A tunnel construction method in strongly weathered mudstone strata

Abstract

The present application relates to the technical field of tunnel construction, and more particularly to a method for tunnel construction in strongly weathered mudstone formations. The method comprises the following steps: S1: excavation of the tunnel entrance, including excavation of the tunnel entrance side, back slope, and entrance; S2: spraying anchors at the tunnel entrance, including installation of anchor rods and protective netting on the upper end wall of the tunnel entrance, followed by spraying concrete on the upper end wall of the tunnel entrance and combining it with the protective netting to form a protective layer; S3: construction of an advanced large pipe shed, including fabrication of an advanced large pipe shed at the tunnel entrance, installation of a steel mesh on the advanced large pipe shed, and formwork support. The advanced large pipe shed is then cast, and after casting, holes are drilled and grouting is performed according to the pipe opening position of the advanced large pipe shed; S4: construction of an advanced small pipe shed, including tunnel excavation, followed by inclined drilling and grouting of holes in the tunnel inner wall; S5: construction of tunnel protection and invert arch, including spraying concrete protection on the tunnel inner wall and erecting formwork for the invert arch and casting concrete. This application has the effect of improving safety.

Description

Technical Field

[0001] The present application relates to the technical field of tunnel construction, and in particular to a method for constructing a tunnel in a strongly weathered mudstone formation. Background Art

[0002] With the rapid expansion of tunnel construction, the challenges and problems encountered during tunnel construction are rapidly increasing, along with the risks involved. Tunnels inevitably pass through complex strata during construction. Highly weathered mudstone, a typical example of weak surrounding rock, is prone to disintegration and collapse when exposed to water, and exhibits unfavorable characteristics such as creep and long-term strength loss.

[0003] When constructing in strongly weathered mudstone, the tunnel body is first excavated. The entrance is then supported and the tunnel is excavated inwards from the entrance, with the excavated sand and gravel removed. Next, the side and back slopes at the tunnel entrance are constructed, followed by the construction of the advanced pipe shed. After this construction is complete, drilling and grouting are carried out to complete the preliminary preparations for tunnel excavation. Then, tunnel excavation begins. During the excavation process, the tunnel inner wall is sprayed with initial concrete, steel support frames are erected, anchor rods and steel mesh are installed, and mesh-sprayed concrete is applied. Finally, the lining and invert arch are constructed.

[0004] In the process of realizing this application, the inventors found that there are at least the following problems in this technology. Since the mudstone has undergone a diagenetic process, a large amount of pore water, interlayer water in minerals, adsorbed water, and chemical water have been lost between the clay particles. Therefore, after weathering, its muddy fine particles have strong water absorption and its fragment content increases. During the construction of the advanced large pipe shed, the fragments are easy to fall and cause damage to the construction workers, resulting in reduced construction safety. Summary of the Invention

[0005] In order to improve construction safety, the present application provides a tunnel construction method in strongly weathered mudstone strata.

[0006] This application provides a tunnel construction method for strongly weathered mudstone strata, which adopts the following technical solutions:

[0007] A tunnel construction method in strongly weathered mudstone strata comprises the following steps:

[0008] S1. Excavation of the tunnel entrance: Excavation of the side, back slope and entrance of the tunnel entrance is carried out;

[0009] S2. Install anchor rods and protective nets on the upper end wall of the opening, then spray concrete on the upper end wall of the opening and combine it with the protective net to form a protective layer;

[0010] S3, advanced large pipe shed construction, advanced large pipe shed is made at the opening, and then the steel mesh is installed on the advanced large pipe shed, and then the formwork support is carried out, and the advanced large pipe shed is poured. After pouring and forming, drilling and grouting are carried out according to the pipe opening position of the advanced large pipe shed;

[0011] S4: Advance small-diameter pipe construction, excavate the tunnel, then drill inclined holes on the inner wall of the tunnel and perform grouting;

[0012] S5. Tunnel protection and invert arch construction: spray concrete protection on the inner wall of the tunnel, and erect formwork for the invert arch and pour concrete.

