Tunnel nested pipe protection structure with anti-seepage and anti-shear capacities

Abstract

The invention belongs to the field of tunnel engineering, and relates to a tunnel nested pipe protection structure with anti-seepage and anti-shear capacities, which comprises a main body tunnel, an external pipe body and a flexible embedded tunnel, the outer pipe body is located between the two main body tunnels, and the outer pipe body and the main body tunnels are of an integrated structure. The flexible embedded tunnel is located in the outer pipe body, and the two ends of the flexible embedded tunnel are connected with the ends of the two main body tunnels through flexible joints correspondingly. A dislocation buffer area is formed between the outer wall of the flexible embedded tunnel and the inner wall of the outer pipe body; a plurality of flexible supporting structures are symmetrically arranged in the dislocation buffering area. By constructing an external tubular space, a nested structure is formed, and dislocation allowance is provided for an internal flexible pipeline; the anti-seepage capacity of the inner pipe is effectively improved through the waterproof barrier and the filling material of the outer pipe; when shear dislocation occurs in the ground layer, shear deformation is dispersed on the flexible embedded tunnel, and the situation that the internal tunnel directly bears large shear force is avoided.

Description

Technical Field

[0001] The invention belongs to the field of tunnel engineering and relates to a tunnel nested pipe protection structure with anti-seepage and anti-shear capabilities. Background Art

[0002] Undersea tunnels are prone to water seepage near geological faults, and when the faults are sheared and dislocated, the tunnel will directly bear strong shear forces, which may lead to structural damage. In addition, due to the extremely long span of the tunnel, once water seepage or structural damage occurs, it will pose a huge threat to personnel safety, making escape extremely difficult, and safety hazards cannot be ignored.

[0003] In response to the seepage and shear resistance problems in cross-fault areas, relevant patents have proposed corresponding solutions. For example, Chinese patent CN216841726U proposes a shield tunnel anti-seepage device. The device reinforces the connection between the segment body through support plates and fixing rods to improve the fixing effect. At the same time, the rubber pad is fitted with the segment body to seal the connection between the segment body, improve the waterproof effect, and reduce the occurrence of leakage and seepage. Chinese patent CN218542269U proposes a tunnel support structure for shear resistance and energy release in layered surrounding rock tunnels. By setting prestressed anchor rods and energy release mechanisms, the requirements of shear resistance and energy release can be met, and the extrusion deformation caused by interlayer shear slip in layered surrounding rocks can be effectively prevented. At the same time, part of the surrounding rock deformation stress is released to protect the initial support in the tunnel from being destroyed and improve safety performance. These technologies have solved the problems of seepage and stability in tunnel engineering to a certain extent.

[0004] However, when facing large shear displacement of geological faults, the tunnel body is directly subjected to large shear forces, which may cause the tunnel to be sheared off. Existing technologies cannot achieve effective disaster prevention and mitigation effects. Therefore, a nested pipe protection solution with anti-seepage and shear resistance is needed to provide more comprehensive protection for submarine tunnels in geological fault areas. Summary of the invention

[0005] The purpose of the present invention is to provide a protection scheme for submarine tunnels, in particular, a nested tube protection scheme for use in geological fault areas, which enhances the tunnel's anti-seepage performance and shear resistance through the nested tube structure. This scheme can effectively solve the problems of water seepage and shear force in submarine tunnels near geological faults, and improve the structural safety and durability of tunnels. This scheme forms a nested structure by constructing an external tubular space to provide a displacement margin for the internal flexible pipeline; the waterproof barrier and filling materials of the outer tube effectively improve the anti-seepage capacity of the inner tube; when shear displacement occurs in the stratum, the shear deformation is dispersed on the flexible embedded tunnel to prevent the internal tunnel from directly bearing large shear forces. It provides a new safety guarantee idea for cross-fault tunnel projects.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A tunnel nested pipe protection structure with anti-seepage and shear resistance capabilities, comprising a main tunnel 1, an external pipe body 2 and a flexible embedded tunnel 4; the external pipe body 2 is located between two sections of the main tunnel 1, the external pipe body 2 and the main tunnel 1 are an integral structure, and the diameter of the external pipe body 2 is greater than the diameter of the main tunnel 1; the flexible embedded tunnel 4 is located in the external pipe body 2, and the two ends of the flexible embedded tunnel 4 are respectively connected to the ends of the two sections of the main tunnel 1 through flexible joints 5; the diameter of the flexible embedded tunnel 4 is the same as the diameter of the main tunnel 1, and a dislocation buffer zone 3 is formed between the outer wall of the flexible embedded tunnel 4 and the inner wall of the external pipe body 2.

