Rock wall reinforcement structure and reinforcement method in small clearance tunnel

Abstract

The present disclosure relates to the technical field of tunnel construction, and specifically to a small-clearance tunnel middle rock wall reinforcement structure and reinforcement method. The small-clearance tunnel middle rock wall reinforcement structure provided by the present disclosure includes a plurality of glass fiber anchor rods, a plurality of tension anchor cables and a plurality of grouting pipes, wherein the first end of the glass fiber anchor rod is used to connect to the side wall of the middle rock wall, and the second end of the glass fiber anchor rod is located in the middle rock wall; the first end of the tension anchor cable is used to connect to one side wall of the middle rock wall, and the second end of the tension anchor cable is used to connect to the other side wall of the middle rock wall; the plurality of grouting pipes include a plurality of first grouting pipes, wherein the first end of the first grouting pipe is used to connect to the side wall of the middle rock wall and to connect to a grouting machine, and the second end of the first grouting pipe is located in the middle rock wall; the plurality of first grouting pipes and the plurality of glass fiber anchor rods are respectively located on both sides of the plurality of tension anchor cables along the height direction of the middle rock wall. The reinforcement effect of the small-clearance tunnel middle rock wall reinforcement structure of the present disclosure is good.

Description

Technical Field

[0001] The present disclosure relates to the technical field of tunnel construction, and in particular to a rock wall reinforcement structure and a reinforcement method in a small clearance tunnel. Background Art

[0002] A small clearance tunnel refers to a special tunnel arrangement in which the thickness of the middle rock wall in the tunnel is less than the minimum clearance of the separated independent double tunnels. At present, small clearance tunnels are widely used. However, plastic damage is very likely to occur during the construction of small clearance tunnels, especially the lower part of the middle rock wall has poor stability and is very easy to crack. Collapse and initial support cracking often occur, and even "rheology" phenomena may occur. Therefore, ensuring the stability of the middle rock wall is the key to the success of small clearance tunnel construction.

[0003] At present, in order to solve the stability problem of the middle rock wall during the construction of small clearance tunnels, the reinforcement of the middle rock wall mainly adopts any method of small pipe grouting, prestressed anchor rods, tension anchor rods, and system anchor rods.

[0004] However, the above reinforcement methods are relatively simple, which may easily lead to non-targeted reinforcement measures, resulting in poor reinforcement effects. Summary of the invention

[0005] In order to solve the above technical problems or at least partially solve the above technical problems, the present disclosure provides a rock wall reinforcement structure and a reinforcement method in a small clearance tunnel.

[0006] On the one hand, the present invention provides a small-clearance tunnel middle rock wall reinforcement structure, including multiple glass fiber anchor rods, multiple tension anchor cables and multiple grouting pipes, the first end of the glass fiber anchor rod is used to connect to the side wall of the middle rock wall, and the second end of the glass fiber anchor rod is located in the middle rock wall; the first end of the tension anchor cable is used to connect to one side wall of the middle rock wall, and the second end of the tension anchor cable is used to connect to the other side wall of the middle rock wall; the multiple grouting pipes include multiple first grouting pipes, the first end of the first grouting pipe is used to connect to the side wall of the middle rock wall and to connect to a grouting machine, and the second end of the first grouting pipe is located in the middle rock wall; the multiple first grouting pipes and the multiple glass fiber anchor rods are respectively located on both sides of the multiple tension anchor cables along the height direction of the middle rock wall.

[0007] Optionally, the first end of the fiberglass anchor rod is located on the side of the second end of the fiberglass anchor rod close to the tension anchor cable, and the first end of the fiberglass anchor rod is located on the side of the second end of the fiberglass anchor rod close to the cave entrance; multiple fiberglass anchor rods are relatively arranged along the thickness direction of the middle rock wall, and in the height direction of the middle rock wall, the fiberglass anchor rods respectively connected to the two side walls of the middle rock wall are staggered and evenly spaced, and the projections of two adjacent fiberglass anchor rods in the height direction of the middle rock wall intersect at one point.

[0008] Optionally, the first end of the first grouting pipe is located on the side of the second end of the first grouting pipe close to the tension anchor cable, and the first end of the first grouting pipe is located on the side of the second end of the first grouting pipe close to the cave entrance; multiple first grouting pipes are relatively arranged along the thickness direction of the middle rock wall, and in the height direction of the middle rock wall, the first grouting pipes respectively connected to the two side walls of the middle rock wall are staggered and evenly spaced, and the projections of two adjacent first grouting pipes in the height direction of the middle rock wall intersect at one point.

[0009] Optionally, in the tunnel excavation direction, the fiberglass anchor rods and the first grouting pipes connected to the same side wall of the middle rock wall are staggered, and the projections of adjacent fiberglass anchor rods and the first grouting pipes connected to different side walls of the middle rock wall intersect with each other in the height direction of the middle rock wall to form an intersection; among the adjacent fiberglass anchor rods and the first grouting pipes connected to the two side walls of the middle rock wall, the distance between the first end of the fiberglass anchor rod and the first end of the first grouting pipe, whichever is closer to the intersection, and the intersection in the tunnel excavation direction is greater than or equal to 60 cm and less than or equal to 100 cm.

[0010] Optionally, the grouting pipe includes a first pipe section and a second pipe section connected in sequence; the end of the first pipe section away from the second pipe section is a cone, the cone is located in the middle rock wall, and the top of the cone is arranged away from the second pipe section; the second pipe section includes an inner pipe section and an outer pipe section connected in sequence, the inner pipe section is located in the middle rock wall, the first pipe section is threadedly connected to the inner pipe section, and the outer diameter of the first pipe section is smaller than the inner diameter of the inner pipe section; the outer pipe section is located outside the middle rock wall, and the side of the inner pipe section close to the outer pipe section is anchored to the middle rock wall by a resin anchor.

[0011] Optionally, the grouting pipe also includes multiple elastic covering members, which correspond one-to-one to the multiple grouting holes; the elastic covering members are arranged on the outside of the second pipe section, and the elastic covering members cover the corresponding grouting holes, the elastic covering members expand outward when grouting is carried out in the grouting pipe, and the elastic covering members shrink inward after grouting is completed in the grouting pipe.

[0012] Optionally, a slurry stop wall is sprayed on the outside of the side wall of the middle rock wall, and the side of the inner pipe section close to the outer pipe section passes through the slurry stop wall; the grouting pipe also includes a valve and a third pipe section, and the valve is arranged on the outer pipe section; the third pipe section is threadedly connected to the side of the outer pipe section away from the inner pipe section, and the end of the third pipe section away from the outer pipe section is used to connect a grouting machine.

[0013] Optionally, the multiple grouting pipes also include multiple second grouting pipes, and the multiple second grouting pipes are relatively arranged in the thickness direction of the middle rock wall; the first end of the second grouting pipe is used to be connected to the side wall of the middle rock wall and to be connected to the grouting machine, and the second end of the second grouting pipe is located in the middle rock wall; in the height direction of the middle rock wall, the multiple second grouting pipes are located between the multiple tension anchor cables, and a second grouting pipe is arranged between two adjacent tension anchor cables, and the spacing between two adjacent second grouting pipes is equal.