[0013] By adopting the above technical solution, when constructing a tunnel in a strongly weathered mudstone formation, first determine the construction axis of the tunnel according to the design drawing, then dig side slopes and back slopes on both sides of the construction portal, then dig the construction portal, drill holes in the upper end wall of the construction portal to install anchor rods, then connect the anchor rods and the protective net, spray concrete on the upper end wall to form a protective layer to reduce the impact of falling debris on subsequent construction; then hoist the components of the advance large pipe shed to the portal, then erect each component in turn, then assemble them, then install a steel mesh between the advance large pipe shed and the inner wall of the portal and connect the steel mesh to the advance large pipe shed, then carry out formwork support, and there is a 10cm-15cm protective layer between the side of the formwork close to the portal axis and the advance large pipe shed ; Then pour concrete. After pouring is completed, drill holes according to the position of the pipe mouth of the advance large pipe shed, and then grouting is performed on the drilled holes; tunnel excavation is carried out. During the tunnel excavation process, inclined holes are drilled on the inner wall of the tunnel and grouting operations are performed to enhance the strength of the tunnel; then the inner wall of the tunnel is sprayed with concrete for protection, and after the concrete spraying is completed, the arch formwork is erected and concrete is poured; by adding the spray reinforcement operation during the construction of the tunnel entrance, on the one hand, the falling of gravel during the construction process can be reduced, thereby enhancing the safety of the construction. On the other hand, the connectivity between the tunnel entrance and the advance large pipe shed can be enhanced, thereby facilitating the stability of subsequent construction, enhancing the construction quality of the tunnel, and further increasing safety.

[0014] Optionally, in step S3, the axis of the pipe of the advance large pipe roof forms an acute angle of 0.5° with the horizontal plane where the tunnel excavation axis is located, and the pipe of the advance large pipe roof is raised along the excavation direction of the tunnel.

[0015] By adopting the above technical solution, when installing the advance large pipe roof, the angle between the axis of the pipe of the advance large pipe roof and the tunnel is set, which is convenient for the subsequent drilling process to make the drill hole rise. This can reduce the protective layer between the drill hole and the tunnel caused by the end of the drill bit drooping due to gravity when the drilling depth is deep, thereby weakening the fixity of the drill hole, maintaining the stability of the tunnel, and thus maintaining safety.

[0016] Optionally, in step S4, when performing inclined drilling, the drilling angle forms an acute angle with the tunnel excavation direction, and is staggered with the pipeline of the advance large pipe rack, with two adjacent hole positions cross-set and connected above the pipeline axis of the advance large pipe rack.

[0017] By adopting the above technical solution, during the tunnel excavation process, the drill holes are inclined along the tunnel excavation direction and form an acute angle with the tunnel excavation direction, and two adjacent drill holes are relatively inclined, so that the two adjacent drill holes are connected above the advance large pipe shed; during grouting and advance small guide tube construction, the drill holes are inclined and connected, which is convenient for connecting the poured concrete into a whole, and is located above the advance large pipe shed, which is convenient for sharing the force, thereby enhancing the stability of the inner wall of the tunnel, reducing the falling of strongly weathered mudstone after encountering water, and thus improving the safety of tunnel construction.

[0018] Optionally, in step S5, when spraying concrete protection on the inner wall of the tunnel, first drill and install the anchor holes and inject grout, then install the protective net, and then spray concrete; after the concrete spraying is completed, install the protective arch frame, install the waterproof board and connect it to the arch frame and connect the waterproof board to the anchor, and then cast the arch formwork.

[0019] By adopting the above technical solution, after the advance small conduit construction is carried out, smaller anchor holes are drilled on the inner wall of the tunnel, and then the anchors are installed. Grouting is carried out. After the grouting is completed, a protective net is installed on the inner wall of the tunnel. The protective net is fixedly connected to the anchor, and then concrete is sprayed. This step can reduce the small gravel on the inner wall of the tunnel that falls when it encounters water, thereby ensuring the cleanliness of the tunnel and reducing the damage caused by small gravel to the human body. After the construction of the protective net is completed, the ground concrete is cleaned, and then the protective arch frame is installed. A waterproof board is installed between the two protective arch frames, and then the arch formwork is cast; by setting the waterproof board and protective arch frame, the influence of the moisture generated by the tunnel itself on the strongly weathered mudstone on the surface of the inner wall of the tunnel can be reduced, thereby further reducing the falling of gravel on the inner wall of the tunnel, thereby improving safety.

[0020] Optionally, in step S3, the advanced large pipe shed includes a shed, a connecting mechanism and a guide tube, and the shed is provided with multiple sheds, and multiple guide tubes are provided on the shed, and the guide tubes are located on the outer wall of the shed and connected to the shed through the connecting mechanism.

[0021] By adopting the above technical solution, after the tunnel entrance is excavated, the scaffolding is transported to the entrance in sequence, and then multiple scaffoldings are preliminarily fixed, and then the guide pipes are arranged at equal intervals along the curvature of the scaffolding, and then the guide pipes are fixed with a connecting mechanism. The structure of the advanced large pipe scaffold is simple, and at the same time, the space of the tunnel entrance is small, and the advanced large pipe scaffold is divided into multiple parts, which is convenient for construction, thereby shortening the construction time and improving the construction efficiency.

