Water-enriched fractured stratum shield wall post-grouting layer anti-scour structure and construction method

Abstract

This invention relates to the field of shield tunnel technology, and more particularly to a scour-resistant structure and construction method for the grouting layer behind the shield tunnel wall in water-rich fractured strata. The structure includes diversion piles, composite segments, and a guide pipe. A ground reinforcement zone is formed by reinforcing the water-rich fractured strata, with the diversion piles arranged intersectingly on the upper side of the reinforcement zone. The composite segments include a segment body and a sump. The sump is located on the outside of the segment body, and after grouting, a water-guiding channel is formed between adjacent sumps. A drainage channel communicating with the water-guiding channel is provided within the segment body. The guide pipe is installed on the segment body, with water-guiding holes on its wall and drainage holes at its end, located at the water-guiding channel. This invention achieves integrated external water interception and pressure relief, internal diversion and drainage, and scour-resistant protection with the sump, weakening the scour effect of groundwater on the grouting layer behind the wall, inhibiting scour and deterioration of the grouting layer, and improving the long-term operational stability of shield tunnels in water-rich fractured strata.

Description

Technical Field

[0001] This invention relates to the field of shield tunnel technology, and in particular to an anti-scour structure and construction method for a grouting layer behind the shield wall in water-rich fractured strata. Background Technology

[0002] Grouting behind the tunnel wall is a crucial step in segment lining construction. During shield tunneling, after the shield tail exits, an annular gap forms between the outer perimeter of the segment and the ground. Cement-based grout or a two-component grout must be injected into this gap promptly. After the grout solidifies, a grouting layer is formed behind the wall, thus constraining segment displacement and bearing the load of the surrounding rock. In water-rich, fractured strata, groundwater conditions are complex, fracture channels are well-developed and highly interconnected, groundwater levels are often high, and seepage paths are diverse.

[0003] Currently, conventional shield tunneling backfill grouting construction mainly relies on the hydraulic and viscosity properties of the grout material itself to resist the dilution and erosion of groundwater. During construction, the grout is injected into the surrounding rock voids through pre-reserved grouting holes in the tunnel lining segments. The cement particles in the grout gradually hydrate and solidify in still or low-flow-velocity environments, eventually forming a stone body with a certain strength. However, under dynamic water conditions, the grout that has not yet solidified is easily dispersed by seepage from fissures, resulting in grout loss and incomplete grouting. Even after the grout has solidified, continuous groundwater runoff will still cause long-term erosion of the grouted stone body, leading to the gradual delamination of the grouting layer. To address the groundwater seepage problem, some existing projects also adopt grouting sealing methods, which involve injecting quick-setting grout into the surrounding rock fissures to form a water-stop curtain, attempting to block groundwater from the outside of the grouting layer.

[0004] When using conventional grouting layer anti-scour schemes, the retention capacity of grout materials in dynamic water environments is limited, and the actual scour resistance of the grouted rock mass is insufficient to meet long-term service requirements, easily leading to structural deterioration during the operational period. Once the grouting layer detaches, the load distribution of the surrounding rock outside the tunnel segments will change, increasing local stress on the segments and potentially inducing structural defects such as segment uplift, joint misalignment, and tunnel leakage. Conversely, when groundwater is blocked by sealing methods, the complete interruption of groundwater flow paths results in high pore water pressure accumulating in the area behind the grouting layer. This high-pressure water continuously erodes weak points in the grouting layer structure, causing secondary detachment. These problems are particularly prominent in water-rich, fractured strata, hindering the long-term operational safety of shield tunnels. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a construction scheme for scour-resistant grouting layer behind shield tunnel walls in water-rich fractured strata that can overcome the aforementioned defects. Through structural optimization and improvement of construction procedures, the long-term stability of the grouting layer in complex water environments is enhanced.

[0006] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions: In a first aspect, embodiments of the present invention provide a scour-resistant structure for the grouting layer behind the shield wall in water-rich fractured strata, comprising: diversion piles, composite segments, and diversion pipes; A ground reinforcement zone is formed by reinforcing the water-rich and fractured strata along the outer side of the shield tunnel excavation outline, and the diversion piles are arranged in a cross pattern on the upper side of the ground reinforcement zone. The composite segment penetrates the formation reinforcement zone and includes a segment body and a bladder. The bladder is located on the outside of the segment body. The segment body has grouting holes that communicate with the bladder. After grouting, a water guide groove is formed between adjacent bladders. A drainage groove that communicates with the water guide groove is provided inside the segment body. The guide pipe is installed on the pipe body, and a water guide hole is provided on the pipe wall. A drain hole is provided at the end of the pipe wall. The water guide hole and the drain hole are connected through the pipe cavity. The drain hole is located at the water guide groove.

[0007] As a further technical solution, the water guiding channel is annular and distributed radially along the outside of the segment body. The guide pipe is located on the upper part of the segment body, where the upper part refers to the position above the middle interface of the segment body.

