Shield tunnel segment structure for active pressure relief and drainage of marine facies soft soil layer and construction method

Abstract

The invention relates to the technical field of underground space engineering, and provides a marine facies soft soil layer active pressure relief and drainage shield tunnel duct piece structure and a construction method.The duct piece structure comprises a plurality of duct piece structure units connected in the longitudinal direction of a tunnel, and surrounding rock is arranged around the multiple duct piece structure units; the segment structure unit comprises a segment layer and an active pressure relief drainage structure arranged between the segment layer and surrounding rock; the active pressure-relief drainage structure comprises a buffer structure layer and a drainage channel, the buffer structure layer is arranged between the segment layer and the surrounding rock, the drainage channel is arranged in the buffer structure layer, and the buffer structure layer comprises a front baffle, a rear baffle and a negative Poisson's ratio material arranged between the front baffle and the rear baffle. According to the scheme, damage of load stress generated by tunnel surrounding rocks to the segment structure is effectively buffered, meanwhile, the influence of disaster loads such as earthquakes on the tunnel segment structure can be effectively reduced, and the tunnel segment structure has good durability, impermeability and adaptability and can adapt to different geological conditions and working environments.

Description

Technical Field

[0001] The invention relates to the technical field of underground space engineering, and in particular to a shield tunnel segment structure and a construction method for an active pressure relief drainage shield tunnel in a marine soft soil layer. Background Art

[0002] Marine soft soil is a special type of soft soil formed by sedimentation in the marine environment. It is widely distributed and has obvious uniqueness and complexity in its genetic environment, physical properties, and mechanical characteristics. This special geological condition has brought many challenges to the construction and operation of subway tunnels. As a commonly used lining structure for subway tunnels, shield segments are annular prefabricated components used to support the tunnel excavation space in subway tunnel construction and are an indispensable part of shield construction. Shield segments not only provide initial and permanent support, but also have multiple characteristics in structure, function and construction.

[0003] However, deep burial depth and high groundwater level often cause a series of impacts on shield tunnel construction and operation. For example, deep burial tunnel segments need to withstand higher vertical stratum pressure and horizontal lateral pressure. High groundwater level also requires tunnel segments to withstand long-term high water pressure, which increases the risk of damage and leakage. Moreover, under the action of disaster loads such as earthquakes, the load stress generated by the tunnel surrounding rock has a more significant destructive effect on the segment structure. There is an urgent need for a shield tunnel segment structure that can effectively buffer the destructive effect of the load stress generated by the tunnel surrounding rock on the segment structure, while reducing the risk of segment leakage. Summary of the invention

[0004] In order to solve the problems existing in the background technology, the present invention proposes a marine soft soil layer active pressure-relief drainage shield tunnel segment structure and construction method. The structure can effectively alleviate the impact of dynamic loads such as large burial, high groundwater level and earthquake on the shield tunnel segment, prevent segment damage, gap expansion, sealing failure and other problems, and improve the safety and stability of the tunnel; at the same time, the method is compatible with the existing tunnel shield method and does not affect the construction progress and quality; and it adopts special materials and structural design, has good durability, impermeability, reliability and adaptability, and can adapt to different geological conditions and working environments.

[0005] To achieve the above-mentioned object, the present invention adopts the following scheme: the segment structure of the active pressure relief drainage shield tunnel in the marine soft soil layer includes a plurality of segment structure units connected along the longitudinal direction of the tunnel, surrounding rocks are arranged around the plurality of segment structure units, the segment structure unit includes a segment layer and an active pressure relief drainage structure arranged between the segment layer and the surrounding rocks; the active pressure relief drainage structure includes a buffer structure layer and a drainage channel, the buffer structure layer is arranged between the segment layer and the surrounding rocks, and the drainage channel is arranged in the buffer structure layer; The buffer structure layer includes a front baffle, a rear baffle, and a negative Poisson's ratio material disposed between the front baffle and the rear baffle, one side of the rear baffle is connected to the tube sheet layer, and the other side of the rear baffle is mechanically interlocked and fixed with the negative Poisson's ratio material through an interlocking joint; The drainage channel includes radial drainage pipes and longitudinal drainage pipes that are interconnected and staggered. The outer sides of the pipe walls of the radial drainage pipes and the longitudinal drainage pipes are evenly provided with a plurality of circular holes. The radial drainage pipes are evenly distributed along the circumference of the pipe sheet layer, and at least one longitudinal drainage pipe is provided along the top and bottom of the tunnel.