[0022] Optionally, the connecting mechanism includes a tightening assembly and a connecting assembly, the tightening assembly includes a tightening screw, a limit block and a first limit nut, the limit blocks are provided at both ends of the tightening screw, and the side walls of the two limit blocks that are close to each other are respectively abutted against the side walls of the two adjacent racks that are away from each other; two first limit nuts are threadedly connected to the tightening screw, the two first limit nuts are located between the two limit blocks, and the two first limit nuts are respectively abutted against the side walls of the two adjacent racks that are close to each other; the connecting assembly is provided on the rack, and the connecting assembly is used to connect the rack and the guide tube.

[0023] By adopting the above technical solution, after the scaffolding is initially fixed, the two ends of the tightening bolt are respectively set between two adjacent scaffoldings, and then the limit block is abutted against the two adjacent scaffoldings, and then the first limit nut is rotated, and the first limit nut drives the two scaffoldings to move away from each other until the vertical planes where the two scaffoldings are located are parallel to each other, and then multiple tightening bolts are installed in sequence and adjusted to the verticality of the scaffolding, and then the scaffolding is firmly fixed, and then the guide tube is fixed to the scaffolding through the connecting assembly, and then the steel mesh and formwork are constructed, and then pouring is carried out; the set tightening assembly has a simple structure, and the tightening assembly facilitates the adjustment of the two adjacent scaffoldings to a parallel state, making the angle adjustment of the guide tube more convenient.

[0024] Optionally, the connecting assembly includes a connecting block, a U-shaped card, a wedge block and a stop block, and a plurality of the connecting blocks are provided on the scaffolding; a fixing groove is provided on the connecting block, and the axis of the fixing groove is set at an angle of 0.5° with the axis of the scaffold, and the fixing grooves on the same axis are clamped with the same guide tube; the U-shaped sleeve is provided on the guide tube and is slidingly connected to the connecting block, and the stop blocks are provided at both ends of the U-shaped card, the wedge block slides on the connecting block and abuts against the stop block, and the wedge block drives the stop block away from the guide tube.

[0025] By adopting the above technical solution, after the guide tube is abutted against the scaffolding, the U-shaped clip is connected to the guide tube, and then the wedge is struck with a hammer. The wedge drives the block to slide in the direction away from the guide tube, so that the U-shaped clip drives the guide tube to press against the fixing groove, thereby making the fixation of the guide tube more convenient, facilitating the installation of the guide tube, and making the assembly of the guide tube simpler and more convenient. At the same time, the abutment between the guide tube and the fixing groove is tighter, and the fixing groove is inclined, making the angle adjustment of the guide tube convenient.

[0026] Optionally, the connecting block is rotatably set on the scaffolding, and the connecting mechanism also includes an adjustment assembly, the adjustment assembly includes a stop block, an adjustment bolt, a first adjustment nut and a second adjustment nut, and the stop blocks are provided on both sides of the scaffolding; the stop block corresponds to the connecting block, and a clamping groove is provided on the stop block; the adjusting bolt is hinged on the connecting block and rotates into the clamping groove, and the first adjusting nut and the second adjusting nut are both threadedly connected to the adjusting bolt and respectively abut against the stop blocks.

[0027] By adopting the above technical solution, when the lengths of tunnels are different, the connecting block can be rotated according to the length of the tunnel, and then the adjusting bolt can be rotated into the clamping groove opened on the stop block, and then the first adjusting nut and the second adjusting nut on both sides can be tightened, so that the angle of the connecting block is fixed, and then the guide tube is clamped in the fixing groove and fixed with a connecting U-shaped clip; the set adjustment component has a simple structure and is easy to operate. At the same time, the set adjustment component realizes the angle adjustment of the guide tube, and at the same time reduces the excessive deviation of the drilling position caused by excessive angle when the tunnel is short, thereby improving the applicability of the structure.

[0028] Optionally, in step S5, a fixing mechanism is provided at the end of the anchor, and the fixing mechanism includes a pulling claw, a first fixing nut, a fixing screw and a second fixing nut. The fixing screw is provided at the end of the anchor, and the pulling claw is slidably connected to the fixing screw, and the pulling claw is hooked with the protective net; the first fixing nut is threadedly connected to the fixing screw, and the first fixing nut abuts against the pulling claw and drives the pulling claw to slide toward the top wall of the tunnel; a through hole is provided on the waterproof board, and the fixing screw passes through the through hole and is threadedly connected to the second fixing nut.

