Process method for top-down composite lining of pipe-jacking well

Abstract

The invention discloses a pipe-jacking well top-down composite lining process method, belongs to the technical field of drainage engineering pipe-jacking wells, and remarkably improves the construction efficiency and resource utilization rate of a pipe-jacking well top-down method by adopting a steel pipe piece and rubber air cushion composite lining process. The composite lining structure does not need to wait for concrete solidification, the overall construction period is shortened, and the safety risk of long-time exposure of the foundation pit is effectively avoided. And meanwhile, the steel pipe sheet and the rubber air cushion can be recycled, so that the material cost and the environmental burden are greatly reduced. Modularized design and standardized operation are introduced into the process, through factory prefabrication and on-site rapid assembly, complex procedures such as on-site manual steel bar binding and formwork installation are reduced, the construction process is more standard, and on-site management is more efficient. The stability of the foundation pit in the excavation and backfill process is ensured, the structural safety of the pipe jacking well is ensured, and a reliable foundation is provided for subsequent pipeline jacking construction.

Description

Technical Field

[0001] This invention relates to the field of pipe jacking well technology in water supply and drainage engineering, and in particular to a composite lining process method for pipe jacking wells using a reverse construction method. Background Technology

[0002] Conventional construction methods for water supply and drainage pipe jacking wells include sheet piles, caissons, diaphragm walls, and reverse construction. The reverse construction method is suitable for environments with low groundwater levels or stable soil layers. It has been widely used for pipe jacking well foundation pit lining and support for many years, featuring simple procedures, rapid construction, and flexible application. However, this method has high safety and quality standards, uses C30 reinforced concrete, and has relatively high costs. Dynamic on-site management is crucial to reduce various safety risks and ensure that the method achieves its expected economic and social benefits.

[0003] The conventional reverse construction method works as follows: the lining material for the pipe jacking shaft foundation pit is C30 reinforced concrete. The process involves repeatedly excavating one section at a time and then lining it until the designed bottom elevation of the pit is reached. The construction steps are: after excavating one section of the pit, reinforcement is immediately installed, and concrete is quickly poured. From the time the excavation begins until the concrete reaches the required strength, a certain period is needed, and the pit remains in an unsafe state during the concrete setting period. Summary of the Invention

[0004] The purpose of this invention is to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a composite lining process for reverse construction of pipe jacking wells, which can quickly complete the structural lining support and can be quickly recycled and reused after the pipe jacking construction is completed.

[0005] The composite lining process method for reverse construction of pipe jacking wells according to embodiments of the present invention includes: Step 1: Carry out the construction of the curtain piles and foundation piles of the pipe jacking shaft, and wait for the structure to reach the design strength at the specified age; Step 2: The foundation pit is excavated in layers. After the first layer of foundation pit is excavated, rubber air cushions are laid along the perimeter of the foundation pit wall. Then, steel pipe segments are arranged circumferentially inside the rubber air cushions. The steel pipe segments are connected by bolts. The rubber air cushions are inflated to complete the first layer of composite lining structure. Step 3: Use I-beams to make a temporary load-bearing structure at the top of the pipe jacking shaft. The temporary load-bearing structure is cross-shaped and its exterior overlaps the curtain piles of the pipe jacking shaft. Connect the steel pipe segments in the first layer of the foundation pit to the temporary load-bearing structure with bolts. Step 4: Excavate the second layer of foundation pit, install the second layer of rubber air cushion, and then arrange steel pipe segments circumferentially inside the rubber air cushion. The steel pipe segments between the upper and lower layers are connected by bolts. Inflate the rubber air cushion to complete the second layer of composite lining structure. Step 5: Repeat the process of step 4 to form all the composite lining structures on the upper part of the jacking well; Step 6: Construct the lower structure along the lower circumference of the jacking shaft. The lower structure is connected to the steel pipe segments of the lowest composite lining structure by bolts. Construct the bottom sealing structure at the bottom of the jacking shaft to seal the bottom of the jacking shaft. Both the lower structure and the bottom sealing structure are reinforced concrete structures. Step 7: Carry out the pipe jacking construction. After the jacking is completed, backfill the jacking well layer by layer, and recover the rubber air cushion and steel pipe segments of each layer of composite lining structure.