[0006] Preferably, the negative Poisson's ratio material comprises a plurality of concave honeycomb structure units, the total thickness of the negative Poisson's ratio material is 22 cm, and the thickness of the concave honeycomb structure units is less than or equal to 0.5 mm.

[0007] Preferably, the interlocking joint includes conical pedestals and plug holes matching the number and position of the conical pedestals, the conical pedestals are evenly distributed on the side wall where the rear baffle contacts the negative Poisson's ratio material, and the plug holes are evenly distributed on the negative Poisson's ratio material.

[0008] Preferably, the conical pedestal includes a truncated cone at the top and a cylindrical pedestal at the bottom, the upper and lower diameter ratio of the truncated cone is 0.75, the diameter of the plug hole is 10% of the diameter of the cylindrical pedestal, and the depth of the plug hole is 17% of the diameter of the conical pedestal.

[0009] Preferably, the front baffle and the rear baffle are both rectangular curved steel plates with a thickness of 0.5 to 1.0 cm, the rear baffle is arranged close to the outer surface of the initial support structure of the tunnel, and the curvature of the front baffle and the rear baffle matches the curvature of the tunnel support structure.

[0010] Preferably, the rear baffle and the tube sheet layer, and the front baffle and the negative Poisson's ratio material are adhesively connected.

[0011] Preferably, the drainage channel is made of PVC material and has a diameter of 0.01 m. The spacing between the plurality of radial drainage pipes is 1.50 m. The diameter of the circular holes is 0.01 m, and the spacing between adjacent circular holes is 0.50 m.

[0012] Preferably, along the water flow direction of the drainage channel, the output end of the drainage channel of the previous pipe segment structure unit is a convex outlet, and the input end of the drainage channel of the next pipe segment structure unit is a concave inlet, and the convex outlet cooperates with the concave inlet.

[0013] The construction method of the active pressure relief drainage shield tunnel segment structure in marine soft soil layer comprises the following steps: Step 1, prefabricating shield segments; Step 1.1, constructing a segment layer according to the design size, the segment layer includes a plurality of segment pieces, each of the segment pieces is 1.50 m long, and rear baffles are respectively pasted on the outer sides of the plurality of segment pieces, and the plurality of segment pieces are respectively a bottom segment piece, a top segment piece, a bottom left segment piece, a bottom right segment piece, a top left segment piece, and a top right segment piece; Step 1.2, according to the position of each segment, radial drainage pipes are installed along the outer side of the rear baffle on each segment, and longitudinal drainage pipes are installed along the outer side of the rear baffle of the bottom segment and the top segment; Step 1.3, after laying the drainage channel, fix the negative Poisson's ratio material on the rear baffle of each pipe segment through an interlocking joint; Step 1.4, after the negative Poisson's ratio material is laid, a front baffle is pasted on the negative Poisson's ratio material of each segment to form a plurality of shield segments, namely, a bottom shield segment, a top shield segment, a bottom shield left segment, a bottom shield right segment, a top shield left segment, and a top shield right segment; Step 2: assembling shield segments on site; Step 2.1: After ensuring that the size of the shield tunneling machine meets the requirements for segment assembly, install the bottom shield segment first; Step 2.2, after the installation of the bottom shield segment is completed, install the bottom shield left segment and the bottom shield right segment, and assemble the radial drainage pipes of each shield segment; Step 2.3, installing the top shield left segment and the top shield right segment, and assembling the radial drainage pipes of each shield segment; Step 2.4, installing the top shield segment, assembling the radial drainage pipes of each shield segment, and completing the assembly of a segment structure unit; Step 2.5, after ensuring that the excavation size of the shield tunneling machine meets the installation requirements of the next segment structure unit, install the next segment structure unit; Step 2.6, install the next segment structure unit according to steps 2.1-2.4, and assemble the longitudinal drainage pipes between adjacent segment structure units.