[0029] By adopting the above technical solution, after the anchor is fixed on the inner wall of the tunnel, the protective net is fitted with the inner wall of the tunnel, and then the first fixing nut is rotated, the first fixing nut drives the pulling claw to slide, and the pulling claw drives the protective net to fit tightly with the inner wall of the tunnel, and then the end of the fixing screw is protected, and then concrete is sprayed, and then the protective arch is fixed on the inner wall of the tunnel, and then the waterproof board is installed, and the end of the fixing screw passes through the waterproof board and is threadedly connected with the second fixing nut; the set fixing mechanism is simple, and can not only fix the inner wall of the tunnel, but also fix the protective net and the waterproof board. The one-time installed anchor realizes multiple functions, thereby reducing working time, thereby improving work efficiency, and at the same time reducing material use and saving resources.

[0030] Optionally, the fixing mechanism includes a sealing assembly, which includes a sealing epoxy, a sealing cap and a stop pin. The sealing epoxy is filled in the penetration hole, the sealing cap is connected to the waterproof board, and the sealing cap is pressed against the sealing epoxy. The stop pin is inserted into the waterproof board and abuts against the sealing cap.

[0031] By adopting the above technical solution, after the waterproof board is installed, the sealing epoxy is filled in the penetration hole so that the sealing epoxy overflows the penetration hole, and then the sealing cap is selected so that the sealing cap abuts the sealing epoxy; the sealing component set up can reduce the water vapor generated in the tunnel from entering the penetration hole, contacting the concrete on the protective net with the inner layer of gravel, thereby further reducing the probability of gravel falling, extending the service life of the tunnel, and improving the stability of the tunnel.

[0032] In summary, this application has the following beneficial technical effects:

[0033] 1. By adding spray reinforcement during tunnel construction, on the one hand, it can reduce the falling of debris during construction, thereby enhancing construction safety. On the other hand, it can enhance the connection between the tunnel entrance and the advance pipe shed, thereby facilitating the stability of subsequent construction, improving the construction quality of the tunnel, and further increasing safety.

[0034] 2. When installing the advance pipe shed, the angle between the axis of the pipe shed and the tunnel is set to facilitate the upward movement of the drill hole during subsequent drilling. This can reduce the risk of the drill bit tip sagging due to gravity when drilling deep, which can reduce the protective layer between the drill hole and the tunnel. This can also weaken the stability of the drill hole, maintain the stability of the tunnel, and thus maintain safety.

[0035] 3. When the lengths of tunnels are different, the connecting block can be rotated according to the length of the tunnel, and then the adjusting bolt can be rotated into the clamping groove on the stop block, and then the first adjusting nut and the second adjusting nut on both sides can be tightened to fix the angle of the connecting block, and then the guide tube can be clamped in the fixing groove and fixed with a connecting U-shaped clip; the setting adjustment component has a simple structure and is easy to operate. At the same time, the setting adjustment component realizes the angle adjustment of the guide tube, and at the same time reduces the excessive deviation of the drilling position caused by excessive angle when the tunnel is short, thereby improving the applicability of the structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flow chart of the tunnel construction method for strongly weathered mudstone formations in an embodiment of the present application;

[0037] Figure 2 This is a schematic diagram of the structure of the tunnel in the embodiment of the present application;

[0038] Figure 3This is a schematic diagram of the overall structure of the advanced large pipe shed in the embodiment of this application;

[0039] Figure 4 This is a schematic diagram of the installation position of the tensioning assembly in the embodiment of the present application;

[0040] Figure 5 This is a schematic structural diagram of the tensioning assembly in an embodiment of the present application;

[0041] Figure 6 This is a schematic diagram of the structure of the connection component in the embodiment of the present application;

[0042] Figure 7 This is a schematic diagram of the installation positions of the protective net and waterproof board in the embodiment of the present application;

[0043] Figure 8 This is an exploded schematic diagram of the fixing mechanism in an embodiment of the present application.

[0044] Reference numerals: 100, advanced large pipe scaffold; 110, scaffolding; 111, tensioning groove; 112, limiting groove; 120, guide pipe; 200, protective net; 300, protective arch; 400, connecting mechanism; 410, tensioning assembly; 411, tensioning screw; 412, limiting block; 413, first limiting nut; 414, second limiting nut; 420, connecting assembly; 421, connecting block; 422, U-shaped clip; 423, wedge; 424 , block; 425, fixing groove; 430, adjusting assembly; 431, stop block; 432, adjusting bolt; 433, first adjusting nut; 434, second adjusting nut; 435, snap-in groove; 500, anchor; 600, fixing mechanism; 610, pull claw; 620, first fixing nut; 630, fixing screw; 640, second fixing nut; 650, sealing assembly; 651, sealing cap; 652, stop pin; 700, waterproof board. DETAILED DESCRIPTION

[0045] The following is combined with Figure 1-8 This application is described in further detail.