[0014] Optionally, the small-clearance tunnel middle rock wall reinforcement structure provided by the present invention also includes a plurality of third grouting pipes, which are arranged at the opening of the middle rock wall, and the third grouting pipes extend along the excavation direction of the tunnel; among the plurality of third grouting pipes, the spacing between two adjacent third grouting pipes is equal, and the plurality of third grouting pipes include a plurality of grouting pipe groups spaced apart along the height direction of the middle rock wall, and each grouting pipe group includes third grouting pipes spaced apart along the thickness direction of the middle rock wall; in the height direction of the middle rock wall, the plurality of third grouting pipes in two adjacent grouting pipe groups are staggered.

[0015] On the other hand, the present disclosure also provides a method for reinforcing a rock wall in a small-clearance tunnel, the method comprising drilling a first mounting hole on a side wall of the rock wall, inserting a second end of a first grouting pipe into the first mounting hole, and grouting the first grouting pipe; spraying a concrete leveling layer on the side wall of the rock wall and performing a tensioning operation; drilling second mounting holes on the side walls on both sides of the rock wall, respectively, and expanding the second mounting holes; installing a first end of a tension anchor cable in a second mounting hole on a side wall on one side of the rock wall, and installing a second end of the tension anchor cable in the rock wall. A second mounting hole is drilled on the side wall on the other side of the wall; a fiber flexible mesh is laid at the opening of the second mounting hole to flatten the side wall of the middle rock wall as a whole; a steel belt is installed to align the holes on the steel belt with the second mounting hole; a conical clamp, a pad tray and a tensioning anchor are installed at the tails of both ends of the tension anchor cable respectively; the tensioning anchor cable is tensioned and anchored; a third mounting hole is drilled on the side wall of the middle rock wall, the second end of the fiberglass anchor rod is inserted into the third mounting hole, and grouting is performed between the fiberglass anchor rod and the hole wall of the third mounting hole.

[0016] Compared with the prior art, the technical solution provided by the embodiments of the present disclosure has the following advantages:

[0017] The embodiment of the present disclosure provides a small-clearance tunnel middle rock wall reinforcement structure, comprising a plurality of glass fiber anchor rods, a plurality of tension anchor cables and a plurality of grouting pipes, wherein the first end of the glass fiber anchor rod is used to be connected to the side wall of the middle rock wall, and the second end of the glass fiber anchor rod is located in the middle rock wall; the first end of the tension anchor cable is used to be connected to one side wall of the middle rock wall, and the second end of the tension anchor cable is used to be connected to the other side wall of the middle rock wall; the plurality of grouting pipes include a plurality of first grouting pipes, the first end of the first grouting pipe is used to be connected to the side wall of the middle rock wall and to be connected to a grouting machine, and the second end of the first grouting pipe is located in the middle rock wall; the plurality of first grouting pipes and the plurality of glass fiber anchor rods are respectively located on both sides of the plurality of tension anchor cables along the height direction of the middle rock wall. In the small clearance tunnel middle rock wall reinforcement structure provided by the embodiment of the present disclosure, glass fiber anchor rods, tension anchor cables and grouting pipes are combined to reinforce the structure of the middle rock wall. Compared with the single reinforcement method in the prior art, the small clearance tunnel middle rock wall reinforcement structure provided by the embodiment of the present disclosure has better reinforcement effect; in addition, the glass fiber anchor rods in the embodiment of the present disclosure react with the water inside the middle rock wall to form a composite reinforcement body that is integrated with the middle rock wall, thereby further enhancing the reinforcement effect of the small clearance tunnel middle rock wall reinforcement structure provided by the embodiment of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0020] Figure 1a A schematic diagram of a local structure of a rock wall reinforcement structure in a small clearance tunnel provided by an embodiment of the present disclosure;

[0021] Figure 1b for Figure 1a A top view of

[0022] Figure 2 A schematic diagram of another partial structure of a rock wall reinforcement structure in a small clearance tunnel provided by an embodiment of the present disclosure;

[0023] Figure 3 A schematic diagram of the relationship between two tunnels during the construction of a rock wall reinforcement structure in a small clearance tunnel provided by an embodiment of the present disclosure;

[0024] Figure 4a A schematic diagram of the structure of a grouting pipe in a rock wall reinforcement structure in a small clearance tunnel provided by an embodiment of the present disclosure;

[0025] Figure 4b for Figure 4a Schematic diagram of the local structure at A in the middle;

[0026] Figure 4c for Figure 4a Schematic diagram of the local structure at B in the middle;

[0027] Figure 5 A diagram showing the use status of a grouting pipe in a rock wall reinforcement structure in a small clearance tunnel provided by an embodiment of the present disclosure;

[0028] Figure 6 A schematic diagram of a process for reinforcing a rock wall in a small clearance tunnel provided by an embodiment of the present disclosure;

[0029] Figure 7a A schematic structural diagram from a first perspective of the method for reinforcing a rock wall in a small-clearance tunnel provided by an embodiment of the present disclosure after tensioning and anchoring the tension anchor cables;

[0030] Figure 7b A schematic structural diagram from a second perspective of the method for reinforcing a rock wall in a small-clearance tunnel provided in an embodiment of the present disclosure after tensioning and anchoring of the tension anchor cables.

[0031] in,

[0032] 1. 1a. Fiberglass anchor rod; 1. Limit line; 11. 31. First end; 2. Tension anchor cable; 3. 3a. First grouting pipe; 4. Second grouting pipe; 5. Third grouting pipe; 6. Intersection; 7. First pipe section; 8. Second pipe section; 81. Grouting hole; 82. Inner pipe section; 83. Outer pipe section; 9. Third pipe section; 10. Middle rock wall; 20. Tunnel; 21. First tunnel; 22. Second tunnel; 30. Valve; 40. Elastic cover; 50. Resin anchor; 60. Stop wall; 70. Direct joint; 80. Fiber flexible mesh; 90. Steel strip; 100. Conical clamp; 110. Pad tray; 120. Tension anchor; 130. Concrete; 140. Grooving; 20a. Leading tunnel; 201. First heading face; 20b. Following tunnel; 202. Second heading face. DETAILED DESCRIPTION

[0033] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0035] A small clearance tunnel refers to a special tunnel arrangement in which the thickness of the middle rock wall in the tunnel is less than the minimum clearance of the separated independent double tunnels. At present, small clearance tunnels are widely used. However, plastic damage is very likely to occur during the construction of small clearance tunnels, especially the lower part of the middle rock wall has poor stability and is very easy to crack. Collapse and initial support cracking often occur, and even "rheology" phenomena may occur. Therefore, ensuring the stability of the middle rock wall is the key to the success of small clearance tunnel construction.

[0036] It should be noted that the above-mentioned rheology refers to the time-related deformation characteristics of an object when it is deformed by force.

[0037] At present, in order to solve the stability problem of the middle rock wall during the construction of small clearance tunnels, the reinforcement of the middle rock wall mainly adopts any of the following methods: small pipe grouting, prestressed anchor rods, tension anchor rods, and system anchor rods. However, the above reinforcement methods are relatively simple. On the one hand, it is easy to lead to non-targeted reinforcement measures, resulting in poor reinforcement effect; on the other hand, it is easy to cause waste of engineering resources, resulting in high construction costs.

