CN117345944A - Buried installation process of large-caliber PCCP pipeline on complex foundation - Google Patents
Buried installation process of large-caliber PCCP pipeline on complex foundation Download PDFInfo
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- CN117345944A CN117345944A CN202311100815.2A CN202311100815A CN117345944A CN 117345944 A CN117345944 A CN 117345944A CN 202311100815 A CN202311100815 A CN 202311100815A CN 117345944 A CN117345944 A CN 117345944A
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- 238000011900 installation process Methods 0.000 title claims abstract description 20
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 53
- 239000010959 steel Substances 0.000 claims abstract description 53
- 239000002689 soil Substances 0.000 claims abstract description 39
- 238000009434 installation Methods 0.000 claims abstract description 33
- 238000000034 method Methods 0.000 claims abstract description 31
- 238000003825 pressing Methods 0.000 claims abstract description 24
- 238000010276 construction Methods 0.000 claims abstract description 21
- 238000012360 testing method Methods 0.000 claims description 30
- 238000009412 basement excavation Methods 0.000 claims description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 18
- 239000004576 sand Substances 0.000 claims description 11
- 238000007789 sealing Methods 0.000 claims description 11
- 238000013461 design Methods 0.000 claims description 8
- 238000007689 inspection Methods 0.000 claims description 6
- 239000004575 stone Substances 0.000 claims description 6
- 238000004140 cleaning Methods 0.000 claims description 5
- 230000002706 hydrostatic effect Effects 0.000 claims description 5
- 238000005266 casting Methods 0.000 claims description 4
- 210000001503 joint Anatomy 0.000 claims description 4
- 230000007547 defect Effects 0.000 claims description 3
- 230000000087 stabilizing effect Effects 0.000 claims description 3
- 238000010998 test method Methods 0.000 claims description 3
- 208000027418 Wounds and injury Diseases 0.000 abstract description 4
- 230000006378 damage Effects 0.000 abstract description 4
- 208000014674 injury Diseases 0.000 abstract description 4
- 238000005538 encapsulation Methods 0.000 abstract description 2
- 238000005516 engineering process Methods 0.000 abstract description 2
- 239000011083 cement mortar Substances 0.000 description 4
- 238000003780 insertion Methods 0.000 description 4
- 230000037431 insertion Effects 0.000 description 4
- 239000004567 concrete Substances 0.000 description 3
- 239000004570 mortar (masonry) Substances 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 239000004568 cement Substances 0.000 description 2
- 238000005056 compaction Methods 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
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- 238000009736 wetting Methods 0.000 description 2
- 241000208125 Nicotiana Species 0.000 description 1
- 235000002637 Nicotiana tabacum Nutrition 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- 238000003889 chemical engineering Methods 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005536 corrosion prevention Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000008157 edible vegetable oil Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
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- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 235000019198 oils Nutrition 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 239000011513 prestressed concrete Substances 0.000 description 1
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L1/00—Laying or reclaiming pipes; Repairing or joining pipes on or under water
- F16L1/024—Laying or reclaiming pipes on land, e.g. above the ground
- F16L1/028—Laying or reclaiming pipes on land, e.g. above the ground in the ground
- F16L1/036—Laying or reclaiming pipes on land, e.g. above the ground in the ground the pipes being composed of sections of short length
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- F16L1/00—Laying or reclaiming pipes; Repairing or joining pipes on or under water
- F16L1/024—Laying or reclaiming pipes on land, e.g. above the ground
- F16L1/06—Accessories therefor, e.g. anchors
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
Abstract
The invention discloses a buried installation process of a large-caliber PCCP pipeline on a complex foundation, which comprises multiple procedures of foundation treatment, foundation pit support, cushion layer pouring, pipeline hanging installation, encapsulation pouring, bell and spigot pressing and the like, wherein the large-caliber PCCP pipeline is installed by an inner installation method, a retaining bar, a steel wire rope and a chain block combined system are adopted, under the cooperation of a hanging excavator, an installation gap between two adjacent pipelines is used as a supporting point, one end of the pipeline to be installed is used as the other supporting point, the two supporting points are clamped by a fixture, after the bell and spigot of the pipeline is centered, a guide chain on the fixture is tensioned, and the pipeline spigot is gradually pulled in until the pipeline is installed in place. The construction technology is relatively simple, easy to operate and relatively low in construction cost, can be operated in a pipe, can avoid the occurrence of injury accidents caused by collapse of the poor soil texture section, and has strong applicability for multi-point operation; the working efficiency is effectively improved, the installation time is reduced, and the integral installation quality of the pipeline can be enhanced.