[0046] The embodiments of the present application disclose a method for constructing a tunnel in a strongly weathered mudstone formation.

[0047] refer to Figure 1 and Figure 2 The method for constructing a tunnel in a strongly weathered mudstone stratum comprises the following steps: S1, excavating a tunnel entrance, first determining the construction axis of the tunnel according to the drawings, then excavating side slopes and back slopes on both sides of the axis, and then excavating the tunnel entrance;

[0048] S2, spray anchoring at the hole opening, drilling holes in the inner wall of the hole opening, then installing anchor rods, grouting, and then connecting the protective net 200 to the inner wall of the hole opening, and then spraying concrete on the upper end wall of the hole opening and combining it with the protective net 200 to form a protective layer;

[0049] S3, the construction of the advance large pipe shed 100, the advance large pipe shed 100 is disassembled and transported to the tunnel entrance, and then assembled at the tunnel entrance. After the assembly is completed, the angle of the advance large pipe shed 100 is adjusted so that the axis of the pipe of the advance large pipe shed 100 is at an angle of 0.5° with the horizontal plane where the axis of the tunnel excavation is located, and the pipe of the advance large pipe shed 100 is raised along the excavation direction of the tunnel to neutralize the sagging amount during drilling. The advance large pipe shed 100 is fixed, and then a steel mesh is installed between the advance large pipe shed 100 and the inner wall of the tunnel entrance and connected to the advance large pipe shed 100. Then, formwork support is carried out and the advance large pipe shed 100 is poured. After pouring and forming, holes are drilled according to the pipe mouth position of the advance large pipe shed 100. After drilling is completed, the holes are cleaned and then grouting is installed after grouting.

[0050] S4. Construction of the advanced small pipe and excavation of the tunnel. As the tunnel is excavated, inclined holes are drilled on the inner wall of the tunnel. When performing the inclined drilling, the drilling angle forms an acute angle with the tunnel excavation direction and is staggered with the pipeline of the advanced large pipe shed 100. Two adjacent holes are arranged crosswise and connected above the pipeline axis of the advanced large pipe shed 100 and grouting is performed, forming a whole above the advanced large pipe shed 100, which is convenient for fixing the tunnel and facilitating force sharing.

[0051] S5. Tunnel protection and inverted arch construction, spray concrete protection on the inner wall of the tunnel. When spraying concrete protection on the inner wall of the tunnel, first drill and install the anchor 500. The installation of the anchor 500 is staggered with the position of the construction drilling of the advance small guide tube construction. Then, grouting is performed after the anchor 500 is installed, and then the protection net 200 is installed. The protection net 200 is sprayed with concrete. After the concrete spraying is completed, the protection arch frame 300 is installed, and the waterproof board 700 is installed and connected to the arch frame and the waterproof board 700 is connected to the anchor 500. Then, the inverted arch formwork is cast, and concrete is cast in the inverted arch formwork, and the fixed end of the protection arch frame 300 is cast in the concrete.

[0052] refer to Figure 3 、 Figure 4 and Figure 5The advanced large pipe shed 100 includes a plurality of scaffolds 110, and in this embodiment, three scaffolds 110 are preferably parallel to each other and the scaffolds 110 are arched; a connecting mechanism 400 for connecting two adjacent scaffolds 110 is provided on the scaffold 110, and the connecting mechanism 400 includes a tightening assembly 410, and the tightening assembly 410 includes a plurality of tightening screws 411, both ends of the tightening screws 411 are threaded, and a plurality of tightening grooves 111 are provided on the outer wall of the scaffold 110, and the plurality of tightening grooves 111 are arranged at equal intervals along the circumference of the scaffold 110, and the two ends of the tightening screws 411 are respectively passed through the tightening grooves 111; the two ends of the tightening screws 411 are fixedly connected to the limiting blocks 412, and the outer wall of the scaffold 110 is provided with a plurality of tightening grooves 111 connected to the tightening grooves 111 The limiting groove 112 is connected to the limit block 412, and the limiting block 412 slides into the tightening groove 111 through the limiting groove 112, and the side walls of the two limiting blocks 412 that are close to each other abut against the side walls of the two adjacent racks 110 that are away from each other; two first limiting nuts 413 are threadedly connected to the tightening screw 411, and the two first limiting nuts 413 are both located between the two limiting blocks 412, and the first limiting nuts 413 abut against the side walls of the two adjacent racks 110 that are close to each other; two second limiting nuts 414 are also threadedly connected to the tightening screw 411, and the two second limiting nuts 414 respectively abut against the side of the two limiting blocks 412 that are away from each other, and the second limiting nuts 414 abut against the tightening groove 111 and limit the tightening screw 411 from separating from the tightening groove 111.

