wings of the inlet head. If the project provides for the priority installation of the heads, then the installation of the links can be done in any direction.
After installing the link in the design position, the sling loops that interfere with the installation of the next link and the installation of insulation must be cut flush with the concrete surface.
It is not allowed to cut off the hinges with a chisel or bend them to avoid chipping the concrete and causing difficulties during installation, because bent hinges prevent the links from being installed in the designed position.
When installing cylindrical links on prefabricated pattern blocks, the links are installed on wooden (not removable) wedges, while ensuring the design gap for laying cement-sand mortar using metal funnels for filling joints and metal screws.
Pipes should be lowered into the trench using jib cranes, pipe layers or gantry cranes.
To determine the reach of 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; b 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); in - 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 corrugated metal pipe, a special bed is cut out of granular materials in the foundation pad, the dimensions of which must meet the requirements. The bed should be cut out using a motor grader equipped with a profiled knife, or rough with an excavator, followed by manual finishing according to a 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 according to the level, taking into account the formation of a construction rise in the pipe tray. By moving the template along the beams and cutting out the soil, they create a bed into which the corrugated pipe is then installed. Deviations of the soil bed profile from the template should not exceed 2-3 cm.
Figure 7 – Installation diagram of the template for cutting out the soil bed in the zero layer
1 - template; 2 - wooden beams; 3 - zero layer; 4 - level of the top of the cushion (should not exceed the lower mark of the ground bed)
After installing the pipe in the design position, soil is added into the gaps between the surface of the lower part of the pipe and the soil bed. The soil is compacted using hand-held wooden bayonets with a diameter of no more than 8 cm, and additional soil filling in the lower quarters (until the pipe is covered by soil at least 120°) with compaction using hand-held electric rammers and a bayonet. Electric tampers and vibration compactors are used to 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.
Next, the zero layer directly next to the pipe should be additionally compacted with a machine with a vibro-impact working element in one or two passes of the machine along the walls of the pipe. If pneumatic rollers are used to compact the soil, additional compaction of the zero layer near the pipe walls should be done using manual electric rammers.
If the pipe is installed on a flat base, then soil should then be poured into the lower quarters of the pipe and compacted with manual electric rammers and a bayonet until the pipe is covered with soil by at least 120°. Subsequent compaction of the soil near the pipe is carried out in the same way as with a profiled bed.
Depending on local conditions, a pipe with bolted lap joints should be installed on a construction site from sections pre-assembled from individual elements at landfills, or from individual elements.
In all cases where it is possible to deliver pipe sections to the site by vehicle or tractors and install them by crane, especially in areas with an estimated minimum outside air temperature below minus 40°C, the method of installation from sections should be the main one. In this case, it is recommended to install pipes “from wheels”, installing sections immediately in the design position after lifting from vehicles.
The length of the sections should be assigned based on the specified design lengths of the culverts. In this regard, it is possible to use sections of different lengths on one structure. When assigning the lengths of pipe sections, it is necessary to take into account the capabilities of available vehicles for transporting structures to the construction site. In intermediate sections the number of links must be odd. The length of sections is recommended to be no more than 10 m.
Pipe assembly should be carried out according to the installation diagram available in the work project. The installation diagram must include: the procedure for installing corrugated elements when assembling and combining sections, the procedure for transporting sections, the procedure for installing bolts, a diagram of special ties and scaffolding for fastening pipes with a diameter of more than 2 m in cross section during assembly.
When installing pipes, you should use a set of tools: socket wrenches, crowbars, hooks with rings, electric or pneumatic impact wrenches, hammers.
The set of bolts supplied to the construction site must include 10 installation 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 work design must take into account the specifics of installing metal structures in the design position, depending on the upper outline of the cushion under the pipe. If the foundation is planned without a bed, it is allowed to install the pipe nearby (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 pipe structural elements, materials, tools and equipment must be delivered to the construction site before pipe assembly begins. When installing pipes “from wheels,” only individual elements are delivered to combine the section.
Installation of pipes with monolithic or prefabricated heads should begin with the assembly of the foundation part of the bottom head, followed by laying the metal structures of the structure (sections, elements) and completing the installation of the heads.
Before starting work, you should check for markings, reject the elements, straighten the bent areas with a wooden hammer and arrange the elements and boxes with fasteners along the axis of the pipe.
