High-strength impermeable shaft and gallery structure and construction method thereof

Abstract

This invention discloses a high-strength anti-seepage tunnel structure and its construction method, relating to the field of tunnel construction technology. It includes a surrounding rock reinforcement layer, a flexible anti-seepage layer, a rigid support layer, and an internal buffer layer. The surrounding rock reinforcement layer consists of grouting anchors and modified cement grout. The flexible anti-seepage layer includes a sealant layer and a waterproof layer, with the sealant layer laid outside the surrounding rock reinforcement layer and the waterproof layer laid outside the sealant layer. The rigid support layer is an anti-seepage reinforced concrete lining with a double-layer steel mesh inside. The internal buffer layer is lightweight high-strength foamed concrete, with a polyethylene isolation membrane laid between it and the rigid support layer. The method describes the specific construction steps and process of this structure. This application, through a dual-coordinated support design of the surrounding rock reinforcement layer and the rigid support layer, overcomes the limitations of traditional support systems with disjointed stress, effectively resists the concentrated stress damage caused by deep mining, and solves the technical problem of local overload failure in existing structures.

Description

Technical Field

[0001] This invention relates to the field of shaft and tunnel construction technology, and in particular to a construction method for high-strength, seepage-resistant shafts and tunnels. Background Technology

[0002] Shaft and tunnel engineering is a crucial link in underground resource extraction and transportation tunnel construction. Its structural stability and impermeability directly determine the safety and service life of the project. In deep mine mining and water-rich strata construction environments, the problems of high ground stress concentration and groundwater seepage are particularly significant, making it difficult for existing support and impermeable structures to simultaneously meet the requirements of high strength and deformation adaptability, thus creating multiple technical obstacles.

[0003] The current mainstream approach in the industry adopts a combination of grouting anchors, reinforced concrete lining, and a single waterproof layer. While this achieves the basic functional requirements, long-term engineering practice has revealed systemic defects. During the hardening stage, the concrete lining is prone to cracking due to its own shrinkage and uneven deformation of the surrounding rock. These cracks become the main channels for groundwater seepage. Simultaneously, traditional cement grout has limited bonding strength and cannot fully fill the surrounding rock fissures to form effective reinforcement. The lack of a synergistic mechanism between the support system and the impermeable layer leads to a broken stress transmission path between the anchors and the lining, making areas of concentrated ground stress susceptible to localized overload failure. Furthermore, the weak bond between the waterproof layer and the lining makes it prone to peeling and breakage under the deformation of the surrounding rock.

[0004] Furthermore, the excessive rigidity of the overall structure prevented it from adapting to minor deformations of the surrounding rock, leading to the continuous propagation of cracks and ultimately resulting in support failure and the risk of groundwater leakage. Attempts to improve the structure, such as increasing the lining thickness or replacing the waterproofing material, failed to resolve the core issue of the disconnect between the rigid support and the flexible impermeable layer, leaving the long-standing contradiction between structural strength, impermeability, and deformation adaptability unresolved. Summary of the Invention

[0005] To address the problem of local overload failure in existing shaft and tunnel structures, this application provides a high-strength, seepage-resistant shaft and tunnel structure and its construction method.

[0006] In a first aspect, this application provides a high-strength, seepage-resistant shaft structure, employing the following technical solution:

[0007] A high-strength anti-seepage tunnel structure, from the outside to the inside of the surrounding rock, includes a surrounding rock reinforcement layer, a flexible anti-seepage layer, a rigid support layer and an internal buffer layer.

[0008] The surrounding rock reinforcement layer consists of grouting anchors and modified cement grout, with the grouting anchors extending to the stable rock strata of the surrounding rock.

[0009] The flexible impermeable layer includes a sealant layer and a waterproof layer. The sealant layer is laid outside the surrounding rock reinforcement layer, and the waterproof layer is laid outside the sealant layer.

[0010] The rigid support layer is a seepage-resistant reinforced concrete lining. A double-layer steel mesh is installed inside the lining. The double-layer steel mesh is fixed by tie bars. An embedded expansion waterstop is installed at intervals along the shaft axis.