[0014] The beneficial effects of the present invention are as follows: first, a buffer structure layer is arranged on the segment layer, which plays a dual role of shock absorption and sealing, thereby effectively buffering the destructive effect of the load stress generated by the tunnel surrounding rock on the segment structure, and at the same time, it can effectively reduce the impact of disaster loads such as earthquakes on the tunnel segment structure; at the same time, in the buffer structure layer, a drainage channel is arranged to facilitate groundwater to bypass the segment layer along the reserved drainage channel, thereby reducing the risk of leakage in the segment layer. The buffer structure layer and the drainage channel together constitute an active pressure-reducing drainage structure, which can improve the stability and safety of shield tunnels in marine soft soil strata.

[0015] Moreover, the active pressure-relieving drainage structure can be designed through prefabricated parts and then realized through on-site splicing. According to the needs of different projects, the active pressure-relieving drainage structure and materials can be redesigned by comprehensively considering the characteristics of buried marine soft soil layers and groundwater to make them more scientific, reasonable and accurate, compatible with the existing tunnel shield method, and not affecting the construction progress and quality.

[0016] In addition, the tailgate is mechanically interlocked and fixed with the negative Poisson's ratio material through an interlocking joint, which not only ensures the rapid assembly of the negative Poisson's ratio material, facilitating large-scale promotion and application, but also saves construction costs.

[0017] Furthermore, the buffer structure layer adopted in this solution includes a front baffle, a rear baffle and a negative Poisson's ratio material arranged between the front baffle and the rear baffle, which has good durability, impermeability, reliability and adaptability, and can adapt to different geological conditions and working environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the longitudinal section of the present invention; Figure 2 This is a schematic diagram of the negative Poisson's ratio material structure of the buffer structure layer in an embodiment of the present invention; Figure 3 Schematic diagram of the longitudinal drainage pipe joint structure of adjacent pipe segment structural units in an embodiment of the present invention; Figure 4 Schematic diagram of the longitudinal drainage pipe arrangement structure in an embodiment of the present invention, (a) is a schematic diagram of the longitudinal section structure of the longitudinal drainage pipe arrangement, (b) is a schematic diagram of the cross-section structure of the longitudinal drainage pipe arrangement; Figure 5 : is a schematic diagram of the radial drainage pipe arrangement structure in an embodiment of the present invention, (c) is a schematic diagram of the longitudinal section structure of the radial drainage pipe arrangement, and (d) is a schematic diagram of the cross-section structure of the radial drainage pipe arrangement; Figure 6 This is a schematic diagram of the water flow direction of the drainage channel in an embodiment of the present invention; Figure 7 This is a schematic diagram of a cross-sectional structure of a buffer structure layer in an embodiment of the present invention; Figure 8 Schematic diagram of the node structure of the connection between the rear baffle and the negative Poisson's ratio material in an embodiment of the present invention; Fig. 9 It is a schematic structural diagram of the working principle of the active pressure relief drainage structure in an embodiment of the present invention.

[0019] Numbers in the figure: 1, surrounding rock; 2, segment layer; 3, buffer structure layer; 301, front baffle; 302, rear baffle; 303, negative Poisson's ratio material; 4, radial drainage pipe; 5, longitudinal drainage pipe; 6, conical pedestal; 601, truncated cone; 602, pedestal; 7, plug hole; 8, circular hole. DETAILED DESCRIPTION

[0020] In order to make the present invention clearer and more understandable, the present invention is described in detail as a preferred embodiment in combination with the accompanying drawings and embodiments. It should be understood that the given embodiment is only one implementation method and does not represent all embodiments.