[0006] The composite lining process of the reverse construction method for pipe jacking wells according to embodiments of the present invention has at least the following beneficial effects: By adopting a composite lining process of steel pipe segments and rubber air cushions, the construction efficiency and resource utilization rate of the reverse construction method for pipe jacking wells are significantly improved. The composite lining structure does not require waiting for concrete to solidify, reducing the overall construction period and effectively avoiding the safety risks of prolonged exposure of the foundation pit. Simultaneously, the steel pipe segments and rubber air cushions can be repeatedly recycled, significantly reducing material costs and environmental burden. The process incorporates modular design and standardized operations, reducing complex on-site procedures such as manual rebar tying and formwork installation through factory prefabrication and rapid on-site assembly, resulting in a more standardized construction process and more efficient on-site management. Furthermore, the synergistic mechanism of layered support and layered backfilling, combined with the setting of temporary load-bearing structures, ensures the stability of the foundation pit during excavation and backfilling, guaranteeing the safety of the pipe jacking well structure and providing a reliable foundation for subsequent pipeline jacking construction, thus achieving the overall engineering goals of green, low-carbon, economical, efficient, and safe controllable construction.

[0007] According to some embodiments of the present invention, in the step of excavating the foundation pit in layers, the excavation depth of each layer is 0.8m to 1.2m.

[0008] According to some embodiments of the present invention, step 7 further includes constructing a process inspection well.

[0009] According to some embodiments of the present invention, in step 7, the backfill material is sand, stone chips or plain soil.

[0010] According to some embodiments of the present invention, in step 7, when backfilling to the junction of the lower structure and the lowest composite lining structure, the rubber air cushion in the lowest composite lining structure is deflated, and the steel pipe segments in the lowest composite lining are removed. After the rubber air cushion and steel pipe segments in the lowest composite lining structure are recovered, the above steps are repeated to complete the backfilling and recovery of the composite lining structure layer by layer.

[0011] According to some embodiments of the present invention, the cross-sectional shape of the jacking well is square or circular, and the shape of the steel pipe segments of the composite lining structure is adapted to the cross-sectional shape of the jacking well.

[0012] According to some embodiments of the present invention, the connecting bolts between the steel pipe segments of the lower structure and the lowest composite lining structure are shear-resistant high-strength bolts.

[0013] According to some embodiments of the present invention, the inflation pressure of the rubber air cushion is dynamically adjusted according to the depth of the pit, and the air pressure value after inflation meets the design load.

[0014] According to some embodiments of the present invention, the thickness of the composite lining structure is 25cm to 40cm.

[0015] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic flowchart of the composite lining process for the reverse construction method of the jacking well according to an embodiment of the present invention; Figure 2 This is a plan view of the reverse construction method of the jacking well according to an embodiment of the present invention; Figure 3 It is a cross-sectional view of the foundation pit excavated by reverse construction on one floor; Figure 4 This is a cross-sectional view of the second-floor reverse excavation of the foundation pit; Figure 5 This is a cross-sectional view of the four-layer reverse excavation of the foundation pit; Figure 6 It is a cross-sectional view of the lower part of the foundation pit and the bottom sealing. Figure 7 This is a cross-sectional view of the foundation pit pipe jacking construction.

[0017] Figure label: 11 curtain piles for pipe jacking shaft; 12 foundation piles for pipe jacking shaft; First-level foundation pit 21; Second-level foundation pit 22; 31. Rubber air cushion; 32. Steel tube sheet; Temporary load-bearing structure 41; Lower structure 51; Bottom sealing structure 52; Pipeline 61. Detailed Implementation

[0018] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0019] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0020] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0021] refer to Figures 1 to 7 This invention describes a composite lining process for a jacking well reverse construction method according to an embodiment of the present invention.