[0038] Therefore, the embodiment of the present disclosure provides a small-clearance tunnel middle rock wall reinforcement structure, including multiple glass fiber anchor rods, multiple tension anchor cables and multiple grouting pipes, the first end of the glass fiber anchor rod is used to be connected to the side wall of the middle rock wall, and the second end of the glass fiber anchor rod is located in the middle rock wall; the first end of the tension anchor cable is used to be connected to one side wall of the middle rock wall, and the second end of the tension anchor cable is used to be connected to the other side wall of the middle rock wall; the multiple grouting pipes include multiple first grouting pipes, the first end of the first grouting pipe is used to be connected to the side wall of the middle rock wall and to connect a grouting machine, and the second end of the first grouting pipe is located in the middle rock wall; the multiple first grouting pipes and the multiple glass fiber anchor rods are respectively located on both sides of the multiple tension anchor cables along the height direction of the middle rock wall. In the small clearance tunnel middle rock wall reinforcement structure provided by the embodiment of the present disclosure, glass fiber anchor rods, tension anchor cables and grouting pipes are combined to reinforce the structure of the middle rock wall. Compared with the single reinforcement method in the prior art, the small clearance tunnel middle rock wall reinforcement structure provided by the embodiment of the present disclosure has better reinforcement effect; in addition, the glass fiber anchor rods in the embodiment of the present disclosure react with the water inside the middle rock wall to form a composite reinforcement body that is integrated with the middle rock wall, thereby further enhancing the reinforcement effect of the small clearance tunnel middle rock wall reinforcement structure provided by the embodiment of the present disclosure.

[0039] The embodiments of the present disclosure will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0040] See also Figure 1a and Figure 1b , Figure 1a A schematic diagram of a local structure of a rock wall reinforcement structure in a small clearance tunnel provided by an embodiment of the present disclosure, Figure 1b for Figure 1a A top view of the Figure 1a and Figure 1b As shown, this embodiment provides a small clearance tunnel middle rock wall reinforcement structure, including a plurality of glass fiber anchor rods 1, a plurality of tension anchor cables 2 and a plurality of grouting pipes, wherein the first end of the glass fiber anchor rod 1 is used to be connected to the side wall of the middle rock wall 10, and the second end of the glass fiber anchor rod 1 is located in the middle rock wall 10. Specifically, the first end of the glass fiber anchor rod 1 is connected to the initial support of the tunnel 20; the first end of the tension anchor cable 2 is used to be connected to one side wall of the middle rock wall 10, and the second end of the tension anchor cable 2 is used to be connected to the other side wall of the middle rock wall 10. The first end of the tension anchor cable 2 is connected to the initial support of the tunnel 20; the plurality of grouting pipes include a plurality of first grouting pipes 3, the first end of the first grouting pipe 3 is used to be connected to the side wall of the middle rock wall 10, and is used to connect the grouting machine, and the second end of the first grouting pipe 3 is located in the middle rock wall 10, specifically, the first end of the first grouting pipe 3 is connected to the initial support of the tunnel 20; the plurality of first grouting pipes 3 and the plurality of glass fiber anchor rods 1 are respectively located on both sides of the plurality of tension anchor cables 2 along the height direction of the middle rock wall 10. In the present embodiment, the fiberglass anchor rod 1, the tension anchor cable 2 and the grouting pipe are combined to reinforce the structure of the middle rock wall 10. Compared with the single reinforcement method in the prior art, the reinforcement effect of the small clearance tunnel middle rock wall reinforcement structure provided by the present embodiment is better; in addition, the fiberglass anchor rod 1 in the present embodiment reacts with the water inside the middle rock wall 10 to form a composite reinforcement body that is integrated with the middle rock wall 10, thereby further enhancing the reinforcement effect of the small clearance tunnel middle rock wall reinforcement structure provided by the present embodiment.

[0041] It should be noted that the height direction of the above-mentioned middle rock wall 10 is Figure 1a The direction of zz in is consistent.

[0042] Further, the tunnel 20 can be the first tunnel 21 in the figure, or the second tunnel 22 in the figure, and the first tunnel 21 and the second tunnel 22 are respectively tunnels on both sides of the middle rock wall 10. In the following description, the tunnel 20 can be limited to the first tunnel 21 or the second tunnel 22, and will not be introduced separately below.

[0043] In a specific implementation of this embodiment, the axial length of the above-mentioned fiberglass anchor rod 1 is 400 cm, and the spacing between two adjacent fiberglass anchor rods 1 in the circumferential direction of the tunnel 20 is 50 cm, and the spacing between two adjacent fiberglass anchor rods 1 in the longitudinal direction of the tunnel 20 is 50 cm; the extension length of the above-mentioned tension anchor cable 2 is between 550 and 570 cm, and the spacing between two adjacent tension anchor cables 2 in the circumferential direction of the tunnel 20 is 100 cm, and the spacing between two adjacent tension anchor cables 2 in the longitudinal direction of the tunnel 20 is between 75 and 100 cm; the axial length of the above-mentioned grouting pipe is 400 cm, and the spacing between two adjacent grouting pipes in the circumferential direction of the tunnel 20 is 100 cm, and the spacing between two adjacent grouting pipes in the longitudinal direction of the tunnel 20 is between 75 and 100 cm. In some other implementations, the parameters such as the size of the fiberglass anchor rod 1, the tension anchor cable 2 and the grouting pipe can also be other numerical ranges, which are not limited here.

[0044] It should be noted that the above-mentioned tunnel 20 is circumferential and Figure 1a The xx direction in the above tunnel 20 is consistent with the xx direction in the above tunnel 20. Figure 1b The yy direction in is consistent.

[0045] In order to further strengthen the structure of the middle part of the middle rock wall 10, in the specific implementation of this embodiment, the multiple grouting pipes also include multiple second grouting pipes 4, and the multiple second grouting pipes 4 are relatively arranged in the thickness direction of the middle rock wall 10; the first end of the second grouting pipe 4 is used to connect to the side wall of the middle rock wall 10 and to connect the grouting machine, and the second end of the second grouting pipe 4 is located in the middle rock wall 10; in the height direction of the middle rock wall 10, the multiple second grouting pipes 4 are located between the multiple tension anchor cables 2, and a second grouting pipe 4 is arranged between two adjacent tension anchor cables 2, and the spacing between the two adjacent second grouting pipes 4 is equal. In the specific implementation of this embodiment, the extension direction of the second grouting pipe 4 is consistent with the thickness direction of the middle rock wall 10, wherein the thickness direction of the middle rock wall 10 is consistent with the aa direction in Figure 1. It should be noted that the second grouting pipe 4 is consistent with the first grouting pipe 3 in structure, shape and size. The structure of the first grouting pipe 3 will be described in detail below, and it is not limited here.

[0046] See also Figure 2 , Figure 2 Another partial structural diagram of the rock wall reinforcement structure in the small clearance tunnel provided by the embodiment of the present disclosure. Figure 2As shown, in order to further enhance the reinforcement effect of the rock wall reinforcement structure in the small clearance tunnel provided by the present embodiment, so as to avoid the collapse of the tunnel 20 located on both sides of the middle rock wall 10, in the present embodiment, the rock wall reinforcement structure in the small clearance tunnel provided by the present embodiment also includes a plurality of third grouting pipes 5, and the plurality of third grouting pipes 5 are arranged at the opening of the middle rock wall 10, and the third grouting pipes 5 extend along the excavation direction of the tunnel; among the plurality of third grouting pipes 5, the spacing between two connected third grouting pipes 5 is equal, and the plurality of third grouting pipes 5 include a plurality of grouting pipe groups spaced apart along the height direction of the middle rock wall 10.

