Tunnel bentonite anti-seepage structure

Abstract

The utility model relates to the technical field of tunnel engineering seepage prevention, in particular to a tunnel bentonite seepage prevention structure. The anti-seepage structure comprises an open-cut tunnel anti-seepage structure and a new Austrian composite tunnel anti-seepage structure, the open-cut tunnel anti-seepage structure comprises an open-cut tunnel inverted arch bottom plate anti-seepage structure, an open-cut tunnel vertical wall anti-seepage structure and an open-cut tunnel vault anti-seepage structure. The novel Austrian-method composite tunnel anti-seepage structure comprises a novel Austrian-method tunnel inverted arch bottom plate anti-seepage structure, a novel Austrian-method tunnel vertical wall anti-seepage structure and a novel Austrian-method tunnel vault anti-seepage structure. According to the technical scheme, the problems that in the prior art, a waterproof roll or a waterproof plate cannot be tightly bonded with a base layer, large-area water mixing is caused, and water seepage, drainage, maintenance and management costs are increased are solved.

Description

Bentonite seepage prevention structure for tunnels Technical Field

[0001] This utility model relates to the field of tunnel engineering seepage prevention technology, and in particular to a bentonite seepage prevention structure for tunnels. Background Technology

[0002] Currently, most underground tunnel projects use waterproof membranes and waterproof boards for seepage prevention. However, this process cannot bond tightly to the base layer, creating gaps between them. As a result, most underground tunnels experience large-scale water seepage, leading to leakage and significant drainage costs. This results in a substantial increase in personnel and costs for tunnel management.

[0003] In view of the problems existing in the above-mentioned existing technologies, it is necessary to study and design a new type of bentonite anti-seepage structure for tunnels, so as to overcome the problems existing in the existing technologies. Summary of the Invention

[0004] The existing waterproof membranes or boards often fail to bond tightly to the substrate, leading to large-area water seepage, increased drainage and maintenance costs, and other technical problems. Therefore, this invention provides a bentonite-based anti-seepage structure for tunnels. This utility model primarily utilizes bentonite's water-retaining effect by adding it between the tunnel wall and the substrate, achieving a unified anti-seepage effect through the material and structure, thus realizing permanent anti-seepage in underground tunnels.

[0005] The technical means adopted in this utility model are as follows:

[0006] A type of bentonite seepage prevention structure for tunnels includes: a seepage prevention structure for open-cut tunnels and a composite seepage prevention structure for tunnels constructed using the New Austrian Tunneling Method (NATM);

[0007] Furthermore, the seepage prevention structure of the cut-and-cover tunnel includes: the seepage prevention structure of the bottom slab of the invert arch of the cut-and-cover tunnel, the seepage prevention structure of the vertical wall of the cut-and-cover tunnel, and the seepage prevention structure of the arch of the cut-and-cover tunnel;

[0008] Furthermore, the New Austrian Tunneling Method (NATM) composite tunnel seepage prevention structure includes: NATM tunnel invert bottom slab seepage prevention structure, NATM tunnel vertical wall seepage prevention structure, and NATM tunnel arch top seepage prevention structure.

[0009] Furthermore, the seepage prevention structure of the invert arch bottom slab of the open-cut tunnel, from bottom to top, consists of: natural base course, aggregate and bentonite graded load-bearing seepage prevention body, 100mm thick concrete cushion layer, tunnel invert arch structure bottom slab, and tunnel roadway construction layer;

[0010] Furthermore, the seepage prevention structure of the cut-and-cover tunnel wall consists of the following components from the outside to the inside: precast reinforced concrete protective slab, bentonite seepage prevention layer, and tunnel inner wall structure. First, the tunnel inner wall structure is constructed, then the precast reinforced concrete protective slab is installed, and the bentonite seepage prevention layer is filled between the precast reinforced concrete protective slab and the tunnel inner wall structure. Finally, plain soil is gradually backfilled and compacted between the precast reinforced concrete protective slab and the natural base layer on both sides of the tunnel.

[0011] Furthermore, the anti-seepage structure of the tunnel arch from bottom to top consists of: the tunnel arch outer wall structure, longitudinal granite ribs, bentonite mortar anti-seepage layer, fiberglass grid, 30mm thick mortar protective layer, and reinforced concrete retaining slab. The tunnel arch outer wall structure is constructed first, followed by the installation of longitudinal granite ribs, with the bentonite mortar anti-seepage layer filled between them. A fiberglass grid is then installed outside the bentonite mortar anti-seepage layer, followed by a 30mm thick mortar protective layer. A reinforced concrete retaining slab is then installed outside the 30mm thick mortar protective layer, and finally, plain soil is backfilled and compacted outside the reinforced concrete retaining slab.