[0011] The internal buffer layer is made of lightweight, high-strength foamed concrete, and a polyethylene isolation membrane is laid between it and the rigid support layer.

[0012] Optionally, the grouting anchor rod is made of high-strength alloy steel, and spiral grouting holes with a diameter of 8-10 mm are provided on the rod body and are evenly distributed along the axial direction of the rod body; the anchoring end is provided with a barb structure.

[0013] Optionally, the grouting anchors are arranged in a quincunx pattern with a spacing of 800-1200mm, and the length of the anchors extends to the stable rock strata of the surrounding rock with a depth of not less than 2.5m. The modified cement grout uses ordinary Portland cement as the base material and incorporates 5%-8% ultrafine silica fume, 2%-3% polypropylene fiber, and 0.5%-1% high-efficiency water-reducing agent. The grouting pressure adopts a graded pressurization mode, gradually increasing from 1.0MPa to 1.5-2.0MPa.

[0014] Optionally, the outer layer of the double-layer steel mesh uses Φ16-20mm threaded steel bars with a spacing of 200-250mm, and the inner layer uses Φ12-14mm threaded steel bars with a spacing of 250-300mm. The double-layer steel mesh is fixed by tie bars with a spacing of 500-600mm. The lining thickness is calculated and determined based on the diameter of the shaft and the magnitude of the ground stress, and is not less than 300mm under normal conditions. The thickness is increased by 10%-15% at stress concentration points such as shaft bends and intersections.

[0015] Optionally, the internal buffer layer is made of lightweight high-strength foamed concrete with a thickness of 50-80mm and a density of ≤800kg / m³, and contains 1%-2% chopped glass fiber to improve crack resistance and toughness.

[0016] Secondly, this application also discloses a construction method for high-strength seepage-resistant tunnels, which adopts the following scheme:

[0017] A construction method for high-strength seepage-resistant tunnels includes the following steps:

[0018] S1. Surrounding rock pretreatment: After the tunnel excavation is completed, the surface of the surrounding rock is cleaned immediately, and temporary support is provided for locally broken surrounding rock to prevent collapse.

[0019] S2. Construction of the surrounding rock reinforcement layer: Arrange the grouting anchor holes in a quincunx pattern. The hole diameter is 10-15mm larger than the anchor diameter, and the drilling depth is 50mm deeper than the anchor length. After the grouting anchor is inserted, the modified cement grout is injected through the grouting hole of the anchor. The staged pressurization mode is adopted. First, the grout is injected at a pressure of 1.0MPa for 30 minutes, and then the pressure is gradually increased to 1.5-2.0MPa for continuous grouting until the grout overflows from the hole. Then, the grouting valve is closed, and the grout is cured for 24 hours until the grout initially sets before proceeding to the next process.

[0020] S3. Construction of Flexible Anti-seepage Layer: Apply polyurethane elastic sealant evenly to the surface of the surrounding rock reinforcement layer, using specialized spraying equipment to ensure uniform thickness, and cure for 8 hours until the sealant is cured; then lay PVC waterproof membrane, which should be laid flat and without wrinkles, and weld the overlaps with a hot melt welding machine. After welding, use a pressure tester to check the weld. If the pressure remains stable at 0.2MPa for 30 minutes without dropping, it is considered qualified.

[0021] S4. Construction of Rigid Support Layer: Tie a double-layer steel mesh, with the outer layer of steel bars close to the flexible impermeable layer. Fix the position of the double-layer steel mesh with tie bars to ensure that the thickness of the protective layer is not less than 30mm; install the formwork, with the verticality deviation of the formwork ≤3‰; after installation, lay the embedded expansion waterstop; pour C40 impermeable concrete, using an immersion vibrator to vibrate in layers until there are no air bubbles on the concrete surface and it does not sink; after pouring, cover with moisturizing material for curing, and the curing time is not less than 14 days.

[0022] S5. Construction of internal buffer layer: After the rigid support layer is cured, a polyethylene isolation film is laid and connected by overlapping, with an overlap width of not less than 50mm; then lightweight high-strength foamed concrete is poured and compacted by light vibration with a plate vibrator to avoid damaging the isolation film. After curing for 7 days until the strength meets the standard, it can be put into use.