[0047] In order to reduce the number of holes drilled in the third grouting pipe 5 and to facilitate the formation of a slurry reinforcement circle, in some optional embodiments, each grouting pipe group includes third grouting pipes 5 spaced apart along the thickness direction of the middle rock wall 10; in the height direction of the middle rock wall 10, multiple third grouting pipes 5 in two adjacent grouting pipe groups are staggered. This arrangement can be understood as a third grouting pipe 5 distributed in the center and six third grouting pipes 5 distributed on the periphery. The connecting lines of the six third grouting pipes 5 form a regular hexagon. In this way, it is convenient to form a slurry reinforcement circle on the periphery of each third grouting pipe 5 to strengthen the structure of the middle rock wall 10 at the cave entrance.

[0048] In order to limit the installation range of the third grouting pipe 5, in the present embodiment, in the thickness direction of the middle rock wall 10, the installation range of the third grouting pipe 5 is the area between the limit lines 1 of the two tunnels 20 and between the upper arch line and the lower arch line of the tunnel 20. More specifically, after the two limit lines 1 are translated 150m toward the middle of the middle rock wall 10, the area between the two limit lines 1 after translation is the installation area of ​​the third grouting pipe 5. It can be understood that the limit line 1 is the dividing line between the space that can be passed by vehicles and the space that cannot be passed by vehicles in the thickness direction of the middle rock wall 10. In some other embodiments, the installation range of the third grouting pipe 5 can also be other areas, which is not limited here.

[0049] In a specific implementation manner of the present embodiment, in the height direction of the middle rock wall 10, the spacing between two adjacent grouting pipe groups is 100 cm, and in the thickness direction of the middle rock wall 10, the spacing between two adjacent third grouting pipes 5 in each grouting pipe group is 50 cm. More specifically, the axial length of the third grouting pipe 5 is 500 cm, the outer diameter of the third grouting pipe 5 is 70 mm, and the wall thickness of the third grouting pipe 5 is 5 mm. In some other implementation manners, the parameters of the third grouting pipe 5 array and the size parameters of the third grouting pipe 5 may be other values, which are not limited here.

[0050] It should be noted that when constructing the rock wall reinforcement structure in the small clearance tunnel provided in this embodiment, the reinforcement structure at the tunnel entrance is constructed first, that is, multiple third grouting pipes 5 are driven first, and then the two tunnels 20 are excavated. It should be noted that the two tunnels should be excavated staggered, that is, after excavating the first tunnel 20, the reinforcement structure in the tunnel is constructed, that is, the glass fiber anchor rod 1, the tension anchor cable 2 and the first grouting pipe 3 are driven, and then the second tunnel 20 is excavated, alternating between the two tunnels.

[0051] In order to explain the order of digging the two tunnels 20, the following is given: Figure 3 For reference, Figure 3 As shown, Figure 3 A schematic diagram of the relationship between two tunnels during the construction process of the rock wall reinforcement structure in the small clearance tunnel provided by the embodiment of the present disclosure. Specifically, during the excavation process of the tunnel 20, the tunnel 20 excavated first is named as the first tunnel 20a, and the tunnel 20 excavated later is named as the later tunnel 20b. Figure 3 As shown, the first working face 201 of the leading tunnel 20a is located on the inner side of the second working face 202 of the following tunnel 20b, and the distance between the first working face 201 and the second working face 202 in the longitudinal direction of the tunnel 20 is between 20 and 40 m. Here, there is no specific limitation on the distance between the first working face 201 and the second working face 202 in the longitudinal direction of the tunnel 20.

[0052] More specifically, in this embodiment, the second face 202 and the invert of the rear tunnel 20b are located between the invert of the leading tunnel 20a and the secondary lining of the leading tunnel 20a. The position of the second face 202 corresponds to the ring section of the initial support of the leading tunnel 20a. The ringed initial support of the leading tunnel 20a has a strong support capacity to resist the stress release caused by the excavation of the rear tunnel 20b, avoiding the collapse of the leading tunnel 20a. At the same time, the ringed initial support of the rear tunnel 20b is ahead of the secondary lining of the leading tunnel 20a, avoiding the stress released by the surrounding rock during the excavation of the rear tunnel 20b directly acting on the secondary lining of the leading tunnel 20a and causing the secondary lining to crack. It should be noted that in the specific construction process, the reserved deformation can be reasonably set according to the monitoring results to avoid the initial support from intruding. By optimizing the construction spacing between the leading tunnel 20a and the rear tunnel 20b, the stability of the middle rock 10 can be improved to a certain extent.

[0053] In order to further enhance the reinforcement effect of the rock wall reinforcement structure in the small clearance tunnel provided by this embodiment, the fiberglass anchor rod 1 and the first grouting pipe 3 in this embodiment should be arranged at an angle. The inclination direction and inclination angle of the fiberglass anchor rod 1 and the first grouting pipe 3 will be specifically introduced below.

[0054] like Figure 1a and Figure 1b As shown, in this embodiment, the first end of the fiberglass anchor rod 1 is located on the side of the second end of the fiberglass anchor rod 1 close to the tension anchor cable 2, and the first end of the fiberglass anchor rod 1 is located on the side of the second end of the fiberglass anchor rod 1 close to the hole opening; the first end of the first grouting pipe 3 is located on the side of the second end of the first grouting pipe 3 close to the tension anchor cable 2, and the first end of the first grouting pipe 3 is located on the side of the second end of the first grouting pipe 3 close to the hole opening.

[0055] In a specific implementation manner of the present embodiment, the circumferential angle of the fiberglass anchor 1 is between 60° and 75°, and the longitudinal leading flat insertion angle of the fiberglass anchor 1 is 45°; the circumferential angle of the first grouting pipe 3 is between 60° and 90°, and the longitudinal leading flat insertion angle of the first grouting pipe 3 is 45°; in some other implementation manners, the inclination angle of the fiberglass anchor 1 and the inclination angle of the first grouting pipe 3 may also be other angle values, which are not limited here.

[0056] Furthermore, in this embodiment, the ultimate load of the glass fiber anchor rod 2 is 285 KN, the tensile strength is 562 MPa, the shear strength is 108 MPa, and the torque is 34 N·m; no specific limitation is made here.

[0057] In order to improve the reinforcement range of the glass fiber anchor rods 1 and the first grouting pipes 3, in the present embodiment, a plurality of glass fiber anchor rods 1 are relatively arranged along the thickness direction of the middle rock wall 10, and in the height direction of the middle rock wall 10, the glass fiber anchor rods 1 respectively connected to the two side walls of the middle rock wall 10 are staggered and evenly spaced, and the projections of two adjacent glass fiber anchor rods 1 in the height direction of the middle rock wall 10 intersect at one point; a plurality of first grouting pipes 3 are relatively arranged along the thickness direction of the middle rock wall 10, and in the height direction of the middle rock wall 10, the first grouting pipes 3 respectively connected to the two side walls of the middle rock wall 10 are staggered and evenly spaced, and the projections of two adjacent first grouting pipes 3 in the height direction of the middle rock wall 10 intersect at one point. In this way, in the height direction of the middle rock wall 10, the projections of adjacent glass fiber anchor rods 1 in the height direction of the middle rock wall 10 intersect, and the projections of adjacent first grouting pipes 3 in the height direction of the middle rock wall 10 intersect, thereby increasing the reinforcement range of the glass fiber anchor rods 1 and the first grouting pipes 3, and further improving the reinforcement effect of the small clear distance tunnel middle rock wall reinforcement structure provided in this embodiment.

[0058] It is not difficult to understand that the adjacent glass fiber anchor rods 1 are distributed on the two side walls of the middle rock wall 10 ; and the adjacent first grouting pipes 3 are distributed on the two side walls of the middle rock wall 10 .