[0012] Furthermore, the gravel and bentonite graded load-bearing seepage barrier is a seepage barrier made of 200-500mm graded gravel and bentonite.

[0013] Furthermore, the anti-seepage structure of the invert arch bottom slab of the New Austrian Tunneling Method (NATM) consists of the following layers from bottom to top: natural base course, aggregate and bentonite graded load-bearing anti-seepage body, 100mm thick concrete cushion layer, tunnel invert arch structure bottom slab, and tunnel roadway construction layer.

[0014] Furthermore, the right outer inner structure of the tunnel wall using the New Austrian Tunneling Method (NATM) consists of, in sequence: the surrounding geological rock of the tunnel, the initial reinforced concrete lining layer, the bentonite mud plaster anti-seepage layer, the formwork that can be removed, the PVA bentonite waterstop strip, and the tunnel reinforced concrete structural wall. First, the truss is installed. Then, the initial reinforced concrete lining layer is constructed outside the surrounding geological rock of the tunnel. The formwork that can be removed is then mounted on the truss. A thick bentonite mud plaster anti-seepage layer is filled between the formwork and the initial reinforced concrete lining layer. Finally, the tunnel reinforced concrete structural wall is constructed outside the formwork. Before constructing the tunnel reinforced concrete structural wall, PVA bentonite waterstop strips are installed outside the formwork.

[0015] Furthermore, the anti-seepage structure of the tunnel arch using the New Austrian Tunneling Method (NATM) consists of the following components from top to bottom: the surrounding geological rock of the tunnel, the reinforced concrete layer of the initial tunnel lining, the bentonite slurry anti-seepage layer, the formwork that can be removed without dismantling, the PVA bentonite waterstop strip, and the external wall structure of the tunnel arch. First, anchor rods and steel mesh are installed on the surrounding geological rock of the tunnel, a truss is erected, the reinforced concrete layer of the initial tunnel lining is constructed, the formwork that can be removed without dismantling is installed, and spherical check valve grouting pipes are pre-embedded on the formwork. PVA bentonite waterstop strips are installed on the outside of the formwork, and the external wall structure of the tunnel arch is constructed on the outside of the formwork. Finally, the bentonite slurry anti-seepage layer is injected between the formwork that can be removed without dismantling and the reinforced concrete layer of the initial tunnel lining through the spherical check valve grouting pipe.

[0016] Furthermore, the thickness of the bentonite mud-plaster anti-seepage layer is ≥50mm.

[0017] Furthermore, the spherical check valve grouting pipe consists of multiple pipes with a spacing of ≤6m.

[0018] Furthermore, the PVA bentonite waterstop strips are arranged vertically on the outside of the non-removable formwork.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The tunnel bentonite seepage prevention structure provided by this utility model achieves secondary waterproofing and seepage prevention by setting PVA bentonite waterstop strips on the outside of the non-removable template.

[0021] 2. The bentonite anti-seepage structure for tunnels provided by this utility model achieves the construction of the initial lining reinforced concrete layer and bentonite layer of the tunnel by setting up a formwork that does not need to be removed, thus saving procedures, reducing labor intensity, improving construction efficiency, and also increasing the strength of the tunnel wall.

[0022] 3. The bentonite anti-seepage structure for tunnels provided by this utility model achieves the absorption and anti-seepage of tunnel water by setting a bentonite anti-seepage layer, avoiding various tedious subsequent matters such as water seepage, maintenance and management.

[0023] 4. The bentonite anti-seepage structure for tunnels provided by this utility model forms an integral water-repellent structure with the bentonite and the tunnel structure, enabling the tunnel mining space to achieve a water-free environment.

[0024] In summary, the technical solution of this utility model solves the problems in the prior art where waterproof membranes or waterproof boards cannot be tightly bonded to the substrate, resulting in large-area water seepage, increased costs for water seepage, drainage, and maintenance. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 is a schematic diagram of the seepage prevention structure of the open-cut tunnel of this utility model;

[0027] Figure 2 is an enlarged schematic diagram of the anti-seepage structure of the bottom plate of the open-cut tunnel arch of this utility model;

[0028] Figure 3 is an enlarged schematic diagram of the anti-seepage structure of the vertical wall of the open-cut tunnel of this utility model;

[0029] Figure 4 is an enlarged schematic diagram of the anti-seepage structure of the open-cut tunnel arch of this utility model;

[0030] Figure 5 is a schematic diagram of the new Austrian Tunneling Method (ATM) composite tunnel seepage prevention structure of this utility model.

