High earth coverage combined structure of common rail and immersed tunnel and construction method

Abstract

The application discloses a kind of high soil covering immersed tube tunnel water bank transition combination structure and its construction method, belong to immersed tube tunnel technical field.The present application includes transition combination structure and corresponding construction method, combination structure is cast-in-place after being formed by cast-in-situ bored pile, prefabricated immersed tube tunnel pipe section is located on the flexible section and adjustment section of the combination structure of water bank transition, onshore section tunnel is located on the rigid section of combination structure, combination structure sets multiple sections to grade adjust ground stiffness, relative to the conventional foundation of the existing onshore section and underwater section of immersed tube tunnel, its ground stiffness is uniformly transitioned, avoids stress concentration of pipe section main body, reduces the settlement difference of onshore section and underwater section, is conducive to protecting the joint sealing and safety of immersed tube tunnel, reduces the risk of pipe joint jointing error during engineering operation.

Description

Technical Field

[0001] This invention belongs to the field of immersed tunnel technology, specifically relating to a combined structure and construction method for waterfront transition in a combined road-rail immersed tunnel with high overburden difference. Background Technology

[0002] With the booming economy, the demand for cross-river transportation in cities is increasing, and more and more underwater tunnels are being planned and constructed. Immersed tunnels are a type of underwater tunnel with many advantages, such as shallow burial depth, rapid grounding, and strong integrity. The construction method involves prefabricating tunnel sections in a dry dock, and after breaking through the dock gate, floating the tunnel sections to the tunnel site for immersion and docking.

[0003] The joints between tunnel segments are a key design challenge in immersed tunnel construction. During construction and operation, significant differences in foundation stiffness between segments lead to substantial settlement variations on both sides of the joint. Misalignment between joints can cause the waterproofing measures at the joints to fail, potentially resulting in major safety accidents. Traditional immersed tunnels use rigid connections at the water-shore junction, where the onshore foundation has high stiffness. However, underwater immersed tunnels often use less stiff foundations such as crushed stone or grouted sand foundations. The backfilling load on top of the segments during later construction can easily trigger secondary settlement. Excessive settlement differences on both sides of the joint not only affect waterproofing measures but also impact the road surface and track bed, affecting traffic safety during operation. Summary of the Invention

[0004] The technical problem this invention aims to solve is that the traditional immersed tunnel uses a rigid transition structure at the water-shore connection point. The difference in foundation stiffness between the onshore tunnel and the underwater tunnel is significant. The secondary settlement caused during the backfilling of the tunnel sections with high soil cover results in a large difference in settlement between the underwater tunnel sections and the onshore tunnel sections. This can easily lead to the failure of the joint waterstop and separation from the road surface or track, affecting the safety of tunnel operation.

[0005] To solve the above-mentioned technical problems, the present invention provides a combined structure and construction method for water-shore transition of immersed tube tunnel with high soil cover.

[0006] This invention is achieved through the following technical solution:

[0007] A combined structure for the transition between the onshore and underwater sections of a high-coverage immersed tunnel includes a rigid section, an adjustment section, a flexible section, and an underwater section. A transition platform is provided at the junction of the onshore tunnel section and the immersed tunnel segment. The transition platform includes bored piles, a hidden beam located at the top of the bored piles, and a load-bearing plate integrally cast with the bored piles and the hidden beam. The bored piles are arranged in at least two rows, each row perpendicular to the axial direction of the immersed tunnel segment. The upper surface of the load-bearing plate is stepped along the tunnel direction, creating different height differences between adjacent sections of the rigid, adjustment, flexible, and underwater sections. The load-bearing plate in the rigid section is connected to the onshore tunnel section. A small waterstop is installed in the gap between the load-bearing plate of the adjustment section and the immersed tunnel section. The space inside the area enclosed by the small waterstop is filled with a grouting foundation. A crushed stone foundation is laid between the load-bearing plate of the flexible section and the immersed tunnel section. The crushed stone foundation extends into the water section. A contact hinge plate and a rubble foundation are laid under the crushed stone foundation in the water section. Part of the contact hinge plate is located between the crushed stone foundation and the load-bearing plate in the water section, and another part is located between the crushed stone foundation and the underwater surface. The rubble foundation is located between the crushed stone foundation and the underwater surface and is connected to the contact hinge plate.

[0008] Furthermore, the load-bearing plate located in the rigid section is provided with a thrust groove in the direction perpendicular to the axial direction of the onshore tunnel section, and a thrust bracket is provided at the bottom of the onshore tunnel section corresponding to the position of the thrust groove, and the thrust bracket is located in the thrust groove.