[0021] Example 1 Combination Figure 1-Figure 9 The present embodiment provides a shield tunnel segment structure for active pressure relief drainage in marine soft soil layer, including a plurality of segment structure units connected along the longitudinal direction of the tunnel, a surrounding rock 1 is arranged around the plurality of segment structure units, the segment structure unit includes a segment layer 2 and an active pressure relief drainage structure arranged between the segment layer 2 and the surrounding rock 1; the active pressure relief drainage structure includes a buffer structure layer 3 and a drainage channel, the buffer structure layer 3 is arranged between the segment layer 2 and the surrounding rock 1, and the drainage channel is arranged in the buffer structure layer 3.

[0022] The marine soft soil layer mainly refers to a layer with a water content of usually 40% to 100%, and even up to 200% in some areas. Because the soil particles are small and have strong water absorption capacity; the porosity range is 1.0 to 2.5, the soil is loose and highly compressible; it is mainly composed of clay and silt, and the particle diameter is usually less than 0.075mm, with high plasticity and low permeability; the marine soft soil has low shear strength, low compression modulus, small consolidation coefficient, and slow drainage and consolidation. This embodiment sets a buffer structure layer 3 on the pipe layer 2 to play a dual role of shock absorption and sealing, thereby effectively buffering the destructive effect of the load stress generated by the tunnel surrounding rock 1 on the pipe layer structure, and at the same time can effectively reduce the impact of disaster loads such as earthquakes on the tunnel pipe structure. In addition, a drainage channel is arranged in the buffer structure layer 3 to facilitate groundwater to bypass the pipe layer 2 along the reserved drainage channel, reducing the risk of pipe leakage. The buffer structure layer 3 and the drainage channel together form an active pressure relief drainage structure, which can be designed through prefabricated parts and then realized through on-site splicing. According to the needs of different projects, the active pressure relief drainage structure and materials can be redesigned by comprehensively considering the characteristics of marine soft soil strata burial and groundwater, so as to be more scientific, reasonable and accurate. The shield tunnel segment structure in this embodiment is intended to improve the stability and safety of the shield tunnel in the marine soft soil stratum.

[0023] The segment layer 2 in this embodiment is a segment structure commonly used in shield tunnels, specifically consisting of six segment pieces, namely, a top segment piece, a top left segment piece, a top right segment piece, a bottom segment piece, a bottom left segment piece and a bottom right segment piece, each of which is 1.50 m long.

[0024] The buffer structure layer 3 includes a front baffle 301, a rear baffle 302 and a negative Poisson's ratio material 303 arranged between the front baffle 301 and the rear baffle 302. One side of the rear baffle 302 is connected to the segment layer 2, and the other side of the rear baffle 302 is mechanically interlocked and fixed with the negative Poisson's ratio material 303 through an interlocking joint. When the tunnel is subjected to excessive load, the buffer structure can act like a spring, absorb energy, and reduce the impact force and stress distribution on the shield tunnel segment. At the same time, the buffer structure can also effectively fill the gap between the segment and the surrounding rock 1, prevent water from infiltrating or seeping out, and improve the waterproof performance of the tunnel. This structure can not only enhance the safety and durability of the tunnel, but also save the construction cost and maintenance cost of the tunnel.