[0023] In summary, this application includes the following beneficial technical effects:

[0024] 1. Creatively enhances load-bearing capacity: Through the dual collaborative support design of "surrounding rock reinforcement layer + rigid support layer", the limitations of traditional support system in terms of stress disconnection are broken. Modified cement grout reinforces the surrounding rock to form a load-bearing shell, and double-layer steel mesh optimizes the stress transfer of the lining. The flexural strength of the structure is increased by 30%-40% compared with the existing scheme. It can withstand ground stress of 15-20MPa, effectively resist the damage of ground stress concentration in deep mining, and solve the technical problem of local overload failure of existing structures.

[0025] 2. Innovative and Optimized Anti-seepage System: Pioneering a dual-protection structure of "flexible composite anti-seepage layer + expansion sealing strip," the combination of polyurethane sealant and waterproof membrane ensures both impermeability and density while adapting to minor deformations of the surrounding rock, avoiding the peeling and damage problems of traditional waterproof layers. Permeability coefficient ≤1×10⁻ 8The flow rate is m / s, which can meet the anti-seepage requirements of high water pressure formations with water pressure ≤3MPa, and the seepage rate is controlled within 0.01L / (m·d), which is an order of magnitude improvement in anti-seepage performance compared with existing technologies.

[0026] 3. Breakthrough Enhanced Deformation Adaptability: The internal buffer layer and the flexible anti-seepage layer form a deformation buffer system that can adapt to the slight deformation of the surrounding rock of ±5mm, effectively absorb impact loads and shrinkage stress, and prevent the rigid structure from cracking due to deformation. This solves the technical contradiction that existing rigid support and flexible anti-seepage are difficult to balance, and extends the service life of the structure to more than 20 years, which is more than 50% higher than that of traditional structures.

[0027] 4. Highly practical and easy to construct: The construction technology for each structural layer is mature and can be seamlessly integrated with existing shaft and tunnel construction processes. No new specialized equipment is required, and materials such as modified cement slurry and foamed concrete are readily available. Construction efficiency is increased by 15%-20% compared to existing solutions, while reducing subsequent operation and maintenance costs, resulting in significant economic and social benefits. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the cross-section of the tunnel engineering structure of this invention;

[0029] Figure 2 This is a schematic diagram of the grouting anchor structure of the present invention.

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. Surrounding rock; 2. Surrounding rock reinforcement layer; 3. Flexible anti-seepage layer; 4. Rigid support layer; 5. Internal buffer layer; 6. Expansion waterstop; 7. Spiral anchor; 21. Anchor rod body; 22. Spiral grouting hole; 23. Anchoring closed end; 24. Grouting port; 25. Spiral barbed structure. Detailed Implementation

[0032] The following is in conjunction with the appendix Figure 1-2 This application will be described in further detail.

[0033] This application discloses a high-strength seepage-resistant tunnel structure, which, from the inside of the surrounding rock 1, includes a surrounding rock reinforcement layer 1, a flexible seepage-resistant layer 3, a rigid support layer 4, and an internal buffer layer 5. The various layers work together to form a complete protection system, as shown in the following specific structure:

[0034] The surrounding rock reinforcement layer 1 consists of grouting anchors and modified cement grout. The grouting anchors are evenly arranged in a quincunx pattern with a spacing of 800-1200 mm. The length of the anchors extends to the stable rock layer of surrounding rock 1, with a depth of not less than 2.5 m. The modified cement grout uses ordinary silicate cement as the base material and incorporates 5%-8% ultrafine silica fume, 2%-3% polypropylene fiber, and 0.5%-1% high-efficiency water-reducing agent. The ultrafine silica fume fills the hydration pores of the cement to improve density, the polypropylene fiber inhibits crack propagation, and the high-efficiency water-reducing agent optimizes the fluidity of the grout. The grouting pressure adopts a graded pressurization mode, gradually increasing from 1.0 MPa to 1.5-2.0 MPa to ensure that the grout fully penetrates and fills the cracks in surrounding rock 1, forming an integral reinforced shell.