[0059] Furthermore, in order to increase the reinforcement range of the fiberglass anchor rods 1 and the first grouting pipes 3, in the specific implementation of the present embodiment, in the excavation direction of the tunnel, the fiberglass anchor rods 1 and the first grouting pipes 3 connected to the same side wall of the middle rock wall 10 are staggered and evenly spaced, and the adjacent fiberglass anchor rods connected to the two side walls of the middle rock wall 10 intersect with the projection of the first grouting pipes 3 in the height direction of the middle rock wall 10 and form an intersection 6.

[0060] Specifically, in order to limit a better reinforcement range, in some optional embodiments, in adjacent fiberglass anchor rods and the first grouting pipe 3 connected to different side walls of the middle rock wall 10, the distance between the first end of the fiberglass anchor rod and the first end of the first grouting pipe 3 close to the intersection 6 and the intersection 6 in the tunnel excavation direction is greater than or equal to 60 cm and less than or equal to 100 cm.

[0061] For easier understanding, see Figure 1b , wherein, taking the glass fiber anchor rod 1a and the first grouting pipe 3a as an example, the first end of the glass fiber anchor rod 1a is named the first end 11, and the first end of the first grouting pipe 3a is named the first end 31. In the excavation direction of the tunnel 20, the distance between the first end 31 and the intersection 6 is closer, and the distance between the first end 31 and the intersection 6 in the excavation direction of the tunnel 20 is between 60 and 100 cm.

[0062] In order to enable the first grouting pipe 3 and the second grouting pipe 4 to be reliably connected to the middle rock wall 10, thereby further improving the reinforcement effect of the small clearance tunnel middle rock wall reinforcement structure provided by this embodiment, in this embodiment, the structure of the grouting pipe is deliberately changed accordingly. The structure of the grouting pipe in this embodiment will be described in detail below.

[0063] See also Figures 4a to 4c , Figure 4a A schematic diagram of the structure of a grouting pipe in a rock wall reinforcement structure in a small clearance tunnel provided by an embodiment of the present disclosure, Figure 4b for Figure 4a Schematic diagram of the local structure at A in the middle. Figure 4c for Figure 4a Schematic diagram of the local structure at B in the figure. Figures 4a to 4cAs shown, in some optional embodiments, the grouting pipe includes a first pipe segment 7, a second pipe segment 8 and a third pipe segment 9 connected in sequence; wherein the first pipe segment 7 is threadedly connected to the second pipe segment 8, and the end of the first pipe segment 7 away from the second pipe segment 8 is a cone, the cone is located in the middle rock wall 10, and the top of the cone is arranged away from the second pipe segment 8; a plurality of grouting holes 81 distributed at intervals are opened on the pipe wall of the second pipe segment 8, and a valve 30 is provided on the second pipe segment 8; the third pipe segment 9 is threadedly connected to the second pipe segment 8, the third pipe segment 9 is located outside the middle rock wall 10, and the end of the third pipe segment 9 away from the second pipe segment 8 is used for connecting a grouting machine; wherein the outer diameters of the first pipe segment 7 and the third pipe segment 9 are both smaller than the inner diameter of the second pipe segment 8.

[0064] Specifically, the end of the first pipe section 7 away from the second pipe section 8 is a cone, which can avoid the occurrence of skew hole phenomenon in the grouting pipe to a certain extent, making the grouting pipe less likely to swing, which is beneficial to grouting, so that the grouting pipe can be reliably connected to the middle rock wall 10; in addition, the first pipe section 7 and the second pipe section 8 are detachably connected, which is convenient for replacing the first pipe section 7 under different working conditions.

[0065] In the specific implementation of this embodiment, the axial length of the first pipe segment 7 is 20 cm, and the outer diameter of the first pipe segment 7 is 65 mm; the outer diameter of the second pipe segment 8 is 70 mm, and the wall thickness of the second pipe segment 8 is 5 mm. Here, the size values ​​of the first pipe segment 7 and the second pipe segment 8 are not limited.

[0066] Furthermore, in the present embodiment, the above-mentioned grouting pipe may be a steel pipe. In some other implementations, the grouting pipe may also be a pipe made of other materials, which is not limited here.

[0067] See also Figure 5 , Figure 5 A diagram of the use status of the grouting pipe in the rock wall reinforcement structure in the small clearance tunnel provided by the embodiment of the present disclosure, wherein the direction of the arrow is the flow direction of the slurry. In some optional embodiments, in order to prevent the slurry from flowing back along the grouting hole 81, the grouting pipe also includes a plurality of elastic covers 40, and the plurality of elastic covers 40 correspond to the plurality of grouting holes 81 one by one; the elastic covers 40 are arranged on the outside of the second pipe section 8, and the elastic covers 40 cover the corresponding grouting holes 81, and the elastic covers 40 expand outwards when the grouting pipe is grouting, and the elastic covers 40 shrink inwards after the grouting of the grouting pipe is completed. In this way, when the slurry flows from the grouting hole 81 to the inside of the middle rock wall 10, under the action of the elastic covers 40, a certain pressure will be generated on the slurry, thereby preventing the slurry from flowing back along the grouting hole 81.

[0068] In a specific implementation of this embodiment, the diameter of the grouting hole 81 is 10 mm, and the elastic cover 40 is formed by a plastic hose wrapped with a rubber belt. Here, there is no specific limitation on the diameter of the grouting hole 81 and the material of the elastic cover 40.

[0069] Furthermore, in order to improve the connection reliability between the grouting pipe and the middle rock wall 10, in this embodiment, the second pipe section 8 includes an inner pipe section 82 and an outer pipe section 83 connected in sequence, the inner pipe section 82 is located in the middle rock wall 10, the first pipe section 7 is threadedly connected to the inner pipe section 82, and the outer diameter of the first pipe section 7 is smaller than the inner diameter of the inner pipe section 82, the grouting hole 81 is opened on the inner pipe section 82, the outer pipe section 83 is located outside the middle rock wall 10, the third pipe section 9 is threadedly connected to the outer pipe section 83, and the valve 30 is arranged on the outer pipe section 83; the side of the inner pipe section 82 close to the outer pipe section 83 is anchored to the middle rock wall 10 by a resin anchor 50. In this way, it is equivalent to making the grouting pipe and the middle rock wall 10 firmly connected at both ends of the grouting pipe, so that the reinforcement effect of the small clearance tunnel middle rock wall reinforcement structure provided by this embodiment is better.

[0070] Furthermore, in order to seal the slurry so that the side of the inner pipe section 82 close to the outer pipe section 83 is reliably connected to the middle rock wall 10, a slurry stop wall 60 can be sprayed on the outside of the middle rock wall 10, and the side of the inner pipe section 82 close to the outer pipe section 83 penetrates the slurry stop wall 60, and in the specific implementation of this embodiment, the compressive strength of the slurry stop wall 60 is not less than 25MPa, and the thickness of the slurry stop wall 60 is 80cm; here, the specific parameters of the slurry stop wall 60 are not limited. In the specific implementation of this embodiment, the slurry stop wall 60 is a concrete slurry stop wall, and here, the type of the slurry stop wall 60 is not limited.

[0071] In some optional embodiments, for certain working conditions, when the length of the inner pipe segment 82 is relatively large, the inner pipe segment 82 can be formed by connecting a plurality of small segments in sequence, and two adjacent small segments can be detachably connected via a direct connector 70, and in a specific implementation of this embodiment, the inner diameter of the direct connector 70 is 70 mm, and the size of the direct connector 70 is not limited.