[0008] As a further technical solution, the guide tube is arranged in multiple rows, with multiple tubes in each row, and the axis of the guide tube is at a set angle to the axis of the tube body.

[0009] As a further technical solution, the inner end of the guide tube has a threaded section, which is installed in the tube body and is fitted with a water-swellable rubber strip. The drain hole is located on the upper side of the threaded section.

[0010] As a further technical solution, a one-way check valve is installed inside the guide tube. The one-way check valve can open the guide tube in the inward-outward direction and close the guide tube in the outward-inward direction.

[0011] As a further technical solution, the inner bottom of the segment body has a track bed, the drainage trough is set at the bottom of the track bed, the bottom of the segment body is provided with a drainage pipe, the drainage pipe is connected to the water guide trough and the drainage trough, and the water guide hole, the cavity, the drainage hole of the water guide pipe, the water guide trough on the outside of the segment body, the drainage pipe in the segment body, and the drainage trough on the inner side of the segment body constitute a drainage path.

[0012] As a further technical solution, the installation position of the bag is staggered from the joint of the segment body assembly, and the bag as a whole spans across both sides of the joint of the segment body.

[0013] As a further technical solution, the bag is made of polyester filament woven molded bag fabric, and the sides of the bag are provided with rubber-impregnated polyester composite edge protectors.

[0014] As a further technical solution, water diversion holes are provided on the outer wall of the diversion pile, and the inside of both the diversion pile and the guide pipe is filled with permeable particles.

[0015] Secondly, embodiments of the present invention also provide a construction method for an anti-scour structure of a grouting layer behind a shield tunnel wall in water-rich fractured strata, comprising the following steps: Comprehensive exploration was conducted on the water-rich fractured strata in the construction section to obtain the location, size, stratum parameters, and groundwater parameters of the fractures. Based on this, the scope of stratum reinforcement, the location of diversion piles, the depth of diversion piles, and the layout scheme of composite segments and diversion pipes were determined. Grouting is carried out along the outer side of the shield tunnel excavation outline into the water-rich and fractured strata to form a stratum reinforcement zone; According to the determined diversion pile layout locations, diversion piles are constructed in the strata outside the shield tunnel excavation outline. The diversion piles are filled with permeable particles and have water diversion holes reserved on the outer wall. The diversion piles are arranged in a cross pattern and at set intervals. After the diversion piles are completed, the shield tunnel is excavated, and the excavation outline is expanded outward by a set distance. During the tunnel boring process, composite segments are assembled. The composite segments include a segment body and a bag set on the outside of the segment body. When the bag is not grouted, it remains in a closed state and fits against the outer wall of the segment body. A water guide groove is formed between adjacent bags. A guide pipe is installed on the segment body. The guide pipe has a water guide hole on its wall and a drain hole at its end. The guide pipe is connected to the reserved opening in the segment body, so that the water guide hole is located in the stratum outside the segment body and the drain hole is located at the water guide groove. Grout is injected into the bladder through grouting holes opened on the segment body. During the grouting process, the bladder expands outward, and after the grouting is completed, a backfill stone layer is formed.

[0016] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages: The anti-scour structure for the grouting layer behind the shield tunnel wall in water-rich fractured strata provided by this invention intercepts and drains groundwater from the surrounding area through diversion piles, diverting most of the groundwater runoff and reducing the impact force of the water flow, thereby mitigating the scouring and erosion effect of groundwater on the grouting layer from the source. Residual seepage water is drained through diversion pipes and drainage channels, releasing water pressure and further reducing the scouring impact of groundwater on the grouting layer. The grouting stone body is encased in a composite bag structure, isolating the grouting consolidation layer from direct scouring by high-speed groundwater, thus physically establishing an anti-scour protective barrier. The synergistic effect of the diversion piles, diversion pipes, and bags achieves integrated external water interception and pressure relief, internal drainage, and scour protection, weakening the scouring effect of groundwater on the grouting layer behind the wall, protecting the integrity of the grouting stone body, inhibiting scouring and deterioration of the grouting layer, preventing segment floating defects, and improving the long-term operational stability of shield tunnels in water-rich fractured strata.

[0017] Advantages of additional aspects of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In addition, the dimensions or spacing between the components are exaggerated to show the position of each component, and the schematic diagrams are for illustrative purposes only.