Description
Technical Field
The invention belongs to the technical field of pipeline installation, and particularly relates to a buried installation process of a large-caliber PCCP pipeline on a complex foundation.
Background
The prestressed steel cylinder concrete pipe (PCCP pipe for short) fully uses the compressive strength of concrete in design, and can bear larger external load than other pipes; the semi-rigid joint of the PCCP has certain rigidity and flexibility, and the performance of adapting to geological changes is stronger than that of other pipes; the pipeline installation and the operation are convenient, so the pipeline installation and the operation are widely popularized and used in large-scale chemical engineering and oil refining projects.
The pipe diameters of gravity flow clean rainwater systems in water supply and drainage and fire-fighting pipe networks of large-scale chemical enterprises are large-caliber PCCP pipes, the specification is DN1000 mm-DN 3200mm, the single weight of DN3200mm can reach 31.05 tons, and the single weight is too large to be used in the prior method; in the past, PCCP pipeline connection is carried out by adopting an external installation method (external pushing) or a manual chain pouring method, but the method has lower overall efficiency of the installation process for large-caliber PCCP pipelines, and the measurement and adjustment of horizontal and vertical errors are difficult to control, so that the overall effect is affected.
In addition, large-scale chemical enterprises are generally built on islands (seasides), underground water is rich, the lower part of the large-scale chemical enterprises contains a large amount of silt, geology is complex, sedimentation problems often exist, a pipeline foundation pit can reach 7 meters at the deepest, potential safety hazards are high, and construction difficulty is extremely high.
Disclosure of Invention
In order to solve the problems, the invention discloses a buried installation process of a large-caliber PCCP pipeline on a complex foundation, which adopts an internal installation method to install, can effectively improve the working efficiency, reduce the installation time, improve the overall installation quality of the pipeline, and avoid the occurrence of injury accidents caused by collapse of a poor soil texture section, and has strong multi-point operation applicability.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
the embedded installation process of the large-caliber PCCP pipeline on the complex foundation comprises the following steps:
foundation treatment measures are formulated according to different geological conditions, pipe ditch earthwork excavation, steel sheet pile supporting, construction drainage reduction, pipeline cushion layer construction, PCCP pipe hoisting in place by a crane, PCCP pipe installation, interface hydraulic test, interface grouting, backfilling pile pulling.
As an improvement of the invention, the foundation treatment measures are formulated according to different geological conditions, and the foundation treatment measures are specifically as follows:
a: the sandy soil and the harder soil area adopt 1:1.5, excavating a slope, reserving a 1.5M wide secondary platform in the slope, and protecting the pile foundation by adopting a single-side steel sheet pile support when the slope is not met under the condition that the slope is released;
b: the silt area and the quicksand soil and the backfill soft soil adopt the double-side steel sheet piles and the top support after being firstly reduced by 1.5 m.
As an improvement of the invention, the pipe ditch earth excavation is specifically as follows:
the method comprises the steps that a GPS is used for carrying out center line positioning before trench excavation, and when a polar coordinate method is used for measuring and placing the center line of a pipeline, a center pile is measured at a starting point, an ending point, a plane folding point, a vertical folding point and a control point of a straight line segment; every 10m of the line is a point, the pile top is nailed with a central nail, and a peg is arranged at a proper position outside the groove; and measuring and placing the position line of the upper opening excavation of the groove according to the central line control pile and the slope placing scheme, marking by scattering white gray lines on site, symmetrically nailing a pair of elevation piles on the outer side of the upper opening line, and nailing Gao Chengding and Gao Chengzhuang of equal height on each pair of elevation piles Cheng Zhuang, wherein the longitudinal distance is 10m.