[0072] In a specific implementation of this embodiment, the axial length of the inner tube section 82 is 2000 mm. Here, the axial length of the inner tube section 82 is not limited.

[0073] The small-clearance tunnel middle rock wall reinforcement structure provided in the present embodiment includes a plurality of glass fiber anchor rods, a plurality of tension anchor cables and a plurality of grouting pipes, wherein the first end of the glass fiber anchor rod is used to be connected to the side wall of the middle rock wall, and the second end of the glass fiber anchor rod is located in the middle rock wall; the first end of the tension anchor cable is used to be connected to one side wall of the middle rock wall, and the second end of the tension anchor cable is used to be connected to the other side wall of the middle rock wall; the plurality of grouting pipes include a plurality of first grouting pipes, wherein the first end of the first grouting pipe is used to be connected to the side wall of the middle rock wall and to be connected to a grouting machine, and the second end of the first grouting pipe is located in the middle rock wall; the plurality of first grouting pipes and the plurality of glass fiber anchor rods are respectively located on both sides of the plurality of tension anchor cables along the height direction of the middle rock wall. In the small clearance tunnel middle rock wall reinforcement structure provided by the embodiment of the present disclosure, glass fiber anchor rods, tension anchor cables and grouting pipes are combined to reinforce the structure of the middle rock wall. Compared with the single reinforcement method in the prior art, the small clearance tunnel middle rock wall reinforcement structure provided by the present embodiment has better reinforcement effect; in addition, the glass fiber anchor rods in the embodiment of the present disclosure react with the water inside the middle rock wall to form a composite reinforcement body that is integrated with the middle rock wall, thereby further enhancing the reinforcement effect of the small clearance tunnel middle rock wall reinforcement structure provided by the present embodiment.

[0074] See also Figure 6 to Figure 7b , Figure 6 A schematic diagram of a process for reinforcing a rock wall in a small clearance tunnel provided in an embodiment of the present disclosure, Figure 7a This is a schematic structural diagram from a first perspective after tensioning and anchoring the tension anchor cables in the rock wall reinforcement method in a small clearance tunnel provided by an embodiment of the present disclosure, Figure 7b This is a schematic diagram of the structure from a second perspective after the tension anchor cables are tensioned and anchored in the rock wall reinforcement method for a small clearance tunnel provided by an embodiment of the present disclosure. Figure 6 to Figure 7b As shown, this embodiment also provides a method for reinforcing a rock wall in a small clearance tunnel, which is used to form the above-mentioned rock wall reinforcement structure in a small clearance tunnel, and the method includes:

[0075] S101, drill a first mounting hole on the side wall of the middle rock wall, insert the second end of the first grouting pipe into the first mounting hole, and grout the first grouting pipe. It should be noted that the first grouting pipe 3 can be replaced by the second grouting pipe 4, that is, this step is also applicable to the second grouting pipe 4.

[0076] More specifically, before the grouting pipe is inserted, the third grouting pipe 5 in the above embodiment should be installed at the cave entrance. After the third grouting pipe 5 is installed, the tunnel 20 is excavated. After the tunnel is excavated for 3m, the reinforcement of the middle rock wall 10 is started, and a grouting pipe is installed once at a certain interval and angle. The arrangement and angle of the grouting pipe can be implemented with reference to the above embodiment. After the middle and lower steps on one side of the middle rock wall 10 in the tunnel are excavated, the grouting pipe holes are marked with red paint at an annular interval of 1m. When drilling, the direction of the drill rod should be adjusted to be consistent with the preset direction of the grouting pipe. Because the middle rock wall 10 is fragile, the grouting pipe should be inserted in time after drilling a hole to prevent the hole from collapsing.

[0077] In the specific implementation of this embodiment, a grouting machine is used to communicate with the grouting pipe during grouting, and the flow of slurry in the grouting pipe is controlled by a valve 30. The grouting slurry uses micro-expansion cement mortar. After the slurry is mixed, grouting should be done as soon as possible. After the grouting is completed, it is cured at a temperature of about 20°C for 3 to 7 days. 42.5# ordinary Portland cement is used, and the cement dosage is not less than 300kg / m 3 Concrete uses UEA (u-type expansive agent for concrete) low-alkali expansion agent, which can basically eliminate the tensile stress caused by concrete shrinkage, reduce or prevent concrete shrinkage cracking, and make the concrete dense. In addition, it also has the effect of early strength of concrete; the dosage of UEA expansion agent is designed to be 10% to 12%, and naphthalene-based high-efficiency water reducer is used, with a dosage of 0.2% to 0.5%. The water reducer can reduce the amount of water used in mixing concrete and improve the strength of concrete. The coarse aggregate is clean crushed stone with a continuous gradation of 5-10mm particle size; the water-cement ratio is 0.41:1, the expansion agent dosage is 11%, the water reducer dosage is 0.5%, and the laboratory ratio of cement: sand: gravel is 1:1.51:2.45; based on the actual geological conditions, a double-liquid speed-regulated high-pressure grouting pump is used to grout from the periphery to the middle, first the edge holes and then the middle holes, and the grouting adopts interval and gap grouting. The grouting control pressure is 0.5-1.5MPa, and the grouting is stopped when the grouting pressure reaches 2.0MPa; the slurry must fill the grouting pipe and the gaps around it; the grouting order is from bottom to top, the slurry is first thin and then thick, the grouting amount is first large and then small, and the grouting pressure is from small to large.

[0078] It should be noted that during construction, data can be analyzed in a timely manner through monitoring and measurement. If an abnormality is found, the grouting pipe can be reinforced for a second time to improve the strength of the middle rock wall 10 and avoid "rheology" in the middle rock wall 10, which may cause cracks in the secondary lining in the later stage.

[0079] Furthermore, before the third grouting pipe 5 is installed at the hole entrance, concrete 130 should be sprayed on both sides of the middle rock wall 10 , and the exposed lengths of the grouting pipe and the glass fiber anchor 1 should be less than or equal to the thickness of the concrete 130 .

[0080] In order to facilitate the fixation of the grouting pipe, the corresponding holes can be cleaned after the drilling is completed, which is not explained in detail here.

[0081] S102, spraying a leveling layer of concrete 130 on the side wall of the middle rock wall 10, and performing a tensioning operation.

[0082] Specifically, the strength of the concrete 130 is C35, and the thickness of the concrete 130 is between 5 and 10 cm; and the above-mentioned tensioning operation is performed by utilizing the stability of the middle rock wall 10 and the prestress of the tension anchor cable 2 .

[0083] S103, drilling second mounting holes on the side walls on both sides of the middle rock wall 10 respectively, and expanding the second mounting holes.

[0084] It should be noted that, compared with drilling the second mounting hole, the same drilling machine is used, and the drill bit is replaced with a Φ95mm drill bit to expand the second mounting hole. The expanded groove 140 is cylindrical, and the depth of the expanded groove 140 is 20-25cm. The diameter of the expanded groove 140 is larger than the diameter of the tension anchor cable 2. When expanding the groove, attention should be paid to aligning the center of the hole opening with the center of the anchor cable opening, and no deviation should be allowed to ensure the smooth installation of the subsequent tension anchor cable 2.

[0085] S104 , installing the first end of the tension anchor cable 2 in the second installation hole on the side wall of one side of the middle rock wall 10 , and installing the second end of the tension anchor cable 2 in the second installation hole on the side wall of the other side of the middle rock wall 10 .