[0053] refer to Figure 3 and Figure 6 , a connecting assembly 420 is provided on the outer wall of the scaffolding 110, and the connecting assembly 420 includes a plurality of connecting blocks 421 rotatably connected to the scaffolding 110, the rotation axis of the connecting block 421 is tangent to the outer wall of the scaffolding 110, and the connecting block 421 is staggered with the tightening screw 411, and a fixing groove 425 is provided on the connecting block 421. When the connecting block 421 is perpendicular to the scaffolding 110, the axis of the fixing groove 425 and the axis of the scaffolding 110 form an acute angle of 0.5°; both ends of the connecting block 421 are provided with There are connecting grooves, and a U-shaped card 422 is passed through the two connecting grooves. Both ends of the U-shaped card 422 are fixedly connected with a stopper 424. The stopper 424 is located on the side of the connecting block 421 close to the scaffolding 110, and the axis of the stopper 424 is perpendicular to the axis of the connecting groove; four wedge blocks 423 are slidably connected to the connecting block 421, and a wedge block 423 is slidably connected on both sides of each connecting groove. The wedge block 423 is located between the connecting block 421 and the stopper 424, and hitting the wedge block 423 can drive the stopper 424 away from the connecting block 421.

[0054] refer to Figure 3 and Figure 6The scaffolding 110 is provided with an adjusting assembly 430, which includes two adjusting bolts 432 hinged at both ends of the connecting block 421. The rotation axis of the adjusting bolt 432 is parallel to the axis of the connecting block 421. A plurality of stop blocks 431 are integrally provided on the scaffolding 110. The stop blocks 431 correspond to the adjusting bolts 432, and the stop blocks 431 are provided with a clamping groove 435 for facilitating the passage of the adjusting bolts 432. The adjusting bolt 432 is threadedly connected with a first adjusting nut 433 and a second adjusting nut 434. The first adjusting nut 433 and the second adjusting nut 434 are respectively located on both sides of the stop block 431 and abut against the stop block 431.

[0055] refer to Figure 7 and Figure 8 , a fixing mechanism 600 is provided on the anchor 500, and the fixing mechanism 600 includes a fixing screw 630 integrally provided on the anchor 500, the fixing screw 630 passes through the protective net 200 and is threadedly connected with a first fixing nut 620 and a second fixing nut 640, a pulling claw 610 is sleeved on the fixing screw 630, the pulling claw 610 abuts against the side of the first fixing nut 620 away from the second fixing nut 640 and is hooked with the protective net 200, and the first fixing nut 620 can drive the pulling claw 610 to slide; a through hole is opened on the waterproof board 700, and the fixing screw The bolt passes through the penetration hole, and the aperture of the penetration hole is larger than the aperture of the fixing bolt to facilitate the penetration of the offset fixing bolt. The waterproof plate 700 is located between the first fixing nut 620 and the second fixing nut 640. The waterproof plate 700 is provided with an embedding groove connected to the penetration hole on the side close to the protective net 200. The first fixing nut 620 can be sunk into the embedding groove so that the waterproof plate 700 fits against the inner wall of the tunnel; a plurality of arc rods can be fitted on the protective net 200, and the arc rods are arranged along the arc surface of the tunnel. The arc rods are connected to the pull claw 610 and abut against the protective net 200 through the pull claw 610.

[0056] refer to Figure 7 and Figure 8 , a sink groove connected to the penetration hole is provided on the side of the waterproof board 700 away from the protective net 200, and the second fixing nut 640 is located in the sink groove; a sealing assembly 650 is provided on the waterproof board 700, and the sealing assembly 650 includes a sealing cap 651 threadedly connected to the sink groove, and the sealing cap 651 is flush with the side wall of the waterproof board 700 away from the protective net 200; the penetration hole is filled with sealing epoxy, and the sealing cap 651 is pressed against the sealing epoxy; a stopping groove is provided on the side of the sealing cap 651 away from the protective net 200, and the waterproof board 700 also has a stopping groove, and the stopping groove on the waterproof board 700 is located at the edge of the sink groove, and the stopping groove on the waterproof board 700 and the stopping groove on the sealing cap 651 form a complete circular groove, and a stopping pin 652 is inserted in the circular groove. After the installation of the sealing cap 651 is completed, the stopping pin 652 can be inserted into the circular groove.

