A pile foundation anti-floating structure for a shield pipe gallery overtop revetment and a construction method

Abstract

This invention discloses a pile foundation anti-buoyancy structure and construction method for a revetment above a shield tunnel, solving the problem of easy uplift and floating of the existing shield tunnel during excavation and unloading, which affects structural safety and service life. The structure includes a tunnel with a river channel excavated above it, the tunnel and the river channel intersecting each other. A U-shaped revetment is constructed on the river section above the tunnel, the revetment being a reinforced concrete structure. The bottom slab of the revetment spans both sides of the tunnel, and pile foundations are arranged in rows parallel to the tunnel on both sides of the bottom surface of the bottom slab. This invention achieves anti-buoyancy of the revetment structure through pile foundations and reduces the risk of lateral displacement of the soil layer above the tunnel after construction disturbance by using anti-lateral displacement frames to separate and solidify the original soil layer. This satisfies the stability requirements of the revetment structure and effectively suppresses the uplift of the existing tunnel below, making it particularly suitable for river engineering projects with oblique crossings, large water level fluctuations, and limited construction space.

Description

Technical Field

[0001] This invention belongs to the technical fields of water conservancy engineering, underground structure engineering and bank protection engineering, and in particular relates to a pile foundation anti-buoyancy structure and construction method for bank protection on shield tunnels. Background Technology

[0002] Shield tunneling is a type of underground utility tunnel, a public tunnel used in cities to centrally lay municipal pipelines such as electricity, communications, broadcasting and television, water supply, drainage, heating, and gas. Underground utility tunnels can centrally lay urban pipelines, effectively solving problems such as repeated excavation and repetitive construction on the surface, and dense overhead power lines in cities.

[0003] When excavating river channels and constructing new revetments above existing shield tunnels, the tunnels are prone to bulging and floating due to their large burial depth (e.g., ≥8m), small diameter (e.g., ≤3m), and often located in areas with high groundwater levels. This is especially problematic under the influence of excavation unloading and water level changes, severely impacting structural safety and service life. Traditional anti-buoyancy measures often focus on the structure's self-weight or ballast, which are insufficient to address complex hydrogeological conditions and the protection requirements of existing structures. Current technologies lack an integrated anti-buoyancy system that can both ensure the stability of the revetment structure and effectively suppress the bulging of the existing tunnels below. This issue is particularly prominent in river engineering projects involving oblique crossings, significant water level fluctuations, and limited construction space. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that the tunnel can easily bulge and float during excavation and unloading above an existing shield tunnel, affecting structural safety and service life. This invention provides a pile-based anti-buoyancy structure and construction method for the revetment above a shield tunnel. It combines the revetment structure with an anti-buoyancy pile group, ensuring the stability of the revetment itself while simultaneously suppressing tunnel floatation by transmitting pull-out force through the pile foundation. Furthermore, the space above the tunnel and below the revetment bottom slab is partitioned and constructed in sections to reinforce the soil layer, increase ballast, and address subsequent problems caused by lateral flow of the original soil layer above the tunnel after construction.

[0005] The technical solution adopted by the present invention to solve its technical problem is: a pile foundation anti-buoyancy structure for the revetment of the shield tunnel, including the tunnel, a river channel excavated above the tunnel, the tunnel and the river channel intersecting each other, a U-shaped revetment constructed on the river channel section above the tunnel, the revetment being a reinforced concrete structure, the bottom plate of the revetment spanning both sides of the tunnel, and pile foundations arranged in rows parallel to the tunnel on both sides of the bottom surface of the bottom plate.

[0006] In this structure, pile foundations are laid on both sides of the bottom slab of the revetment structure above the pipe gallery. The pile foundation structure is set in one or more rows on both sides of the pipe gallery. When multiple rows are set, the pile foundations in different rows are aligned laterally. Drilled cast-in-place piles are used during the construction of the pile foundations. The pile body passes through the soil layer that may float and enters the stable layer, which effectively suppresses the risk of the pipe gallery floating under the river excavation and water level changes.

[0007] Preferably, the pile foundation is a bored cast-in-place pile, and one or more rows of pile foundations are set on both sides of the pipe gallery.