As an improvement of the invention, aiming at silt areas, quicksand soil and backfill soft soil, the steel sheet pile support is a support mode of adopting small tooth mouth Larson IV type steel sheet piles and a steel support at the top at two sides of a foundation pit, and the steel sheet pile is driven by adopting a single pile driving method.
As an improvement of the invention, aiming at silt areas, quicksand soil and backfill loose soil, the method for replacing the pipeline cushion layer by casting stones and squeezing silts is adopted before construction: firstly, placing rubble, covering 300mm, cleaning up silt in a pipe ditch, and paving 200mm broken stone as a whole layer.
As an improvement of the invention, the PCCP pipeline is installed, two sealing rubber rings are firstly arranged on the outer side of a steel socket of the PCCP pipeline, a cross bar is arranged at the non-socket end of the PCCP pipeline, a fixed rod is arranged at the socket in the installed pipeline, the fixed rod is connected with the cross bar by using a steel wire rope and a chain block, and a person operates in the pipe and gradually pulls in the pipeline socket through the chain block.
As an improvement of the invention, the interface hydrostatic test is that after the pipeline is connected, the pressurizing pump joint is connected with the steel external joint of the pipeline, and the steel sealing joint in the eyelet on the other side is removed, so that the pressurizing can be performed;
the joint pressing test is divided into three times, the first joint pressing test is performed, water is pressed from a water inlet hole at the lower part of the joint, and the upper exhaust hole is exhausted; sealing the hole by adopting a steel sealing joint after the exhaust is finished; gradually pressurizing to 0.2Mpa, stabilizing the pressure for 5 minutes, then gradually pressurizing to the pressure required by the design, and maintaining the pressure for 5 minutes without dropping, thus obtaining the qualified product. And pulling out the unqualified pressed pipeline, and eliminating the defect and reinstalling after finding the cause. And (3) performing secondary joint pressing test, namely performing secondary joint pressing on the joint of the first section of pipeline installed in advance after each 3 sections of PCCPs are installed, wherein the test method is the same as that of the first joint pressing test. And (3) performing third joint pressing inspection, wherein the third joint pressing inspection is performed after the backfilling of the pipe roof is completed. The test pressure is the working pressure required by design, and the test pressure is kept to be unchanged for 5 minutes, namely the test pressure is qualified.
As an improvement of the invention, when the bent pipe or the special pipe of the PCCP pipe is installed, the lower surface of the bent pipe or the special pipe is protected, and after the installation is finished, the support and the special pipe are cast into a pipe fitting together.
As an improvement of the invention, the joint grouting is performed on the front 10 sections of pipelines after 20 sections of PCCP pipelines are installed, and then the joint grouting is performed by adopting a 120-degree annular belt foundation for encapsulation casting.
As an improvement of the invention, the backfilling pile pulling is to backfill the pile to 300mm of the elevation of the pipe top by sand layering, pull the pile and backfill the pile to the designed elevation by using the original soil.
The beneficial effects of the invention are as follows:
the invention aims at PCCP pipes with large pipe diameters, the internal installation method is adopted, a combined system of a retaining bar, a steel wire rope and a chain block is adopted, under the cooperation of a hanging excavator, an installation gap between two adjacent pipes is used as one supporting point, one end of the pipe to be installed is used as the other supporting point, the two supporting points are clamped by the equipment, after bell and spigot jacks of the pipe are centered, a guide chain on the equipment is tensioned, and the pipe spigot is gradually pulled in until the pipe spigot is installed in place. Compared with a 'pipeline butt joint machine', the construction technology is relatively simple to install, easy to operate and relatively low in construction cost, can be operated in a pipe, can avoid the occurrence of injury accidents caused by collapse of a poor soil texture section, and has strong multi-point operation applicability; the working efficiency is effectively improved, the installation time is reduced, and the integral installation quality of the pipeline can be enhanced.