[0057] The implementation principle of a tunnel construction method in a strongly weathered mudstone formation in an embodiment of the present application is as follows: when constructing a tunnel in a strongly weathered mudstone formation, first determine the construction axis of the tunnel according to the design drawing, then dig side slopes and back slopes on both sides of the construction entrance, then dig the construction entrance, drill holes in the upper end wall of the construction entrance to install anchor rods, then connect the anchor rods and the protective net 200, and spray concrete on the upper end wall to form a protective layer to reduce the impact of falling gravel on subsequent construction.

[0058] After the first and second adjusting nuts 433 and 434 are tightened, the first and second adjusting nuts 434 are tightened, and the second and second adjusting nuts 435 are tightened. 34, so that the angle of the connecting block 421 is fixed; then multiple guide tubes 120 are placed in the fixing groove 425 in sequence, and the U-shaped card 422 is put on the guide tube 120 and passed through the connecting groove, and then the construction personnel hit the wedge block 423 with a hammer, the wedge block 423 drives the stop block 424 away from the connecting block 421, and the stop block 424 drives the U-shaped card 422 to press against the guide tube 120; then a steel mesh is installed between the advance large pipe shed 100 and the inner wall of the hole and the steel mesh is connected to the advance large pipe shed 100, and then the formwork support is carried out. There is a 10cm-15cm protective layer between the side of the formwork close to the axis of the hole and the advance large pipe shed 100; then concrete is poured. After the pouring is completed, drilling operations are carried out according to the position of the pipe mouth of the advance large pipe shed 100, and then the drilled holes are grouting.

[0059] Tunnel excavation is carried out. During the tunnel excavation process, inclined holes are drilled on the inner wall of the tunnel and grouting operations are performed to enhance the strength of the tunnel; and anchor holes 500 are drilled on the inner wall of the tunnel, and the anchors 500 are installed and fixed by grouting. Then the protective net 200 is fitted to the inner wall of the tunnel, and the claws 610 and the first fixing nuts 620 are installed on the fixing bolts. Then the arc rod 660 is connected to the claws 610. After the protective net 200 is fixed, concrete is sprayed, and then the protective arch frame 300 is installed. Then the waterproof board 700 is installed between the two protective arch frames 300, and then the second fixing nut 640 is threadedly connected to the fixing bolt. The second fixing nut 640 drives the waterproof board 700 to press against the concrete protective layer. Then the penetration hole is filled with sealing epoxy, and then the sealing cap 651 is threadedly connected to the groove. Then the stop pin 652 is installed, and then the arch formwork is erected and concrete is poured.

[0060] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for constructing a tunnel in strongly weathered mudstone strata, characterized in that: The following steps are involved: S1. Excavation of the tunnel entrance: Excavation of the side, back slope and entrance of the tunnel entrance is carried out; S2, spray anchoring at the hole opening, installing anchor rods and a protective net (200) on the upper end wall of the hole opening, and then spraying concrete on the upper end wall of the hole opening and combining it with the protective net (200) to form a protective layer; S3, construction of the advanced large pipe shed (100), making the advanced large pipe shed (100) at the opening, then installing the steel mesh on the advanced large pipe shed (100), then performing formwork support, pouring the advanced large pipe shed (100), after pouring and forming, drilling and grouting according to the pipe mouth position of the advanced large pipe shed (100); the advanced large pipe shed (100) includes a scaffold (110), a connecting mechanism (400) and a guide pipe (120), the scaffold (110) is provided with a plurality of the guide pipes (120), the guide pipes (120) are located on the outer wall of the scaffold (110) and The connecting mechanism (400) is connected to the shelf (110); the connecting mechanism (400) includes a tensioning assembly (410) and a connecting assembly (420); the tensioning assembly (410) includes a tensioning screw (411), a limit block (412) and a first limit nut (413); both ends of the tensioning screw (411) are provided with the limit blocks (412); the side walls of the two limit blocks (412) that are close to each other abut against the side walls of the two adjacent shelves (110) that are away from each other; the tensioning screw (411) is threadedly connected to two first limit nuts (413); the two first limit nuts (413) are threadedly connected to the tensioning screw (41 ... The positioning nut (413) is located between the two limiting blocks (412), and the two first limiting nuts (413) respectively abut against the side walls of two adjacent scaffolds (110) that are close to each other; the connecting assembly (420) is provided on the scaffold (110), and the connecting assembly (420) is used to connect the scaffold (110) and the guide tube (120); the connecting assembly (420) includes a connecting block (421), a U-shaped card (422), a wedge block (423) and a stop block (424), and a plurality of the connecting blocks (421) are provided on the scaffold (110); each of the connecting blocks (421) is provided with a There is a fixing groove (425), the axis of the fixing groove (425) is set at an angle of 0.5° with the axis of the scaffold (110), and the fixing grooves (425) on the same axis are all clamped with the same guide tube (120); the U-shaped clamp (422) is sleeved on the guide tube (120) and is slidably connected to the connecting block (421), and the stop blocks (424) are provided at both ends of the U-shaped clamp (422), the wedge block (423) slides on the connecting block (421) and abuts against the stop block (424), and the wedge block (423) drives the stop block (424) away from the guide tube (120); S4: Advance small-diameter pipe construction, excavate the tunnel, then drill inclined holes on the inner wall of the tunnel and perform grouting; S5. Tunnel protection and invert arch construction: spray concrete protection on the inner wall of the tunnel, and erect formwork for the invert arch and pour concrete.