[0019] Figure 1 This is an overall schematic diagram of the structure of the present invention; Figure 2 This is a diagram showing the arrangement of diversion piles according to the present invention; Figure 3 This is a schematic diagram of the diversion pile of the present invention; Figure 4 This is a front elevation view of the present invention; Figure 5 This is a schematic diagram showing the angle between the guide tube and the tube body of the present invention; Figure 6 This is a schematic diagram of the composite tube sheet of the present invention (only one bladder is shown). Figure 7 This is a schematic diagram of the overall flow guide tube of the present invention; In the diagram: 1. Diversion pipe; 2. Water diversion channel; 3. Segment body; 4. Grouting hole; 5. Bag; 6. Drainage channel; 7. Track bed; 8. Diversion pile; 9. Composite segment; 10. Drainage pipe; 11. Ground reinforcement zone; 12. Composite edge protection; 13. Water diversion hole; 14. Permeable particles; 15. Drainage hole; 16. One-way check valve; 17. Threaded section; 18. Water-swellable rubber strip; 19. Water diversion hole; Detailed Implementation To more clearly illustrate the technical solutions of the embodiments in this specification, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this specification. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the linguistic context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0020] Generally speaking, the terms "comprising" and "including" only indicate that the steps and elements are explicitly identified, and these steps and elements do not constitute an exclusive list. The method or apparatus may also include other steps or elements.

[0021] Example 1 This disclosure provides a typical embodiment of an anti-scour structure for the grouting layer behind the shield tunnel wall in water-rich fractured strata. This structure is mainly applied to shield tunnel projects in water-rich fractured strata. In such strata, groundwater occurrence conditions are complex, fracture channels are well-developed and highly interconnected, groundwater levels are often high, and seepage paths are diverse. Conventional shield tunnel wall grouting construction mainly relies on the hydraulic and viscosity properties of the grout material itself to resist the dilution and erosion of groundwater. However, under dynamic water conditions, the grout that has not yet solidified is easily dispersed by fracture seepage. Even after the grout solidifies, continuous groundwater runoff will still cause long-term erosion of the grouting stone body, leading to the gradual delamination of the grouting layer. In response to the groundwater seepage problem, existing projects have also adopted grouting sealing methods. However, after completely cutting off the groundwater runoff path, high pore water pressure will accumulate in the rear area of ​​the grouting layer. High-pressure water will continuously erode the weak points of the grouting layer structure, leading to secondary delamination of the grouting layer. Therefore, this embodiment provides an anti-scouring structure for the grouting layer behind the shield wall in water-rich fractured strata.

[0022] like Figure 1 , Figure 2As shown, the scour-resistant structure of the grouting layer behind the shield tunnel wall in water-rich fractured strata includes diversion piles 8, composite segments 9, and a guide pipe 1. A stratum reinforcement zone 11 is formed by reinforcing the water-rich fractured strata along the outer side of the shield tunnel excavation outline. The diversion piles 8 are arranged intersectingly on the upper side of the stratum reinforcement zone 11. The composite segments 9 penetrate the stratum reinforcement zone 11 and include a segment body 3 and a bladder 5. The bladder 5 is located on the outer side of the segment body 3. Grouting holes 4 communicating with the bladder 5 are opened on the segment body 3. After grouting, a water-guiding channel 2 is formed between adjacent bladders 5. A drainage channel 6 communicating with the water-guiding channel 2 is provided inside the segment body 3. The guide pipe 1 is installed on the segment body 3. Water-guiding holes 13 are provided on the pipe wall of the guide pipe 1, and a drainage hole 15 is provided at the end of the pipe wall. The water-guiding holes 13 and the drainage hole 15 are connected through a pipe cavity. The drainage hole 15 is located at the water-guiding channel 2.

[0023] In this embodiment, the diversion piles 8 serve to intercept and guide water from the periphery, inhibiting the intrusion of groundwater into the reinforced area and keeping the reinforced area relatively dry, thereby reducing the scouring load on the internal grouting layer. The diversion piles 8 are arranged crosswise on the upper side of the reinforced area 11, which can more comprehensively cover the direction of incoming water and improve the water interception effect.

[0024] The composite segment 9 is a composite component combining the segment body 3 and the bladder 5. The bladder 5 is located on the outside of the segment body 3. Before grouting, the bladder 5 is in a closed state and adheres to the outer wall of the segment. During grouting, grout is injected into the bladder 5 through the grouting holes 4 on the segment body 3, causing the bladder 5 to expand outwards. After grouting, the bladder 5 encapsulates the grouting material, forming a backfill grouting stone layer that protects the internal grouting stone body and prevents groundwater from directly eroding the grouting material. Simultaneously, the gaps between adjacent bladders 5 form a water-guiding channel 2 after grouting, providing a flow channel for seepage. A drainage channel 6, connected to the water-guiding channel 2, is installed inside the segment body 3 to further discharge the seepage collected in the water-guiding channel 2.

[0025] The diversion pipe 1 is installed on the pipe segment body 3. The water guide hole 13 on the pipe wall is used to collect residual seepage water from the surrounding rock side. The seepage water enters the cavity of the diversion pipe 1 through the water guide hole 13, and then flows into the water guide channel 2 through the drain hole 15 at the end of the pipe wall, and finally flows into the drainage channel 6 for discharge. The drain hole 15 of the diversion pipe 1 is located at the water guide channel 2 to ensure a smooth drainage path.