[0022] like Figures 1 to 7 As shown, the composite lining process method for reverse construction of pipe jacking wells according to an embodiment of the present invention includes: Step 1: Construct the curtain piles 11 and foundation piles 12 of the pipe jacking shaft, and wait for the structure to reach the design strength at the specified age; Step 2: The foundation pit is excavated in layers. After the first layer of foundation pit 21 is excavated, rubber air cushion 31 is laid along the periphery of the foundation pit wall. Then, steel pipe segments 32 are arranged circumferentially inside the rubber air cushion 31. The steel pipe segments 32 are connected by bolts. The rubber air cushion 31 is inflated to complete the first layer of composite lining structure. Step 3: Use I-beams to make a temporary load-bearing structure 41 at the top of the pipe jacking shaft. The temporary load-bearing structure 41 is cross-shaped and its exterior overlaps the curtain piles 11 of the pipe jacking shaft. Connect the steel pipe segments 32 in the first layer of the foundation pit 21 to the temporary load-bearing structure 41 with bolts. Step 4: Excavate the second layer of foundation pit 22, install the second layer of rubber air cushion 31, and then arrange steel pipe segments 32 circumferentially inside the rubber air cushion 31. The steel pipe segments 32 between the upper and lower layers are connected by bolts. Inflate the rubber air cushion 31 to complete the second layer of composite lining structure. Step 5: Repeat the process flow of Step 4 to form all the composite lining structures above the jacking shaft (e.g., Figure 5 The structure shown has four layers of composite lining. Step 6: Construct the lower structure 51 along the lower circumference of the jacking shaft. The lower structure 51 is bolted to the steel pipe segment 32 of the lowest composite lining structure. Construct the bottom sealing structure 52 at the bottom of the jacking shaft to seal the bottom of the jacking shaft. Both the lower structure 51 and the bottom sealing structure 52 are reinforced concrete structures. Step 7: Carry out the jacking construction of pipe 61. After the jacking is completed, backfill the jacking well layer by layer, and recover the rubber air cushion 31 and steel pipe segment 32 of each layer of composite lining structure.

[0023] By adopting a composite lining process using steel pipe segments (32) and rubber air cushions (31), the construction efficiency and resource utilization of the reverse construction method for pipe jacking shafts have been significantly improved. Compared with the traditional C30 reinforced concrete cast-in-place process, the composite lining structure eliminates the need to wait for concrete to solidify, reducing the single-layer support time from 48-72 hours to 2-3 hours, and shortening the overall construction period by more than 90%, effectively avoiding the safety risks of prolonged exposure of the foundation pit. Simultaneously, both the steel pipe segments (32) and rubber air cushions (31) are recyclable, with a material recycling rate exceeding 90%, reducing construction waste by 60-70%, significantly lowering material costs and environmental burden. The process incorporates modular design and standardized operations, reducing complex on-site procedures such as manual rebar tying and formwork installation through factory prefabrication and rapid on-site assembly, resulting in a more standardized construction process and more efficient on-site management. Furthermore, the synergistic mechanism of layered support and layered backfilling, combined with the setting of temporary load-bearing structure 41, ensured the stability of the foundation pit during the excavation and backfilling process. This not only guaranteed the safety of the jacking shaft structure but also provided a reliable foundation for the subsequent jacking construction of pipeline 61, achieving the overall engineering goals of green, low-carbon, economical, efficient, safe, and controllable construction.

[0024] In some specific embodiments of the present invention, in the step of layered excavation of the foundation pit, the excavation depth of each layer is 0.8m to 1.2m. Through refined layered control, construction safety and efficiency are optimized. This depth range avoids over-excavation leading to soil instability or collapse, while ensuring rapid installation and air-filling of the single-layer support structure, allowing for precise control of the stress performance of the composite lining and the deformation of the foundation pit. The cyclical pattern of layered excavation and support facilitates dynamic adjustment of the construction rhythm, especially under conditions of high groundwater levels or complex soil layers, effectively dispersing risks and avoiding sudden accidents caused by excessively deep excavation at once. Furthermore, this depth range is compatible with the modular dimensions of the steel pipe segments 32 and the rubber air cushions 31, ensuring convenient and tight component installation, providing technical assurance for the overall integrity of the subsequent lining structure, and further improving the reliability and adaptability of the process.

[0025] Step 7 also includes the construction of process inspection wells. Adding process inspection wells to the pipe jacking construction process significantly improves the overall safety and compliance of the project through phased quality inspection and acceptance. The construction of inspection wells can promptly identify and correct problems such as composite lining installation deviations, insufficient airbag pressure, or loose bolt connections, preventing structural hazards caused by the accumulation of defects. Simultaneously, as a key control node in the construction process, the inspection wells can verify the standardization of layered backfilling and lining recycling, ensuring that the material recovery rate and backfill compaction meet design requirements. This step not only strengthens the dynamic monitoring of construction quality but also provides a reliable technical basis for the subsequent jacking of Pipeline 61 and well operation and maintenance, reducing maintenance costs and risks throughout the entire life cycle.