When rejecting elements and fasteners, you should check the markings of the elements, the geometric dimensions of the elements and fasteners, and the quality of the 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 grades of steel, the element and the stamp of the quality control department of the plant and the factory inspector of Glavmostroy must be indicated. The brand of the element conventionally indicates the diameter of the pipe and the thickness of the sheet. Each package of corrugated elements must have a tag indicating the brand of the element, grade of steel, thickness of the element, pipe diameter, manufacturer and year of manufacture. The geometric dimensions of structural elements and fasteners must meet the requirements of the project and these Instructions.
The surface of the zinc protective coating of pipes should not have visible cracks, nicks, sagging on the joining surfaces and places not coated with zinc. The use of items with these defects is not permitted. Defects in the protective coating are corrected by the manufacturer.
Before installing the elements, to ensure the required clearance in the bolt holes, the excess retained bitumen mastic should be melted in advance using mandrels of a reference diameter heated to a temperature of plus 130°C.
The contacting 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) placed in the middle of the longitudinal joints. In this case, one end of the element should 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 correctly assembled pipe links, all element marks should 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 strictly the same.
The links are combined into a section using standard elements. When installing these elements at the junction of three sheets, the 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 – Sequence of assembling a pipe section from individual links
A- the amount of displacement of longitudinal joints,
1–9 - order of installation of elements when combining links A And B
Figure 9 – Layout of longitudinal joint bolts:
1 ,2 - 1st and 2nd rows of inner sheet bolts, respectively
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- size of the shift step of longitudinal joints
Longitudinal joints in links should be placed with ligation - mutual shift by the amount A, equal to one to four pitches of the holes of the transverse joints. The displacement 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 to be installed are at the junction of the three elements.
The bolts should be tightened with electric wrenches IE-3101 or pneumatic wrenches IP-3103, as well as socket and ring wrenches.
It is allowed to use other electric impact wrenches of small mass (2-3 kg), providing a tightening torque of 15-20 kgf×m.
When tightening the bolts, it is necessary to ensure that the convex and concave washers are in the correct position.
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 placed in the end links should not be tightened, which makes it easier to install standard elements with their insertion into the gaps of the longitudinal joints between the elements of the end links.
Before starting work, you should prepare the elements intended to connect the sections, fasteners, and also deliver the necessary tools and equipment.
The pipe should be installed on a planned base or nearby (near the design axis of the pipe). The sections are laid on wooden beams for unobstructed installation of bolts in the lower part.
Sections in the designed position, as a rule, should be installed by crane. When slinging sections, measures must be taken to prevent the possibility of damage to the protective coating. The slings are placed at a distance of a quarter of the section length from their ends.
The sections should be combined according to the diagram shown in Figure 10. First, the ends of the sections are installed using a truck crane so that the longitudinal joints are located at the same level, then the connecting elements are installed.
Before starting pipe installation, all steps must be completed. preparatory work.
If there is no level area at the pipe construction site next to the prepared base, then light wooden scaffolding should be prepared for pipe assembly, placing it near the design axis of the pipe.
According to the first scheme, the pipe should be built up gradually with standard elements (the numbers show the sequence of their installation). The elements are carried and held in the required position with special hooks. The centering of the holes in the elements for installing bolts is carried out using mandrels, inserting them into holes located next to the holes into which the bolt is inserted. When installing elements in places where three sheets overlap, contact of 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 tie is made at the junction of the three elements with long mounting bolts, which are then replaced with ordinary ones. After installing bolts in a link of elements 11 And 12 continue assembling the next section of the pipe, and in the link from the elements 5 And 6 install and tighten all bolts.
According to the second scheme, the lower elements are first laid out along the entire length of the pipe, connecting them with bolts in the middle part. Then two other link elements are installed through one link (see Figure 3.5, numbers in parentheses). Next, the remaining elements of the missing links are sequentially mounted, completing the installation by installing and tightening all the bolts.
Between the link in which all the bolts are tightened and the assembled link there must be at least three links with tightened bolts.
When installing pipes on a construction site, pre-assembly of the links and their subsequent connection can also be carried out. For pipes with a diameter of 2 m or more, this assembly technology is preferable.
The links are assembled on a specially prepared site with wooden flooring in close proximity to the pipe being constructed. The assembled links are installed with a crane on the base, placing wooden beams under each link and orienting them along the pipe (after installing and tightening all the bolts, the beams are removed from under the pipe).