[0026] The diversion pile 8 intercepts and drains the surrounding groundwater, the diversion pipe 1 and the water diversion channel 2 divert residual seepage water, and the bag 5 acts as an anti-erosion protective barrier to wrap the grouting stone body. The three work together to reduce the erosion force from the source and set up an anti-erosion protective barrier to prevent the grouting layer from being eroded, deteriorated and failed.

[0027] The water diversion channel 2 is annular and distributed radially along the outer side of the tunnel segment 3. The diversion pipe 1 is located at the upper part of the tunnel segment 3, which refers to the position above the middle interface of the tunnel segment 3. Setting the water diversion channel 2 as annular and radially distributed allows seepage water to form a circumferential collection channel on the outer side of the tunnel segment 3, facilitating the unified collection of seepage water from all directions. The diversion pipe 1 is located at the upper part of the tunnel segment 3 because groundwater is more likely to seep in from the upper part under gravity. Placing the diversion pipe 1 at the upper part allows for more effective collection of residual seepage water, and its placement at the upper part facilitates timely release of water pressure.

[0028] like Figure 4 , Figure 5 As shown, the diversion pipes 1 are arranged in multiple rows, with multiple pipes in each row, and the axis of the diversion pipes 1 forms a set angle with the axis of the tunnel segment body 3. Arranging multiple rows and multiple pipes 1 increases the drainage coverage and drainage capacity. The diversion pipes 1 are arranged at an angle rather than vertically, allowing them to cover a larger area on the upper side of the tunnel segment body 3, thus diverting as much seepage water as possible from above the segment. The diversion pipes 1 also act as radial anchoring components for the tunnel segment; when arranged at an angle, multiple rows and multiple pipes 1 can provide anchoring constraints on the tunnel segment body 3 and the formation from multiple directions, improving formation stability.

[0029] like Figure 7 As shown, the inner end of the diversion pipe 1 has a threaded section 17, which is installed in the segment body 3. The threaded section 17 is fitted with a water-swellable rubber strip 18, and a drainage hole 15 is located on the upper side of the threaded section 17. The diversion pipe 1 uses high-rigidity rigid pipe material, serving not only as a drainage channel but also as a radial anchoring component for the segment, improving formation stability. The threaded section 17 securely connects the diversion pipe 1 to the pre-reserved opening in the segment body 3, forming an integral connection between the diversion pipe 1 and the segment body 3. The water-swellable rubber strip 18 expands upon contact with groundwater, effectively preventing groundwater and sediment from seeping into the segment through the gap between the diversion pipe 1 and the segment, thus providing a sealing effect. The drainage hole 15, located on the upper side of the threaded section 17, allows seepage water to drain out through the drainage hole 15 without entering the segment body 3. The interior of the diversion pipe 1 is filled with permeable particles 14, achieving water permeability and conduction through the gaps between the particles, while also enhancing the radial stiffness of the diversion pipe 1. The permeable particles 14 can be made of quartz sand. The gaps between the quartz sand particles can ensure water permeability and have high compressive strength, which can keep the water passage of the pipe cavity from being blocked under the pressure of the surrounding rock.

[0030] Furthermore, a one-way check valve 16 is installed inside the diversion pipe 1. The one-way check valve 16 can facilitate the inward-outward axial direction of the diversion pipe 1 and block the outward-inward axial direction. The one-way check valve 16 can prevent water from flowing back into the strata inside the tunnel, ensuring the one-way nature of the drainage system. In the later maintenance stage, high-pressure water can be reversed through the one-way check valve 16 to flush the inside of the diversion pipe 1, remove calcium ion scale and sediment deposits, unclog the water passage of the diversion pipe 1, prevent drainage channel blockage, and extend the service life of the structure.

[0031] The inner bottom of the tunnel segment 3 has a track bed 7, and a drainage trough 6 is located at the bottom of the track bed 7. A drainage pipe 10 is installed at the bottom of the tunnel segment 3, and the drainage pipe 10 is connected to the water guide trough 2 and the drainage trough 6. The water guide hole 13, the cavity, and the drainage hole 15 of the guide pipe 1, along with the water guide trough 2 on the outside of the tunnel segment 3, the drainage pipe 10 in the tunnel segment 3, and the drainage trough 6 on the inside of the tunnel segment 3, constitute the drainage path. The track bed 7 is the basic structure at the bottom of the tunnel. The drainage trough 6 is located at the bottom of the track bed 7 to facilitate the centralized discharge of collected seepage water. The drainage pipe 10 is connected to the water guide trough 2 and the drainage trough 6 to form a complete drainage path: residual seepage water from the surrounding rock side enters the cavity of the guide pipe 1 through the water guide hole 13, is discharged into the water guide trough 2 through the drainage hole 15, collects at the bottom of the tunnel segment through the water guide trough 2, and is led out through the drainage pipe 10 into the drainage trough 6 inside the tunnel segment. The entire drainage path forms a directional water guide channel from the surrounding rock to the inside of the tunnel inside the tunnel segment 3, realizing the orderly drainage of residual seepage water.