[0025] Specifically, the negative Poisson's ratio material 303 includes a plurality of concave honeycomb structure units, the total thickness of the negative Poisson's ratio material 303 is 22 cm, and the thickness of the concave honeycomb structure unit is less than or equal to 0.5 mm. The sizes of the negative Poisson's ratio material 303, the front baffle 301, and the rear baffle 302 are consistent to ensure that they can cover the entire pipe layer. The negative Poisson's ratio material 303 will expand outward when compressed and shrink inward when stretched, and has good elasticity and plasticity. Moreover, the negative Poisson's ratio material 303 in this embodiment uses a unit with a concave honeycomb structure, which can absorb part of the energy generated by the impact, play an impact-resistant role between the tunnel pipe segment and the surrounding rock 1, and provide buffering and sealing. The negative Poisson's ratio material 303 with a concave honeycomb structure can absorb part of the energy generated by the impact, thereby improving the impact resistance of the structure. As a buffer material, when facing the deformation of marine soft soil foundation and earthquake load, when the wall thickness of the structural unit is less than or equal to 0.5 mm, the densification phenomenon can be effectively avoided, thereby maintaining the negative Poisson's ratio effect; the negative Poisson's ratio material 303 of the concave honeycomb structure can reduce the global maximum peak force, increase the buffering time, and improve the buffering efficiency; the negative Poisson's ratio material 303 of the concave honeycomb structure can effectively fill the gap between the pipe segment and the surrounding rock 1 to prevent the infiltration or seepage of water flow, thereby protecting the integrity of the pipe segment and the surrounding rock 1. In addition, the mesh of the concave honeycomb structure is filled with flexible materials such as high-elastic silicone rubber. This material has high strength and good corrosion resistance, is suitable for underground environments, and the silicone rubber core has excellent buffering and shock absorption performance.

[0026] Specifically, the interlocking joint includes a conical column 6 and a plug hole 7 that matches the number and position of the conical column 6. The conical column 6 is evenly distributed on the side wall of the rear baffle 302 in contact with the negative Poisson's ratio material 303, and the plug hole 7 is evenly distributed on the negative Poisson's ratio material 303. The interlocking joint is a joint form that realizes connection and force transmission through mechanical interlocking between the positive and negative parts. As the node structure of the specific connection point between the rear baffle 302 and the buffer material, the densely distributed anisotropic anchoring nodes on the rear baffle 302 can better fit with the negative Poisson's ratio material 303 and fully exert the buffering effect. As a preferred embodiment, in this embodiment, the interlocking joint is only set on the rear baffle and the negative Poisson's ratio material 303 that are constructed first, and the interlocking joint is no longer set between the front baffle 301 and the negative Poisson's ratio material 303 that are set close to the surrounding rock 1. This not only ensures the rapid assembly of the negative Poisson's ratio material 303, which is conducive to large-scale promotion and application, but also saves construction costs.

[0027] As a preferred embodiment of this embodiment, the conical column 6 includes a truncated cone 601 at the top and a cylindrical column 602 at the bottom, the upper and lower diameter ratio of the truncated cone 601 is 0.75-0.8, the diameter of the plug hole 7 is greater than or equal to 10% of the diameter of the cylindrical column 602, and the depth of the plug hole 7 is greater than or equal to 17% of the diameter of the conical column 6. In this embodiment, the diameter of the cylindrical column 602 is 20 mm and the height is 30 mm. The arrangement form and spacing design of the cylindrical column 602 on the rear baffle 302 can be designed to be directional matching with the structure of the negative Poisson's ratio material 303. The diameter of the plug hole 7 is designed to be 22 mm, which is slightly larger than the diameter of the cylindrical column 602 of 20 mm, leaving a gap of about 10%, and the depth is designed to be 35 mm, which is greater than the height of the cylindrical column 602 of 30 mm. In this way, a certain amount of buffer deformation space can be reserved. By making the size of the plug-in hole 7 slightly larger than the conical column base 6, not only the processing tolerance requirements are taken into consideration, but also a certain degree of compressible buffer gap is achieved. At the same time, the gap ratio is controlled to ensure the overall stiffness requirements after mechanical connection.

[0028] Specifically, the front baffle 301 and the rear baffle 302 are both rectangular curved steel plates with a thickness of 0.5 to 1.0 cm. The rear baffle 302 is arranged close to the outer surface of the initial support structure of the tunnel. The curvature of the front baffle 301 and the rear baffle 302 matches the curvature of the tunnel support structure to ensure good contact and support effects.