[0009] Furthermore, the depth to which the bored pile penetrates the rock strata is not less than 1m.

[0010] Furthermore, the bored pile is provided with reserved reinforcing bars that overlap with the hidden beam.

[0011] Furthermore, the crushed stone foundation is a crushed stone layer with furrows.

[0012] Furthermore, the miniature waterstop is equipped with a mounting base.

[0013] The present invention also provides a construction method for a water-shore transition composite structure for a high-coverage immersed tunnel as described above, specifically including the following steps:

[0014] S1. After the temporary cofferdam for the immersed tunnel is completed, bored piles will be constructed first.

[0015] S2. After the piles are completed, the hidden beams are constructed. After the hidden beams are completed, the load-bearing plates are constructed to complete the transition pile cap structure.

[0016] S3. Lay the contact hinge plate and rubble foundation, and then lay the crushed stone foundation;

[0017] S4. Install small waterstops below the immersed tunnel sections of the adjustment section's load-bearing plate to form a closed enclosure area;

[0018] S5. Immersion tunnel segment placement and docking construction procedure;

[0019] S6. Use a grouting device to grout the small waterstop enclosure area below the immersed tunnel section to form a grouting foundation.

[0020] Furthermore, after the settlement of the immersed tunnel reaches the control value during construction or operation, a grouting device is used to reinforce the grouting foundation below the immersed tunnel section.

[0021] Compared with the prior art, the beneficial effects of this invention are as follows:

[0022] 1. The present invention provides a water-shore transition combination structure and construction method for immersed tunnels with high soil cover, which integrates the water-shore joint of the immersed tunnel, so that the underwater immersed tunnel sections and the onshore tunnel sections settle in tandem, ensuring water-stopping effect and safe operation.

[0023] 2. In the water-shore transition combination structure and construction method of the immersed tunnel with high soil cover provided by the present invention, the grouting foundation in the transition pier structure located below the immersed tunnel section can effectively reduce the settlement of the immersed tunnel in water, realize the control of uneven settlement of the section under the repeated action of multiple loads during the construction backfilling period and the operation period, prevent the phenomenon of vehicle jumping on municipal roads and the track bed detachment of high-speed rail, and effectively ensure the safety requirements of tunnel passage.

[0024] In summary, the transitional composite structure and corresponding construction method provided by this invention involve casting the composite structure in place after the bored piles are completed. The precast immersed tunnel sections are located on the flexible and adjustment sections of the composite structure in the water-shore transition, while the onshore tunnel section is located on the rigid section of the composite structure. The composite structure is designed with multiple sections to adjust the foundation stiffness in stages. Compared with the conventional foundations of existing immersed tunnel sections in the water, this method provides a more uniform transition in foundation stiffness, avoids stress concentration in the main body of the tunnel sections, reduces the settlement difference between the onshore and underwater sections, helps protect the joint sealing and safety of the immersed tunnel, and reduces the risk of leakage due to misalignment of the tunnel section joints during project operation. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the overall transitional combination structure of the present invention;

[0026] Figure 2 This is a plan view of the transitional combination structure of the present invention;

[0027] Figure 3 This is a schematic diagram of the transition platform structure of the present invention;

[0028] Figure 4for Figure 1 Enlarged detail of point A in the middle.

[0029] The attached diagram is labeled as follows: 1-onshore tunnel section, 2-immersed tunnel segment, 3-drilled pile, 4-hidden beam, 5-load-bearing plate, 6-small waterstop, 7-grouting foundation, 8-contact hinge plate, 9-gravel foundation, 10-rubble foundation, 11-grouting pipeline, 12-grouting device, 13-thrust bracket, 14-temporary cofferdam. Detailed Implementation

[0030] Exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0031] like Figures 1 to 4 As shown, this invention provides an embodiment of a combined structure for a high-coverage immersed tunnel waterfront transition, including a transition platform structure located below the main body of the tunnel at the waterfront transition point, supporting the main tunnel body at the waterfront transition point and the backfill layer above the tunnel. The immersed tunnel is a reinforced concrete structure, typically constructed using a full-section casting process. Depending on different traffic needs, the tunnel includes highway tunnel openings, track openings, and corridor openings.