[0032] like Figure 6 As shown, the installation position of the bag 5 is staggered from the joint of the segment body 3, and the bag 5 is straddled on both sides of the joint of the segment body 3. By staggering the installation position of the bag 5 from the joint of the segment body 3 and straddling both sides of the joint, the opening and displacement deformation of the segment joint are suppressed, and the joint support stiffness is improved.

[0033] The grout bag 5 is made of polyester filament woven fabric, with rubber-impregnated polyester composite edge protectors 12 on its sides. The polyester filament woven fabric itself has excellent tensile strength, tear resistance, and water erosion resistance. After grouting, the fabric constrains the grout material, preventing groundwater from directly eroding the internal grout-formed stone. The rubber-impregnated polyester composite edge protectors 12 reinforce and seal the sides of the grout bag 5, improving its resistance to erosion and abrasion, and preventing water erosion from damaging the grout layer behind the wall. When polyester filament woven fabric is used for the grout bag 5, cement solid particles are trapped inside during grouting, increasing the density and strength of the grout-formed stone inside the grout bag 5.

[0034] like Figure 3 , Figure 7As shown, a water inlet hole 19 is provided on the outer wall of the diversion pile 8, and both the diversion pile 8 and the guide pipe 1 are filled with permeable particles 14. The water inlet hole 19 on the outer wall of the diversion pile 8 is used to collect surrounding groundwater and allow it to enter the interior of the diversion pile 8. The permeable particles 14 filling the interior of the diversion pile 8 achieve water permeability and conduction through the gaps between the particles, guiding the groundwater to the outside. The permeable particles 14 filling the interior of the diversion pile 8 and the guide pipe 1 can both be made of quartz sand. The gaps between the quartz sand particles ensure both water permeability and high compressive strength, which can keep the water passage unblocked under the pressure of the surrounding rock.

[0035] Example 2 This embodiment provides a construction method for an anti-scour structure of a grouting layer behind a shield tunnel wall in water-rich fractured strata, including the following steps.

[0036] Comprehensive exploration was conducted on the water-rich fractured strata of the construction section to obtain information on fracture location, fracture size, strata parameters, and groundwater parameters. Based on this, the scope of strata reinforcement, the location and depth of diversion piles 8, and the layout scheme of composite segments 9 and diversion pipe 1 were determined. The comprehensive exploration combined ground-penetrating radar and borehole drilling to accurately determine the location and size of fractures, record key strata and groundwater parameters, provide a basis for subsequent construction, and plan the layout scheme of composite segments 9 and diversion pipe 1.

[0037] Grouting reinforcement is carried out along the outer side of the shield tunnel excavation outline towards the water-rich fractured strata, forming a stratum reinforcement zone 11. Stratum grouting reinforcement can inject grouting material into the fractures to pre-consolidate the loose fractured strata, seal some small fractures, reduce disordered groundwater seepage, and at the same time provide a stable stratum foundation for the subsequent installation of diversion piles 8 and composite segments 9.

[0038] According to the determined layout of the diversion piles 8, diversion piles 8 are constructed within the stratum surrounding the shield tunnel excavation outline. The interior of each diversion pile 8 is filled with permeable particles 14, and water inlets 19 are pre-reserved on its outer wall. The diversion piles 8 are arranged in a crisscross pattern at predetermined intervals. The diversion piles 8 form an effective external interception and water diversion channel. External groundwater is diverted to the outside through the diversion piles 8, reducing the intrusion of groundwater into the reinforced area behind the tunnel wall and keeping the reinforced area relatively dry. After the construction of the diversion piles 8 is completed, a pumping test can be conducted to verify the water diversion and interception effect of the diversion piles 8.

[0039] After the diversion pile 8 is completed, the shield tunnel is excavated. The excavation outline is expanded outward by a set distance to reserve space for the expansion and deformation of the grouting bag 5 and for grouting filling. During the excavation process, water inflow points are promptly identified and groundwater flow changes are monitored. After excavation, loose rocks and debris on the surrounding rock wall are cleaned to ensure a smooth wall surface.

[0040] During tunnel boring machine (TBM) excavation, composite segments 9 are assembled. Each composite segment 9 includes a segment body 3 and pockets 5 positioned on the outside of the segment body 3. Before grouting, the pockets 5 remain closed and adhere to the outer wall of the segment body 3, forming a water-guiding groove 2 between adjacent pockets 5. After segment assembly, temporary supports are installed to ensure the positional accuracy of the segment rings. The pockets 5 are installed at staggered positions relative to the segment assembly joints, spanning both sides of the joint. After grouting, the pockets 5 provide cross-joint support.