[0086] Specifically, two people cooperate to use the tension anchor cable 2 to support and slowly send it into the second installation hole. It should be noted that the tension anchor cable 2 cannot be repeatedly pulled and pulled to achieve the extension from the side wall on one side of the middle rock wall 10 to the side wall on the other side of the middle rock wall 10, ensuring that the tension anchor cable 2 in the middle rock wall 10 is horizontally connected.

[0087] In some optional embodiments, the tension anchor cable 2 adopts HZS35-300-0.5 type NPR anchor cable with a diameter of 21.8 mm, a length determined according to the thickness of the middle rock wall 10, a strength grade of 1860 MPa, and a length of the tension anchor cable 2 leaking out of the expansion groove 140 greater than or equal to 30 cm.

[0088] S105 , laying a fiber flexible mesh 80 at the opening of the second installation hole, and paving the side wall of the middle rock wall 10 as a whole.

[0089] In some optional embodiments, the fiber flexible mesh 80 is a mesh made of high-strength polyester fiber flexible material, and the mesh size is 100 mm×100 mm.

[0090] It should be noted that the fiber flexible mesh 80 must be laid closely to the wall surface of the middle rock wall 10, and the fiber flexible mesh 80 is fixed with a Φ10mm steel bar spacing of 1m. The fiber flexible mesh 80 has good toughness, small mesh, and high strength, and can adapt to the uneven surface of the concrete 130 leveling layer, which is beneficial to increase the force area between the tension anchor cable 2 and the concrete 130 leveling layer when the tension anchor cable 2 is tensioned in the later stage, and provide sufficient reaction force for the steel belt 90 installed later, avoiding damage to the concrete 130 leveling layer during the tensioning process of the tension anchor cable 2, thereby affecting the stability of the middle rock wall 10.

[0091] S106, installing the steel strip 90, so that the hole on the steel strip 90 is aligned with the second installation hole. The hole on the steel strip 90 is aligned with the second installation hole to ensure smooth installation of the subsequent tapered fixture 100, the backing plate tray 110 and the tension anchor 120.

[0092] In some optional embodiments, the steel strip 90 is a steel strip with a width of 280-300 mm, a thickness of 2.8 mm, and a material of Q235.

[0093] In a specific implementation manner of this embodiment, after the tensioning and anchoring construction of the tension anchor cables 2 is completed, the steel belt 90 can connect all the tension anchor cables 2 on the middle rock wall 10 into a whole, so that the tension anchor cables 2 form a bearing arch effect, effectively ensuring the overall stability of the middle rock wall 10 during the excavation of the tunnel 20.

[0094] S107, respectively install the conical clamp 100, the pad tray 110 and the tension anchor 120 at the tails of both ends of the tension anchor cable 2 in sequence.

[0095] The length of the conical fixture 100 is 100 mm less than the depth of the expanded groove 140 , and the diameter of the conical fixture 100 at half of its length is larger than the diameter of the expanded groove 140 , so as to ensure that the conical fixture 100 can smoothly enter the expanded groove 140 .

[0096] Specifically, push the conical clamp 100 between the steel belt 90 and the flat fiber flexible mesh 80. It should be noted that it cannot be pushed directly into the expansion groove 140. Then, install the pad tray 110 and push the pad tray 110 to a position close to the steel belt 90. Finally, push the tensioning anchor 120 to a position close to the pad tray 110.

[0097] S108, tensioning and anchoring the tension anchor cable 2.

[0098] Specifically, the tensioning jack is installed on the tensioning anchor 120, and the jack oil pump is turned on to tension the tension anchor 2. The jack drives the tensioning anchor 120, and the tensioning anchor 120 drives the end of the tension anchor 2 to perform prestressing in the direction away from the side wall of the middle rock wall 10. It should be noted that the tensioning prestress should be controlled at 30t-35t; when the tension anchor 2 reaches the designed prestress, the jack stroke ends, and after holding the load for 10-15 minutes, it quickly reverses and returns to achieve one-time tensioning.

[0099] It should be noted that during the return stroke of the jack, the tension anchor cable 2 itself will generate a retraction force that will pull the tension anchor 120 and the pad tray 110 in the reverse direction. The pad tray 110 will drive the conical clamp 100 in the reverse direction to push the conical clamp 100 into the expansion groove 140 of the leveling layer of the concrete 130. Since the expansion groove 140 is cylindrical, the front end of the conical clamp 100 can easily enter the expansion groove 140, and the tail end of the conical clamp 100 is limited by the expansion groove 140, which will cause the opening at the tail end of the conical clamp 100 to close instantly. The closed conical clamp 100 will clamp the tension anchor cable 2. At this time, the tension anchor cable 2 will stop retracting and maintain a permanent prestressed load holding state.

[0100] At this time, the installation of the prestressed anchor cable of the tension anchor cable 2 is completed, the tensioning jack is removed, the exposed part of the tension anchor cable 2 is cut off with a hydraulic cutter, and the excess tension anchor cable 2 is cut off.

[0101] S109, drilling a third mounting hole on the side wall of the middle rock wall, inserting the second end of the fiberglass anchor into the third mounting hole, and performing grouting between the fiberglass anchor and the hole wall of the third mounting hole. The grouting slurry is consistent with the slurry in the grouting pipe, and the grouting can be performed by a grouting machine, which will not be described in detail here.

[0102] Specifically, the drilling is positioned according to the arrangement plan of the glass fiber anchor rod 1, and a three-arm drilling rig is used for drilling, and the drilling depth and direction are strictly controlled; the remaining water and residue in the borehole are washed clean with high-pressure air.

[0103] The method for reinforcing the rock wall in a small clear distance tunnel provided in the present embodiment comprises drilling a first mounting hole on the side wall of the rock wall, inserting the second end of the first grouting pipe into the first mounting hole, and grouting the first grouting pipe; spraying a concrete leveling layer on the side wall of the rock wall to perform a tensioning operation; drilling second mounting holes on the side walls on both sides of the rock wall respectively, and expanding the second mounting holes; installing the first end of the tension anchor cable in the second mounting hole on the side wall on one side of the rock wall, and installing the second end of the tension anchor cable in the second mounting hole on the side wall on the other side of the rock wall. The second mounting hole on the side wall; a fiber flexible mesh is laid at the opening of the second mounting hole, and the side wall of the middle rock wall is flattened as a whole; a steel belt is installed to align the hole on the steel belt with the second mounting hole; a conical clamp, a pad tray and a tensioning anchor are installed at the tail of both ends of the tension anchor cable respectively; the tensioning anchor cable is tensioned and anchored; a third mounting hole is drilled on the side wall of the middle rock wall, the second end of the glass fiber anchor rod is inserted into the third mounting hole, and grouting is performed between the glass fiber anchor rod and the hole wall of the third mounting hole. The reinforcement method for the small clearance tunnel middle rock wall provided in this embodiment has a good reinforcement effect.