Drawings
Fig. 1 is a schematic view of a PCCP pipe installation according to the present invention.
Fig. 2 is a schematic diagram of a hydrostatic test of an interface according to the present invention.
Description of the embodiments
The present invention is further illustrated in the following drawings and detailed description, which are to be understood as being merely illustrative of the invention and not limiting the scope of the invention.
Taking XX artificial island refining integrated project of the tobacco stand of Shandong province as an example, water supply and drainage and fire-fighting pipe network engineering of the gravity flow clean rainwater system has pipe diameter specification of more than or equal to DN1000mm, wherein embedded prestressed steel cylinder concrete pipe is used, the total number of pipe meters is 13729 meters, the pipe specification mainly comprises DN1000mm, DN1200mm, DN1400mm, DN1600mm, DN1800mm, DN2000mm, DN2200mm, DN2400mm, DN2600mm, DN2800mm, DN3200mm, and the single pipe of DN3200mm can weigh 31.05 tons; because of the artificial island, the underground water is rich, the lower part contains a large amount of silt, the geology is complex, and the deepest pipeline foundation pit reaches 7 meters.
For PCCP pipes with small pipe diameters, an external installation method is generally adopted for installation, and for PCCP pipes with large pipe diameters, an internal installation method is adopted. Because the net size of DN3000 pipeline is 4980mm, after two pipelines are installed, the installation seam between bell and spigot is 20mm, so the installation size of pipeline is 5000mm, the built-in method is bumper bar, wire rope, chain block combined system, set up the cross bar at PCCP pipeline non-socket end, set up the dead lever in the socket department in the installed finished pipeline, use wire rope and chain block to connect dead lever and cross bar, make the pipeline slowly evenly get into through chain block as shown in figure 1, until install in place.
The method is relatively simple to install and easy to operate, can effectively improve the working efficiency, reduce the installation time and strengthen the integral installation quality of the pipeline; and large-scale equipment does not need to be purchased, the construction cost is relatively low, the operation can be carried out in the pipe, the occurrence of injury accidents caused by collapse of the poor soil texture section can be avoided, and the applicability of multi-point operation is strong.
The specific embedded installation process comprises the following steps:
1. geological evaluation: foundation treatment measures are formulated according to different geological conditions
The area is mainly viscous filling soil (silt) and sandy filling soil, and the excavation depth is 5-8.5m;
(1) The sandy soil and the harder soil area are excavated by adopting a 1:1.5 slope, a 1.5M wide secondary platform is reserved in the slope, the secondary platform is close to the constructed area of the pile foundation, and a certain safety distance is reserved to protect the pile foundation by adopting a unilateral steel sheet pile support under the condition that the slope laying requirement is not met, so that the pile body is prevented from being damaged due to soil pressure difference;
(2) The silt area and the quicksand soil and the backfill soft soil adopt double-side steel sheet piles and top supports (the silt soil has certain fluidity, the double-side steel sheet piles have reliable safety to the supports, the excavation engineering amount is reduced, the disturbance of surrounding soil is reduced, and the surrounding pile foundations and structures are protected).
2. Measuring pay-off
When the line central line is measured and placed by adopting a polar coordinate method, a center pile is measured and placed at a starting point, an ending point, a plane folding point, a vertical folding point, a control point of a straight line segment and the like;
every 10m of the line is a point, the pile top is nailed with a central nail, and a peg is arranged at a proper position outside the groove; and measuring and placing the position line of the upper opening excavation of the groove according to the central line control pile and the slope placing scheme, marking by scattering white gray lines on site, symmetrically nailing a pair of elevation piles on the outer side of the upper opening line, and nailing Gao Chengding and Gao Chengzhuang of equal height on each pair of elevation piles Cheng Zhuang, wherein the longitudinal distance is 10m.
