An improved CRD tunnel construction technology

Abstract

The invention relates to the technical field of building construction, and discloses an improved CRD construction method tunnel construction process, comprising the following steps: S1. backfilling and counter-pressure in a collapsed area; S2. constructing a pipe shed at the bottom of the backfill area; S3. backfilling and compacting the arch cavity with concrete; S4. excavating a left upper step, and initially supporting the left part of a longitudinal partition wall and a transverse partition wall to form a ring; S5. excavating a right upper step, and initially supporting the right part of a longitudinal partition wall and a transverse partition wall to form a ring; S6. removing the transverse partition wall and the longitudinal partition wall; S7. excavating and supporting a left lower step; S8. excavating and supporting a right lower step; S9. setting an invert and filling concrete. The invention makes the overall structure of the tunnel have better firmness by backfilling the collapsed area with counter-pressure and supporting the backfill area with the pipe shed, reduces the amount of temporary supporting materials used, shortens the construction period, reduces the amortization cost of tunnel excavation and support system equipment, and improves the construction efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, in particular to an improved CRD method tunnel construction process. Background Art

[0002] Tunnels are engineering structures buried in the ground, and are a form of human use of underground space. Tunnels can be divided into traffic tunnels, hydraulic tunnels, municipal tunnels, mining tunnels, and military tunnels.

[0003] For the collapse and mud burst of the vault of large-section karst tunnels, backfill counter-pressure reinforcement is generally adopted, and the middle partition wall (CD method), cross middle partition wall method (CRD method), and single and double side wall pilot tunnel method are used for excavation. The advantages of these methods are that they are conducive to supporting the collapsed body and well controlling the sinking of the vault surrounding rock. However, in large-section karst tunnels, the rock layer is often hard. Except for the unstable collapse body, the rest of the surrounding rock is relatively stable. The disadvantages of using conventional CD method, CRD method, and single and double side wall pilot tunnel method are that there are many auxiliary construction processes, complex structural stress, large amount of temporary support materials and slow construction progress.

[0004] Therefore, it is necessary to provide an improved CRD tunnel construction process to solve the above technical problems. Summary of the invention

[0005] The object of the present invention is to provide an improved CRD tunnel construction process to solve the problems raised in the above background technology.

[0006] Based on the above ideas, the present invention provides the following technical solutions: an improved CRD tunnel construction process, comprising the following steps:

[0007] S1. Backfill back pressure in the collapsed area;

[0008] S2. Build a pipe shed at the bottom of the backfill area;

[0009] S3. The arch cavity is backfilled with concrete to make it dense;

[0010] S4. Excavate the upper step on the left side and initially support the left side of the longitudinal partition wall and the transverse partition wall to form a ring;

[0011] S5. Excavate the upper step on the right side and initially support it into a ring through the right part of the longitudinal partition wall and the transverse partition wall;

[0012] S6. Remove transverse and longitudinal partition walls;

[0013] S7. Excavation and support of the lower step on the left side;

[0014] S8. Excavation and support of the lower step on the right side;

[0015] S9. Set up the invert and fill it with concrete.

[0016] As a further solution of the present invention, the pipe shed in the above step S2 is constructed by the root tube method, and a steel cage is planted inside the pipe shed.

[0017] As a further solution of the present invention, after the construction of the pipe roof is completed, the root canal method is used to drill holes at the collapsed positions obliquely above the arch crown and arch waist to find out the location of the cavity, and a pumping pipe is welded at the position of the steel pipe head. The cavity position is backfilled with concrete with a thickness of 5 meters to 8 meters, so that the concrete within 5 meters to 8 meters of the arch crown is filled densely.

[0018] As a further solution of the present invention, the transverse partition wall and the longitudinal partition wall each include a plurality of wall panels, and adjacent wall panels are fixedly connected via a connecting assembly.

[0019] As a further solution of the present invention, the connection assembly includes a connection tube, which is fixedly mounted on a side wall of the wall panel. A connection groove is formed on the side wall of the wall panel away from the connection tube, and the connection tube is adapted to the connection groove.

[0020] As a further solution of the present invention, the connecting assembly also includes a connecting rope, a rope threading channel is opened in the wall panel, one end of the rope threading channel is connected to the inner cavity of the connecting tube, and the other end of the rope threading channel is connected to the inner cavity of the connecting groove, and the connecting rope passes through the connecting tube, the rope threading channel and the connecting groove in sequence.