[0104] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0105] The above description is only a specific embodiment of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A rock wall reinforcement structure in a small clearance tunnel, characterized in that: It comprises a plurality of glass fiber anchor rods (1), a plurality of tension anchor cables (2) and a plurality of grouting pipes. The first end of the glass fiber anchor rod (1) is used to be connected to the side wall of the middle rock wall (10), and the second end of the glass fiber anchor rod (1) is located inside the middle rock wall (10); The first end of the tension anchor cable (2) is used to be connected to one side wall of the middle rock wall (10), and the second end of the tension anchor cable (2) is used to be connected to the other side wall of the middle rock wall (10); The plurality of grouting pipes include a plurality of first grouting pipes (3), wherein the first ends of the first grouting pipes (3) are used to be connected to the side walls of the middle rock wall (10) and to be connected to a grouting machine, and the second ends of the first grouting pipes (3) are located inside the middle rock wall (10); the plurality of first grouting pipes (3) and the plurality of glass fiber anchor rods (1) are respectively located on both sides of the plurality of tension anchor cables (2) along the height direction of the middle rock wall (10); The first end of the glass fiber anchor rod (1) is located on a side of the second end of the glass fiber anchor rod (1) close to the tension anchor cable (2), and the first end of the glass fiber anchor rod (1) is located on a side of the second end of the glass fiber anchor rod (1) close to the hole; A plurality of the glass fiber anchor rods (1) are arranged relatively along the thickness direction of the middle rock wall (10); in the height direction of the middle rock wall (10), the glass fiber anchor rods (1) respectively connected to the two side walls of the middle rock wall (10) are staggered and evenly spaced, and the projections of two adjacent glass fiber anchor rods (1) in the height direction of the middle rock wall (10) intersect at one point; The first end of the first grouting pipe (3) is located on a side of the second end of the first grouting pipe (3) close to the tension anchor cable (2), and the first end of the first grouting pipe (3) is located on a side of the second end of the first grouting pipe (3) close to the hole; A plurality of the first grouting pipes (3) are arranged relatively along the thickness direction of the middle rock wall (10); in the height direction of the middle rock wall (10), the first grouting pipes (3) respectively connected to the two side walls of the middle rock wall (10) are staggered and evenly spaced, and the projections of two adjacent first grouting pipes (3) in the height direction of the middle rock wall (10) intersect at one point; The grouting pipe comprises a first pipe section (7) and a second pipe section (8) which are connected in sequence; One end of the first pipe section (7) facing away from the second pipe section (8) is a cone, the cone is located in the middle rock wall (10), and the top of the cone is arranged away from the second pipe section (8); The second pipe section (8) comprises an inner pipe section (82) and an outer pipe section (83) which are connected in sequence, the inner pipe section (82) being located in the middle rock wall (10), the first pipe section (7) being threadedly connected to the inner pipe section (82), the outer diameter of the first pipe section (7) being smaller than the inner diameter of the inner pipe section (82), and a plurality of grouting holes (81) distributed at intervals being provided on the side wall of the inner pipe section (82); The outer pipe section (83) is located outside the middle rock wall (10), and a side of the inner pipe section (82) close to the outer pipe section (83) is anchored to the middle rock wall (10) by means of a resin anchoring agent (50); The grouting pipe further comprises a plurality of elastic covering members (40), wherein the plurality of elastic covering members (40) correspond one-to-one to the plurality of grouting holes (81); The elastic covering member (40) is arranged on the outside of the second pipe section (8), and the elastic covering member (40) covers the corresponding grouting hole (81); the elastic covering member (40) expands outwards when grouting is performed in the grouting pipe, and the elastic covering member (40) contracts inwards after grouting is completed in the grouting pipe.

2. The rock wall reinforcement structure in a small clearance tunnel according to claim 1, characterized in that: In the excavation direction of the tunnel (20), the glass fiber anchor rods (1) and the first grouting pipes (3) connected to the same side wall of the middle rock wall (10) are staggered and evenly spaced, and the projections of the adjacent glass fiber anchor rods and the first grouting pipes (3) connected to two side walls of the middle rock wall (10) in the height direction of the middle rock wall (10) intersect to form an intersection (6); In the adjacent glass fiber anchor rods (1) and the first grouting pipes (3) connected to different side walls of the middle rock wall (10), the distance between the first end of the glass fiber anchor rod (1) and the first end of the first grouting pipe (3) close to the intersection (6) and the intersection (6) in the excavation direction of the tunnel (20) is greater than or equal to 60 cm and less than or equal to 100 cm.

3. The rock wall reinforcement structure in a small clearance tunnel according to claim 1, characterized in that: A slurry stop wall (60) is sprayed on the outside of the side wall of the middle rock wall (10), and a side of the inner pipe section (82) close to the outer pipe section (83) penetrates the slurry stop wall (60); The grouting pipe further comprises a valve (30) and a third pipe section (9), wherein the valve (30) is arranged on the outer pipe section (83); The third pipe section (9) is threadedly connected to a side of the outer pipe section (83) facing away from the inner pipe section (82), and an end of the third pipe section (9) facing away from the outer pipe section (83) is used for connecting to a grouting machine.

4. The rock wall reinforcement structure in a small clearance tunnel according to claim 1 or 2, characterized in that: The plurality of grouting pipes further comprises a plurality of second grouting pipes (4), and the plurality of second grouting pipes (4) are arranged opposite to each other in the thickness direction of the middle rock wall (10); The first end of the second grouting pipe (4) is used to be connected to the side wall of the middle rock wall (10) and is used to be connected to the grouting machine, and the second end of the second grouting pipe (4) is located inside the middle rock wall (10); In the height direction of the middle rock wall (10), the plurality of second grouting pipes (4) are located between the plurality of tension anchor cables (2), and one second grouting pipe (4) is provided between two adjacent tension anchor cables (2), and the spacing between two adjacent second grouting pipes (4) is equal.

5. The rock wall reinforcement structure in a small clearance tunnel according to claim 1 or 2, characterized in that: It also comprises a plurality of third grouting pipes (5), wherein the plurality of third grouting pipes (5) are arranged at the opening of the middle rock wall (10), and the third grouting pipes (5) extend along the excavation direction of the tunnel (20); Among the plurality of third grouting pipes (5), the spacing between two adjacent third grouting pipes (5) is equal, and the plurality of third grouting pipes (5) comprise a plurality of grouting pipe groups spaced apart along the height direction of the middle rock wall (10), and each of the grouting pipe groups comprises third grouting pipes (5) spaced apart along the thickness direction of the middle rock wall (10); In the height direction of the middle rock wall (10), the plurality of third grouting pipes (5) in two adjacent grouting pipe groups are distributed in a staggered manner.

6. A method for reinforcing rock walls in a small clearance tunnel, characterized in that: The reinforcement method is applied to the rock wall reinforcement structure in a small clearance tunnel according to claim 1, and the method comprises: Drilling a first mounting hole on the side wall of the middle rock wall (10), inserting the second end of the first grouting pipe into the first mounting hole, and injecting grout into the first grouting pipe; Spraying a concrete (130) leveling layer on the side wall of the middle rock wall (10) and performing a tensioning operation; Drilling second mounting holes on the side walls on both sides of the middle rock wall (10) respectively, and expanding the second mounting holes; Installing the first end of the tension anchor cable (2) in the second installation hole on the side wall of one side of the middle rock wall (10), and installing the second end of the tension anchor cable (2) in the second installation hole on the side wall of the other side of the middle rock wall (10); Laying a fiber flexible mesh sheet (80) at the opening of the second installation hole, and paving the side wall of the middle rock wall (10) as a whole; Installing the profiled steel belt (90) so that the hole on the profiled steel belt (90) is aligned with the second installation hole; A conical clamp (100), a pad tray (110) and a tension anchor (120) are respectively installed in sequence at the tails of both ends of the tension anchor cable (2); tensioning and anchoring the tension anchor cable (2); A third mounting hole is drilled on the side wall of the middle rock wall (10), the second end of the glass fiber anchor rod (1) is inserted into the third mounting hole, and grouting is performed between the glass fiber anchor rod (1) and the hole wall of the third mounting hole.

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