Construction method of river-crossing pipeline
By constructing cofferdams in the river channel and excavating foundation trenches, the problems of ground subsidence and dependence on ship and machinery equipment during cross-river pipeline construction were solved, achieving safe and efficient pipeline installation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA RAILWAY 23RD BUREAU GRP 4TH ENG CO LTD
- Filing Date
- 2026-03-04
- Publication Date
- 2026-04-17
AI Technical Summary
Existing methods for constructing cross-river pipelines pose a risk of ground subsidence in loose sand layers and cannot utilize large vessels and machinery in shallow water conditions, resulting in high construction safety risks and technological limitations.
A cofferdam is built in the river channel and steel sheet piles are driven to excavate the foundation trench, forming a dry construction area. The two sides of the foundation trench are stabilized by lateral supports. Pipe pushing equipment is installed in the pushing workshop to push the pipeline. After the foundation trench is backfilled, the river channel is restored to flow.
This approach avoids the problems of ground subsidence in loose sand layers and reliance on large ships and machinery, optimizes construction techniques, reduces safety risks, minimizes the occupation of the river channel during construction, and improves construction efficiency and safety.
Smart Images
Figure CN121876236A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of water conservancy and municipal pipeline construction technology, and in particular to a construction method for cross-river pipelines. Background Technology
[0002] In municipal and water conservancy engineering projects, the construction technology of large-diameter cross-river pipelines plays a crucial role in long-distance water conveyance and inter-basin water transfer projects. However, under complex geological and hydrological conditions, the application of traditional construction methods faces many limitations.
[0003] Currently, the main methods for constructing cross-river pipelines are pipe jacking or immersed pipe methods. Pipe jacking involves using jacking equipment to push the pipeline from the working shaft across the riverbed to the receiving shaft. This method requires a certain degree of soil stability and is typically suitable for clay, silty clay, or rock formations. However, when the pipeline route needs to cross thick sand layers beneath the riverbed, this process has significant drawbacks: the loose structure and high fluidity of the sand layer make it prone to collapse during jacking, leading to uncontrolled surface subsidence. This can cause construction accidents such as tunneling machine deviation and jamming, and in severe cases, even catastrophic consequences like water inrush, posing extremely high safety risks.
[0004] Immersed tunnel construction typically involves excavating a trench in the riverbed, floating prefabricated tunnel sections to their designated locations, and then precisely sinking them into place. This process heavily relies on specialized equipment such as large floating cranes and tugboats for transporting, positioning, and sinking the tunnel sections. However, in some inland waterways, especially during the dry season when water levels are low and navigation is not ideal, the water depth often fails to meet the navigation and operational requirements of large vessels, preventing the access of immersed tunnel equipment and thus limiting the implementation of this method.
[0005] Taking a cross-river pipeline project as an example, according to the on-site geological survey of the riverbed, the pipeline traverses an area mainly composed of sand layers, and the river water level is relatively shallow, making the working conditions during the dry season extremely challenging. If the pipe jacking method is used, there is a significant safety risk of instability during tunneling through the sand layers; if the immersed tube method is used, large working vessels cannot enter due to water depth limitations, making construction difficult. Under such complex environmental conditions, numerous constraints, and high safety risks, traditional single construction methods can no longer meet the project requirements.
[0006] Therefore, how to avoid the construction risks of pipe jacking in sand layers, while overcoming the dependence of immersed pipe method on large ship and machinery equipment, optimizing and innovating existing construction technology, and exploring a feasible method suitable for complex shallow water channels and large-diameter pipe installation has become an urgent technical problem to be solved in this field. Summary of the Invention
[0007] The purpose of this invention is to overcome the technical problems of existing pipeline construction processes being unable to simultaneously avoid instability during tunneling in sand layers and dependence on large ship machinery and equipment, and to provide a construction method for cross-river pipelines.