Figure 11 – Pipe installation diagram (end view):
A- the amount of displacement of longitudinal joints;
1–12 - order of installation of elements when assembling a pipe
When assembling pipes with a diameter of more than 2 m, the project must provide portable scaffolding for installers. For pipes with a diameter of 3 m, scaffolding is arranged inside the pipe with a height of 1.3 m and a plan size of 2 × 2 m, as well as external scaffolding (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, scaffolding is arranged with a height of 0.5-0.8 m.
Bordering corners are installed when the bolts located at a distance of 0.3-0.5 m from the ends in the longitudinal joints of the end links of the pipe are not tightened.
Acceptance of the installed pipe must be documented.
General provisions. Small culverts: bridges up to 25 m long and pipes are among the mass objects of railway construction. The number of small culverts along 1 km of the route depends on the shape of the terrain. Thus, for the railways of the Urals and Eastern Siberia, the number of small bridges (numerator) and pipes (denominator) is: for flat terrain - 0.1/0.24, for hilly terrain - 0.14/0.53, for mountainous terrain - 0 ,21/0.9 pieces/km, and their share of the total number of culverts N: 26/58, 18/74.6 and 15.5/79.5%, respectively.
Thus, in total, small bridges and pipes make up from 84 to 95% N. Small bridges and pipes are erected according to standard designs from factory-made structures. Most widespread V last years received round prefabricated reinforced concrete pipes with holes of 1.0, 1.5 and 2.0 m in one-, two- and three-point versions; rectangular precast reinforced concrete pipes with holes 1.0; 1.5; 2.0; 3.0, 4.0 m in one- and two-point performance; rectangular concrete pipes with openings of 2, 3, 4, 5 and 6 m; corrugated metal pipes with holes 1.0; 1.5; 2.0 and 3.0 m.
The pipe consists of an inlet head, a pipe body and an outlet head (Fig. 9.4). Both the pipe heads and body are mounted from separate blocks. There are three types of foundations. On solid foundations, such as rock, type I foundations are used, consisting only of patterned blocks (for round pipes) or slabs (for rectangular pipes). On relatively weak foundations, foundations are made of monolithic concrete - type III. In other conditions, type II foundations are used, which differ from type I foundations by an additional lower row of rectangular blocks. The foundation under the heads is laid to great depth. The pipe consists of 1 m long links and head blocks. Weight of installation elements of typical reinforced concrete pipes: foundation blocks 0.75...4 t, round links 0.9...4.2 t, rectangular 3.5...10.3 t, parts of heads 2.4...6.9 t. Foundation blocks laid by crane on a layer of crushed stone (sand and gravel) preparation 0.10...0.20 m thick.
Rice. 9.4. Precast concrete pipes:
a - round; b - rectangular; / - portal wall of the head; 2 - links; 3 - conical link; 4 - slope wing of the head; 5 - head foundation slabs; 6 - crushed stone preparation; 7 - foundation blocks; 8 - pattern blocks; 9 - foundation slabs; 10 - tray
Metal pipes without a foundation are assembled from factory-made corrugated elements, produced in standard and northern versions. Elements made of steel with a thickness of 1.5...2.5 mm have corrugations (ridges) 32.5 mm high with a pitch of 130.0 mm. Using bolts, the elements are combined into links. To protect against corrosion, pipe elements are coated with a layer of zinc and special bitumen mastics or polymer enamels. Lay pipes on sandy or sand and gravel cushion thickness of at least 0.40 m with a particle size no larger than 50 mm. Corrugated pipes are arranged, as a rule, without heads. At the end sections of the pipe, anti-filtration under-channel screens are installed - waterproof bridges made of clay soil, crushed clay, concrete and other materials.
Complex of construction works culverts includes: preparatory work, construction of pits, preparation of foundations, installation of foundations, installation of pipe bodies, waterproofing. Before the construction of pipes begins, the design organization must secure in kind and hand over according to the certificate construction organization in the presence of the customer, the point of intersection of the axis of the embankment and the longitudinal axis of the pipe, required amount alignment signs securing the longitudinal OSB pipe and the altitude benchmark (Fig. 9.5), clear and plan the construction site, arrange drainage systems and entrances, source and place materials according to a plan previously developed and drawn on a scale of 1:500 or 1:200 construction site. The construction site plan (Fig. 9.6) is drawn up on the basis of decisions made in a standard work project.