[0041] A guide pipe 1 is installed on the tunnel segment 3. The guide pipe 1 has a water-guiding hole 13 on its wall and a drainage hole 15 at its end. The guide pipe 1 is connected to a pre-reserved opening in the tunnel segment 3, with the water-guiding hole 13 located in the formation outside the tunnel segment 3 and the drainage hole 15 located at the water-guiding channel 2. The guide pipe 1 is made of a high-rigidity material and also acts as a radial anchoring component for the tunnel segment, improving formation stability. Water-permeable particles 14 are filled inside the guide pipe 1, maintaining permeability through the gaps between the particles and simultaneously increasing the radial stiffness of the guide pipe 1. The guide pipe 1 has a threaded section 17 and a water-swellable rubber strip 18, which are connected to the pre-reserved opening in the tunnel segment 3 to form a whole, preventing seepage into the tunnel segment through the gaps. A one-way check valve 16 is installed at the inner end of the guide pipe 1. Residual seepage water from the surrounding rock side enters the cavity of the guide pipe 1 through the guide hole 13, and then flows into the guide channel 2 through the drainage hole 15. It then collects at the bottom of the segment through the guide channel 2 and is led out through the drainage pipe 10 into the drainage channel 6 inside the segment.

[0042] Grout is injected into the bladder 5 through the grouting holes 4 on the tunnel segment 3. During the grouting process, the bladder 5 expands outward, forming a backfill stone layer after grouting. The grout can be an anti-dispersion cement-based paste grout, which is injected into the bladder 5 through the grouting holes 4 inside the tunnel segment. During the grouting and pressurization process, the bladder 5 expands outward, and the polyester filament woven molded bag cloth restrains the grout to form the backfill stone layer. Rubber-impregnated polyester composite edge protector 12 protects the sides of the bladder 5. After grouting until the bladder 5 is full and the gaps are filled tightly, curing is carried out. After the grout reaches the design strength, the diversion pile 8 and the drainage system of water guide channel 2-drainage pipe 1-drainage channel 6 are continuously maintained to complete the construction of preventing the backfill stone layer of the shield tunnel in water-rich fractured strata from erosion and deterioration.

[0043] Specific process: (1) Stratigraphic exploration: A combination of ground-penetrating radar and borehole exploration is used to conduct comprehensive exploration of the water-rich fractured strata in the construction section, to determine the location and scale of fracture development, record key parameters of strata and groundwater, determine the scope of strata reinforcement, the location and depth of diversion pile 8, and plan the layout scheme of composite segment 9 and diversion pipe 1, so as to provide a basis for subsequent shield tunneling construction.

[0044] (2) Ground reinforcement: Grouting reinforcement is carried out along the outer side of the shield tunnel excavation outline to the water-rich fissured strata. Grouting material is injected into the fissures to form ground reinforcement zone 11, which pre-consolidates the loose fissured strata, seals some small fissures, reduces disorderly groundwater seepage, and provides a stable ground foundation for the subsequent installation of diversion piles 8 and composite segments 9.

[0045] (3) Setting up diversion piles 8: According to the location determined by the detection, diversion piles 8 are constructed in the stratum outside the shield tunnel excavation outline. The inside of the diversion piles 8 is filled with permeable quartz sand particles 14, and water diversion holes 19 are reserved on the outer wall. The diversion piles 8 are arranged at 5m intervals and cross each other. The groundwater in the outer perimeter is introduced to the outside through the diversion piles 8 to form an external interception and water diversion channel; to reduce the intrusion of groundwater into the reinforced area behind the wall, and to keep the reinforced area relatively dry as much as possible. After the construction of the diversion piles 8 is completed, a water pumping test is carried out to check the water diversion and interception effect of the diversion piles 8.

[0046] (4) Tunnel excavation and expansion by 10cm: After the diversion pile 8 is completed for water diversion and pressure relief and the stratum is reinforced, the shield tunnel excavation operation is carried out. The excavation outline is expanded outward by 10cm to reserve space for the expansion and deformation of the bag 5 and grouting filling. During the excavation process, water inflow points are checked in a timely manner and the changes in groundwater flow are monitored. After excavation, loose rocks and debris on the surrounding rock wall are cleaned to ensure that the wall surface is flat.

[0047] (5) Installation of composite segment 9: Composite segment 9 is assembled during shield tunneling; Composite segment 9 is a composite component consisting of segment body 3 and high-strength polyester filament woven bag 5; When the bag 5 is not grouted, it remains in a closed state and adheres to the outer wall of the segment, and a guide channel is formed between the bags 5; The installation position of the bag 5 is staggered from the segment assembly joint, and the bag 5 spans across both sides of the segment joint; Grouting holes 4 are provided on the segment, and after the bag 5 is filled with grout, it can achieve joint cross-joint support, improve the joint support rigidity, and at the same time, the bag 5 wraps the grouting material to protect the grouting stone body, block the groundwater from directly scouring the grouting layer behind the wall, and relieve the concentrated stress of the bag 5 at the joint. The outer layer of the bladder bag 5 is made of high-strength polyester filament woven molded bag fabric. The sides of the bladder bag 5 are provided with rubber-impregnated polyester composite edge protectors 12 to prevent groundwater flow from eroding the bladder bag 5 and causing deterioration of the grouting layer behind the wall. After the segments are assembled, temporary supports are provided for fixation to ensure the positional accuracy of the segment rings.