[0031] Figure 6 is an enlarged schematic diagram of the anti-seepage structure of the bottom plate of the tunnel arch of the new Austrian Tunneling Method (NATM).

[0032] Figure 7 is an enlarged schematic diagram of the new Austrian Tunneling Method vertical wall seepage prevention structure of this utility model;

[0033] Figure 8 is an enlarged schematic diagram of the new Austrian Tunneling Method (NATM) tunnel arch anti-seepage structure of this utility model.

[0034] In the diagram: 1. Natural base layer; 2. Gravel and bentonite graded load-bearing seepage barrier; 3. 100mm thick concrete cushion layer; 4. Tunnel invert arch structure bottom slab; 5. Tunnel roadway structural layer; 6. Precast reinforced concrete guard plate; 7. Bentonite seepage barrier layer; 8. Tunnel interior wall structure; 9. Tunnel interior wall structure; 10. Plain soil; 11. Reinforced concrete fixed guard plate; 12. 30mm thick mortar protective layer; 13. Fiberglass grid; 14. Bentonite mud plaster seepage barrier layer; 15. Longitudinal granite ribs; 16. Tunnel arch outer wall structure; 17. Tunnel geological surrounding rock; 18. Tunnel initial lining reinforced concrete layer; 19. No-removal formwork; 20. PVA bentonite waterstop strip; 21. Spherical check valve grouting pipe. Detailed Implementation

[0035] It should be noted that, where there is no conflict, the embodiments and features in the embodiments of this utility model can be combined with each other. The present utility model will now be described in detail with reference to the accompanying drawings and embodiments.

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this utility model or its application or use. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0037] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to the present invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0038] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0039] In the description of this utility model, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this utility model and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this utility model. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0040] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0041] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be construed as limiting the scope of protection of this utility model.

[0042] Example 1

[0043] As shown in Figures 1-2, this utility model provides a bentonite seepage prevention structure for tunnels, including: a seepage prevention structure for open-cut tunnels and a composite seepage prevention structure for tunnels constructed using the New Austrian Tunneling Method (NATM).

[0044] The seepage prevention structure of open-cut tunnels includes: seepage prevention structure of the invert bottom plate of the open-cut tunnel, seepage prevention structure of the vertical wall of the open-cut tunnel, and seepage prevention structure of the arch top of the open-cut tunnel;

[0045] The New Austrian Tunneling Method (NATM) composite tunnel seepage prevention structure includes: NATM tunnel invert arch bottom slab seepage prevention structure, NATM tunnel vertical wall seepage prevention structure, and NATM tunnel arch top seepage prevention structure.

[0046] The anti-seepage structure of the invert arch bottom slab of the cut-and-cover tunnel consists of the following layers from bottom to top: 1. Natural base course; 2. Gravel and bentonite graded load-bearing anti-seepage body; 3. 100mm thick concrete cushion layer; 4. Tunnel invert arch bottom slab; and 5. Tunnel roadway structure layer.

[0047] The seepage prevention structure of the cut-and-cover tunnel wall consists of the following components from the outside to the inside: precast reinforced concrete protective plate 6, bentonite seepage prevention layer 7, and tunnel inner wall structure 8. The tunnel inner wall structure 8 is constructed first, then the precast reinforced concrete protective plate 6 is installed, and the bentonite seepage prevention layer 7 is filled between the precast reinforced concrete protective plate 6 and the tunnel inner wall structure 8. Finally, plain soil 10 is gradually backfilled and compacted between the precast reinforced concrete protective plate 6 and the natural base layer 1 on both sides of the tunnel.

[0048] The anti-seepage structure of the tunnel arch from bottom to top consists of: tunnel arch outer wall structure 16, longitudinal granite ribs 15, bentonite mortar anti-seepage layer 14, fiberglass grid 13, 30mm thick mortar protective layer 12, and reinforced concrete fixed retaining plate 11. The tunnel arch outer wall structure 16 is constructed first, followed by the installation of longitudinal granite ribs 15. Bentonite mortar anti-seepage layer 14 is then filled between the longitudinal granite ribs 15. Fiberglass grid 13 is installed outside the bentonite mortar anti-seepage layer 14, followed by the construction of a 30mm thick mortar protective layer 12 outside the fiberglass grid 13. A reinforced concrete fixed retaining plate 11 is then installed outside the 30mm thick mortar protective layer 12. Finally, plain soil 10 is backfilled and compacted outside the reinforced concrete fixed retaining plate 11.