[0008] This invention provides a construction method for a cross-river pipeline, comprising:
[0009] S1: Construct a cofferdam in the river channel so that the top of the cofferdam is higher than the water surface; drive steel sheet piles on both sides of the excavation location of the foundation trench, excavate the foundation trench from the top of the cofferdam downward between the steel sheet piles on both sides, and install several transverse supports between the steel sheet piles on both sides. S2: Drain the water from the foundation trench; excavate a foundation pit on the bank at one end of the foundation trench to form a pushing work area, and connect the pushing work area with the foundation trench; S3: Install a pipe pushing device in the pushing work chamber and install a slide rail in the base trench; S4: Hoist the pipe into the pushing work chamber and position it, and use the pipe pushing equipment to push the pipe along the slide rail into the base trench; S5: Repeat S4, and push several of the pipes into the trench one end to the other, until the trench is filled with several of the pipes along the length of the trench. S6: Backfill the foundation trench, dismantle the pipeline pushing equipment and backfill the foundation pit, dismantle the sheet piles and cofferdam, and complete the pipeline construction.
[0010] This invention involves constructing a cofferdam in a river channel, driving sheet piles onto the cofferdam, excavating a foundation trench, and then pumping water to create an open, dry construction area in the trench. Lateral supports between the sheet piles on both sides stabilize the cofferdam structure after excavation. A foundation pit is then excavated on the riverbank to form a pushing work area connected to the trench. Pipe pushing equipment can then be installed in this work area for pipeline pushing construction. The pipeline pushing construction is similar to pipe jacking. Because the trench is excavated and pumped out, creating an open, dry construction area with sheet piles on both sides, the pipeline can avoid the influence of sand flow above and to the sides during the pushing operation. However, all pipelines are within the trench... After the pipe is pushed into place, the trench is backfilled to bury the pipeline in the riverbed strata. After the sheet piles are removed, the river channel above the pipeline is restored to flow, and the pipeline construction is completed. The construction method of this invention avoids the risks of ground subsidence and structural instability caused by directly jacking pipes in the loose sand layer of the riverbed, which can lead to a decline in project quality, safety hazards, or even construction accidents. On the other hand, it also avoids the disadvantages of not being able to use large working vessels to implement the immersed pipe method in shallow water conditions, which restricts construction. The construction process is optimized, the safety risks are controllable, the pipeline construction working environment under unfavorable conditions is improved, and the safety risks of river-related construction are reduced.
[0011] Preferably, the river channel is divided into two halves along its width direction. First, S1~S6 are performed on either half to complete the pushing and installation of the pipeline in that half of the river channel. Then, S1~S5 are repeated on the other half to complete the pushing and installation of the pipeline in the other half. Then, the pipelines in the two halves are joined together. Then, S6 is performed.
[0012] When constructing pipelines using the construction method of this invention, the river channel can be divided into two halves along its width for sequential construction, i.e., construction in two phases. After constructing a cofferdam to block the river in one half (phase one), the other half (phase two) can remain navigable, minimizing the river channel occupation caused by pipeline construction and reducing the impact on navigation. Similarly, after the completion of phase one, the cofferdam and sheet piles in the non-closed areas of phase one can be removed to restore the flow of the river in phase one half, and then the river channel in phase two half can be blocked, thus maintaining navigation during construction.
[0013] Preferably, the river channel is divided into two halves along its width direction, and S1~S5 are performed simultaneously on each half to push and install the pipes in each half of the river channel; then the pipes in the two halves are joined together; and then S6 is performed.
[0014] When constructing pipelines in waterways that do not involve navigation, to improve construction efficiency, construction work can be carried out simultaneously on both halves of the pipeline. This involves pushing the pipeline from both banks towards the middle. It's important to note that when constructing the cofferdam to close the flow, sufficient space must be left between the two halves as a flow channel to allow water to flow downstream, preventing upstream water from overflowing the cofferdam and entering the dry construction area in the trench after pumping. The pipeline construction in the flow channel can be considered a closure section. After both halves of the pipeline are in place, the trench for one half can be backfilled, and the cofferdam and sheet piles removed to restore the waterway for that half. Then, a cofferdam is constructed in the aforementioned flow channel area to close the flow and pump water to create a dry construction area. The other half of the pipeline can then be used for pipe jacking again, closing the two halves. Finally, the trench is backfilled, and the remaining cofferdam and sheet piles are removed to restore flow.
[0015] Preferably, S1 further includes: before the foundation trench is excavated, a construction access road is built on top of the cofferdam.