[0008] Preferably, the minimum distance between the pile foundation and the utility tunnel is not less than 1.5 times the outer diameter of the utility tunnel and not less than 5 meters. Sufficient distance should be maintained between the pile foundation and the utility tunnel during construction to avoid disturbance caused by the pile foundation construction.

[0009] Preferably, the bottom plate of the revetment is at least 2 meters thick.

[0010] Preferably, a graded filter stone strip is installed on the outer side of the revetment sidewalls, and a permeable geotextile is wrapped around the outside of the graded filter stone strip. The outside of the permeable geotextile is backfilled with graded crushed stone. Drainage pipes are embedded in the wall body on both sides, with the outer end of the drainage pipe higher than the inner end, and the outer end of the drainage pipe is located at the graded filter stone strip. The wall drainage system works in conjunction with the pile foundation anti-buoyancy system to reduce buoyancy fluctuations caused by water level changes.

[0011] Preferably, the height difference between the bottom plate of the revetment and the upper surface of the utility tunnel is not less than 1 times the outer diameter of the utility tunnel.

[0012] Preferably, the bottom surface of the base plate directly above the utility tunnel is provided with anti-lateral displacement frames, and the inner side of each anti-lateral displacement frame is solidified cement-soil. During river excavation, the original soil layer above the utility tunnel is disturbed to some extent. In the subsequent process, with the continuous change of groundwater level, the original soil layer above the utility tunnel is at risk of lateral flow. This structure sets up anti-lateral displacement frames with steel plate frames under the base plate, which can divide and frame the original soil layer, preventing the utility tunnel from floating due to lateral flow of the original soil layer. At the same time, it can solidify the original soil layer within the frames to form cement-soil, further enhancing the bearing capacity and the effect of resisting lateral flow.

[0013] Preferably, the anti-lateral displacement frame is constructed by vertically driving crisscrossing steel plates into the soil layer for separation.

[0014] Preferably, the side length of the anti-lateral displacement frame is 1-2.5m, and the height difference between the bottom of the anti-lateral displacement frame and the top surface of the pipe gallery is 0.5-1.5m.

[0015] A construction method for a pile foundation anti-buoyancy structure for a shield tunnel revetment, comprising the following steps: S1 marks the direction of river excavation and the orientation and depth of existing utility tunnels; S2 consists of bored cast-in-place piles used for anti-buoyancy on both sides of the initial ground construction of the pipe gallery. The piles will be installed after the concrete has reached the required curing time before proceeding to the next construction step. The piles on the same side are evenly spaced. S3, the base slab construction is completed in sections along the pipe gallery. S3.1, Excavate one compartment of the pipe gallery and cover it with soil (single compartment width 2-4 meters), leaving at least three meters of soil at the bottom of the compartment above the pipe gallery. S3.2, Welded anti-lateral displacement frames are driven into the bottom of the silo. Each frame is then sequentially grouted and cured to solidify the original soil within the frame into cement-soil. S3.3 Continue excavation to the bottom elevation of the foundation slab, pour the foundation slab, and connect the foundation slab with the corresponding pile foundations on both sides of the pipe gallery. S3.4, Repeat construction steps S3.1-3.3 in skip-pour construction until the entire base slab is poured; S4. Construct the side wall. After the concrete reaches the required curing time, construct the graded filter stone strip. Wrap the outside of the graded filter stone strip with permeable geotextile and backfill the outside with graded crushed stone.

[0016] This invention achieves anti-buoyancy of the revetment structure through pile foundations and solidifies the original soil layer by separating and solidifying it through anti-lateral displacement frames, thereby reducing the risk of lateral displacement of the soil layer above the utility tunnel after construction disturbance. It can not only meet the stability requirements of the revetment structure, but also effectively suppress the floating of the existing utility tunnel below. It is especially applicable in river engineering projects with oblique crossings, large water level changes, and limited construction space. Attached Figure Description

[0017] The invention will now be further described with reference to the accompanying drawings.

[0018] Figure 1 This is an elevation view of an anti-buoyancy structure according to the present invention.

[0019] Figure 2 This is a side view of an anti-buoyancy structure according to the present invention.