[0021] As a further solution of the present invention, an installation cavity is provided in the wall panel, an adjustment block is slidably installed in the installation cavity, a through hole is provided on the adjustment block, and the connecting cable passes through the through hole.

[0022] As a further solution of the present invention, a screw is threadedly installed on the wall panel, one end of the screw is rotatably connected to the adjustment block, and the other end of the screw is fixedly installed with an adjustment disk, and the adjustment disk is provided with an adjustment hole.

[0023] As a further solution of the present invention, a fixing plate is fixedly installed on the side wall of the wall panel, a notch is provided on the side wall of the wall panel away from the fixing plate, the fixing plate is adapted to the notch, a reinforcement block is slidably installed on the fixing plate, a reinforcement groove is provided on the notch, and the reinforcement block is adapted to the reinforcement groove.

[0024] As a further solution of the present invention, an adjusting ring is fixedly installed on the screw rod, a connecting ring is rotatably installed on the adjusting ring, an L-shaped rod is fixedly connected to the connecting ring, the L-shaped rod is slidably arranged in the wall panel, and one end of the L-shaped rod away from the connecting ring is fixedly connected to the reinforcement block.

[0025] As a further solution of the present invention, the longitudinal partition wall and the transverse partition wall are fixedly connected to the inner wall of the tunnel through locking foot anchor pipes, and the installation of the longitudinal partition wall and the transverse partition wall can be reinforced by the locking foot anchor pipes.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention makes the overall structure of the tunnel more solid by backfilling the collapsed area with counter pressure and supporting the backfill area with pipe sheds. During the construction process, the tunnel can be supported only by longitudinal partition walls and transverse partition walls to prevent tunnel collapse during construction. Compared with the traditional CRD method, this method reduces the amount of temporary support materials used, shortens the construction period, reduces the amortization cost of tunnel excavation and support system equipment, and improves construction efficiency.

[0028] 2. The present invention forms transverse partition walls and longitudinal partition walls by fixedly connecting a plurality of wall panels. After the tunnel construction is completed, the transverse partition walls and longitudinal partition walls can be disassembled so that the wall panels can be reused. The rotation of the adjusting disk can drive the screw to rotate. When the screw rotates, it moves relative to the wall panel, thereby driving the adjusting block to move, so that the connecting cable close to the adjusting block is bent, thereby tightening the connecting cable. The movement of the wall panel can be guided by the connecting cable, so that the connecting tube can be directly inserted into the connecting groove, making the installation of the wall panel more convenient, and the connection between the wall panels can be reinforced by the connecting cable. At the same time, when the screw moves, it can drive the adjusting ring to move. When the adjusting ring moves, it drives the reinforcement block to move through the L-shaped rod, so that the reinforcement block is inserted into the reinforcement groove, thereby reinforcing the two adjacent wall panels, so that the transverse partition wall and the longitudinal partition wall have stronger compressive strength and better supporting effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the construction method of the present invention;

[0030] Figure 2 It is a schematic diagram of the three-dimensional structure of the wall panel of the present invention;

[0031] Figure 3 is a schematic diagram of the cross-sectional structure of the wallboard of the present invention;

[0032] Figure 4 For the present invention Figure 3 A is an enlarged structural diagram of FIG.

[0033] In the figure: 1. longitudinal partition wall; 2. transverse partition wall; 4. concrete tunnel wall; 5. pipe shed; 6. landslide area; 7. wall panel; 701. connecting groove; 702. reinforcement groove; 703. installation cavity; 8. connecting tube; 9. fixing plate; 10. adjusting block; 11. screw rod; 12. adjusting disk; 1201. adjusting hole; 13. reinforcement block; 14. L-shaped rod; 15. adjusting ring; 16. connecting ring; 17. connecting rope; 18. locking foot anchor pipe. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] See also Figure 1 In an embodiment of the present invention, an improved CRD tunnel construction process includes the following steps:

[0036] S1. Backfill and counterpressure in the collapsed area 6: clean up the rocks and soil around the collapsed area 6, backfill and counterpressure, and use the accumulated soil to form a barrier to pump concrete into the vault cavity;

[0037] S2. A pipe shed 5 is constructed at the bottom of the backfill area. The soil at the top can be supported by the pipe shed 5. The pipe shed 5 is constructed by the root pipe method. A steel cage is planted inside the pipe shed 5. After the construction of the pipe shed 5 is completed, a root pipe method is used to drill holes at the collapsed position above the arch and the waist to find out the location of the cavity. A pumping pipe is welded at the position of the steel pipe head. The cavity is backfilled with concrete with a thickness of 5 meters to 8 meters, so that the concrete is densely filled within 5 meters to 8 meters of the arch;