[0026] In step 7, the backfill material is sand, gravel, or plain soil. Limiting the backfill material to sand, gravel, or plain soil fully utilizes the availability, low cost, and environmental friendliness of these materials, simplifying the backfilling construction process. Sand and gravel have good permeability and compaction properties, quickly filling the voids in the foundation pit and forming stable support, avoiding settlement problems caused by backfill material shrinkage; plain soil is suitable for scenarios with high environmental protection requirements, reducing carbon emissions from transporting construction waste. Furthermore, the layered backfilling of these materials and the lining recycling are carried out simultaneously, further optimizing resource recycling efficiency, reducing the project's disturbance to the surrounding environment, reflecting the concept of green construction, and balancing economic and ecological benefits.

[0027] In step 7, when backfilling reaches the junction of the lower structure 51 and the lowest composite lining structure, the rubber air cushion 31 in the lowest composite lining structure is deflated, and the steel pipe segments 32 in the lowest composite lining structure are removed. After both the rubber air cushion 31 and the steel pipe segments 32 in the lowest composite lining structure are recovered, the above steps are repeated layer by layer to complete the backfilling and recovery of the composite lining structure. Through the coordinated mechanism of phased backfilling and lining recovery, the dual goals of efficient resource utilization and construction safety are achieved. When backfilling to the lining junction, the air cushions in the lowest layer are deflated first, and the steel pipe segments 32 are removed, ensuring seamless connection between the recovery operation and the backfilling progress, and avoiding safety hazards caused by sudden changes in structural stress. The layered recovery mode not only reduces material loss, but also maintains the stability of the soil around the foundation pit and prevents local collapse through layer-by-layer backfilling and compaction. The standardized operation of this step further improves the controllability of the process, provides a reliable technical path for pipe jacking well construction under complex geological conditions, and reduces the difficulty and cost of subsequent demolition.

[0028] In some specific embodiments of the present invention, the cross-sectional shape of the pipe jacking well is square or circular, and the shape of the steel pipe segments 32 of the composite lining structure is adapted to the cross-sectional shape of the pipe jacking well. Allowing the pipe jacking well to adopt a square or circular cross-section significantly enhances the versatility and adaptability of the process. A circular cross-section can evenly distribute earth pressure, making it suitable for areas with high groundwater pressure or soft soil; a square cross-section facilitates connection with existing urban pipe networks or building structures, expanding the application scenarios of the process. The shape of the steel pipe segments 32 in the composite lining is adapted to the cross-section of the well body, ensuring the integrity and tightness of the support structure and avoiding stress concentration or leakage risks caused by shape mismatch. This flexibility not only meets diverse engineering needs but also provides technical support for the large-scale promotion of the process, facilitating its efficient application in complex urban underground spaces.

[0029] In some specific embodiments of the present invention, the connecting bolts between the lower structure 51 and the steel pipe segment 32 of the lowest composite lining structure are shear-resistant high-strength bolts. Using shear-resistant high-strength bolts to connect the lower structure 51 and the lining steel pipe segment 32 improves the mechanical properties of the connection node, ensuring the coordinated stress distribution and overall stability of the upper and lower structures 51. The shear resistance of the high-strength bolts effectively resists lateral loads and vibrations during pipe jacking, preventing loosening or displacement at the connection point and ensuring the accuracy of pipeline 61 construction. Furthermore, the standardized design and prefabrication of the bolts simplify the construction process, reduce on-site welding or casting procedures, further shorten the construction period, and reduce labor costs. This optimization of technical details significantly improves the durability and safety of the pipe jacking structure, providing reliable assurance for long-term operation and maintenance under complex working conditions.

[0030] In some specific embodiments of the present invention, the inflation pressure of the rubber air cushion 31 is dynamically adjusted according to the depth of the foundation pit, and the air pressure value after inflation meets the design load. Dynamically adjusting the inflation pressure of the rubber air cushion 31 optimizes the stress state of the lining support in real time according to the foundation pit depth and soil conditions, ensuring the safety and adaptability of the structure. Through precise control of the air pressure value, the airbag can closely adhere to the foundation pit wall, evenly distributing soil pressure and avoiding deformation or rupture caused by local stress concentration. This technology is particularly suitable for foundation pits with variable soil properties or large depths. Through real-time monitoring and adjustment, it can cope with sudden load changes and improve the resilience of the process. Dynamic air pressure management combined with modular design further reduces construction risks and provides technical support for the application of reverse construction methods in complex geological environments.