[0049] The gravel and bentonite graded load-bearing seepage barrier 2 is a seepage barrier made of 200-500mm graded gravel and bentonite.

[0050] The anti-seepage structure of the invert arch bottom slab of the New Austrian Tunneling Method (NATM) consists of the following layers from bottom to top: 1. Natural base course; 2. Gravel and bentonite graded load-bearing anti-seepage body; 3. 100mm thick concrete cushion layer; 4. Tunnel invert arch structure bottom slab; and 5. Tunnel roadway structure layer.

[0051] The right outer inner part of the tunnel wall anti-seepage structure of the New Austrian Tunneling Method (NATM) consists of: tunnel geological surrounding rock 17, tunnel initial lining reinforced concrete layer 18, bentonite mud anti-seepage layer 14, formwork 19 (removable), PVA bentonite waterstop strip 20, and tunnel reinforced concrete structural wall 9. First, the truss is installed. Then, the tunnel initial lining reinforced concrete layer 18 is constructed outside the tunnel geological surrounding rock 17. The formwork 19 (removable) is installed on the truss. A thick bentonite mud anti-seepage layer 14 is filled between the formwork 19 and the tunnel initial lining reinforced concrete layer 18. Finally, the tunnel reinforced concrete structural wall 9 is constructed outside the formwork 19. Before constructing the tunnel reinforced concrete structural wall 9, PVA bentonite waterstop strip 20 is installed outside the formwork 19.

[0052] The anti-seepage structure of the tunnel arch from top to bottom using the New Austrian Tunneling Method (NATM) consists of: tunnel geological surrounding rock 17, tunnel initial lining reinforced concrete layer 18, bentonite mud plaster anti-seepage layer 14, formwork 19 (removable), PVA bentonite waterstop strip 20, and tunnel arch outer wall structure 16. First, initial lining anchors and steel mesh are installed on the tunnel geological surrounding rock 17, a truss is erected, and the tunnel initial lining reinforced concrete layer 18 is constructed. The formwork 19 (removable) is then installed, and a spherical check valve grouting pipe 21 is pre-embedded on the formwork 19. PVA bentonite waterstop strip 20 is then installed on the outside of the formwork 19. The tunnel arch outer wall structure 16 is then constructed on the outside of the formwork 19. Finally, the bentonite mud plaster anti-seepage layer 14 is injected between the formwork 19 and the tunnel initial lining reinforced concrete layer 18 through the spherical check valve grouting pipe 21.

[0053] The thickness of the bentonite mud-plaster seepage prevention layer 14 is ≥50mm.

[0054] The spherical check valve grouting pipe 21 consists of multiple pipes with a spacing of ≤6m.

[0055] PVA bentonite waterstop strips 20 are arranged vertically on the outside of the non-removable formwork 19.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A bentonite seepage-proof structure for tunnels, characterized in that: The aforementioned bentonite seepage prevention structure for tunnels includes: a seepage prevention structure for open-cut tunnels and a composite seepage prevention structure for tunnels constructed using the New Austrian Tunneling Method (NATM); the seepage prevention structure for open-cut tunnels includes: a seepage prevention structure for the bottom slab of the invert of the open-cut tunnel, a seepage prevention structure for the vertical walls of the open-cut tunnel, and a seepage prevention structure for the crown of the open-cut tunnel; the composite seepage prevention structure for tunnels constructed using the New Austrian Tunneling Method (NATM) includes: a seepage prevention structure for the bottom slab of the invert of the New Austrian Tunnel, a seepage prevention structure for the vertical walls of the New Austrian Tunnel, and a seepage prevention structure for the crown of the New Austrian Tunnel.