[0020] Figure 3 This is a plan view of an anti-buoyancy structure according to the present invention.

[0021] In the diagram: 1. Pipe gallery, 2. Pile foundation, 3. Bank protection, 4. Bottom slab, 5. Side wall, 6. Drainage pipe, 7. Graded filter stone belt, 8. Permeable geotextile, 9. Graded crushed stone, 10. Anti-lateral displacement frame. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0023] Example 1: A pile foundation anti-buoyancy structure for the revetment of a shield tunnel, such as... Figure 1-3As shown. This structure includes a pipe gallery 1 with a diameter of 3 meters, buried 8 meters below ground level. A river channel is excavated above the pipe gallery 1, and the pipe gallery and the river channel intersect. A U-shaped revetment 3 is constructed on the river channel section above the pipe gallery. The revetment 3 is a reinforced concrete structure. The bottom slab 4 of the revetment spans both sides of the pipe gallery 1, and pile foundations 2 are arranged in rows parallel to the pipe gallery 1 on both sides of the bottom surface of the bottom slab 4. Figure 2 , 3 As shown, two rows of pile foundations 2 are set on each of the two sides of the pipe gallery 1. The distance between two adjacent rows of pile foundations 2 is 1.5 meters, and the distance between two adjacent pile foundations in the same row is 1.5 meters. The pile foundations 2 are bored cast-in-place piles with a diameter of 1 meter. The minimum distance between the innermost pile foundation 2 and the outer wall of the pipe gallery is 5 meters. The bottom slab 4 of the revetment is 2 meters thick, and the height difference between the bottom surface of the bottom slab 4 and the top surface of the pile foundations is 3 meters. The cast-in-place piles are rigidly connected to the bottom slab of the revetment 4. The outer side of the side wall 5 of the revetment 3 is provided with a graded filter stone strip 7, and the outer side of the graded filter stone strip 7 is wrapped with a permeable geotextile 8. The outer side of the permeable geotextile 8 is backfilled with graded crushed stone 9. Drainage pipes 6 are buried in the wall body of both sides. The drainage pipes 6 are higher on the outside and lower on the inside, and the outer end of the drainage pipes 6 is set at the graded filter stone strip 7.

[0024] A lateral displacement prevention frame 10 is installed on the bottom surface of the base plate 4 directly above the utility tunnel 1, with the inner side of each lateral displacement prevention frame 10 being solidified cement-soil. The lateral displacement prevention frame 10 is constructed by vertically driving crisscrossing steel plates into the soil layer for separation. In this example, the side length of the lateral displacement prevention frame 10 is 2.5 meters, and the height difference between the bottom of the lateral displacement prevention frame and the top surface of the utility tunnel is 0.5 meters.

[0025] Example 2: A construction method for a pile foundation anti-buoyancy structure for a shield tunnel revetment, used for the construction of the structure in Example 1, including the following steps: S1 marks the direction of river excavation and the orientation and depth of existing utility tunnels; S2 consists of bored cast-in-place piles used for anti-buoyancy on both sides of the initial ground construction of the pipe gallery. The piles will be installed after the concrete has reached the required curing time before proceeding to the next construction step. The piles on the same side are evenly spaced. S3, the base slab construction is completed in sections along the pipe gallery. S3.1, Excavate the top layer of soil for the pipe rack in one compartment (in this example, the width of a single compartment is 2.5 meters), and leave at least three meters of soil at the bottom of the compartment above the pipe rack. S3.2, Welded anti-lateral displacement frames are driven into the bottom of the silo. Each frame is then sequentially grouted and cured to solidify the original soil within the frame into cement-soil. S3.3 Continue excavation to the bottom elevation of the foundation slab, pour the foundation slab, and connect the foundation slab with the corresponding pile foundations on both sides of the pipe gallery. S3.4, Repeat construction steps S3.1-3.3 in skip-pour construction until the entire base slab is poured; S4. Construct the side wall. After the concrete reaches the required curing time, construct the graded filter stone strip. Wrap the outside of the graded filter stone strip with permeable geotextile and backfill the outside with graded crushed stone.