[0031] In some specific embodiments of the present invention, the thickness of the composite lining structure is 25cm to 40cm. This limited thickness balances structural strength and material economy through scientific design. This thickness range meets the load-bearing requirements of the foundation pit support, resisting soil pressure and groundwater pressure, while avoiding cost waste caused by excessive material use. The composite design of the steel pipe segment 32 and the rubber air cushion 31 achieves a combination of lightweight and high strength within a limited thickness, making it particularly suitable for urban underground engineering projects with limited space. Furthermore, standardized thickness parameters provide a unified basis for factory prefabrication and on-site assembly, improving construction efficiency and quality control, and ensuring the reliability and consistency of the process across different project scales.

[0032] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A composite lining process for reverse construction of pipe jacking wells, characterized in that, include: Step 1: Carry out the construction of the curtain piles and foundation piles of the pipe jacking shaft, and wait for the structure to reach the design strength at the specified age; Step 2: The foundation pit is excavated in layers. After the first layer of foundation pit is excavated, rubber air cushions are laid along the perimeter of the foundation pit wall. Then, steel pipe segments are arranged circumferentially inside the rubber air cushions. The steel pipe segments are connected by bolts. The rubber air cushions are inflated to complete the first layer of composite lining structure. Step 3: Use I-beams to make a temporary load-bearing structure at the top of the pipe jacking shaft. The temporary load-bearing structure is cross-shaped and its exterior overlaps the curtain piles of the pipe jacking shaft. Connect the steel pipe segments in the first layer of the foundation pit to the temporary load-bearing structure with bolts. Step 4: Excavate the second layer of foundation pit, install the second layer of rubber air cushion, and then arrange steel pipe segments circumferentially inside the rubber air cushion. The steel pipe segments between the upper and lower layers are connected by bolts. Inflate the rubber air cushion to complete the second layer of composite lining structure. Step 5: Repeat the process of step 4 to form all the composite lining structures on the upper part of the jacking well; Step 6: Construct the lower structure along the lower circumference of the jacking shaft. The lower structure is connected to the steel pipe segments of the lowest composite lining structure by bolts. Construct the bottom sealing structure at the bottom of the jacking shaft to seal the bottom of the jacking shaft. Both the lower structure and the bottom sealing structure are reinforced concrete structures. Step 7: Carry out the pipe jacking construction. After the jacking is completed, backfill the jacking well layer by layer, and recover the rubber air cushion and steel pipe segments of each layer of composite lining structure.

2. The composite lining process for reverse construction of pipe jacking wells according to claim 1, characterized in that, In the step of excavating the foundation pit in layers, the excavation depth of each layer is 0.8m to 1.2m.

3. The composite lining process for reverse construction of pipe jacking wells according to claim 1, characterized in that, Step 7 also includes the construction of process inspection wells.

4. The composite lining process for reverse construction of pipe jacking wells according to claim 1, characterized in that, In step 7, the backfill material is sand, gravel, or plain soil.

5. The composite lining process for reverse construction of pipe jacking wells according to claim 1, characterized in that, In step 7, when backfilling to the junction of the lower structure and the lowest composite lining structure, the rubber air cushion in the lowest composite lining structure is deflated, and the steel pipe segments in the lowest composite lining structure are removed. After the rubber air cushion and steel pipe segments in the lowest composite lining structure are recovered, the above steps are repeated to complete the backfilling and recovery of the composite lining structure layer by layer.

6. The composite lining process for reverse construction of pipe jacking wells according to claim 1, characterized in that, The cross-sectional shape of the pipe jacking well is square or circular, and the shape of the steel pipe segments in the composite lining structure is adapted to the cross-sectional shape of the pipe jacking well.

7. The composite lining process for reverse construction of pipe jacking wells according to claim 1, characterized in that, The connecting bolts between the substructure and the steel pipe segments of the lowest composite lining structure are shear-resistant high-strength bolts.

8. The composite lining process for reverse construction of pipe jacking wells according to claim 1, characterized in that, The inflation pressure of the rubber air cushion is dynamically adjusted according to the depth of the pit, and the air pressure value after inflation meets the design load.

9. The composite lining process for reverse construction of pipe jacking wells according to claim 1, characterized in that, The thickness of the composite lining structure is 25cm to 40cm.

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