Rice. 9.5. Scheme for securing the pipe location on the route:
1 – outrigger posts (stakes); 2 – point and guard with the inscription “axis”, “picket” and “plus”; 3 – benchmark
Rice. 9.6. Construction site plan for the construction of a rectangular pipe:
1 – links of the pipe body and ends; 2 – blocks of slope wings; 3 – foundation slabs; 4 – box with cement; 5 – water tank; 6 – sand; 7 – crushed stone; 8 – concrete mixer; 9 – power plant; 10 – trailer for storing tools; I ST, II ST, III CT – crane parking places during installation work; α min, α max – minimum and maximum angles of rotation of the crane boom when installing pipe body links; l booms – maximum boom radius at which it is possible to install pipe body links
From the axis of the pipe, the outline of the pit is marked and secured with metal stakes. Depending on the volume of work, the nature of the soil, the shape of the pit and other local conditions, the development of soil in the pit involves: bulldozers, hydraulic excavators, a backhoe with a bucket with a capacity of 0.15...0.65 m 3 or cranes with grab equipment. When digging pits under water and in unstable water-saturated soils, ground bridges, bottomless boxes or sheet piling with drainage are installed. The top of the sheet piling should be 0.2...0.4 m above the maximum groundwater level, and for channel supports - 0.7 m above the accepted working water horizon in the river. In winter, when the soil is naturally frozen, it is allowed to develop pits up to 4 m deep without fastening. The pits are developed with a shortage of 10...20 cm to the design marks. The final cleaning of the bottom of the pit is carried out manually immediately before installing the foundation. Excavations longer than 20 m in unstable soils and in the presence of groundwater are developed section by section. The bottom of the pit in longitudinal direction Under a block foundation, pipes are planned along a circular arc. In this case, the amount of construction lift depends on the type of soil and the height of the embankment. The construction rise along the axis of the embankment for foundations made of sandy loam, loam and clay is taken to be 1/40, and for sandy and gravel soils - 1/80 of the height of the embankment. After acceptance of the pit, crushed stone preparation is arranged. Crushed stone is delivered by dump trucks and unloaded into buckets, and then by crane into the pit in a layer 10 cm thick and compacted with pneumatic rammers. The marks of the top of the crushed stone are checked with a level. Level the crushed stone manually with shovels.
Installation of reinforced concrete pipes. Before the start of installation work, at a distance of 1 m from the pit, a cast-off of boards and beams is arranged, marking on it the axis of the pipe, the contours of the foundation and other dimensions.
The installation of pipes begins with the installation of the foundation in the direction from the outlet to the inlet head. First, use a crane to lay the bottom row of head foundation blocks to the level of the base of the pipe body foundation. Then the bevels of the shallow part of the pit with the deeper part are filled with a sand-gravel mixture and cement mortar is poured. The blocks of the upper part of the foundation are laid in rows. When excavating a pit in sections, the foundation is installed to the full height within the section. The blocks, cleared of dirt, are laid on a layer of cement mortar of grade no lower than 150, 1...2 cm thick. The deviation in the rows in height should not exceed 5 mm. The vertical seams between the blocks are filled with mortar. During the installation process, the horizontality of the rows within the section and the slope of the pipe are checked. The filling of the pit sinuses is carried out after acceptance of the foundation. Backfilling is carried out in layers 15...20 cm thick with thorough compaction of the soil in each layer using electric rammers. Installation of pipe foundations in sloping areas is carried out in sections 3...4 m long, starting from the foundation of the outlet head
Installation of the pipe heads and body begins with the outlet head. First, the head blocks are installed. When installing portal walls and sloping head wings, braces or inventory struts are used. Then the pipe links are mounted using special clamps or brackets. Round links are installed on pattern blocks. To ensure the required gap of 2 cm, the links are laid on wooden wedges. A solution with a cone draft of 11...13 cm is first laid and compacted on one side of the link, until it appears on the other side. The missing amount of solution is supplemented.
When laying sections of rectangular pipes, it is necessary to ensure that they are firmly supported on the foundation slabs. Do not knock or wedge links with crushed stone. This can lead to damage and even destruction of the links. Seams 1 cm wide are left between the pipe links, and 3 cm wide between sections (3...4 links). Interfering mounting loops are cut off with an autogen. It is prohibited to cut down or bend the loops.
The seams between the links are filled with tow impregnated with bitumen (Fig. 9.7). And then all the joints, except expansion joints, are filled from the inside with grade 300 cement mortar. From the outside they are filled with bitumen. Before waterproofing, the surface of the pipe is cleaned.