[0016] To facilitate the entry and exit of construction equipment in the construction area, a construction access road needs to be built on top of the cofferdam after the cofferdam is filled. The construction access road can be formed on both sides of the foundation trench to facilitate subsequent foundation trench excavation.
[0017] Preferably, S1 further includes: before the cofferdam is filled, setting up a sludge curtain on both sides of the cofferdam filling location.
[0018] To prevent the unrestricted spread of particulate and suspended pollutants generated during cofferdam construction, trench excavation, and sheet pile installation and anchoring, which could cause water pollution, pollution barriers are installed upstream and downstream of the construction area on both sides of the cofferdam construction site. These barriers can contain the particulate and suspended pollutants within their range, preventing pollution spread and protecting the river's ecological environment.
[0019] Preferably, in S2, after the water in the base trench is drained, the bottom of the base trench is leveled, a crushed stone and sand cushion layer is laid at the bottom of the base trench, and a concrete base is constructed on the crushed stone and sand cushion layer; in S3, the slide rail is installed on the concrete base.
[0020] After the foundation trench is excavated, in order to prevent the risk of collapse when bearing the pressure of the pipeline during subsequent construction, it is necessary to level and reinforce the bottom of the trench. Specifically, after leveling the bottom of the trench, a crushed stone and sand cushion layer can be laid and a concrete base can be constructed for reinforcement and stability. In addition, the slide rail can also be installed with the concrete base as the foundation. When the pipeline is pushed into the foundation trench, the weight of the pipeline can be supported by the crushed stone and sand cushion layer and the concrete base. The pipeline can also slide along the slide rail and be pushed into place.
[0021] Preferably, in S3, before the pipeline pushing equipment is installed, the wall opposite to the foundation trench in the pushing work area is reinforced with jet grouting piles and a concrete back wall is constructed.
[0022] The working end of the pipeline pushing equipment faces the trench, and it can apply a pushing force to push the pipeline into the trench. At the same time, the pipeline pushing equipment will also be subject to the reaction force applied by the pipeline. By reinforcing the trench wall with jet grouting piles and constructing a concrete back wall in the pushing working chamber, the tail end of the pipeline pushing equipment can be held against the reaction force, so that the pipeline pushing equipment remains stable in the pushing working chamber and avoids the pipeline pushing equipment from deviating, which would affect the accuracy and stability of the pushing construction operation.
[0023] Preferably, S3 further includes: applying lubricant to the slide rail; S4 further includes: installing a braking device on the pipe in the first section.
[0024] To reduce the resistance encountered by the pipeline during the pushing process, grease or other lubricants can be applied to the slide rails as a lubricant to reduce drag. At the same time, a braking device can be installed on the first section of the pipeline to brake it in time after the pipeline is pushed into place, so as to prevent it from moving beyond the installation position and causing it to collide with the steel sheet piles at the end of the foundation trench, thus ensuring the safety of the pushing operation.
[0025] Preferably, in S6, the method of backfilling the foundation trench includes: filling backfill material in layers on both sides and top of the pipe, and stacking rubble on top of the backfill material for weight.
[0026] After all the pipes in the trench are pushed into place, the pipes can be stably buried and anchored in the stratum by backfilling the backfill material on both sides and above the pipes in the trench. Then, the backfill material can be compacted by using boulders for weight, which further strengthens the pipes and the surrounding stratum.
[0027] Preferably, in step S6, before backfilling the foundation trench, grouting is performed at the bottom of the pipe for reinforcement.
[0028] During the pushing process, the pipe is suspended above the crushed stone and sand cushion layer via a concrete base and sliding rails. After the pipe is pushed into place, the backfill material may have difficulty entering the space between the bottom of the pipe and the crushed stone and sand cushion layer, potentially leaving a hollow, unsupported area. Grouting can be used to reinforce the pipe's support and anchorage in the space between the bottom of the pipe and the crushed stone and sand cushion layer. This is especially important for large-diameter pipes, as grouting increases the support area at the bottom of the pipe, preventing stress concentration and thus avoiding deformation after long-term use and extending the pipe's service life.