[0035] The grouting anchor rod body 21 is made of high-strength alloy steel. Spiral grouting holes, 8-10mm in diameter, are evenly distributed along the axial direction of the rod body to ensure the grout diffuses evenly from the rod body to the surrounding rock fissures. A barbed structure is provided at the anchoring end of the anchor rod to enhance the anchoring force between the anchor rod and the grout.

[0036] Flexible anti-seepage layer 3: Adopting a composite structure of "polyurethane elastic sealant + polyvinyl chloride (PVC) waterproof membrane", it forms the first line of anti-seepage defense; a 2-3mm thick layer of polyurethane elastic sealant is evenly sprayed on the surface of the surrounding rock 1 reinforcement layer to fill the uneven areas of the reinforcement layer surface, while also having a certain degree of deformation adaptability; after the sealant cures, a PVC waterproof membrane with a thickness of not less than 1.5mm is laid, with an overlap width of not less than 100mm, and connected by hot melt welding process. The welding temperature is controlled at 180-220℃ to ensure that the weld strength is not less than that of the membrane body. After welding, an airtightness test is performed, and no air leakage is considered qualified.

[0037] Rigid support layer 4: This is a seepage-resistant reinforced concrete lining, serving as the main load-bearing structure. The concrete strength grade is not lower than C40, and the seepage resistance grade is not lower than P8. An appropriate amount of expansion agent is added to compensate for shrinkage. A double-layer steel mesh is installed inside the lining. The outer layer of steel bars (close to the flexible seepage-resistant layer 3) uses Φ16-20mm threaded steel with a spacing of 200-250mm, and the inner layer of steel bars uses Φ12-14mm threaded steel with a spacing of 250-300mm. The double-layer steel mesh is fixed by tie bars with a spacing of 500-600mm. The lining thickness is calculated based on the shaft diameter and the magnitude of ground stress, and is not less than 300mm under normal conditions. The thickness is increased by 10%-15% at stress concentration points such as shaft bends and intersections. In addition, an embedded expansion waterstop 6 is installed every 5-8m along the shaft axis. The waterstop is embedded at 1 / 2 of the lining thickness, forming a double seepage-resistant defense line with the flexible seepage-resistant layer 3.

[0038] Internal buffer layer 5: Located inside the rigid support layer 4, it is made of lightweight high-strength foamed concrete with a thickness of 50-80mm and a density of ≤800kg / m³, with 1%-2% short-cut glass fiber added to improve crack resistance and toughness; a polyethylene isolation film is laid between the buffer layer and the rigid support layer 4 to avoid mutual restraint of shrinkage deformation between the two, and at the same time, it can absorb the local impact load transmitted from the surrounding rock 1 and reduce the stress concentration of the rigid support layer 4.

[0039] The high-strength, seepage-resistant tunnel structure provided in this embodiment effectively solves the problems of insufficient crack resistance, poor synergy between support and seepage-resistant systems, and lack of deformation adaptability in traditional tunnel support schemes in deep mining and water-rich strata through its multi-layered composite design. This structure can significantly improve the overall stability and seepage resistance of the tunnel, effectively suppress crack formation, optimize stress transmission paths, and adapt to the deformation of the surrounding rock, thereby avoiding support failure and groundwater leakage, and ensuring the safety and long-term service of the tunnel project.

[0040] This application further proposes a construction method for high-strength seepage-resistant tunnels, which includes the following steps:

[0041] The first step is the pretreatment of the surrounding rock 1. This step is carried out immediately after the tunnel excavation is completed. Its purpose is to clean the surface of the surrounding rock 1 and provide temporary support for locally fractured surrounding rock 1 to prevent collapse. Pretreatment of the surrounding rock 1 is the foundation for subsequent construction layers. By removing loose rocks, topsoil, and other debris, a clean and stable working surface is provided for subsequent grouting, spraying, and paving. Simultaneously, temporary support is provided for locally unstable surrounding rock 1, such as through localized shotcreting, temporary anchor bolts, or steel arches. This effectively controls the deformation of the surrounding rock 1, ensures construction safety, and creates favorable conditions for subsequent permanent support.