[0048] (6) Setting up a diversion pipe 1: Select a pipe with high rigidity as the diversion pipe 1, which also serves as a radial anchoring component for the pipe segment to improve the stability of the formation; fill the cavity of the diversion pipe 1 with permeable quartz sand particles 14, rely on the gaps between the particles to maintain the permeability, and at the same time improve the radial rigidity of the diversion pipe 1; reserve drainage holes 15 in the pipe wall, and install a one-way check valve 16 at the inner end of the diversion pipe 1; set up a threaded section 17 and a water-swellable rubber strip 18 in the diversion pipe 1, and connect it to the reserved opening in the pipe segment body 3 to form a whole, so as to prevent seepage water from seeping into the pipe segment along the gap; after the residual seepage water on the surrounding rock side enters the cavity of the diversion pipe 1 through the water guide hole 13, it is discharged into the water guide channel 2 through the drainage hole 15, and is collected to the bottom of the pipe segment through the water guide channel 2, and is led out through the drainage pipe 10 into the drainage channel 6 inside the pipe segment. During later maintenance, high-pressure water can be introduced in reverse through the one-way check valve 16 to flush the cavity of the guide pipe 1, flushing away calcium ion scale and silt deposits, and preventing blockage of the drainage channel.

[0049] (7) Grouting: Inject anti-dispersion cement-based paste grout into the bladder 5. The grouting material is injected into the bladder 5 through the grouting hole 4 inside the segment. During the grouting and pressurization process, the bladder 5 expands outward. The high-strength polyester filament woven bladder 5 constrains the grouting material to form a back wall grouting stone layer. The rubber-impregnated polyester composite edge protector 12 protects the side of the bladder 5. Grouting is carried out until the bladder 5 is full and the gaps are filled tightly. After the grouting is completed, curing is carried out. When the grouting body reaches the design strength, the drainage system of the diversion pile 8, water guide channel 2-drainage pipe 1-drainage channel 6 is continuously maintained to complete the construction of preventing the back wall grouting layer from being eroded and deteriorated in the shield tunnel of water-rich fissure strata.

[0050] By employing geological exploration, geological reinforcement, external water diversion piles (8), special slab bags (5) for composite segment support (9), and internal water diversion and pressure relief via diversion pipes (1) and water diversion channels (2), the system integrates external water interception and pressure relief, internal drainage, and scour protection via slab bags (5). This weakens the scouring effect of groundwater on the grouting layer behind the wall, protects the integrity of the grouting stone body, inhibits the scouring, deterioration, and voiding of the grouting layer, avoids segment floating defects, and improves the long-term operational stability of shield tunnels in water-rich and fissured strata.

[0051] In summary, the present invention has the following advantages: (1) Internal and external coordinated water diversion to reduce scouring force: the outer diversion pile 8 serves as an external water diversion to divert most of the groundwater runoff and reduce the impact force of the water flow; the internal diversion pipe 1, combined with the water diversion channel 2, diverts residual seepage water and releases water pressure, thereby reducing the scouring and erosion effect of groundwater on the grouting layer from the source of power.

[0052] (2) The composite structure of the bag 5 has excellent anti-erosion protection effect: the composite pipe segment 9 integrates the bag 5. The base of the bag 5 is made of high-strength polyester filament woven molded bag cloth, which is tensile and tear resistant and water flow erosion resistant; the side rubber impregnated polyester composite edge protector 12 strengthens the impact and wear resistance of the side of the bag 5 and protects the integrity of the grouting layer.

[0053] (3) Multifunctional reuse of components: The diversion pipe 1 is made of high-rigidity hard pipe material, which not only serves as a drainage channel, but also acts as a radial anchoring component for the pipe segment, thereby improving the stability of the formation.

[0054] (4) Good long-term stability: It combines water diversion and pressure relief with physical barrier protection, rather than simply blocking groundwater, reducing the risk of damage from high-pressure water accumulation, inhibiting the scouring and deterioration of the grouting layer, and reducing the cost of repair and maintenance of later defects.

[0055] (5) The 5-bag is arranged across the joint, and the support effect at the joint is significant: the 5-bag and the segment assembly joint are staggered and cross the joint on both sides. After the 5-bag is filled with grout, it can form obvious cross-joint support constraint on the segment joint position, and suppress the segment joint opening, misalignment and deformation.