[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides a construction method for a cross-river pipeline. The method involves constructing a cofferdam in the river channel, driving sheet piles onto the cofferdam, excavating a foundation trench, and then pumping water to create an open, dry construction area in the trench. Lateral supports are used between the sheet piles on both sides to stabilize the cofferdam structure after excavation. A foundation pit is then excavated on the riverbank to form a pushing work area connected to the foundation trench. Pipe pushing equipment can then be installed in the pushing work area for pipeline pushing construction. The pipeline pushing construction is similar to pipe jacking operations. Because the foundation trench is pumped out and the open, dry construction area is created by the sheet piles on both sides, the pipeline pushing operation avoids the influence of sand flow above and on both sides. After all the pipelines are pushed into place in the foundation trench, the trench is backfilled to bury the pipelines in the riverbed strata. After the sheet piles are removed, the river channel above the pipeline is restored to flow, and the pipeline construction is completed. The construction method of this invention avoids the risks of ground subsidence and structural instability caused by directly jacking pipes in the loose sand layer of the riverbed, which can lead to a decline in project quality, safety hazards, and even construction accidents. On the other hand, it also avoids the disadvantages of not being able to use large working vessels to implement the immersed tube method in shallow water conditions, which restricts construction. It optimizes the construction process, makes safety risks controllable, improves the pipeline construction working environment under unfavorable conditions, and reduces the safety risks of river-related construction.
[0030] 2. This invention optimizes the construction process of long-distance cross-river pipelines by using hydraulic jacks to horizontally push the pipeline, replacing the process of vertically hoisting the pipeline from the top of the river cofferdam with lifting equipment. This reduces the top width of the river-crossing cofferdam, significantly reducing the amount of earth and stone to be filled, saving a large amount of cost for purchasing earth and stone, resulting in significant economic benefits. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of the cross-section of the foundation trench, the sheet piles on both sides, and the cofferdam.
[0032] Figure 2 for Figure 1 A magnified view of a portion of point A in the middle.
[0033] Figure 3 This is a cross-sectional diagram of the push work area.
[0034] Figure 4 This is a top view of the base trench and the pushing work area.
[0035] Figure 5 A schematic diagram illustrating the construction of dividing the river channel into two halves.
[0036] Figure 6 This is a flowchart illustrating the construction method.
[0037] Marked in the image: 1. Foundation trench, 2. Sheet piles, 3. Lateral supports, 4. Pushing work platform, 5. Cofferdam, 6. Construction access road, 7. Sewage curtain, 8. Crushed stone and sand cushion layer, 9. Concrete base, 10. Slide rail, 11. Pipeline, 12. Concrete back wall, 13. Pushing work platform, 14. Hydraulic jack, 15. River channel, 16. Riverbank. Detailed Implementation
[0038] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.
[0039] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.
[0040] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," and "parallel" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, or parallel, but rather that it can be slightly tilted or have a deviation. For example, "horizontal" merely means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but that it can be slightly tilted. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," or "parallel" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.
[0041] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.
[0042] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, nine, or even more than nine.
[0043] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.
[0044] Example This embodiment provides a construction method for a cross-river pipeline.
[0045] like Figures 1 to 6 As shown, the construction method for the cross-river pipeline in this embodiment includes the following steps: S1: Construct a cofferdam 5 in the river channel 15 so that the top of the cofferdam 5 is higher than the water surface; drive steel sheet piles 2 on both sides of the excavation position of the foundation trench 1, excavate the foundation trench 1 from the top of the cofferdam 5 between the steel sheet piles 2 on both sides, and install several transverse supports 3 between the steel sheet piles 2 on both sides. S2: Drain the water from the trench 1; excavate a pit on the bank at one end of the trench 1 to form a pushing work room 4, so that the pushing work room 4 is connected to the trench 1; S3: Install pipe 11 pushing equipment in push workroom 4, and install slide rail 10 in base trench 1; S4: Hoist the pipe 11 into the pushing work room 4 and place it in place. Use the pipe 11 pushing equipment to push the pipe 11 along the slide rail 10 into the foundation trench 1. S5: Repeat S4, push several pipes 11 into the trench 1 one by one and connect them end to end until the trench 1 is filled with several pipes 11 along the length of the trench 1. S6: Backfill the foundation trench 1, remove the pipeline 11 pushing equipment and backfill the foundation pit, remove the steel sheet pile 2 and cofferdam 5, and complete the construction of pipeline 11.