[0042] Next is the construction procedure of the surrounding rock 1 reinforcement layer. In this procedure, the grouting anchor holes are arranged in a plum blossom pattern. The hole diameter is 10 - 15 mm larger than the anchor rod diameter, and the drilling depth is 50 mm deeper than the anchor rod length. After implanting the grouting anchor rod, the modified cement slurry is injected through the grouting holes自带注浆孔 in the anchor rod. The grouting adopts a stepped pressure injection mode. First, grout is injected at a pressure of 1.0 MPa for 30 minutes, then the pressure is gradually increased to 1.5 - 2.0 MPa for continuous grouting until the slurry overflows from the hole mouth. Subsequently, the grouting valve is closed, and after 24 hours of curing until the slurry begins to set, the next process can be entered. The plum blossom pattern arrangement ensures the uniform distribution of the grouting anchor rods in the surrounding rock 1, thus achieving the integral reinforcement of the surrounding rock 1. The design of the drilling size and depth aims to ensure that the anchor rods can be fully implanted and provide sufficient space for the slurry to spread. The stepped pressure injection mode enables the slurry to fully penetrate and spread in the cracks of the surrounding rock 1. Gradually increasing the grouting pressure helps to overcome the resistance of the surrounding rock 1, ensures the dense filling of the slurry, and at the same time avoids local damage to the surrounding rock 1 caused by high-pressure grouting at one time. The overflow of the slurry from the hole mouth is a sign of full grouting, and the initial setting curing ensures the early strength of the slurry, providing a stable foundation for subsequent construction.

[0043] Then is the construction procedure of the flexible anti-seepage layer 3. In this procedure, polyurethane elastic sealant is evenly sprayed on the surface of the surrounding rock 1 reinforcement layer. A special spraying device is used to ensure uniform thickness, and it is cured for 8 hours until the sealant solidifies. Subsequently, PVC waterproof coiled material is laid. The coiled material should be laid flat without wrinkles, and the lap joints are welded with a hot melt welder. After welding, the weld seams are detected with a pneumatic detector. If the air pressure remains stable at 0.2 MPa for 30 minutes without dropping, it is considered qualified. Spraying the polyurethane elastic sealant forms a continuous and seamless flexible waterproof layer, which can effectively fill the tiny irregularities and cracks on the surface of the surrounding rock 1, providing the first anti-seepage barrier. The use of a special spraying device ensures the uniformity of the sealant thickness, thus ensuring the overall anti-seepage effect. Laying the PVC waterproof coiled material provides the second and stronger anti-seepage barrier. Its flexibility can adapt to the tiny deformation of the surrounding rock 1. The hot melt welding technology ensures the tightness of the lap joints of the coiled material, and strict pneumatic detection is the key means to verify the weld quality, ensuring that the entire flexible anti-seepage layer 3 forms a closed waterproof system, effectively preventing groundwater from infiltrating.

[0044] Next is the construction process of the rigid support layer 4. This step includes binding a double-layer steel mesh, with the outer layer of steel bars close to the flexible impermeable layer 3. The position of the double-layer steel mesh is fixed by tie bars to ensure that the protective layer thickness is not less than 30mm. Then, the formwork is installed, with a verticality deviation of ≤3‰. After installation, the embedded expansion waterstop 6 is laid. Next, C40 impermeable concrete is poured, using an immersion vibrator to vibrate in layers until the concrete surface is free of air bubbles and does not settle. After pouring, it is covered with a moisturizing material for curing, with a curing time of not less than 14 days. The binding of the double-layer steel mesh provides sufficient tensile and shear strength for the rigid support layer 4, and the proximity of the outer layer of steel bars to the flexible impermeable layer 3 helps protect the impermeable layer and works synergistically. The control of tie bars and the thickness of the protective layer ensures the effective stress of the steel bars. Precise installation and verticality control of the formwork are key to ensuring the geometric dimensions and stress uniformity of the lining. The placement of the embedded expansion waterstop 6 provides additional water-stopping protection at the concrete construction joints. The pouring and layered vibration of C40 impermeable concrete are designed to ensure its density and uniformity, eliminate internal air bubbles and pores, thereby significantly improving its strength and impermeability. Adequate moisture retention curing is essential to ensure complete hydration of the concrete and to achieve its design strength and durability.