Claims

1. A pile foundation anti-buoyancy structure for a bank protection structure above a tunnel boring machine (TBM) utility tunnel, comprising a utility tunnel, wherein a river channel is excavated above the utility tunnel, and the utility tunnel and the river channel intersect each other, characterized in that: The river section above the utility tunnel is equipped with a U-shaped revetment, which is a reinforced concrete structure. The bottom slab of the revetment spans both sides of the utility tunnel, and pile foundations are installed in rows parallel to the utility tunnel on both sides of the bottom surface of the bottom slab.

2. The pile foundation anti-buoyancy structure for the overlying revetment of a shield tunnel as described in claim 1, characterized in that: The pile foundation is a bored cast-in-place pile, and one or more rows of pile foundations are set on both sides of the pipe gallery.

3. The pile foundation anti-buoyancy structure for the overlying revetment of a shield tunnel as described in claim 1, characterized in that: The minimum distance between the pile foundation and the pipe gallery shall not be less than 1.5 times the outer diameter of the pipe gallery and not less than 5 meters.

4. The pile foundation anti-buoyancy structure for the overlying revetment of a shield tunnel as described in claim 1, characterized in that: The bottom plate of the revetment is no less than 2 meters thick.

5. The pile foundation anti-buoyancy structure for the overlying revetment of a shield tunnel as described in claim 1, characterized in that: The revetment has a graded filter stone strip installed on the outer side of the side wall. The outer side of the graded filter stone strip is covered with permeable geotextile. The outer side of the permeable geotextile is backfilled with graded crushed stone. Drainage pipes are buried in the walls of both sides, with the outer side of the drainage pipes being higher than the inner side. The outer end of the drainage pipes is located at the graded filter stone strip.

6. The pile foundation anti-buoyancy structure for the overlying revetment of a shield tunnel as described in claim 1, characterized in that: The height difference between the bottom plate of the revetment and the upper surface of the utility tunnel shall not be less than 1 times the outer diameter of the utility tunnel.

7. The pile foundation anti-buoyancy structure for the overlying revetment of a shield tunnel as described in claim 1, characterized in that: The bottom surface of the base plate directly above the utility tunnel is provided with anti-lateral displacement frames, and the inside of each anti-lateral displacement frame is solidified cement soil.

8. The pile foundation anti-buoyancy structure for the overlying revetment of a shield tunnel as described in claim 1, characterized in that: The anti-lateral displacement frame is constructed by vertically driving crisscrossing steel plates into the soil layer for separation.

9. A pile foundation anti-buoyancy structure for a shield tunnel revetment as described in claim 1, characterized in that: The side length of the anti-lateral displacement frame is 1-2.5m, and the height difference between the bottom of the anti-lateral displacement frame and the top surface of the pipe gallery is 0.5-1.5m.

10. A construction method for a pile foundation anti-buoyancy structure used for a revetment overlying a shield tunnel, characterized in that: The construction of the pile foundation anti-buoyancy structure for the overlying revetment of the shield tunnel as described in any one of claims 1 to 8 includes the following steps: S1 marks the direction of river excavation and the orientation and depth of existing utility tunnels; S2 consists of bored cast-in-place piles used for anti-buoyancy on both sides of the initial ground construction of the pipe gallery. The piles will be installed after the concrete has reached the required curing time before proceeding to the next construction step. The piles on the same side are evenly spaced. S3, the base slab construction is completed in sections along the pipe gallery. S3.1, Excavate one compartment of the pipe gallery and cover it with soil (single compartment width 2-4 meters), leaving at least three meters of soil at the bottom of the compartment above the pipe gallery. S3.2, Welded anti-lateral displacement frames are driven into the bottom of the silo. Each frame is then sequentially grouted and cured to solidify the original soil within the frame into cement-soil. S3.3 Continue excavation to the bottom elevation of the foundation slab, pour the foundation slab, and connect the foundation slab with the corresponding pile foundations on both sides of the pipe gallery. S3.4, Repeat construction steps S3.1-3.3 in skip-pour construction until the entire base slab is poured; S4. Construct the side wall. After the concrete reaches the required curing time, construct the graded filter stone strip. Wrap the outside of the graded filter stone strip with permeable geotextile and backfill the outside with graded crushed stone.

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