3. Construction of steel sheet piles
The two sides of the foundation pit adopt a small tooth mouth Larson IV-shaped steel sheet pile and a top steel support supporting mode, the length of the steel sheet pile is 9/12m, the digging depth is more than 5.2 m, 12m steel sheet piles are selected, the steel sheet pile purlines are HW400 x 400, the supports are HW400 x 400 or 600 circular pipe loose ends, the distance is @10 m (anchor bolt drawknot), the piling construction machine is positioned on soil body outside a pipe ditch, the construction is carried out according to the on-site temporary road separation and segmentation, and the piling construction machine is arranged from two sides of a section of the seal head in sequence; the excavation stage is planned to adopt a back shovel to lay a steel plate below the excavator for operation, and the excavator is located in the foundation trench and starts to excavate soil from the end head.
4. Steel sheet pile driving device
Adopts a single pile driving method: the single pile driving method uses one or two steel plates as a group, starts to perform block-by-block insertion from one corner until the project is finished, specifically, firstly, a crane is used for hoisting the steel plate pile to the insertion point for pile insertion, the locking notch is aligned during pile insertion, and a pile cap is sleeved after each block is inserted, and the pile is lightly hammered; in the piling process, two theodolites are used for controlling in two directions in order to ensure the verticality of the steel sheet pile; in order to prevent the plane displacement of the center line of the locking notch, a clamping plate can be arranged at the locking notch of the steel sheet pile in the piling proceeding direction to prevent the displacement of the sheet pile; the position and direction of the first steel sheet pile and the second steel sheet pile to be driven should ensure precision so as to play a role in guiding the sample plate, so that the measurement should be carried out once every 1m of driving, and the steel bars or the steel plates should be welded and fixed with the support immediately after the driving to a preset depth.
5. Digging groove
The trench excavation of the steel plate pile section is performed along the steel plate pile in a straight downward direction, a backhoe is adopted during the excavation (a support is additionally arranged after the excavation is performed to a depth of 2.5 meters, the excavation is performed in a layered manner, the length of a common excavator arm does not meet the soil collecting requirement, the long-arm excavator is called according to the excavation depth for construction), a steel plate is paved below the trench for operation, and the excavator is located in a foundation trench to excavate soil from the end head; because the cohesive soil has large water content, is in a flowing plastic shape, is easy to collapse, and is piled up with sand barrages at a certain distance in a foundation pit when necessary, the clay is prevented from flowing back into the pit, and the dump truck is equipped to directly pull to an earthwork storage yard in the excavation process without backfilling conditions.
Preparing for open drainage in the excavated foundation pit, and adopting two precipitation modes: light well-point precipitation and open trench precipitation.
6. Pipeline cushion layer construction
If the construction area is laid in silt, quicksand and soft soil, a method of changing and filling by throwing stones and squeezing silt is used on site, firstly, rubble is put in to cover 300mm, then the silt in a pipe trench is cleaned up, and then 200mm broken stone is laid as a whole layer; and then casting in sections.
7. PCCP (prestressed concrete cylinder pipe) pipeline installation
And (3) adopting a 220T crawler crane and a digging machine to construct by matching with an internal pressure method.
After the pipeline is lifted and put down in the ditch, the excavator assists in butting the faucet of the pipe orifice, and the 220T crane is responsible for lifting and hovering the pipeline; after the butt joint of the pipeline interface is finished, the inner pull rod and the chain block are fixed.