[0045] Finally, the construction steps for the internal buffer layer 5 are as follows. This step is carried out after the rigid support layer 4 has been cured. First, a polyethylene isolation membrane is laid, connected by an overlap method with an overlap width of not less than 50mm. Then, lightweight high-strength foamed concrete is poured, and lightly compacted using a plate vibrator to avoid damaging the isolation membrane. It is then cured for 7 days until the strength meets the requirements before being put into use. The laying of the polyethylene isolation membrane creates an independent interface between the rigid support layer 4 and the internal buffer layer 5, preventing direct bonding between the two. This allows the buffer layer to undergo relative displacement with the rigid support layer 4 when absorbing deformation of the surrounding rock 1, effectively protecting the rigid support layer 4 from excessive stress. Controlling the overlap width ensures the continuity of the isolation membrane. The pouring and light compaction of the lightweight high-strength foamed concrete aims to form a uniform and dense buffer layer while avoiding damage to the underlying isolation membrane. Sufficient curing ensures that the foamed concrete reaches its design strength and buffering performance.

[0046] The above construction methods enable the systematic and efficient construction of high-strength, seepage-resistant tunnel structures. Specifically, the pretreatment of the surrounding rock 1 provides a stable foundation for subsequent construction, effectively controlling the initial stability of the surrounding rock 1. The construction of the reinforcement layer for the surrounding rock 1, through precise grouting anchor placement and graded pressurized grouting, achieves deep reinforcement and initial water stoppage of the surrounding rock 1, creating favorable conditions for the subsequent construction of the flexible seepage-resistant layer 3, and significantly improving the overall stability and bearing capacity of the surrounding rock 1. The construction of the flexible seepage-resistant layer 3 employs a dual seepage-resistant measure combining sprayed sealant and laid waterproof membrane. Strict welding quality inspection ensures the continuity, integrity, and reliability of the seepage-resistant layer, effectively blocking groundwater infiltration into the tunnel. Simultaneously, its flexibility allows it to adapt to minor deformations of the surrounding rock 1 without failure. The construction of the rigid support layer 4, through precise rebar tying, formwork installation, waterstop placement, and layered vibration and thorough curing of C40 impermeable concrete, ensured the high strength, high density, and excellent impermeability of the lining, providing solid structural support and long-term impermeability protection for the tunnel. The construction of the internal buffer layer 5, through the laying of a polyethylene isolation membrane and the pouring of lightweight, high-strength foamed concrete, established an effective buffer mechanism between the rigid support layer 4 and the surrounding rock 1. This mechanism absorbs and disperses the impact of deformation of the surrounding rock 1 and changes in ground stress on the rigid support layer 4, significantly improving the overall deformation resistance and durability of the tunnel structure. Simultaneously, it avoided damage to the isolation membrane during construction, ensuring the long-term effectiveness of the buffer layer. Overall, this construction method, through meticulous step-by-step construction and strict quality control, ensured the functional realization of each layer and good bonding between layers, thus giving the constructed tunnel structure excellent high strength, high impermeability, and long service life.

[0047] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A high-strength, seepage-resistant shaft / tunnel structure, characterized in that: From the outside to the inside of the surrounding rock, it includes a surrounding rock reinforcement layer, a flexible anti-seepage layer, a rigid support layer, and an internal buffer layer. The surrounding rock reinforcement layer consists of grouting anchors and modified cement grout, with the grouting anchors extending to the stable rock strata of the surrounding rock. The flexible impermeable layer includes a sealant layer and a waterproof layer. The sealant layer is laid outside the surrounding rock reinforcement layer, and the waterproof layer is laid outside the sealant layer. The rigid support layer is a seepage-resistant reinforced concrete lining. A double-layer steel mesh is installed inside the lining. The double-layer steel mesh is fixed by tie bars. An embedded expansion waterstop is installed at intervals along the shaft axis. The internal buffer layer is made of lightweight, high-strength foamed concrete, and a polyethylene isolation membrane is laid between it and the rigid support layer.