[0046] This invention involves constructing a cofferdam 5 in a river channel 15, driving sheet piles 2 onto the cofferdam 5, excavating a foundation trench 1, and then pumping water to create an open, dry construction area in the foundation trench 1. Lateral supports 3 are used between the sheet piles 2 on both sides to stabilize the cofferdam 5 structure after excavation on both sides of the foundation trench 1. A foundation pit is then excavated on the riverbank 16 to form a pushing work area 4 connected to the foundation trench 1. Pipe pushing equipment can then be installed in the pushing work area 4 to push the pipe 11. The pipe pushing construction is similar to pipe jacking. Because the foundation trench 1 is excavated and pumped out, and the sheet piles 2 on both sides create an open, dry construction area, the pipe 11 can avoid the influence of sand flow above and on both sides during the pushing operation. After all the pipes 11 are pushed into place in the foundation trench 1, the foundation trench 1 is backfilled to bury the pipes 11 in the riverbed stratum. After the steel sheet piles 2 are removed, the river channel 15 above the pipes 11 is restored to flow, and the construction of the pipes 11 is completed. The construction method of this invention avoids the structural instability caused by directly jacking pipes in the loose sand layer of the riverbed, which can lead to a decline in project quality, safety hazards, or even construction accidents. On the other hand, it also avoids the disadvantage of not being able to use large working vessels to implement the immersed pipe method in shallow water conditions, which restricts construction. It optimizes the construction process, makes safety risks controllable, improves the construction working environment of the pipes 11 under unfavorable conditions, and reduces the safety risks of river-crossing construction.
[0047] The lateral support 3 in step S1 above can be a hydraulic strut, hydraulic cylinder, screw, or other equipment; in step S2 above, when pumping water, a water collection well is set up in the foundation pit or trench 1, and a high-power water pump is used for drainage.
[0048] Optionally, the river channel 15 is divided into two halves along its width direction. First, either half is selected and steps S1 to S6 are performed to complete the pushing and installation of the pipe 11 in one half of the river channel 15. Then, steps S1 to S5 are repeated on the other half to complete the pushing and installation of the pipe 11 in the other half. Then, the pipes 11 in the two halves are joined together. Then, step S6 is performed again.
[0049] When constructing pipeline 11 using the construction method of this invention, the river channel 15 can be divided into two halves along its width and constructed sequentially, that is, in two phases. After the cofferdam 5 is filled in one half (first phase) to block the flow of the river channel 15, the other half (second phase) of the river channel 15 can remain navigable, thus minimizing the occupation of the river channel 15 by the construction of pipeline 11 and reducing the impact on the navigation of the river channel 15. Similarly, when the first phase of the project is completed, the cofferdam 5 and sheet piles 2 in the non-closed area of the first phase can be removed first to restore the flow of the river channel 15 in the half where the first phase is located, and then the river channel 15 in the half where the second phase is located can be blocked. This also achieves the goal of maintaining the navigation of the river channel 15 while constructing.
[0050] Optionally, the river channel 15 is divided into two halves along its width direction, and the above steps S1 to S5 are performed simultaneously on the two halves to complete the pushing and installation of the pipes 11 in the two halves of the river channel 15; then the pipes 11 in the two halves are joined together; and then the above step S6 is performed.
[0051] When constructing pipeline 11 in a river channel 15 that does not involve navigation, to improve construction efficiency, construction work on both halves can be carried out simultaneously. That is, the pipeline can be pushed from both riverbanks 16 towards the middle at the same time. It should be noted that when constructing the cofferdam 5 to cut off the flow, sufficient space needs to be reserved between the two halves as a flow channel to allow water in the river channel 15 to flow downstream, preventing upstream water from overflowing the cofferdam 5 and entering the dry construction area in the trench 1 after pumping. For the construction of pipeline 11 in the flow channel, it can be used as a closure section. After the two halves of pipeline 11 are pushed into place, the trench 1 of one half of pipeline 11 can be backfilled first, and the cofferdam 5 and sheet piles 2 can be removed to restore that half of the river channel 15. Then, the cofferdam 5 can be constructed in the aforementioned flow channel area to cut off the flow and pump water to form a dry construction area. Then, the other half of pipeline 11 can be used for pipe jacking again to close the two halves of pipeline 11. Finally, the trench 1 is backfilled, and the remaining cofferdam 5 and sheet piles 2 are removed to restore the flow.