[0029] Specifically, the rear baffle 302 and the tube sheet layer 2 , and the front baffle 301 and the negative Poisson's ratio material 303 are all bonded and connected.

[0030] The drainage channel includes radial drainage pipes 4 and longitudinal drainage pipes 5 that are interlaced and connected to each other. The outer sides of the pipe walls of the radial drainage pipes 4 and the longitudinal drainage pipes 5 are evenly provided with a plurality of circular holes 8. The radial drainage pipes 4 are evenly arranged along the circumference of the pipe sheet layer 2, and at least one longitudinal drainage pipe 5 is arranged along the top and bottom of the tunnel. In this embodiment, one longitudinal drainage pipe 5 is arranged along the top and bottom of the tunnel.

[0031] Specifically, the drainage channel is made of PVC, with a diameter of 0.01m, the spacing between the multiple radial drainage pipes 4 is 1.50m, the diameter of the circular hole 8 is 0.01m, and the spacing between adjacent circular holes 8 is 0.50m. The tunnel includes multiple tunnel sections, each of which is composed of multiple pipe segment structure units. The drainage channels of the multiple pipe segment structure units in this embodiment are connected. When the water in the marine soft soil layer enters the buffer structure layer 3, the water in the buffer structure layer 3 can enter the drainage channel through the circular hole 8, and then be discharged from the pipe segment structure through the connected drainage channels. In this embodiment, since each pipe segment layer 2 is 1.5 meters long, each pipe segment structure unit is provided with a radial drainage pipe 4.

[0032] Preferably, along the water flow direction of the drainage channel, the output end of the drainage channel of the previous pipe segment structure unit is a convex outlet, and the input end of the drainage channel of the next pipe segment structure unit is a concave inlet. The convex outlet cooperates with the concave inlet to make the drainage channel connection of adjacent pipe segment structure units more compact.

[0033] Example 2 This embodiment provides a construction method for a shield tunnel segment structure with active pressure relief drainage in a marine soft soil layer, comprising the following steps: Step 1, prefabricating shield segments; Step 1.1, construct the pipe segment layer 2 according to the design size, the pipe segment layer 2 includes multiple pipe segment pieces, each of which is 1.50m long, and the rear baffles 302 are respectively pasted on the outer sides of the multiple pipe segment pieces. The multiple pipe segment pieces are respectively a bottom pipe segment piece, a top pipe segment piece, a bottom left pipe segment piece, a bottom right pipe segment piece, a top left pipe segment piece and a top right pipe segment piece.

[0034] Step 1.2, according to the position of each pipe segment, a radial drainage pipe 4 is installed along the outer side of the rear baffle 302 on each pipe segment, and a longitudinal drainage pipe 5 is installed along the outer side of the rear baffle 302 of the bottom pipe segment and the top pipe segment.

[0035] Step 1.3, after laying the drainage channel, fix the negative Poisson's ratio material 303 on the rear baffle 302 of each pipe segment through the interlocking joint. The negative Poisson's ratio material 303 can be quickly and accurately installed on the rear baffle 302 through the interlocking joint, which is conducive to large-scale promotion and application, and saves construction costs.

[0036] Step 1.4, after the negative Poisson's ratio material 303 is laid, the front baffle 301 is pasted on the negative Poisson's ratio material 303 of each segment to form a plurality of shield segments, namely, the bottom shield segment, the top shield segment, the bottom shield left segment, the bottom shield right segment, the top shield left segment and the top shield right segment. In this way, the buffer structure layer 3 and the drainage channel in the active pressure relief drainage structure are respectively installed on the outside of each segment to form a shield segment, which is convenient for later construction and assembly.

[0037] Step 2: assembling shield segments on site; Step 2.1: After ensuring that the size of the shield tunneling machine excavation meets the requirements for segment assembly, install the bottom shield segment first.

[0038] Step 2.2, after the installation of the bottom shield segments is completed, install the bottom shield left segment and the bottom shield right segment, and assemble the radial drainage pipes of each shield segment.