2. The method for constructing a tunnel in a strongly weathered mudstone formation according to claim 1, characterized in that: In step S3, the axis of the pipe of the advance large pipe shed (100) and the horizontal plane where the tunnel excavation axis is located form an acute angle of 0.5°, and the pipe of the advance large pipe shed (100) is raised along the excavation direction of the tunnel.

3. The method for constructing a tunnel in a strongly weathered mudstone formation according to claim 1, characterized in that: In step S4, when performing inclined drilling, the drilling angle forms an acute angle with the tunnel excavation direction, and is staggered with the pipeline of the advance large pipe shed (100), with two adjacent hole positions being cross-set and connected above the pipeline axis of the advance large pipe shed (100).

4. The method for constructing a tunnel in a strongly weathered mudstone formation according to claim 1, wherein: In step S5, when spraying concrete protection on the inner wall of the tunnel, first, the anchor (500) is drilled and installed and grouting is performed, then the protection net (200) is installed, and then concrete spraying is performed; after the concrete spraying is completed, the protection arch frame (300) is installed, the waterproof board (700) is installed and connected to the arch frame, and the waterproof board (700) is connected to the anchor (500), and then the inverted arch formwork is cast.

5. The method for constructing a tunnel in a strongly weathered mudstone formation according to claim 1, wherein: The connecting block (421) is rotatably arranged on the scaffold (110). The connecting mechanism (400) further includes an adjusting assembly (430), the adjusting assembly (430) including a stop block (431), an adjusting bolt (432), a first adjusting nut (433) and a second adjusting nut (434). The stop blocks (431) are arranged on both sides of the scaffold (110); the stop blocks (431) correspond to the connecting block (421), and a clamping groove (435) is provided on the stop blocks (431); the adjusting bolt (432) is hinged on the connecting block (421) and rotates into the clamping groove (435), and the first adjusting nut (433) and the second adjusting nut (434) are both threadedly connected to the adjusting bolt (432) and respectively abut against the stop blocks (431).

6. The method for constructing a tunnel in strongly weathered mudstone strata according to claim 4, characterized in that: In step S5, a fixing mechanism (600) is provided at the end of the anchor (500), and the fixing mechanism (600) includes a pulling claw (610), a first fixing nut (620), a fixing screw (630) and a second fixing nut (640). The fixing screw (630) is provided at the end of the anchor (500), and the pulling claw (610) is slidably connected to the fixing screw (630). The pulling claw (610) is hooked with the protective net (200); the first fixing nut (620) is threadedly connected to the fixing screw (630), and the first fixing nut (620) abuts against the pulling claw (610) and drives the pulling claw (610) to slide toward the top wall of the tunnel; a through hole is provided on the waterproof board (700), and the fixing screw (630) passes through the through hole and is threadedly connected to the second fixing nut (640).

7. The method for constructing a tunnel in strongly weathered mudstone strata according to claim 6, characterized in that: The fixing mechanism (600) includes a sealing assembly (650), and the sealing assembly (650) includes a sealing epoxy, a sealing cap (651) and a stop pin (652). The sealing epoxy is filled in the penetration hole, the sealing cap (651) is connected to the waterproof board (700), and the sealing cap (651) is pressed against the sealing epoxy. The stop pin (652) is inserted into the waterproof board (700) and is in contact with the sealing cap (651).

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