[0052] This invention features a scientifically sound and rational construction deployment, with regional risk management to prevent significant losses in case of accidents. During the pipeline 11 installation process, it enables rapid placement of the cross-river pipeline 11, facilitating the overall construction organization of the cross-river pipeline 11 installation. It integrates various construction technologies, including river-crossing cofferdam 5, sheet pile 2 for waterstop and support, deep foundation pit, dewatering, foundation pit backfilling, hoisting, welding, corrosion protection, jacking, closure, cofferdam 5 removal, and environmental protection. This effectively mitigates various safety risks associated with river-crossing areas 15, reduces costs, and offers a more rational construction organization with strong applicability.
[0053] In this embodiment, step S1 further includes: before excavating the foundation trench 1, constructing a construction access road 6 on top of the cofferdam 5.
[0054] To facilitate the entry and exit of construction equipment in the construction area, a construction access road 6 needs to be built on top of the cofferdam 5 after the cofferdam 5 is filled. The construction access road 6 can be formed on both sides of the foundation trench 1 to facilitate the subsequent excavation of the foundation trench 1.
[0055] In this embodiment, step S1 further includes: before the cofferdam 5 is filled, setting up a sludge curtain 7 on both sides of the cofferdam 5 filling location.
[0056] To prevent the unrestricted spread of particulate and suspended pollutants generated during the construction of cofferdam 5, excavation of foundation trench 1, and installation and anchoring of sheet piles 2, which could cause water pollution, a pollution barrier 7 is installed upstream and downstream of the construction area on both sides of the cofferdam 5 construction site. This barrier can contain the particulate and suspended pollutants within the range of the pollution barrier 7, preventing pollution from spreading and protecting the ecological environment of the river 15.
[0057] In this embodiment, in step S2 above, after the water in the foundation trench 1 is drained, the bottom of the foundation trench 1 is leveled, a crushed stone and sand cushion layer 8 is laid at the bottom of the foundation trench 1, and a concrete base 9 is constructed on the crushed stone and sand cushion layer 8; in step S3 above, the slide rail 10 is installed on the concrete base 9.
[0058] After the trench 1 is excavated, in order to prevent the risk of collapse when bearing the pressure of the pipeline 11 during subsequent construction, it is necessary to level and reinforce the bottom of the trench. Specifically, after leveling the bottom of the trench, a crushed stone and sand cushion layer 8 can be laid and a concrete base 9 can be constructed for reinforcement and stability. In addition, the slide rail 10 can also be installed on the concrete base 9. When the pipeline 11 is pushed into the trench 1, the weight of the pipeline 11 can be supported by the crushed stone and sand cushion layer 8 and the concrete base 9. The pipeline 11 can also slide along the slide rail 10 and be pushed into place. Specifically, after the trench 1 is excavated and formed and the base is treated, an 800mm thick graded crushed stone and sand cushion layer 8 is laid and compacted at the bottom of the trench 1. Then, two parallel C30 concrete strip foundations are poured as concrete bases 9. A 24-type rail is embedded and fixed in advance on the strip foundation as the slide rail 10.
[0059] In this embodiment, before the installation of the pipeline 11 pushing equipment in step S3, the wall opposite to the foundation trench 1 in the pushing work room 4 is reinforced with jet grouting piles and a concrete back wall 12 is constructed.
[0060] The working end of the pipe 11 pushing device faces the trench 1, and can apply a pushing force to push the pipe 11 into the trench 1. At the same time, the pipe 11 pushing device will also be subject to the reaction force applied by the pipe 11. By reinforcing the trench 1 wall with jet grouting piles and constructing a concrete back wall 12 in the pushing working chamber 4, the tail end of the pipe 11 pushing device can be held against to withstand the reaction force on the pipe 11 pushing device, so that the pipe 11 pushing device remains stable in the pushing working chamber 4, and avoids the pipe 11 pushing device from deviating, which would affect the operation accuracy and stability of the pushing construction.