[0008] A plurality of flexible support structures 6 are symmetrically arranged in the displacement buffer zone 3 , and two ends of the flexible support structures 6 are fixedly connected to the outer wall of the flexible embedded tunnel 4 and the inner wall of the external pipe body 2 respectively.

[0009] Beneficial effects of the present invention:

[0010] 1. Enhanced anti-seepage performance: Through the dual protection of the external pipe body and anti-seepage materials, the impact of fault seepage on the tunnel is effectively reduced, ensuring the dryness and safety of the tunnel interior.

[0011] 2. Disperse shear stress: Increase the distance between the shear ends. When shear displacement occurs in the stratum, the shear deformation is dispersed on the flexible embedded tunnel, preventing the tunnel from directly bearing large shear forces, thereby effectively improving the tunnel's shear resistance and reducing the risk of damage.

[0012] 3. Improve structural safety: Through flexible nesting design, the requirements of anti-seepage and shear resistance are taken into account, providing a new safety guarantee idea for cross-fault tunnel projects and improving the overall safety of the tunnel.

[0013] 4. Adaptability to complex geological conditions: This solution can adapt to complex environmental conditions near geological faults and has significant engineering application potential and safety assurance significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is the overall schematic diagram of the flexible nested tube scheme;

[0015] Figure 2 It is a cross-sectional schematic diagram of the flexible nested tube scheme;

[0016] Figure 3 This is a schematic diagram of the shear protection of the flexible nested pipe when the stratum dislocation occurs;

[0017] In the figure: 1. Main tunnel; 2. External pipe body; 3. Shift buffer zone; 4. Flexible embedded tunnel; 5. Flexible joint; 6. Flexible support structure. DETAILED DESCRIPTION

[0018] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0019] The design of a tunnel nested pipe protection structure with anti-seepage and shear resistance of the present invention includes the following aspects:

[0020] 1. Construct an external tubular space: When the tunnel is excavated near a geological fault, an external tubular space larger than the tunnel diameter is formed by expanding the excavation diameter, providing the tunnel with sufficient displacement margin to cope with the impact of the displacement of the geological fault.

[0021] 2. Construct a flexible embedded tunnel: A flexible tunnel with lower rigidity than a conventional tunnel is built inside the external tubular space. The space between the flexible tunnel and the outer pipe body is filled with anti-seepage soft material, while ensuring that the flexible tunnel is effectively supported to enhance the tunnel's anti-seepage performance and shear resistance.

[0022] 3. Application of anti-seepage materials: Fill the space between the external pipe and the flexible embedded tunnel with anti-seepage soft materials, such as polymer elastic materials, rubber concrete, etc. These materials can absorb shear deformation and prevent water seepage, thereby reducing the impact of fault seepage on the tunnel.

[0023] 4. Optimization of support structure: A flexible support structure is arranged between the flexible tunnel and the filling material to ensure that the embedded tunnel is evenly stressed, adapt to the displacement, and further improve the shear resistance of the tunnel.

[0024] like Figure 1-3 As shown, a tunnel nested pipe protection structure with anti-seepage and anti-shear capabilities includes a main tunnel 1, an external pipe body 2 and a flexible embedded tunnel 4. The main tunnel 1 and the flexible embedded tunnel 4 are connected by a flexible joint 5, and a certain amount of activity space is reserved. Between the external pipe body 2 and the flexible embedded tunnel 4 is a displacement buffer 3, which is filled with anti-seepage soft material, and a flexible support structure 6 is arranged between the flexible tunnel and the filling material to ensure that the embedded tunnel is evenly stressed and adapts to displacement.

[0025] The structure of the flexible joint 5 is a bellows-type flexible joint, which is made of high-strength rubber (such as chloroprene rubber (CR) or ethylene propylene diene monomer rubber (EPDM)) or polymer composite materials (such as polyurethane (PU) or fluororubber (FKM)), and has good elastic deformation ability and waterproof performance. The two ends of the flexible joint 5 are respectively connected to the main tunnel 1 and the flexible embedded tunnel 4 through flanges, and the flanges are fixed with bolts to ensure the firmness and sealing of the connection. A waterproof sealing ring is provided inside the flexible joint 5, and a waterproof coating is applied on the outside to prevent groundwater from infiltrating. The bellows structure allows the flexible joint 5 to have a certain displacement capacity in the axial, radial and angular directions, thereby adapting to the tunnel deformation caused by the movement of geological faults, while maintaining the continuity and sealing of the tunnel.