As shown in figure 1, a cross bar is placed in the installed pipe, a fixed rod is arranged at the socket in the installed pipe, and a manual pulling machine is used for connecting the pull rods at two sides in the pipe. The hand pulling block is manually operated to enable the pipeline socket to be slowly inserted into the bell mouth, the left-right deviation is adjusted by using the hand pulling machines at the left side and the right side, and the crane and the digging machine are matched to adjust the height of the pipeline. And (3) manually observing whether the slit light of the faucet is uniform at the pipe joint, and enabling the faucet to slowly enter the faucet if the slit light is uniform. During the entry process, the person outside the tube carefully observes the slipping-in of the rubber ring. The human in the pipe uses the ruler (or the limiting block) to measure the circumferential clearance of the interface uniformly, and the tension machines at the two sides are used for adjustment at any time. The circumferential gap of the interface is controlled by a limiting block, and the pipe pulling is stopped after the circumferential gap meets the requirement of 15mm < d <28 mm. Placing a horizontal guiding rule with the length of 1m at the mounting pipe orifice, after the guiding rule is horizontal, utilizing a plumb bob on the midpoint of the guiding rule to determine the center line of the pipe, namely the point of the plumb bob on the inner bottom of the pipe, namely the side key of the elevation of the pipe bottom, using a theodolite to determine whether the axis of the pipe meets the requirement (less than or equal to 50 mm), using a level meter to determine whether the elevation of the inner bottom of the pipe meets the requirement (less than or equal to 50 mm) axis, simultaneously manually backfilling and tamping the two sides of the bottom of the pipe after the elevation meets the requirement, then slowly placing and removing a pulling machine to enable the pipe to be completely landed, re-checking the axis and the elevation, and after all the pipe is qualified, using a test pump to test leakage of the pipe joint. The annular gap at the joint should be uniform and straight and meet the design requirement, the construction unit must measure the joint socket installation gap at four points of up, down, left and right, the pipeline must be cushioned after installation, and the pipe body must not be suspended and rocked to be fixed.
If the rubber ring is found to be out of the groove (or crushed) in the process of installing the pipe, the pipe is installed after the rubber ring is removed and replaced, but the joint and the rubber ring are required to be cleaned again and coated with edible vegetable oil.
The special pipe and fittings are installed as in the PCCP pipe. When the special-shaped pipe is installed, the lower surface of the special-shaped pipe is protected, and after the special-shaped pipe is installed, the support and the special-shaped pipe are cast together in the pipe fitting installation process.
8. Interface hydrostatic test
After the butt joint of the pipeline is finished, the pressing pump joint is connected with the steel external joint of the pipeline, and the steel sealing joint in the eyelet on the other side is removed, so that the pressing can be performed.
The joint pressing test is divided into three times, the first joint pressing test is performed, water is pressed from a water inlet hole at the lower part of the joint, and the upper exhaust hole is exhausted; after the exhaust is finished (water flows out uniformly), sealing the hole by adopting a steel sealing joint; gradually pressurizing to 0.2Mpa, stabilizing the pressure for 5 minutes, then gradually pressurizing to the pressure required by the design, and maintaining the pressure for 5 minutes without dropping, thus obtaining the qualified product. And pulling out the unqualified pressed pipeline, and eliminating the defect and reinstalling after finding the cause. And (3) performing secondary joint pressing test, namely performing secondary joint pressing on the joint of the first section of pipeline installed in advance after each 3 sections of PCCPs are installed, wherein the test method is the same as that of the first joint pressing test. And (3) performing third joint pressing inspection, wherein the third joint pressing inspection is performed after the backfilling of the pipe roof is completed. The test pressure is the working pressure required by design, and the test pressure is kept to be unchanged for 5 minutes, namely the test pressure is qualified.
9. Joint gap grouting
(1) After each 20 sections of PCCP pipes are installed in a single line, joint grouting is performed on the first 10 sections of pipes. The surface of the inner cement mortar should be smooth and flat, and the outer cement mortar should be full in full filling in the whole circumference.
(2) And (3) grouting an outer joint: the pipe has larger outer diameter, adopts manual external pointing, and is used for removing sundries at the joint before pointing, and cleaning or scrubbing with water to ensure the cleaning and wetting of the joint, wherein the external pointing is fully compacted, the external cement mortar is prepared from 1 part of cement: (1-2) sand, wherein the sand is clean medium and fine sand, and water spraying maintenance is needed after external pointing is finished.