[0061] Before the installation of pipe 11, a pushing platform 13, power supply and hydraulic jacks 14, and a top cap are installed in the pushing work area 4. After the pipe 11 is hoisted into position in the pushing work area 4 for welding, inspection, and corrosion protection, it is pushed forward section by section. This transfers the pipe 11 connection welding, inspection, and corrosion protection construction processes, which were carried out in the deep foundation pit, to the sloped excavation foundation pit on land. This avoids the risks of collapse, water inrush, and sand inrush faced by personnel working in the confined space of the deep foundation pit for a long time, improves working conditions, and ensures the safety of personnel and equipment. The use of jack-in equipment and sliding rails provides a fixed-point connection operation for pipe 11 in the sloped excavation foundation pit, eliminating the need for special equipment and reducing cost.
[0062] Alternatively, step S3 may further include: applying lubricant to the slide rail 10; step S4 may further include: installing a brake device (not shown in the figure) on the first section of pipe 11.
[0063] To reduce the resistance encountered by the pipe 11 during the pushing process, grease or other lubricants can be applied to the slide rail 10 as a lubricant to reduce resistance. At the same time, a braking device can be installed on the first section of the pipe 11 to brake it in time after the pipe 11 is pushed into place, so as to prevent it from moving beyond the installation position and causing it to collide with the steel sheet pile 2 at the end of the trench 1, thus ensuring the safety of the pushing operation.
[0064] In this embodiment, the method of backfilling the foundation trench 1 in step S6 above includes: filling backfill material in layers on both sides and top of the pipe 11, and stacking rubble on top of the backfill material for weight.
[0065] After all the pipes 11 in the trench 1 have been pushed into place, the pipes 11 can be stably buried and anchored in the stratum by backfilling the backfill material on both sides and above the pipes 11 in the trench 1. Then, the backfill material can be compacted by using boulders for weight, which further strengthens the pipes 11 and the surrounding stratum. Specifically, when the pipes 11 are pushed and slid to the end of the trench 1, the backfill material on both sides and the top of the pipes 11 is filled in layers, and thick boulders with a diameter of not less than 2m are thrown in for weight.
[0066] Alternatively, in step S6 above, before backfilling the foundation trench 1, grouting is performed at the bottom of the pipe 11 for reinforcement.
[0067] During the pushing process, the pipe 11 is suspended above the crushed stone and sand cushion layer 8 via the concrete base 9 and the slide rail 10. After being pushed into place, during backfilling, the backfill material may have difficulty entering the space between the bottom of the pipe 11 and the crushed stone and sand cushion layer 8, potentially leaving a hollow, unsupported area. Grouting can be injected into the space between the bottom of the pipe 11 and the crushed stone and sand cushion layer 8 to strengthen the support and anchorage of the pipe 11. Especially for large-diameter pipes 11, grouting can increase the support area at the bottom of the pipe 11, avoid stress concentration, and prevent deformation of the pipe 11 after long-term use, thereby increasing the service life of the pipe 11.
[0068] It should be noted that, Figure 6 The flowchart shown is a schematic diagram of the steps of a method included in this invention. The order of steps shown is only a specific embodiment. In other embodiments, some different steps can be performed simultaneously or in a different order. This invention does not specifically limit the order of steps that are not necessary. As long as the final technical effect can be achieved, it is within the protection scope of this invention.
[0069] In summary, this invention provides a construction method for cross-river pipelines. This involves constructing a cofferdam in the river channel, driving sheet piles onto the cofferdam, excavating a foundation trench, and then pumping water to create an open, dry construction area in the trench. Lateral supports are used between the sheet piles on both sides to stabilize the cofferdam structure after excavation. A foundation pit is then excavated on the riverbank to form a pushing work area connected to the foundation trench. Pipe pushing equipment can then be installed in this work area for pipeline pushing construction. The pipeline pushing construction is similar to pipe jacking operations. Because the foundation trench is pumped out and the open, dry construction area is created by the sheet piles on both sides, the pipeline pushing operation can avoid the influence of sand flow above and on both sides. However, after all the pipelines are pushed into place in the foundation trench, the trench is backfilled and the pipelines are buried in the riverbed strata. After the sheet piles are removed, the river channel above the pipeline is restored, and the pipeline construction is completed. The construction method of this invention avoids the risks of ground subsidence and structural instability caused by directly jacking pipes in the loose sand layer of the riverbed, which can lead to a decline in project quality, safety hazards, or even construction accidents. On the other hand, it also avoids the disadvantages of not being able to use large working vessels to implement the immersed tube method in shallow water conditions, which restricts construction. It optimizes the construction process, makes safety risks controllable, improves the pipeline construction working environment under unfavorable conditions, and reduces the safety risks of river-related construction.