[0026] The flexible support structure 6 is a multi-directional hinged support structure, made of high-strength elastic material (such as rubber, polyurethane or polymer composite material), and its main body is a bellows or spring-shaped, which can provide elastic deformation in the axial, radial and angular directions. The two ends of the flexible support structure 6 are connected to the external pipe body 2 and the flexible embedded tunnel 4 through flanges or hinged joints to ensure uniform force and allow a certain displacement. The flexible support structure 6 can be filled with damping materials (such as viscoelastic materials) to further absorb shear stress and reduce vibration transmission.

[0027] The outer tube body 2 is made of a material with a certain bearing and supporting capacity, and its structural dimensions, density, elastic modulus and Poisson's ratio are determined by the tunnel design bearing capacity, stratum shear displacement margin design, the geological environment of the tunnel and relevant specifications. The specific material can be selected from high-strength concrete (such as C50 and above), steel pipe (such as Q345B) or fiber-reinforced composite material (such as GFRP) to meet different geological conditions and bearing requirements.

[0028] The flexible embedded tunnel 4 is made of deformable material, and its structural size, density, elastic modulus and Poisson's ratio are determined by its designed bearing capacity, designed deformation range and traffic space requirements. The specific material can be a steel shell-concrete composite pipe, a polymer composite material (such as polyurethane) or a rubber-steel composite pipe to ensure that it has good deformation capacity and bearing performance.

[0029] The type and thickness of the filling material in the displacement buffer zone 3 are determined by the space between the external pipe body and the flexible embedded tunnel, the anti-seepage index, and the deformation design range. The specific material can be selected from polymer elastic materials (such as polyurethane elastomers), rubber concrete or foam concrete to provide good anti-seepage and deformation absorption capabilities.

[0030] The design parameters of the flexible support structure 6, including its material selection, geometric dimensions and layout, are determined by the stress characteristics of the flexible tunnel and the activity of the geological fault to ensure that the shear stress can be effectively dispersed when the geological fault moves and protect the tunnel structure from damage. The specific material can be selected from high-strength steel (such as Q345B), fiber-reinforced composite materials (such as GFRP) or rubber-steel composite support to provide sufficient elasticity and strength.

[0031] The specific preparation and use process is as follows:

[0032] 1. Preliminary preparation

[0033] Conduct detailed exploration of geological fault areas to determine fault locations, fault activity, stratum shear characteristics, and water seepage risks. Optimize design parameters based on exploration results, including excavation diameter, outer tube and embedded tunnel dimensions, fill material type and thickness. Select shield machines or drill-and-blast equipment suitable for large-diameter excavations to ensure they can cope with complex geological conditions. Equip construction equipment with anti-seepage material injection devices and flexible supports.

[0034] 2. Tunnel excavation to the fault area

[0035] Increase the excavation diameter in the fault area to form a tubular space larger than the main diameter of the main tunnel 1, and reserve enough displacement buffer. When increasing the excavation diameter, it is necessary to strengthen the surrounding strata to avoid strata collapse. Grouting reinforcement or freezing reinforcement is carried out in the fault area to stabilize the strata and control groundwater leakage. The grouting material should be concrete or composite materials with excellent impermeability and shear resistance.

[0036] 3. External pipe construction

[0037] In the expanded excavation space, the outer pipe body 2 is constructed by assembly or cast-in-place construction. The outer pipe material is made of high-strength concrete or steel pipe, and waterproof measures are strengthened. A waterproof barrier is set on the outside of the outer pipe, combined with a spray waterproof layer and a drainage system to effectively resist fault seepage.

[0038] 4. Embedded flexible tunnel construction

[0039] A flexible embedded tunnel 4 is constructed inside the external pipe body 2, and the material selected is a composite material with low rigidity and high ductility, such as a steel shell-concrete composite pipe. The flexible tunnel can be assembled in sections, and each section is connected by a flexible joint 5, leaving a certain amount of space for movement. An impermeable soft material (such as a polymer elastic material, rubber concrete, etc.) is injected into the displacement buffer zone 3 between the flexible embedded tunnel 4 and the external pipe body 2. This material can absorb shear deformation and prevent water seepage. A flexible support structure 6 is arranged between the external pipe body 2 and the flexible embedded tunnel 4 to ensure that the flexible embedded tunnel 4 is evenly stressed and adapts to the displacement.