[0038] S3. The arch cavity is backfilled with concrete to make it dense, and the top of the tunnel can be reinforced with concrete;

[0039] S4. Excavate the left upper step, and initially support it into a ring through the left part of the longitudinal partition wall 1 and the transverse partition wall 2, and pour concrete on the inner wall of the left upper tunnel: Use the CRD method to excavate the heading face, first excavate the side of the upper step arch with a smaller collapse volume, and initially support it into a ring. The initial support needs to be placed on a stable and hard rock layer, and strong locking anchor rods are installed. The CRD method is an existing technology, so it is not described in detail;

[0040] S5. Excavate the upper step on the right side, and initially support it into a ring through the right part of the longitudinal partition wall 1 and the transverse partition wall 2, and pour concrete on the inner wall of the upper right tunnel: Use the improved CRD method to excavate the heading face, excavate the upper step on the right side, and initially support it into a ring. The initial support should be placed on a stable and hard rock layer, and reinforced locking anchors should be installed;

[0041] S6. Remove the horizontal partition wall 2 and the longitudinal partition wall 1;

[0042] S7. Excavate and support the lower step on the left side, and pour concrete on the inner wall of the lower left tunnel;

[0043] S8. Excavation and support of the lower step on the right side, and pouring concrete on the inner wall of the lower right tunnel to form a complete concrete tunnel wall 4;

[0044] S9. Set up an invert and fill it with concrete. The invert is the arc-shaped part at the bottom of the tunnel. The tunnel can be reinforced by the invert. The invert is a reverse arch structure set at the bottom of the tunnel to improve the stress conditions of the upper supporting structure. It is one of the main components of the tunnel structure. On the one hand, it can effectively transfer the stratum pressure above the tunnel through the tunnel side wall structure or the load on the road surface to the underground, and it can also effectively resist the reaction force from the stratum below the tunnel.

[0045] By backfilling the collapsed area 6 with counter pressure and supporting the backfill area with the pipe shed 5, the overall structure of the tunnel is made more solid. During the construction process, the tunnel only needs to be supported by the longitudinal partition wall 1 and the transverse partition wall 2 to prevent the tunnel from collapsing during the construction process. Compared with the traditional CRD method, this method reduces the amount of temporary support materials used, the shortened construction period reduces the amortization cost of tunnel excavation and support system equipment, and improves construction efficiency.

[0046] See also Figures 2 to 4 In the embodiment of the present invention, the transverse partition wall 2 and the longitudinal partition wall 1 each include a plurality of wall panels 7, and the adjacent wall panels 7 are fixedly connected by a connecting assembly. The transverse partition wall 2 and the longitudinal partition wall 1 are formed by the fixed connection of the plurality of wall panels 7. After the tunnel construction is completed, the transverse partition wall 2 and the longitudinal partition wall 1 can be disassembled so that the wall panels 7 can be reused.

[0047] In this embodiment, preferably, the connecting assembly includes a connecting tube 8, and the connecting tube 8 is fixedly installed on one side wall of the wall panel 7. A connecting groove 701 is provided on the side wall of the wall panel 7 away from the connecting tube 8. The connecting tube 8 is adapted to the connecting groove 701, so that the connecting tube 8 can be inserted into the connecting groove 701, thereby realizing a fixed connection between the two wall panels 7. The angle between the connecting tube 8 and the connecting groove 701 and the wall panel 7 can be set according to needs, so that the transverse partition wall 2 and the longitudinal partition wall 1 can be set to an arc shape, a straight line shape, etc. according to usage requirements.

[0048] In this embodiment, preferably, the connecting component also includes a connecting cable 17, a rope threading channel is opened in the wall panel 7, one end of the rope threading channel is connected to the inner cavity of the connecting tube 8, and the other end of the rope threading channel is connected to the inner cavity of the connecting groove 701, the connecting cable 17 passes through the connecting tube 8, the rope threading channel and the connecting groove 701 in sequence, and the connecting cable 17 is preferably a steel cable. During construction, one end of the connecting cable 17 is fixedly connected to the inner wall of the tunnel, and then the connecting cable 17 passes through the connecting tube 8, the rope threading channel and the connecting groove 701 in sequence, so that the connecting cable 17 can guide the movement of the wall panel 7, so that the connecting tube 8 can be directly inserted into the connecting groove 701, and the connection between the wall panels 7 can be reinforced by the connecting cable 17, and at the same time, the installation of the wall panels 7 is made more convenient.