[0039] Step 2.3, install the top shield left segment and the top shield right segment, and assemble the radial drainage pipes of each shield segment.

[0040] Step 2.4, install the top shield segment, assemble the radial drainage pipes of each shield segment, and complete the assembly of a segment structure unit.

[0041] Step 2.5, after ensuring that the excavation size of the shield tunneling machine meets the installation requirements of the next segment structure unit, proceed with the installation of the next segment structure unit.

[0042] Step 2.6, install the next pipe segment structure unit according to steps 2.1-2.4, assemble the longitudinal drainage pipes between adjacent pipe segment structure units, and match the concave inlets and convex outlets of the drainage channels of adjacent pipe segment structure units to make the drainage channels of adjacent pipe segment structure units more densely connected.

[0043] This solution can effectively alleviate the impact of dynamic loads such as large burial, high groundwater level and earthquake on shield tunnel segments, prevent segment damage, gap expansion, sealing failure and other problems, and improve the safety and stability of the tunnel; at the same time, this solution can be quickly installed and fixed, is compatible with existing tunnel shield methods, and does not affect the construction progress and quality; and it adopts an active pressure-relief drainage structure composed of a buffer structure layer 3 and a drainage channel, which has good durability, impermeability, reliability and adaptability, and can adapt to different geological conditions and working environments.

[0044] The specific implementation methods described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned specific implementation methods, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned specific implementation methods can still be modified, or some of the technical features therein can be replaced by equivalents. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the specific implementation methods of the present application, and should all be included in the protection scope of the present application.

Claims

1. A segment structure of an active pressure relief drainage shield tunnel in a marine soft soil layer, comprising a plurality of segment structure units connected along the longitudinal direction of the tunnel, wherein surrounding rocks (1) are arranged around the plurality of segment structure units, and characterized in that: The segment structure unit comprises a segment layer (2) and an active pressure-relief drainage structure arranged between the segment layer (2) and the surrounding rock (1); the active pressure-relief drainage structure comprises a buffer structure layer (3) and a drainage channel, the buffer structure layer (3) being arranged between the segment layer (2) and the surrounding rock (1), and the drainage channel being arranged in the buffer structure layer (3); The buffer structure layer (3) comprises a front baffle (301), a rear baffle (302), and a negative Poisson's ratio material (303) arranged between the front baffle (301) and the rear baffle (302); one side of the rear baffle (302) is connected to the tube sheet layer (2); and the other side of the rear baffle (302) is mechanically interlocked and fixed with the negative Poisson's ratio material (303) via an interlocking joint; The drainage channel comprises radial drainage pipes (4) and longitudinal drainage pipes (5) which are interconnected and staggered, and the outer sides of the pipe walls of the radial drainage pipes (4) and the longitudinal drainage pipes (5) are evenly provided with a plurality of circular holes (8), the radial drainage pipes (4) are evenly distributed along the circumference of the pipe sheet layer (2), and at least one longitudinal drainage pipe (5) is provided along the top and bottom of the tunnel.

2. The active pressure relief drainage shield tunnel segment structure for marine soft soil layer according to claim 1 is characterized by: The negative Poisson's ratio material (303) comprises a plurality of concave honeycomb structure units, the total thickness of the negative Poisson's ratio material (303) is 22 cm, and the thickness of the concave honeycomb structure units is less than or equal to 0.5 mm.

3. The active pressure relief drainage shield tunnel segment structure for marine soft soil layer according to claim 1 is characterized by: The interlocking joint comprises a conical column (6) and a plug-in hole (7) whose number and position match the conical column (6); the conical column (6) is evenly distributed on the side wall of the rear baffle (302) in contact with the negative Poisson's ratio material (303); and the plug-in holes (7) are evenly distributed on the negative Poisson's ratio material (303).