2. The high-strength seepage-resistant shaft structure according to claim 1, characterized in that: The grouting anchor rod is made of high-strength alloy steel, and spiral grouting holes are evenly distributed along the axial direction of the rod. The diameter of the grouting holes is 8-10mm. The anchoring end is provided with a barb structure.

3. The high-strength seepage-resistant shaft structure according to claim 2, characterized in that: The grouting anchors are arranged in a quincunx pattern with a spacing of 800-1200mm. The length of the anchors extends to the stable rock strata of the surrounding rock, with a depth of not less than 2.5m. The modified cement grout uses ordinary Portland cement as the base material and incorporates 5%-8% ultrafine silica fume, 2%-3% polypropylene fiber, and 0.5%-1% high-efficiency water-reducing agent. The grouting pressure adopts a graded pressurization mode, gradually increasing from 1.0MPa to 1.5-2.0MPa.

4. The high-strength seepage-resistant shaft structure according to claim 3, characterized in that: The outer layer of the double-layer steel mesh uses Φ16-20mm threaded steel bars with a spacing of 200-250mm, while the inner layer uses Φ12-14mm threaded steel bars with a spacing of 250-300mm. The double-layer steel mesh is fixed by tie bars with a spacing of 500-600mm. The lining thickness is calculated and determined based on the shaft diameter and the magnitude of ground stress, and is not less than 300mm under normal conditions. The thickness is increased by 10%-15% at stress concentration points such as shaft bends and intersections.

5. A high-strength seepage-resistant shaft structure according to claim 4, characterized in that: The internal buffer layer is made of lightweight, high-strength foamed concrete with a thickness of 50-80mm and a density of ≤800kg / m³, and contains 1%-2% short-cut glass fiber to improve crack resistance and toughness.

6. A construction method for a high-strength seepage-resistant tunnel, used to construct the high-strength seepage-resistant tunnel as described in claim 5, characterized in that: Includes the following steps: S1. Surrounding rock pretreatment: After the tunnel excavation is completed, the surface of the surrounding rock is cleaned immediately, and temporary support is provided for locally broken surrounding rock to prevent collapse. S2. Construction of the surrounding rock reinforcement layer: Arrange the grouting anchor holes in a quincunx pattern. The hole diameter is 10-15mm larger than the anchor diameter, and the drilling depth is 50mm deeper than the anchor length. After the grouting anchor is inserted, the modified cement grout is injected through the grouting hole of the anchor. The staged pressurization mode is adopted. First, the grout is injected at a pressure of 1.0MPa for 30 minutes, and then the pressure is gradually increased to 1.5-2.0MPa for continuous grouting until the grout overflows from the hole. Then, the grouting valve is closed, and the grout is cured for 24 hours until the grout initially sets before proceeding to the next process. S3. Construction of Flexible Anti-seepage Layer: Apply polyurethane elastic sealant evenly to the surface of the surrounding rock reinforcement layer, using specialized spraying equipment to ensure uniform thickness, and cure for 8 hours until the sealant is cured; then lay PVC waterproof membrane, which should be laid flat and without wrinkles, and weld the overlaps with a hot melt welding machine. After welding, use a pressure tester to check the weld. If the pressure remains stable at 0.2MPa for 30 minutes without dropping, it is considered qualified. S4. Construction of Rigid Support Layer: Tie a double-layer steel mesh, with the outer layer of steel bars close to the flexible impermeable layer. Fix the position of the double-layer steel mesh with tie bars to ensure that the thickness of the protective layer is not less than 30mm; install the formwork, with the verticality deviation of the formwork ≤3‰; after installation, lay the embedded expansion waterstop; pour C40 impermeable concrete, using an immersion vibrator to vibrate in layers until there are no air bubbles on the concrete surface and it does not sink; after pouring, cover with moisturizing material for curing, and the curing time is not less than 14 days. S5. Construction of internal buffer layer: After the rigid support layer is cured, a polyethylene isolation film is laid and connected by overlapping, with an overlap width of not less than 50mm; then lightweight high-strength foamed concrete is poured and compacted by light vibration with a plate vibrator to avoid damaging the isolation film. After curing for 7 days until the strength meets the standard, it can be put into use.

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