[0049] In this embodiment, preferably, an installation cavity 703 is opened in the wall panel 7, and an adjusting block 10 is slidably installed in the installation cavity 703. A through hole is opened on the adjusting block 10, and the connecting rope 17 passes through the through hole. When the connecting rope 17 is relatively loose, the connection between the wall panels 7 may not be tight. Therefore, the adjusting block 10 is provided. When the connecting rope 17 needs to be tightened, the adjusting block 10 is slid so that the connecting rope 17 close to the adjusting block 10 is bent, thereby tightening the connecting rope 17.

[0050] In this embodiment, preferably, a screw rod 11 is threadedly installed on the wall panel 7, one end of the screw rod 11 is rotatably connected to the adjusting block 10, and an adjusting disk 12 is fixedly installed on the other end of the screw rod 11, and an adjusting hole 1201 is opened on the adjusting disk 12; insert a round rod into the adjusting hole 1201, and then rotate the round rod to drive the adjusting disk 12 to rotate, and when the adjusting disk 12 rotates, the screw rod 11 is driven to rotate, and when the screw 11 rotates, it moves relative to the wall panel 7, thereby driving the adjusting block 10 to move.

[0051] See also Figure 3 and Figure 4 In the embodiment of the present invention, a fixing plate 9 is fixedly installed on the side wall of the wall panel 7, a notch is provided on the side wall of the wall panel 7 away from the fixing plate 9, the fixing plate 9 is matched with the notch, a reinforcement block 13 is slidably installed on the fixing plate 9, a reinforcement groove 702 is provided on the notch, the reinforcement block 13 is matched with the reinforcement groove 702; when the reinforcement block 13 is inserted into the reinforcement groove 702, two adjacent wall panels 7 can be reinforced.

[0052] In this embodiment, preferably, an adjusting ring 15 is fixedly installed on the screw rod 11, a connecting ring 16 is rotatably installed on the adjusting ring 15, an L-shaped rod 14 is fixedly connected to the connecting ring 16, the L-shaped rod 14 is slidably arranged in the wall panel 7, and the end of the L-shaped rod 14 away from the connecting ring 16 is fixedly connected to the reinforcement block 13; when the screw rod 11 moves, the adjusting ring 15 can be driven to move, and when the adjusting ring 15 moves, the reinforcement block 13 is driven to move through the L-shaped rod 14, so that the reinforcement block 13 is inserted into the reinforcement groove 702, thereby reinforcing the two adjacent wall panels 7, so that when the adjusting disk 12 is rotated, not only the connecting rope 17 can be tightened, but also the reinforcement block 13 can be driven to move through the adjusting ring 15, the connecting ring 16 and the L-shaped rod 14, so that the two wall panels 7 cannot be relatively far away, thereby reinforcing the connection between the two wall panels 7.

[0053] In this embodiment, preferably, the longitudinal partition wall 1 and the transverse partition wall 2 are fixedly connected to the inner wall of the tunnel by means of locking foot anchor pipes 18, and the installation of the longitudinal partition wall 1 and the transverse partition wall 2 can be reinforced by means of the locking foot anchor pipes 18; in actual applications, concrete can be sprayed on the longitudinal partition wall 1 and the transverse partition wall 2 for reinforcement, and the concrete can be peeled off during disassembly, which can save a lot of concrete compared to the prior art.

[0054] According to the construction schedule of karst landslide treatment, mechanical equipment is arranged for entry, commissioning and material supply in advance. The project department organizes joint acceptance of relevant equipment and materials. Those that fail the acceptance will be refused entry. According to the construction progress, the mechanical equipment entering the site can be reasonably allocated and used among the construction teams to ensure continuous and smooth construction; strengthen advanced geological forecasting and adhere to the construction principle of forecasting before excavation; incorporate deformation observation into process management, conduct measurement data analysis in time, and guide construction. During the excavation of the tunnel, the temporary drainage system should be improved to ensure that there is no water accumulation and prevent the softening of the steel frame base; the steel support is set up with wedges and the surrounding rock, and there are connecting components in the longitudinal direction, and the bottom angle should be firm. The steel support is welded with the anchor rod outcrop and the steel mesh as much as possible to enhance its joint support effect; the locking anchor rod should be applied as soon as possible after the initial spraying of the excavation, and then sprayed again. During the construction of the locking anchor rod, it is necessary to ensure that the anchoring agent roll is fully soaked, and the soaking time is required to be controlled at about 2.5 minutes; secondly, it is necessary to ensure that the anchoring agent roll is full.