4. The active pressure relief drainage shield tunnel segment structure for marine soft soil layer according to claim 3 is characterized by: The conical pedestal (6) comprises a truncated cone (601) at the top and a cylindrical pedestal (602) at the bottom, the ratio of the upper and lower diameters of the truncated cone (601) is 0.75, the diameter of the plug hole (7) is 10% of the diameter of the cylindrical pedestal (602), and the depth of the plug hole (7) is 17% of the diameter of the conical pedestal (6).

5. The active pressure relief drainage shield tunnel segment structure for marine soft soil layer according to claim 1 is characterized by: The front baffle (301) and the rear baffle (302) are both rectangular curved steel plates with a thickness of 0.5 to 1.0 cm. The rear baffle (302) is arranged close to the outer surface of the initial support structure of the tunnel. The curvature of the front baffle (301) and the rear baffle (302) matches the curvature of the tunnel support structure.

6. The active pressure relief drainage shield tunnel segment structure for marine soft soil layer according to claim 5 is characterized by: The rear baffle (302) and the tube sheet layer (2), as well as the front baffle (301) and the negative Poisson's ratio material (303) are all adhesively connected.

7. The active pressure relief drainage shield tunnel segment structure for marine soft soil layer according to claim 1 is characterized by: The drainage channel is made of PVC and has a diameter of 0.01 m. The spacing between the plurality of radial drainage pipes (4) is 1.50 m. The diameter of the circular holes (8) is 0.01 m, and the spacing between adjacent circular holes (8) is 0.50 m.

8. The active pressure relief drainage shield tunnel segment structure for marine soft soil layer according to claim 1 is characterized by: Along the water flow direction of the drainage channel, the output end of the drainage channel of the previous pipe segment structure unit is a convex outlet, and the input end of the drainage channel of the next pipe segment structure unit is a concave inlet, and the convex outlet matches the concave inlet.

9. The method for constructing a segment structure of an active pressure-relief drainage shield tunnel in a marine soft soil layer according to any one of claims 1 to 8, characterized in that: The steps include: Step 1, prefabricating shield segments; Step 1.1, constructing a segment layer (2) according to the design dimensions, the segment layer (2) comprising a plurality of segment pieces, each of the segment pieces being 1.50 m long, and affixing rear baffles (302) to the outer sides of the plurality of segment pieces, respectively, the plurality of segment pieces being a bottom segment piece, a top segment piece, a bottom left segment piece, a bottom right segment piece, a top left segment piece, and a top right segment piece; Step 1.2, according to the position of each segment, radial drainage pipes (4) are installed along the outer side of the rear baffle (302) on each segment, and longitudinal drainage pipes (5) are installed along the outer side of the rear baffle (302) of the bottom segment and the top segment; Step 1.3, after the drainage channel is laid, the negative Poisson's ratio material (303) is respectively fixed on the rear baffle (302) of each pipe segment through an interlocking joint; Step 1.4, after the negative Poisson's ratio material (303) is laid, a front baffle (301) is pasted on the negative Poisson's ratio material (303) of each segment to form a plurality of shield segments, namely, a bottom shield segment, a top shield segment, a bottom shield left segment, a bottom shield right segment, a top shield left segment, and a top shield right segment; Step 2: assembling shield segments on site; Step 2.1: After ensuring that the size of the shield tunneling machine meets the requirements for segment assembly, install the bottom shield segment first; Step 2.2, after the installation of the bottom shield segment is completed, install the bottom shield left segment and the bottom shield right segment, and assemble the radial drainage pipes of each shield segment; Step 2.3, installing the top shield left segment and the top shield right segment, and assembling the radial drainage pipes of each shield segment; Step 2.4, installing the top shield segment, assembling the radial drainage pipes of each shield segment, and completing the assembly of a segment structure unit; Step 2.5, after ensuring that the excavation size of the shield tunneling machine meets the installation requirements of the next segment structure unit, install the next segment structure unit; Step 2.6, install the next segment structure unit according to steps 2.1-2.4, and assemble the longitudinal drainage pipes between adjacent segment structure units.

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