As glued waterproofing, a fabric impregnated with bitumen or a fiberglass mesh is used, two layers of which are laid on a layer of hot bitumen mastic and the laid layers are covered with it.
Coating waterproofing consists of two layers of hot or cold bitumen mastic with a thickness of 1.5...3 mm. It is applied to the surface of the pipe primed with varnish. When carrying out work in winter, internal heating of the pipe is used. The ends of the pipe are covered with shields, and it outer surface insulate.
Rice. 9.7. Pasted and coating waterproofing:
a - the seam is formed by pipe links; b - intersectional weld of pipes on foundations; 1 - link; 2 - glued link insulation; 3 - bitumen mastic; 4 - coating; 5 - tow; 6 - jointing
The installed pipe is covered with soil. The height of the backfill should be 0.5 m above the pipe, and the width at the top should be equal to the width of the pipe block, the steepness of the slopes should not be steeper than 1:1. Backfilling is carried out in layers with soil compaction using electric rammers and rollers on pneumatic tires. In winter, the thickness of the backfill above the pipe is increased to 1 m and it is covered with thawed, or better yet, draining soil. At the same time, make sure that large stones, frozen clods of soil, ice floes and snow do not get into the backfill soil.
Strengthening and Finishing work produced after filling roadbed to design marks in accordance with the project.
The pipe installation work is carried out in-line by a complex team consisting of three units of 4 people each. The first link carries out preparatory and excavation work, the second - installation, the third - waterproofing and backfilling of the pipe with soil. Team members must have several skills.
Mechanization means - bulldozers, self-propelled jib cranes with a lifting capacity of up to 15 tons, concrete mixers with a capacity of up to 100 liters, mobile power plants with a capacity of up to 8 kW, cars, pumping units, mobile units for heating bitumen, vibrators and electric rammers, rollers, etc.
Installation of metal culverts. The excavation is poured and compacted along the planned and cleaned bottom of the pit. sand cushion 1 m wide than the diameter of the pipe and at least 0.4 m thick (Fig. 9.8). Sand from dump trucks is unloaded into a pit, leveled with a bulldozer and compacted with rollers or loaded dump trucks.
Rice. 9.8. Backfilling a cushion under a metal pipe:
a - in two stages; 6 - s preliminary device box; c - with filling of the zero layer; 1 - part of the cushion, poured before laying the pipe; 2 - the same after installation; 3 - zero layer
During the construction process, the cushions arrange the necessary construction lifting of the pipe tray. After installing the base, anti-filtration screens are installed under the outermost links of the 2.8 m long pipe. The thickness and width of the screens must correspond to the dimensions of the cushion. To form screens, the base under the outer links is loosened, cement is added, thoroughly mixed and compacted manually with tampers. Then the final layout of the base is made and, using cast-off material, the cord is pulled along the axis of the pipe.
The pipe is assembled from individual elements or after pre-assembling sections, which are assembled either at a centralized assembly base or at the pipe construction site. The length of the sections is determined by the capabilities of the available transport. When loading and unloading pipe elements and sections, hemp ropes are used, and with steel slings, tarpaulin pads are used to prevent damage to the coating. It is prohibited to hook elements with sling hooks through existing holes, or to drop packages and sections from a height. When assembling a pipe from individual elements that have three standard elements in a link, first lay the lower elements along the axis of the pipe along the length of the section or pipe, connecting them with 3...4 bolts. The longitudinal seams of even links should be on one line, and odd ones - on the other (Fig. 9.9). Then the other two elements of the link are also mounted on 3...4 bolts in the middle of the longitudinal seam. Centering of the holes is done using crowbars, inserting them into adjacent holes. Three links from the one being assembled, all the bolts are placed and tightened. When assembling pipes large diameter For temporary fastening of elements, transverse ties are used.
Rice. 9.9. Placement of joints of pipe elements 1…6
When pre-assembling sections from links, the elements are installed in vertical positions and connected to each other with 3…4 bolts. The assembled links are connected in threes, and the three-link sections are connected with one intermediate link, resulting in one seven-link assembly section or whip. The pipe sections are installed with a crane on a profiled base on wooden pads so that the longitudinal seams of the connected ends of the sections have the same overlap and are located at the same level. The distance between the ends of the sections should be equal to the useful width of the element - 910 mm. The sections are then connected to each other using standard connecting elements. The joints are overlapped in the same way as when joining links.