[0032] The transition structure of this invention comprises a rigid section, an adjustment section, a flexible section, and an underwater section. The transition platform is a cast-in-place reinforced concrete structure, including bored piles 3, a load-bearing plate 5, and a hidden beam 4 installed inside the load-bearing plate 5. Below the hidden beam 4 are the bored piles 3 that penetrate into the rock strata. The bored piles 3 are located below the hidden beam 4 of the main body of the transition platform. After the bored piles 3 are completed, the reserved reinforcing bars overlap with the upper hidden beam 4. The bored piles 3, the hidden beam 4, and the load-bearing plate 5 are cast as a whole to share the load. The length of the bored piles 3 is determined according to the actual geological conditions. To ensure that the settlement meets the design requirements, the length of the bored piles 3 penetrating into the rock strata must be no less than 1m.

[0033] In this embodiment, the bored piles 3 are arranged in two rows, each row is arranged in a direction perpendicular to the axial direction of the immersed tunnel, one row is located below the joint of the immersed tunnel section 2, and the other row is located at the end of the transition platform away from the joint of the section.

[0034] The upper surface of the load-bearing plate 5 is stepped along the tunnel direction, so that the vertical drop between adjacent sections of the rigid section, the adjustment section, the flexible section and the underwater section is formed in sequence. The load-bearing plate 5 located in the rigid section abuts against the tunnel 1 on the shore. The gap between the load-bearing plate 5 located in the adjustment section and the immersed tunnel section 2 is provided with a small waterstop 6. The space inside the area enclosed by the small waterstop 6 is filled with a grouting foundation 7. The load-bearing plate 5 of the flexible section and the immersed tunnel section 2 are laid with a crushed stone foundation 9. The crushed stone foundation 9 extends to the underwater section. The crushed stone foundation 9 in the underwater section is laid with a contact hinge plate 8 and a rubble foundation 10. Part of the contact hinge plate 8 is located between the crushed stone foundation 9 and the load-bearing plate 5 in the underwater section, and another part is located between the crushed stone foundation 9 and the underwater surface. The rubble foundation 10 is located between the crushed stone foundation 9 and the underwater surface and is connected to the contact hinge plate 8. The foundation stiffness of the flexible section is between that of the rigid section and the underwater section, ensuring a uniform transition in foundation stiffness and preventing stress concentration in the concrete caused by hard supports below the pipe section, which could lead to damage.

[0035] The crushed stone foundation 9 is a crushed stone pad with furrows, which is laid using special paving equipment. The rubble stone foundation 10 is a rubble stone pad, or a block stone pad, or a mixed rubble stone and block stone pad. The thickness of the crushed stone foundation 9 and the rubble stone foundation 10 should be determined according to the design.

[0036] like Figure 4 As shown, the small waterstop 6 is equipped with an installation base. The small waterstop 6 has a certain compressibility. After being pressed against the bottom surface of the immersed tunnel section 2, the small waterstop 6 encloses the space between the bottom surface of the immersed tunnel section 2 and the load-bearing plate 5 of the adjustment section to form a sealed cavity. The grouting device 12 fills the sealed cavity with grouting material through the grouting pipeline 11 in multiple times to form the grouting foundation 7.

[0037] The contact hinge plate 8 is positioned above the hidden beam 4 at the end edge of the transition pier body near the water level. The hidden beam 4 at the end of the transition pier has a stepped top surface. A portion of the contact hinge plate 8, including its end, lies between the crushed stone foundation 9 and the lower top surface of the hidden beam 4 at the end of the transition pier. Another portion of the contact hinge plate 8 lies between the crushed stone foundation 9 and the underwater surface. The other end of the contact hinge plate 8 connects to the rubble foundation 10. The contact hinge plate 8 has a certain rotation angle, allowing for a certain angular displacement of the tunnel segment 2 during subsequent settlement adjustment.

[0038] The rigid section's load-bearing plate 5 has a thrust groove in the direction perpendicular to the axial direction of the onshore section tunnel 1. The bottom of the onshore section tunnel 1 has a thrust bracket 13 at the position corresponding to the thrust groove. The thrust bracket 13 is located in the thrust groove. The thrust bracket 13 is an axial displacement limiting structure for the onshore section tunnel 1. Its function is to prevent displacement caused by deformation along the tunnel direction due to temperature rise or fall of the tunnel structure.

[0039] After prefabrication in the dry dock, the immersed tunnel segment 2 is floated to the tunnel site for immersion and docking. The design of the immersed tunnel segment requires reinforcement of the lifting area and surrounding structures to ensure strength meets requirements. The onshore tunnel section 1 is typically constructed using open-cut or cut-and-cover methods and docks with the immersed tunnel within a cofferdam to form a complete tunnel structure.