[0070] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A construction method for a cross-river pipeline, characterized in that, include: S1: Construct a cofferdam (5) in the river channel (15) so that the top of the cofferdam (5) is higher than the water surface; drive steel sheet piles (2) on both sides of the excavation position of the foundation trench (1), excavate the foundation trench (1) from the top of the cofferdam (5) between the steel sheet piles (2) on both sides, and install several transverse supports (3) between the steel sheet piles (2) on both sides. S2: Drain the water in the trench (1); excavate a pit on the bank at one end of the trench (1) to form a pushing work room (4), so that the pushing work room (4) is connected to the trench (1). S3: Install a pipe (11) pushing device in the pushing workroom (4) and install a slide rail (10) in the base trench (1). S4: Hoist the pipe (11) into the pushing work room (4) and use the pipe (11) pushing device to push the pipe (11) along the slide rail (10) into the base trench (1); S5: Repeat S4, and push several of the pipes (11) into the base trench (1) one after another and connect them end to end until several of the pipes (11) fill the base trench (1) along the length direction of the base trench (1). S6: Backfill the foundation trench (1), remove the pipeline (11) pushing equipment and backfill the foundation pit, remove the steel sheet pile (2) and cofferdam (5) to complete the construction of the pipeline (11).
2. The construction method for cross-river pipelines according to claim 1, characterized in that, Divide the river channel (15) into two halves along the width direction. First, select any one of the two halves and implement S1~S6 to complete the pushing and installation of the pipe (11) in the half of the river channel (15). Then repeat S1~S5 on the other half to complete the pushing and installation of the pipe (11) in the other half. Then close the pipes (11) of the two halves together. Then implement S6.
3. The method of constructing a river-crossing pipeline according to claim 1, wherein The river (15) is divided into two halves along the width direction of the river (15). S1~S5 are performed simultaneously on the two halves to push and install the pipes (11) in the two halves of the river (15); then the pipes (11) in the two halves are closed; then S6 is performed.
4. The method of constructing a river-crossing pipeline according to claim 1, wherein S1 also includes: before the foundation trench (1) is excavated, a construction access road (6) is built on top of the cofferdam (5).
5. The method of constructing a river-crossing pipeline according to claim 1, wherein S1 also includes: before the cofferdam (5) is filled, setting up a sludge curtain (7) on both sides of the cofferdam (5) filling position.
6. The method of constructing a river-crossing pipeline according to claim 1, wherein In S2, after the water in the foundation trench (1) is drained, the bottom of the foundation trench (1) is leveled, a crushed stone and sand cushion layer (8) is laid at the bottom of the foundation trench (1), and a concrete base (9) is constructed on the crushed stone and sand cushion layer (8); in S3, the slide rail (10) is installed on the concrete base (9).
7. The method of constructing a river-crossing pipeline according to claim 1, wherein In S3, before the pipeline (11) pushing equipment is installed, the wall opposite to the foundation trench (1) in the pushing work room (4) is reinforced with jet grouting piles and a concrete back wall (12) is constructed.
8. The method of constructing a river-crossing pipeline according to claim 1, wherein S3 further includes: applying lubricant to the slide rail (10); S4 further includes: installing a brake device on the pipe (11) in the first section.
9. The method of constructing a river-crossing pipeline according to claim 1, wherein In S6, the method of backfilling the foundation trench (1) includes: filling backfill material in layers on both sides and top of the pipe (11), and stacking rubble on top of the backfill material for weight.
10. The construction method for a cross-river pipeline according to claim 1, characterized in that, In S6, before backfilling the foundation trench (1), grouting is performed at the bottom of the pipe (11) to reinforce it.