To add rigidity, border corners 40x40x4 mm, 4.7 m long, are installed at the ends of the pipe, which are attached to the links with bolts.
Upon completion of the quality check of installation work and cleaning of the pipe surface, an additional waterproofing coating is made from bitumen mastics. To cover 1 m2 of surface, 0.3...0.4 kg of bitumen varnish and 2...3 kg of mastic are consumed. The primer is varnished using a paint sprayer, avoiding clots, smudges and bubbles. No later than 24 hours, a layer of bitumen mastic 2 mm thick is applied using a mobile bitumen installation. Quality waterproofing works is formalized by an act. After eliminating the deficiencies, but no later than three days, the pipe is backfilled with soil. Corrugated metal pipes are backfilled with sandy and coarse soil with a particle size of up to 50 mm. Backfilling to a height of 0.5 m above the top of the pipe is done simultaneously on both sides in equal layers with careful compaction of each layer. The soil is compacted using a vibro-impact machine. To better compact the soil near the pipe, backfilling is carried out in inclined layers (Fig. 9.10). With a backfill height above the top of the pipe of 0.5 m, the load from machines passing over the pipe should not exceed 98 kN, with a backfill height of 0.8 m - 108...196 kN.
The standard time for assembling sections from individual elements is 4.8 man-hours per 1 m of pipe, for laying sections on wooden spacers is 1.26 man-hours per 1 section, for assembling pipes from sections is 6.5 people. -h per 1 joint, for installing a border corner - 1.4 man-hours per 1 head, for installing an additional protective layer with bitumen mastic - 0.3 man-hours per 1 m2 of pipe surface, for installing an anti-filtration screen - 0 .99 person-hour per 1 m 3 (E5-3).
To install one pipe with a diameter of 1.5 m and a length of 26.5 m, it will take 7 hours, including layout and preparatory work.
Rice. 9.10. Backfilling a metal pipe with inclined layers and compaction:
1 - pipe; 2 - line of closest approach to the pipe; 3 - vibration impact machine; 4 - bullet layer
Lecture 29. Installation of concrete and reinforced concrete pipelines
LECTURE PLAN
ADDITIONAL LITERATURE
1. Popov A.I., Tsionsky A.L., Khripunov V.A. Production of reinforced concrete pressure vibrohydropressed pipes. - M.: Stroyizdat 1979.
2. Maps of labor processes. Installation of external water supply and sewerage networks. Sh-10-9.1 and KKT-Yu.O-Z.M., Stroyizdat, 1563, 1986.
3. VNII Vodgeo. Installation instructions for reinforced concrete, cast iron,
asbestos-cement pipelines. - M.: Stroyizdat, 1979.
4. Pereshivkin A.D., Aleksandrov A.A., Gotovtsev V.I. Installation of pressure
pipelines with butt joints on rubber seals. - M.: Stroyizdat, 1986.
TECHNICAL MEANS
- filmstrip "Installation of external pipelines from non-metallic
pipes."
2. Poster "Concrete and reinforced concrete pipes".
3. Poster "Methods of installation of socketed reinforced concrete pipes and the devices used."
4. Poster "Installation of pipelines from reinforced concrete pipes."
Reinforced concrete and concrete pipes, vibrating hydraulic presses are used for laying pressure water lines. and centrifuge. reinforced concrete socket pipes of 3 classes (1st for pressure 1.8 MPa, 2nd - 1.3 MPa and 3rd 0.6-0.7 MPa) with a length of 5 m and a diameter of 500,600,700,800,1000, 1200, 1400 to 1600 mm with the mass of vibrohydropresses. pipes from 1.32 to 8.2 tons and centrifuge. from 1.43 to 9.63 tons.
For free-flow For pipelines, concrete free-pressure pipes with a diameter of 100-1000 mm l = 1-2 m are used, as well as reinforced concrete free-pressure pipes with a diameter of 400,500,600,800,100C,1200,1400,1600,2000,2400 mm and seam pipes with a diameter of 400,2400,3000,3400,4000 mm . Gravity pipes come in two varieties - norms. strength (M), lay. to a depth of 3-5 m (above the top) and reinforced (at), laid to a depth of 5-6 m.