[0055] With this method, the karst landslide treatment construction of Tianba 5 Yanshe Tunnel, Qinlan Tunnel, Jiazhuan Tunnels 1-3, Xiaodongshan Tunnels 2-4, and Nongyan Tunnel was successfully completed. By rationally designing and calculating the stability of the landslide body according to the on-site conditions, and carefully formulating and implementing the construction plan using the improved CRD method, the karst landslide treatment of 8.5 tunnels was completed smoothly and efficiently, reducing the use of temporary support materials by 1 / 3 and shortening the construction period by 1 / 5 compared to the original plan. In addition to effectively reducing construction costs through reasonable support system design and construction, the temporary support of the upper step is removed before the lower step construction, which can reduce construction interference, shorten the construction period and reduce the amortization cost of tunnel excavation and support system equipment. The Yanshe Tunnel cost 3 million, the Qinlan Tunnel cost 4 million, the Jiazhuan No. 1-3 Tunnels cost 5 million, the Xiaodongshan No. 2-4 Tunnels cost 1 million, and the Nongyan Tunnel cost 2 million. Compared with the traditional CRD method, this method reduces the amount of temporary support materials by 1 / 3, and the shortened construction period reduces the amortization cost of tunnel excavation and support system equipment, and improves work efficiency. It has been well received by the owner, design and supervision units.

[0056] Tingshe Tunnel is a three-lane small clearance separation type extra-long tunnel. Located at 750m east of Yaozhai Village, Fengshan County, the tunnel is generally oriented north-south. The tunnel adopts a small clearance separation design, with the left tunnel being 3377m long and the right tunnel being 3350.5m long, with a designed longitudinal slope of -2.49%; the maximum buried depth of the tunnel is about 350m.

[0057] On June 16, 2021, when the construction site reached K76+284.4 of the left tunnel, a filled karst cave was developed. The filling material was low liquid limit clay, which was distributed throughout the entire face. During the construction, the arch collapsed. According to on-site visual observation, the collapsed cavity developed to about 8 meters above the arch and was about 10 meters wide. The surrounding rock grade at this location is: Grade IV, and the lining structure type is S4-B lining.

[0058] After on-site discussion, it was decided to use the improved CRD method to deal with karst landslides:

[0059] (1) Clear the rocks and soil around the landslide area, backfill and counter-pressure. Use the accumulated soil to form a barrier to pump concrete into the vault cavity.

[0060] (2) Level the upper step working platform, use the root tube method to construct a large pipe shed, plant a steel cage inside the pipe shed and inject grout.

[0061] (3) After the construction of the pipe shed is completed, the root canal method is used to drill holes at the collapsed positions of the arch crown and arch waist to find out the location of the cavity. A pumping pipe is welded at the steel pipe head position, and the hollow position is backfilled with 5 meters of C30 fine stone concrete to make the filling dense within 5 meters of the arch.

[0062] (4) The improved CRD method is used to excavate the tunnel face, with the right side being the priority. After the right side has advanced 5 meters, exploratory holes are drilled diagonally to the upper left to find out the location of the cavity and backfill with fine stone concrete.

[0063] By adopting the improved CRD construction method, temporary middle partition wall supports and reinforced locking foot anchor pipes were set up on the left and right sides of the upper step guide pit, which increased the stability of the collapsed body, reduced the arch settlement, and had high safety performance, without any quality or safety accidents.

[0064] Working principle: The present invention makes the overall structure of the tunnel more solid by backfilling the collapsed area 6 with counter pressure and supporting the backfill area with the pipe shed 5. During the construction process, the tunnel can be supported only by the longitudinal partition wall 1 and the transverse partition wall 2 to prevent the tunnel from collapsing during the construction process. Compared with the traditional CRD method, this method reduces the amount of temporary support materials used, shortens the construction period, reduces the amortization cost of tunnel excavation and support system equipment, and improves the construction efficiency; the transverse partition wall 2 and the longitudinal partition wall 1 are formed by the fixed connection of multiple wall panels 7. After the tunnel construction is completed, the transverse partition wall 2 and the longitudinal partition wall 1 can be disassembled. , so that the wall panel 7 can be reused; after multiple wall panels 7 are installed, the round rod is inserted into the adjusting hole 1201, and then the round rod is rotated to drive the adjusting disk 12 to rotate. When the adjusting disk 12 rotates, it drives the screw rod 11 to rotate. When the screw rod 11 rotates, it moves relative to the wall panel 7, thereby driving the adjusting block 10 to move, so that the connecting cable 17 close to the adjusting block 10 is bent, so that the connecting cable 17 is tightened. At the same time, when the screw rod 11 moves, it can drive the adjusting ring 15 to move. When the adjusting ring 15 moves, it drives the reinforcement block 13 to move through the L-shaped rod 14, so that the reinforcement block 13 is inserted into the reinforcement groove 702, thereby reinforcing the two adjacent wall panels 7.