(3) And (5) jointing an inner joint: the internal joint adopts manual pointing trowelling. Before pointing, sundries at the joint should be removed, and water is used for spray washing or brushing to ensure the cleaning and wetting of the joint. The inner pointing should be compact and smooth. The mortar comprises 1 part of cement: (1.5-2) sand, wherein the sand is clean medium and fine sand, and water spraying maintenance is needed after inner pointing is finished.
(4) The cement mortar is less in dosage and less than 0.4m, manual stirring is adopted when the quality meets the 6.15-style regulation in GB748, the mortar with the existing hardening phenomenon is not used, and the mortar is not allowed to be mixed with water again by any method.
And after grouting, adopting a 120-degree annular belt foundation to encapsulate and cast the PCCP pipeline.
10. Groove backfill and pile pulling
Backfilling after the pipeline joint hydrostatic test is qualified and the corrosion prevention is finished, and removing accumulated water and sundries in the groove before backfilling; and (3) backfilling the pipeline in the silt region to 300mm in elevation at the top of the pipeline by using sand, backfilling the pipeline to the designed elevation by using original soil, and backfilling the pipeline in the sand region by directly using the original soil. Backfilling should be performed symmetrically from both sides of the pipe and rammed in layers without damaging the pipe and the corrosion protection.
The thickness of each layer of virtual soil is not more than 300mm by mechanical tamping, the thickness of each layer of virtual soil is not more than 200mm by manual tamping, the compaction degree is not less than 0.92, and the detection unit synchronously samples and detects the compaction degree;
and when backfilling to half the height, pile pulling is performed, and then backfilling is continued.
Acceptance results after engineering is completed:
the difference of the pipeline installation height Cheng Pian is within +/-20 mm; the axis deviation is also within + -20 mm; pipe joint mounting gap: 25+5 to 25-10 mm; the pipeline joint is pressed to meet the standard.
By the embedded installation process of the large-caliber PCCP pipeline on the complex foundation, the installation period is shortened by 90 days, and the construction cost is reduced by 30%.
It should be noted that the foregoing merely illustrates the technical idea of the present invention and is not intended to limit the scope of the present invention, and that a person skilled in the art may make several improvements and modifications without departing from the principles of the present invention, which fall within the scope of the claims of the present invention.
Claims (10)
1. The embedded installation process of the large-caliber PCCP pipeline on the complex foundation is characterized in that: the method comprises the following steps:
foundation treatment measures are formulated according to different geological conditions, pipe ditch earthwork excavation, steel sheet pile supporting, construction drainage reduction, pipeline cushion layer construction, PCCP pipe hoisting in place by a crane, PCCP pipe installation, interface hydraulic test, interface grouting, backfilling pile pulling.
2. The buried installation process of a large caliber PCCP pipe on a complex foundation according to claim 1, wherein: the foundation treatment measures are formulated according to different geological conditions, and are specifically as follows:
a: the sandy soil and the harder soil area adopt 1:1.5, excavating a slope, reserving a 1.5M wide secondary platform in the slope, and protecting the pile foundation by adopting a single-side steel sheet pile support when the slope is not met under the condition that the slope is released;
b: the silt area and the quicksand soil and the backfill soft soil adopt the double-side steel sheet piles and the top support after being firstly reduced by 1.5 m.