2. The bentonite seepage prevention structure for tunnels according to claim 1, characterized in that: The cut-and-cover tunnel arch bottom slab seepage prevention structure, from bottom to top, consists of: natural base course (1), aggregate and bentonite graded load-bearing seepage prevention body (2), 100mm thick concrete cushion layer (3), tunnel arch bottom slab (4), and tunnel roadway structure layer (5); the cut-and-cover tunnel vertical wall seepage prevention structure, from outside to inside, consists of: precast reinforced concrete guard plate (6), bentonite seepage prevention layer (7), and tunnel inner wall structure (8); first, the tunnel inner wall structure (8) is constructed, then the precast reinforced concrete guard plate (6) is installed, and the bentonite seepage prevention layer (7) is filled between the precast reinforced concrete guard plate (6) and the tunnel inner wall structure (8). Then, plain soil (10) is gradually backfilled and compacted between the precast reinforced concrete guard plate (6) and the natural base course (1) on both sides of the tunnel; the cut-and-cover tunnel arch top seepage prevention structure, from bottom to top, consists of: natural base course (1), aggregate and bentonite graded load-bearing seepage prevention body (2), 100mm thick concrete cushion layer (3), tunnel arch bottom slab (4), and tunnel roadway structure layer (5); The structure consists of the following components in sequence: tunnel arch outer wall structure (16), longitudinal granite ribs (15), bentonite mud plaster anti-seepage layer (14), fiberglass grid (13), 30mm thick mortar protective layer (12), and reinforced concrete fixed plate (11). The tunnel arch outer wall structure (16) is constructed first, and then the longitudinal granite ribs (15) are installed. The bentonite mud plaster anti-seepage layer (14) is filled between the longitudinal granite ribs (15). Fiberglass grid (13) is set outside the bentonite mud plaster anti-seepage layer (14). The 30mm thick mortar protective layer (12) is constructed outside the fiberglass grid (13). The reinforced concrete fixed plate (11) is set outside the 30mm thick mortar protective layer (12). Finally, plain soil (10) is backfilled and compacted outside the reinforced concrete fixed plate (11).

3. The bentonite seepage prevention structure for tunnels according to claim 2, characterized in that: The gravel and bentonite graded load-bearing seepage barrier (2) is a seepage barrier made of 200-500mm graded gravel and bentonite graded.

4. The bentonite seepage prevention structure for tunnels according to claim 1, characterized in that: The anti-seepage structure of the invert arch bottom slab of the New Austrian Tunneling Method (NATM) tunnel, from bottom to top, consists of: natural base course (1), aggregate and bentonite graded load-bearing anti-seepage body (2), 100mm thick concrete cushion layer (3), tunnel invert arch structure bottom slab (4), and tunnel roadway structure layer (5); the anti-seepage structure of the vertical wall of the NATM tunnel, from right to left to inside, consists of: tunnel geological surrounding rock (17), tunnel initial lining reinforced concrete layer (18), bentonite mud anti-seepage layer (14), formwork that does not need to be removed (19), and PVA bentonite waterstop. Article (20) and the tunnel reinforced concrete structure wall (9); First, the truss is installed, and then the tunnel initial lining reinforced concrete layer (18) is constructed outside the tunnel geological surrounding rock (17). The formwork (19) is installed on the truss, and a thick bentonite mud anti-seepage layer (14) is filled between the formwork (19) and the tunnel initial lining reinforced concrete layer (18). Finally, the tunnel reinforced concrete structure wall (9) is constructed outside the formwork (19); the tunnel reinforced concrete structure wall (9) Before construction, PVA bentonite waterstop strips (20) are installed on the outside of the formwork (19) that can be removed. The new Austrian Tunneling Method (NATM) tunnel arch anti-seepage structure consists of the following from top to bottom: tunnel geological surrounding rock (17), tunnel initial lining reinforced concrete layer (18), bentonite mud anti-seepage layer (14), formwork that can be removed (19), PVA bentonite waterstop strips (20) and tunnel arch outer wall structure (16). First, initial lining anchors and steel mesh are set on the tunnel geological surrounding rock (17), trusses are erected, and tunnel initial lining is carried out. For the construction of the reinforced concrete lining layer (18), the formwork (19) is installed and a spherical check valve grouting pipe (21) is pre-embedded on the formwork (19). PVA bentonite waterstop strips (20) are installed on the outside of the formwork (19). The tunnel arch outer wall structure (16) is constructed on the outside of the formwork (19). Finally, a bentonite mud anti-seepage layer (14) is injected between the formwork (19) and the initial reinforced concrete lining layer (18) through the spherical check valve grouting pipe (21).

5. The tunnel bentonite seepage prevention structure according to claim 4, characterized in that: The thickness of the bentonite mud impermeable layer (14) is ≥50mm.

6. The bentonite seepage prevention structure for tunnels according to claim 4, characterized in that: The spherical check valve grouting pipe (21) consists of multiple pipes with a spacing of ≤6m.

7. The bentonite seepage prevention structure for tunnels according to claim 4, characterized in that: The PVA bentonite waterstop strips (20) are arranged vertically on the outside of the non-removable template (19).

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