[0065] The above description is a detailed description of the preferred feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modified changes completed under the technical spirit suggested by the present invention should fall within the patent scope covered by the present invention.

Claims

1. An improved CRD tunnel construction process, characterized in that: The following steps are involved: S1. Backfill back pressure in the collapsed area; S2. Build a pipe shed at the bottom of the backfill area; S3. The arch cavity is backfilled with concrete to make it dense; S4. Excavate the upper step on the left side and initially support the left side of the longitudinal partition wall and the transverse partition wall to form a ring; S5. Excavate the upper step on the right side and initially support it into a ring through the right part of the longitudinal partition wall and the transverse partition wall; S6. Remove transverse and longitudinal partition walls; S7. Excavation and support of the lower step on the left side; S8. Excavation and support of the lower step on the right side; S9. Set up the invert and fill it with concrete; The transverse partition wall (2) and the longitudinal partition wall (1) both comprise a plurality of wall panels (7), and adjacent wall panels (7) are fixedly connected via a connecting assembly; The connection assembly comprises a connection tube (8), the connection tube (8) being fixedly mounted on a side wall of the wall panel (7), a connection groove (701) being provided on the side wall of the wall panel (7) away from the connection tube (8), and the connection tube (8) being adapted to the connection groove (701); The connection assembly further comprises a connection rope (17); a rope threading channel is provided in the wall panel (7); one end of the rope threading channel is communicated with the inner cavity of the connection cylinder (8); the other end of the rope threading channel is communicated with the inner cavity of the connection groove (701); the connection rope (17) passes through the connection cylinder (8), the rope threading channel and the connection groove (701) in sequence; An installation cavity (703) is provided in the wall panel (7), an adjustment block (10) is slidably installed in the installation cavity (703), a through hole is provided on the adjustment block (10), and the connection cable (17) passes through the through hole.

2. The improved CRD tunnel construction process according to claim 1 is characterized by: In the above step S2, the pipe shed is constructed by the root pipe method, and a steel cage is planted inside the pipe shed.

3. The improved CRD tunnel construction process according to claim 2 is characterized by: After the construction of the pipe shed is completed, the root canal method is used to drill holes at the collapsed positions obliquely above the arch crown and arch waist to find out the location of the cavity. The pumping pipe is welded at the position of the steel pipe head, and the cavity position is backfilled with concrete with a thickness of 5 meters to 8 meters, so that the concrete within 5 meters to 8 meters of the arch crown is filled densely.

4. The improved CRD tunnel construction process according to claim 1 is characterized by: A screw rod (11) is threadedly mounted on the wall panel (7), one end of the screw rod (11) is rotatably connected to the adjustment block (10), and an adjustment disk (12) is fixedly mounted on the other end of the screw rod (11), and an adjustment hole (1201) is provided on the adjustment disk (12).

5. The improved CRD tunnel construction process according to claim 4 is characterized by: A fixing plate (9) is fixedly mounted on the side wall of the wall panel (7); a notch is provided on the side wall of the wall panel (7) away from the fixing plate (9); the fixing plate (9) is adapted to the notch; a reinforcing block (13) is slidably mounted on the fixing plate (9); a reinforcing groove (702) is provided on the notch; the reinforcing block (13) is adapted to the reinforcing groove (702).

6. The improved CRD tunnel construction process according to claim 5 is characterized by: An adjusting ring (15) is fixedly mounted on the screw rod (11), a connecting ring (16) is rotatably mounted on the adjusting ring (15), an L-shaped rod (14) is fixedly connected to the connecting ring (16), the L-shaped rod (14) is slidably arranged in the wall panel (7), and one end of the L-shaped rod (14) away from the connecting ring (16) is fixedly connected to the reinforcing block (13).

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