3. The buried installation process of a large caliber PCCP pipe on a complex foundation according to claim 1, wherein: the pipe ditch earthwork excavation is specifically as follows:
the method comprises the steps that a GPS is used for carrying out center line positioning before trench excavation, and when a polar coordinate method is used for measuring and placing the center line of a pipeline, a center pile is measured at a starting point, an ending point, a plane folding point, a vertical folding point and a control point of a straight line segment; every 10m of the line is a point, the pile top is nailed with a central nail, and a peg is arranged at a proper position outside the groove; and measuring and placing the position line of the upper opening excavation of the groove according to the central line control pile and the slope placing scheme, marking by scattering white gray lines on site, symmetrically nailing a pair of elevation piles on the outer side of the upper opening line, and nailing Gao Chengding and Gao Chengzhuang of equal height on each pair of elevation piles Cheng Zhuang, wherein the longitudinal distance is 10m.
4. The buried installation process of a large caliber PCCP pipe on a complex foundation according to claim 1, wherein: aiming at silt areas, quicksand soil and backfill soft soil, the steel sheet pile support is a support mode of adopting small tooth mouth Lassen IV type steel sheet piles and a steel support at the top at two sides of a foundation pit, and the steel sheet pile is driven by adopting a single pile driving method.
5. The buried installation process of a large caliber PCCP pipe on a complex foundation according to claim 1, wherein: aiming at silt areas and quicksand soil and soft soil backfilling, the method for replacing the pipeline cushion layer by casting stones and squeezing silts is adopted before construction: firstly, placing rubble, covering 300mm, cleaning up silt in a pipe ditch, and paving 200mm broken stone as a whole layer.
6. The buried installation process of a large caliber PCCP pipe on a complex foundation according to claim 1, wherein: the PCCP pipeline is installed, two sealing rubber rings are firstly arranged on the outer side of a steel socket of the PCCP pipeline, a cross bar is arranged at the non-socket end of the PCCP pipeline, a fixed rod is arranged at the socket in the installed pipeline, the fixed rod is connected with the cross bar through a steel wire rope and a chain block, a person operates in the pipe, and the pipeline socket is gradually pulled in through the chain block.
7. The buried installation process of a large caliber PCCP pipe on a complex foundation according to claim 1, wherein: the interface hydrostatic test is that after the pipeline is in butt joint, the pressurizing pump joint is connected with the steel external joint of the pipeline, and the steel sealing joint in the eyelet on the other side is removed to perform pressurizing;
the joint pressing test is divided into three times, the first joint pressing test is performed, water is pressed from a water inlet hole at the lower part of the joint, and the upper exhaust hole is exhausted; sealing the hole by adopting a steel sealing joint after the exhaust is finished; gradually pressurizing to 0.2Mpa, stabilizing the pressure for 5 minutes, then gradually pressurizing to the pressure required by the design, and maintaining the pressure for 5 minutes without dropping, thus obtaining the qualified product. And pulling out the unqualified pressed pipeline, and eliminating the defect and reinstalling after finding the cause. And (3) performing secondary joint pressing test, namely performing secondary joint pressing on the joint of the first section of pipeline installed in advance after each 3 sections of PCCPs are installed, wherein the test method is the same as that of the first joint pressing test. And (3) performing third joint pressing inspection, wherein the third joint pressing inspection is performed after the backfilling of the pipe roof is completed. The test pressure is the working pressure required by design, and the test pressure is kept to be unchanged for 5 minutes, namely the test pressure is qualified.
8. The buried installation process of a large caliber PCCP pipe on a complex foundation according to claim 1, wherein: when the bent pipe or the special pipe of the PCCP pipe is installed, the lower surface of the bent pipe or the special pipe is protected, and after the installation is finished, the support and the special pipe are poured together to form a pipe fitting.
9. The buried installation process of a large caliber PCCP pipe on a complex foundation according to claim 1, wherein: and the joint grouting is performed on the front 10 sections of pipelines after 20 sections of PCCP pipelines are installed, and then the PCCP pipelines are encapsulated and poured by adopting a 120-degree annular belt foundation.
10. The buried installation process of a large caliber PCCP pipe on a complex foundation according to claim 1, wherein: and the backfilling pile pulling is to backfill the pile to 300mm of the elevation of the pipe top by using sand layers, pull the pile, and backfill the pile to the designed elevation by using original soil.
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