[0056] While the specific embodiments of the present invention have been described above, they are not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A scour-resistant structure for the grouting layer behind the shield tunnel wall in water-rich fractured strata, characterized in that, include: Diversion piles, composite segments, and guide pipes; A ground reinforcement zone is formed by reinforcing the water-rich and fractured strata along the outer side of the shield tunnel excavation outline, and the diversion piles are arranged in a cross pattern on the upper side of the ground reinforcement zone. The composite segment penetrates the formation reinforcement zone and includes a segment body and a bladder. The bladder is located on the outside of the segment body. The segment body has grouting holes that communicate with the bladder. After grouting, a water guide groove is formed between adjacent bladders. A drainage groove that communicates with the water guide groove is provided inside the segment body. The guide pipe is installed on the pipe body, and a water guide hole is provided on the pipe wall. A drain hole is provided at the end of the pipe wall. The water guide hole and the drain hole are connected through the pipe cavity. The drain hole is located at the water guide groove.

2. The anti-scour structure of the grouting layer behind the shield wall in water-rich fractured strata as described in claim 1, characterized in that, The water guide channel is annular and distributed radially along the outside of the segment body. The guide pipe is located on the upper part of the segment body, which refers to the position above the middle interface of the segment body.

3. The anti-scour structure of the grouting layer behind the shield tunnel wall in water-rich fractured strata as described in claim 2, characterized in that, The guide tubes are arranged in multiple rows, with multiple tubes in each row, and the axis of the guide tubes is at a set angle to the axis of the tube body.

4. The anti-scour structure of the grouting layer behind the shield wall in water-rich fractured strata as described in claim 1, characterized in that, The inner end of the guide tube has a threaded section, which is installed in the tube body and is fitted with a water-swellable rubber strip. The drain hole is located on the upper side of the threaded section.

5. The anti-scour structure of the grouting layer behind the shield tunnel wall in water-rich fractured strata as described in claim 1, characterized in that, A one-way check valve is installed inside the guide tube. The one-way check valve can open the guide tube in the inward-outward direction and close the guide tube in the outward-inward direction.

6. The anti-scour structure of the grouting layer behind the shield wall in water-rich fractured strata as described in claim 1, characterized in that, The inner bottom of the segment body has a track bed, the drainage trough is set at the bottom of the track bed, and the bottom of the segment body is provided with a drainage pipe. The drainage pipe is connected to the water guide trough and the drainage trough. The water guide hole, the cavity, the drainage hole of the water guide pipe, the water guide trough on the outside of the segment body, the drainage pipe in the segment body, and the drainage trough on the inner side of the segment body constitute a drainage path.

7. The anti-scour structure of the grouting layer behind the shield tunnel wall in water-rich fractured strata as described in claim 1, characterized in that, The installation position of the bag is staggered from the joint of the segment body assembly, and the bag as a whole spans across both sides of the joint of the segment body.

8. The anti-scour structure of the grouting layer behind the shield tunnel wall in water-rich fractured strata as described in claim 1, characterized in that, The bag is made of polyester filament woven molded bag fabric, and the sides of the bag are provided with rubber-impregnated polyester composite edge protectors.

9. The anti-scour structure of the grouting layer behind the shield tunnel wall in water-rich fractured strata as described in claim 1, characterized in that, The outer wall of the diversion pile is provided with a water diversion hole, and the inside of the diversion pile and the diversion pipe are filled with water-permeable particles.

10. A construction method for an anti-scour structure of a grouting layer behind a shield tunnel wall in water-rich fractured strata, characterized in that, Includes the following steps: Comprehensive exploration was conducted on the water-rich fractured strata in the construction section to obtain the location, size, stratum parameters, and groundwater parameters of the fractures. Based on this, the scope of stratum reinforcement, the location of diversion piles, the depth of diversion piles, and the layout scheme of composite segments and diversion pipes were determined. Grouting is carried out along the outer side of the shield tunnel excavation outline into the water-rich and fractured strata to form a stratum reinforcement zone; According to the determined diversion pile layout locations, diversion piles are constructed in the strata outside the shield tunnel excavation outline. The diversion piles are filled with permeable particles and have water diversion holes reserved on the outer wall. The diversion piles are arranged in a cross pattern and at set intervals. After the diversion piles are completed, the shield tunnel is excavated, and the excavation outline is expanded outward by a set distance. During the tunnel boring process, composite segments are assembled. The composite segments include a segment body and a bag set on the outside of the segment body. When the bag is not grouted, it remains in a closed state and fits against the outer wall of the segment body. A water guide groove is formed between adjacent bags. A guide pipe is installed on the segment body. The guide pipe has a water guide hole on its wall and a drain hole at its end. The guide pipe is connected to the reserved opening in the segment body, so that the water guide hole is located in the stratum outside the segment body and the drain hole is located at the water guide groove. Grout is injected into the bladder through grouting holes opened on the segment body. During the grouting process, the bladder expands outward, and after the grouting is completed, a backfill stone layer is formed.

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