[0040] The construction method for the above-mentioned high-coverage immersed tunnel water-shore transition composite structure specifically includes the following steps:

[0041] S1. After the temporary cofferdam for the immersed tunnel is completed, the bottom bored piles will be constructed first: After the temporary cofferdam 14 is constructed, leakage detection between piles will be carried out first. After the internal water stoppage of the temporary cofferdam 14 meets the design requirements, the foundation treatment will be carried out. After the foundation is ready for construction, the bored piles 3 will be constructed. The bored piles 3 are rigid and adjustable support structures. After the piles are completed, they need to be tested to ensure the quality of pile construction and accurate positioning.

[0042] S2. After the piles are completed, the hidden beam 4 is constructed. After the hidden beam 4 is completed, the load-bearing plate 5 is constructed to complete the transition pile cap structure.

[0043] After the bored pile 3 is completed, the hidden beam 4 and the load-bearing plate 5 of the transition cap are constructed. The reinforcing bars of the hidden beam 4 within the bored pile 3 and the load-bearing plate 5 are interlocked and poured to form a unified load-bearing structure. During the construction of the transition cap, it is necessary to monitor the structural settlement in real time to ensure that the elevation of the connection point meets the design requirements.

[0044] S3. Lay the contact hinge plate 8 and the rubble foundation 10, and then lay the crushed stone foundation 9.

[0045] S4. Install small waterstops 6 below the immersed tunnel section 2 of the adjustment section load-bearing plate 5 to form a closed enclosure area, and check the sealing performance.

[0046] S5, the immersed tunnel section 2 is immersed and connected.

[0047] The onshore section 1 is an underground structure constructed using either the open-cut or cut-and-cover method. The immersed tunnel section 2 is connected to the onshore section 1 within the temporary cofferdam 14, together forming the tunnel structure.

[0048] After the immersed tunnel segment 2 is prefabricated in the dry dock, it is floated out of the dry dock and floated to the temporary cofferdam 14 for floating, sinking and docking.

[0049] S6. Use grouting device 12 to perform foundation grouting on the area enclosed by the small waterstop 6 below the immersed tunnel section 2. Relevant technicians use grouting device 12 to fill and reinforce the internal cavity enclosed by the small waterstop 6. The grouting material is selected according to design requirements, and the grout enters below the immersed tunnel section 2 through grouting pipe 11. After filling, a filling quality inspection is performed. If the quality meets design requirements, a backfill layer is constructed. After the backfill layer is completed, the road surface and track bed are then constructed.

[0050] After the settlement of the immersed tunnel reaches the control value during construction or operation, the grouting device 12 is used to grout and reinforce the immersed tunnel section 2. At this time, the settlement of the immersed tunnel section 2 reaches the convergence state.

[0051] Multiple grouting operations during the construction and operation phases ensure that the grouting foundation 7 at the joint location remains in a compacted state, thereby coordinating and controlling the settlement of the immersed tunnel and reducing the settlement difference on both sides of the joint.

[0052] The working principle of this invention: Traditional immersed tunnels have a high-stiffness foundation on land, while the crushed stone foundation of underwater immersed tunnels has a lower-stiffness foundation. This significant difference in foundation stiffness leads to a large settlement difference between the two sides of the tunnel joint from the construction stage to the long-term operation stage. Uneven settlement can cause road surface bumps and track bed delamination in municipal roads, threatening operational safety. This invention provides a water-shore transition combination structure and construction method for high-coverage immersed tunnels. A transition combination structure is set below the water-shore joint of the immersed tunnel. A grouting foundation is set between the transition combination structure and the main tunnel body. Multiple grouting sessions can be performed during construction and operation to ensure that the grouting foundation at the joint remains compacted, thus coordinating and controlling the settlement of the immersed tunnel and reducing the settlement difference between the two sides of the joint.

[0053] This invention is applicable to the waterfront joint of immersed tunnels, providing a stiffness transition at this joint location to eliminate the problem of excessive settlement differences caused by uneven transitions in traditional foundations. Simultaneously, a contact-type hinge plate is installed on the water-near side, reserving sufficient space for settlement rotation in the immersed tunnel, ensuring coordinated settlement during later tunnel operation. The flexible system ensures waterproofing at the tunnel joint. The grouting filling module located below the immersed tunnel can reinforce the underlying grouting foundation multiple times during construction and operation, preventing the foundation from becoming hollow and reducing its bearing capacity due to fine particles being lost through the boulders skeleton under hydraulic transport after long-term operation. This structure and its construction method are simple and clear, effectively controlling tunnel settlement and solving the problem of misalignment between tunnel sections harming the road surface and track bed, making it highly suitable for the waterfront joint of immersed tunnels.