Concrete and reinforced concrete pipes are laid on natural and artificial foundations. The joints of pressure pipes are made socket and coupling with waterproof sealing with rubber seals, and the joints of non-pressure pipes are socket and seam sealed with resin or bituminized strand, asbestos-cement or cement lock, as well as asphalt mastic.
Before laying pipes in a trench, they, as well as couplings, must undergo an external inspection during their acceptance to identify possible defects, as well as check the dimensions of the pipes. Pipe quality check consists in establishing compliance of their main characteristics with GOST and technical specifications (TU).
Laying out pipes along the edge of the trench. Socketed concrete and reinforced concrete, as well as other pipes are laid out along the pipeline route different ways, the choice of which is determined by the type and load capacity of the cranes accepted, designed to lower pipes into the trench.
Installation of pressure pipelines. Pressure pipelines are mounted from socketed and smooth reinforced concrete pressure pipes, manufactured in factories using vibration-hydropressing or centrifugation methods and meeting the quality requirements (for more details, see)
Installation of pipelines from socketed reinforced concrete pipes are carried out in the following sequence: delivery of pipes and laying them out along the trench, delivering them to the installation site; preparing the sleeve end of the pipe and installing a rubber sealing ring on it; insertion of the pipe being laid with the sleeve end with a rubber ring into the previously laid socket; giving the newly laid pipe its design position; final sealing of the joint; preliminary testing of the finished section of the uncovered pipeline (and for pipes of large diameters only butt joints) for leaks; backfilling of this area with compaction of earth in the cavities; final testing of a buried pipeline. Pipe installation is carried out using cranes, pneumatic wheeled or crawler cranes. Pipes from the trench berm to the laying site are fed with a socket forward during installation. Before laying the first pipe, a concrete stop is installed at the beginning of the route, ensuring a stable position for the first two or three pipes when they are connected.
The recommended arrangement of mechanisms, pipe-laying workers and pipe layout during pipeline installation is shown in Fig. 1, a. When laying, first, using a template, mark on the smooth end of the laid pipe the depth of its embedding into the laid socket. After installing the installation crane in the middle of the pipe being laid, a semi-automatic clamp is lowered onto it and it is slinged. In the absence of such a grip, the pipes are slung using slings or traverses with towels. The pipe is then fed into the trench using a crane. At a height of 0.5 m from its bottom, the lowering of the pipe is stopped, a rubber ring is put on its smooth end, after which it is inserted into the socket of the previously laid pipe and smoothly lowered onto the prepared base. Wherein Special attention pay attention to centering the sleeve end of the inserted coarse with a rubber ring relative to the lead-in chamfer of the socket of the previously laid pipe.
To check the position of the pipe being laid (Fig. 1, c), a running sight is placed 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 of the cast-off. After aligning the pipe vertically, the grip is removed from it, the valve is released for installation of the next pipe, and the position of the pipe in the planet begins to be aligned. For this purpose, inventory poles are installed plumb: one at the end of the pipe being laid, and the other at the previously laid one. Using a fixed pole installed in the well or on an installed section of the pipeline, the correct laying of the pipe in plan is checked. If necessary, it will be mixed in the right direction. After this, using a tension device, insert the smooth end of the pipe to be laid into the socket of the previously laid one all the way, while ensuring that the rubber ring is evenly rolled into the socket slot. Having joined the pipes, remove the tension device and tamp the pipe with soil to a height of 1/4 of its diameter with layer-by-layer compaction using hand tampers.
When installing water pipelines from socketed reinforced concrete pipes, the most labor-intensive process is the insertion of the sleeve end of a coarse pipe with a rubber ring into the socket of a previously laid one. To facilitate this operation, various devices, devices and mechanisms are used that determine the appropriate methods for installing pipelines. In particular, they use two- and three-cable external tensioning devices (Fig. 2, a, b), rack and pinion or hydraulic jacks (Fig. 2, c), internal tensioning devices, lever and gear winches (Fig. 2, d, e), bulldozers and excavators (Fig. 2, f, g).
To install pipes with a diameter of 500, 700, 900 mm, a universal hydraulic device of the Orgtekhvodsgroy Glavvolgovodstroy trust is also used (Fig. 2, h), which is first fixed to the pipe and then lowered into the trench together with the pipe. After checking the accuracy of the centering of the pipe and the correct location of the rubber ring, the pipe is connected to the pipeline under the action of the hydraulic cylinder.