[0040] 5. Closing and testing

[0041] Ensure that the joints between the outer tube 2 and the main tunnel 1 and the flexible embedded tunnel 4 are well sealed. Set up a monitoring system in the fault area, including displacement, stress and water seepage monitoring. Perform shear and seepage tests on the fault area to ensure that the nested structure meets the design requirements. Fully check the integrity of the nested structure to confirm that there are no gaps in the filling material and no deviation of the flexible tunnel.

Claims

1. A tunnel nested pipe protection structure with anti-seepage and shear resistance, characterized in that: The tunnel nested pipe protection structure with anti-seepage and anti-shear capabilities comprises a main tunnel (1), an external pipe body (2) and a flexible embedded tunnel (4); the external pipe body (2) is located between two sections of the main tunnel (1), the external pipe body (2) and the main tunnel (1) are an integrated structure, and the diameter of the external pipe body (2) is greater than the diameter of the main tunnel (1); the flexible embedded tunnel (4) is located in the external pipe body (2), and the two ends of the flexible embedded tunnel (4) are respectively connected to the ends of the two sections of the main tunnel (1) through flexible joints (5); the diameter of the flexible embedded tunnel (4) is the same as the diameter of the main tunnel (1), and a displacement buffer zone (3) is formed between the outer wall of the flexible embedded tunnel (4) and the inner wall of the external pipe body (2).

2. A tunnel nested pipe protection structure with anti-seepage and anti-shear capabilities according to claim 1, characterized in that: A plurality of flexible support structures (6) are symmetrically arranged in the displacement buffer zone (3), and two ends of the flexible support structures (6) are respectively fixedly connected to the outer wall of the flexible embedded tunnel (4) and the inner wall of the external tube body (2).

3. The tunnel nested pipe protection structure with anti-seepage and anti-shear capabilities according to claim 1 is characterized in that: The structure of the flexible joint (5) is a bellows-type flexible joint. The two ends of the flexible joint (5) are respectively connected to the main tunnel (1) and the flexible embedded tunnel (4) through flanges, and the flanges are fixed with bolts. The interior of the flexible joint (5) is provided with a waterproof sealing ring, and the exterior is coated with a waterproof coating.

4. The tunnel nested pipe protection structure with anti-seepage and anti-shear capabilities according to claim 1 is characterized in that: The flexible joint (5) is made of high-strength rubber or a polymer composite material; the high-strength rubber is, for example, chloroprene rubber or EPDM rubber; the polymer composite material is, for example, polyurethane or fluororubber.

5. The tunnel nested pipe protection structure with anti-seepage and anti-shear capabilities according to claim 1 is characterized in that: The flexible support structure (6) is in the shape of a bellows or a spring, and both ends of the flexible support structure (6) are connected to the external pipe body (2) and the flexible embedded tunnel (4) through flanges or hinged joints.

6. The tunnel nested pipe protection structure with anti-seepage and anti-shear capabilities according to claim 1 is characterized in that: The flexible support structure (6) is made of a high-strength elastic material, and the interior of the flexible support structure (6) is filled with a damping material; the high-strength elastic material is rubber or polyurethane.

7. The tunnel nested pipe protection structure with anti-seepage and anti-shear capabilities according to claim 1 is characterized in that: The material of the external pipe body (2) is high-strength concrete, steel pipe or fiber-reinforced composite material; the high-strength concrete is C50 or above, the steel pipe is Q345B, and the fiber-reinforced composite material is GFRP.

8. The tunnel nested pipe protection structure with anti-seepage and anti-shear capabilities according to claim 1, characterized in that: The flexible embedded tunnel (4) is made of a deformable material, and the material is selected from a steel shell-concrete composite pipe, a polymer composite material or a rubber-steel composite pipe, and the polymer composite material is polyurethane.

9. The tunnel nested pipe protection structure with anti-seepage and anti-shear capabilities according to claim 1, characterized in that: The filling material in the displacement buffer zone (3) is selected from a polymer elastic material, rubber concrete or foam concrete, and the polymer elastic material is a polyurethane elastomer.

10. The tunnel nested pipe protection structure with anti-seepage and anti-shear capabilities according to claim 1, characterized in that: The flexible support structure (6) is made of high-strength steel, fiber-reinforced composite material or rubber-steel composite support; the high-strength steel is Q345B, and the fiber-reinforced composite material is GFRP.

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