[0054] Therefore, the waterfront transition combination structure of the present invention has wide applicability, good settlement control effect, is conducive to the long-term safe operation of tunnels, and is easy to promote and use.

[0055] The present invention has been described in detail above through embodiments, but the content described is only an exemplary embodiment of the present invention and should not be considered as limiting the scope of the present invention. The scope of protection of the present invention is defined by the claims. Any technical solutions designed by those skilled in the art using the technical solutions described in the present invention, or similar technical solutions designed by those skilled in the art under the inspiration of the technical solutions of the present invention, within the substance and scope of protection of the present invention, to achieve the above-mentioned technical effects, or equivalent changes and improvements made to the scope of the application, should still fall within the patent protection scope of the present invention. It should be noted that, for clarity, descriptions of some components and processes that are not directly and obviously related to the scope of protection of the present invention but are known to those skilled in the art have been omitted in the description of the present invention.

Claims

1. A combined structure for waterfront transition in a high-coverage immersed tunnel, characterized in that, The tunnel comprises a rigid section, an adjustment section, a flexible section, and an underwater section. A transition platform is installed at the junction of the onshore tunnel section and the immersed tunnel segment. The transition platform includes bored piles, a hidden beam at the top of the bored piles, and a load-bearing plate integrally cast with the bored piles and hidden beam. The bored piles are arranged in at least two rows, each row perpendicular to the axial direction of the immersed tunnel segment. The upper surface of the load-bearing plate is stepped along the tunnel direction, creating different height differences between adjacent sections of the rigid, adjustment, flexible, and underwater sections. The load-bearing plate in the rigid section abuts against the onshore tunnel section, while the transition platform in the adjustment section... A small waterstop is installed in the gap between the load-bearing plate of the flexible section and the immersed tunnel section. The space inside the area enclosed by the small waterstop is filled with a grouting foundation. A crushed stone foundation is laid between the load-bearing plate of the flexible section and the immersed tunnel section. The crushed stone foundation extends into the water section. A contact hinge plate and a rubble foundation are laid under the crushed stone foundation in the water section. Part of the contact hinge plate is located between the crushed stone foundation and the load-bearing plate in the water section, and another part is located between the crushed stone foundation and the underwater surface. The rubble foundation is located between the crushed stone foundation and the underwater surface and is connected to the contact hinge plate.

2. The waterfront transition composite structure for a high-coverage immersed tunnel according to claim 1, characterized in that, The load-bearing plate located in the rigid section is provided with a thrust groove in the direction perpendicular to the axial direction of the onshore tunnel section, and a thrust bracket is provided at the bottom of the onshore tunnel section corresponding to the position of the thrust groove, and the thrust bracket is located in the thrust groove.

3. The waterfront transition composite structure for a high-coverage immersed tunnel according to claim 1, characterized in that, The depth to which the bored pile penetrates the rock strata shall not be less than 1m.

4. The waterfront transition composite structure for a high-coverage immersed tunnel according to claim 1, characterized in that, The bored pile is equipped with reserved reinforcing bars that overlap with the hidden beam.

5. The waterfront transition composite structure for a high-coverage immersed tunnel according to claim 1, characterized in that, The crushed stone foundation is a crushed stone layer with furrows.

6. The waterfront transition composite structure for a high-coverage immersed tunnel according to claim 1, characterized in that, The miniature waterstop is equipped with a mounting base.

7. A construction method for a waterfront transition composite structure for a high-coverage immersed tunnel as described in any one of claims 1 to 6, specifically comprising the following steps: S1. After the temporary cofferdam for the immersed tunnel is completed, bored piles will be constructed first. S2. After the piles are completed, the hidden beams are constructed. After the hidden beams are completed, the load-bearing plates are constructed to complete the transition pile cap structure. S3. Lay the contact hinge plate and rubble foundation, and then lay the crushed stone foundation; S4. Install small waterstops below the immersed tunnel sections of the adjustment section's load-bearing plate to form a closed enclosure area; S5. Immersion tunnel segment placement and docking construction procedure; S6. Use a grouting device to grout the small waterstop enclosure area below the immersed tunnel section to form a grouting foundation.

8. The construction method according to claim 7, characterized in that, After the settlement of the immersed tunnel reaches the control value during construction or operation, a grouting device is used to reinforce the grouting foundation below the immersed tunnel section.

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