When choosing a method for installing reinforced concrete pipes, take into account the availability necessary equipment and mechanisms, as well as local construction conditions. Installation of pipelines using a bulldozer (Fig. 2, e) can only be carried out if the bulldozer is also used for work on leveling the base of the trench, i.e. when it is possible to combine two work operations. Trust Tsentrospetsstroy has manufactured a small-sized bulldozer based on the T-54 V tractor with a blade width of 1.25 m, which is used for installing pipelines with a diameter of 500 mm or more while simultaneously leveling the base of trenches. The pipeline installation method using an internal tension device can only be recommended for pipes with a diameter of 800 mm or more. Pipeline installation using an excavator (Fig. 2g) is carried out when laying pipes in water-saturated soils or in cramped construction conditions, when it is not possible to tear off trenches in advance, and an excavator located nearby can be used to install pipes. When connecting pipes, you cannot push the smooth end completely into the socket, i.e. to the full stop, and a gap should be left between the end of the smooth end and the thrust surface of the socket for pipes with a diameter of up to 1000 mm - 15 mm, and for pipes with a diameter of more than 1000 mm - 15 mm. To ensure water tightness of butt joints, ellipse of pipes, sockets and couplings should not be allowed or Bad quality pipe surfaces and use low-quality rubber rings. The rings in the slot of socket and coupling joints should be compressed by 40-50% of the thickness of their section. If the tightness (waterproofness) of the joints is damaged, additional rubber rings or individual sections of them are installed directly on the defective area using a special removable clamp (Fig. 2, i). If reinforced concrete pipes are damaged or have significant defects, they are removed and replaced with inserts made of steel pipes using steel transition pipes
Installation of pipelines with coupling butt joints of pipes has a number of differences. So, after centering and checking the correct placement of the rough along the cord, plumb line and sighting line at the ends of the connected pipes, markings are made with marks that determine the initial position of the rubber rings - distances a (360.370) and b (70.80 mm). When installing pipes, the coupling is installed in its original position so that its end on the working side coincides with the mark marked on the pipe. The rubber ring is placed near the working end of the coupling and then, using a caulk, it is inserted into the conical slot of the coupling flush with its end. At the same time, a rubber ring is also put on the second pipe and placed at a distance of 6 from its end. Next, with the help of mounting devices, the coupling is moved towards the pipe being joined and at the same time the first rubber ring is rolled up. Once the coupling on the second pipe reaches the marks at a distance of 6 from its end, a second rubber ring is inserted into the coupling slot. During further advancement of the coupling, this ring is also rolled up, due to which the required final position of the rubber rings at the joint is achieved.
Installation of non-pressure pipelines. They are made from concrete and reinforced concrete pipes using socket, coupling or seam butt joints. Joints socket pipes sealed with hemp strands or other sealants sealed with asbestos cement or rubber rings, and seam pipes with asphalt mastic, bitumen-rubber gaskets and other sealants sealed with cement-sand mortar. Free-flow socket and coupling pipes are connected with a gap between the smooth end of the pipe and the thrust surface of the socket equal to 10 and 15 mm for pipes with a diameter of 700 and more than 700 mm, respectively.
Installation of pipelines from socketed and coupling pipes sealed with rubber rings is carried out using the same methods as pressure water pipelines. Sealing of joints with hemp strands is done by caulking the socket to half its depth with two or three turns of tarred or bituminized hemp strands with a caulked asbestos-cement mixture (30% asbestos, 70% cement).
Installation of pipelines from seam free-flow pipes involves the need to seal seam joints. In this case, the joints of pipes with a diameter of more than 1000 mm are sealed around the entire perimeter with hemp strands and rubbed with a cement mortar of a 1:1 composition with a device outside the belt made of this mortar. The joints of Maltsevo pipes with a diameter of 2000-4000 mm, laid on concrete or reinforced concrete bases, are sealed with gunite over a reinforcing mesh. In this case, the pipes are laid into the trench with a crane using a mounting bracket. The installation of pipes is carried out in the following sequence: mark the position of the pipe on the base; they rig the pipe and lower it into the trench; lay the pipe on the base and check its position; caulk the joint with a strand of resin and seal it with cement mortar; wrap the joint with reinforcing mesh and seal it.
Fig.1
A - general scheme organization of work
b – pipe laying and alignment
1 – pipes
3 – trenches
4 – pits for sealing joints
5 – pincer grip
6 – way sight
7 – sew-on sights
