Large-deformation surrounding rock control structure and construction method for deep-buried water-rich karst tunnel

Abstract

The present application relates to a large-deformation surrounding rock control structure for a large-buried deep water-rich karst tunnel and a construction method thereof, which comprises the following steps: checking the deformation of the initial support; supporting the arch-protecting steel frame; full-face seamless steel pipe grouting reinforcement; backfilling the counter-pressure hole slag; setting the advanced small guide pipe; stepwise excavation of the hole slag; chiseling and cutting the joint; replacing the deformed steel arch; and re-spraying the concrete.

Description

Technical Field

[0001] This invention relates to the control structure for large deformation surrounding rock in deep-buried water-rich karst tunnels and its construction method. It is mainly applicable to the reinforcement and treatment of lining structures in deep-buried water-rich karst tunnels that suffer from serious defects such as arch deformation, initial support cracking, misalignment, and rockfall due to insufficient bearing capacity. Background Technology

[0002] Extensive engineering practice shows that large deformation of tunnel surrounding rock is characterized by large deformation volume, rapid deformation rate, and long deformation duration. When a tunnel traverses a deep, water-rich, karst, weak, and fractured rock mass, geological hazards such as cracking, rockfall, muck spillage, and collapse often occur simultaneously with the large deformation. Traditional technical measures for treating large deformation tunnels mainly include:

[0003] 1) Pressure-limited discharge is achieved by burying drainage pipes to reduce water pressure and ensure the safety of the tunnel structure;

[0004] 2) Strengthen the surrounding rock through strong pre-support or anchoring support to improve the self-supporting capacity of the surrounding rock;

[0005] 3) Use step or super-step construction method, increase temporary support, and use shotcrete to seal the surrounding rock in time;

[0006] 4) Strengthen the initial support by using a combination of techniques such as lengthening and densifying the circumferential anchor bolts, thickening the concrete spray layer, adding a base plate and locking anchor bolts (pipes), and erecting a retractable temporary support steel frame. Under the strong initial support, the displacement of the surrounding rock is kept within a controllable range, which plays a role in unloading and transferring secondary stress to the deeper parts of the surrounding rock.

[0007] However, when the tunnel is located in a deep, water-rich karst area, the fault causes the rock mass to break up and slide between layers. Under the action of groundwater dynamics, it is easy to form dissolution channels. Water flows through the tunnel arch, arch waist, sidewalls and other locations, causing serious initial support collapse and arch deformation. It also seriously encroaches on the secondary lining thickness and tunnel clearance, posing a great safety hazard. In such cases, the above-mentioned technical measures can no longer meet the requirements. Summary of the Invention

[0008] The purpose of this invention is to replace deformed steel arches in tunnels, re-spray concrete on collapsed initial supports, and reinforce loose surrounding rock structures while ensuring safety, thereby improving tunnel safety. This invention provides a simple and effective control structure for large deformation surrounding rock in deep-buried water-rich karst tunnels and its construction method.

[0009] To achieve the above-mentioned application objectives, this application adopts the following technical solution: a large deformation surrounding rock control structure and its construction method for a deep-buried water-rich karst tunnel, including surrounding rock, reinforced anchor rods and arch walls within the surrounding rock, deformed steel arch frames caused by water inrush within the surrounding rock, and deformation bulges in the initial support concrete caused by the deformation section of the deformed steel arch frame, and also includes arch protection steel frames, locking foot guide pipes, seamless steel pipes, positioning bars, tunnel debris, advanced guide pipes, reinforcing grout, cutting seams, connecting bars, replaced steel arch frames, steel arch frames to be replaced, cutting tool main unit box, diamond butterfly cutting tool, rotating shaft, concrete breaker hammer joint, breaker hammer vibrator, and conical drill bit;

[0010] The deformed steel arch frame is temporarily reinforced on both sides by protective arch steel frames. The arch feet and arching lines on both sides of the protective arch steel frames are equipped with locking foot guides, and the protective arch steel frames are positioned by positioning ribs to improve the overall load-bearing performance of the protective arch steel frames. The steel arch frame to be replaced is used to replace the deformed steel arch frame to obtain the replaced steel arch frame. The connecting ribs are used to weld the steel arch frame to be replaced.

[0011] Seamless steel pipes were installed along the entire arch wall and reinforced by grouting.

[0012] The initial support deformation section of the tunnel was backfilled with cavitation debris and subjected to counter-pressure through the arch wall;

[0013] Before excavating the muck of the counter-pressure body, advanced small guide pipes were installed and the surrounding rock was reinforced with reinforcing grout. The tail of the advanced small guide pipes was fixed to the arch support steel frame. The muck of the counter-pressure body was excavated in a stepped manner, and the deformed steel arch frame was replaced in time after each section was excavated.

[0014] The cutting seam is located on both sides of the deformed steel arch frame, and the cutting seam is cut using a diamond butterfly cutting blade. The initial support of the cut seam is removed using a tapered drill bit. The diamond butterfly cutting blade is fixed to the cutting blade main unit box via a rotating shaft. The cutting blade main unit box is fixed to the boom of the excavator. The tapered drill bit is mounted on the breaker vibrator. The breaker vibrator is fixed to the concrete breaker joint. The concrete breaker joint can also be mounted on the boom of the excavator.

[0015] Furthermore, the arch support steel frame is closely attached to the arch wall, providing support for the arch wall.

[0016] Furthermore, cement grout is injected into both the locking foot guide tube and the seamless steel pipe for reinforcement. The water-cement ratio of the cement grout is 1:1, and the grouting pressure is 0.5 to 1 MPa.

[0017] Furthermore, the caving muck is backfilled in layers with counter-pressure, and each section of the caving muck is excavated in a stepped manner as each section of the advanced small guide pipe is installed.

[0018] Furthermore, the width of the kerf is the distance between the two diamond butterfly cutting blades.

[0019] This invention also provides a construction method for the large deformation surrounding rock control structure of a deep-buried water-rich karst tunnel, comprising the following steps:

[0020] S00, Initial support deformation inspection:

[0021] A full-length inspection of the water-rich karst section of the tunnel was conducted. The number of arch frame deformation sections and initial support concrete deformation bulges that occurred during the initial support were counted. Loosening of the reinforcing anchor rods was checked, and corresponding deformed steel arch frames were marked on the arch wall.

[0022] S10. Erecting the arch support steel frame:

[0023] Support arch steel frames are installed on both sides of the arch wall markings, and small locking pipes are installed on the arch feet and arch rise lines on both sides of each support arch steel frame.

[0024] After the locking foot pipe is installed, it should be reinforced with reinforcing grout in a timely manner. The grout should be cement grout with a water-cement ratio of 1:1. The grouting pressure should be 0.5-1MPa, and the grouting should be stopped after maintaining the pressure for 10 minutes.

[0025] S20, full-section seamless steel pipe grouting reinforcement:

[0026] After the arch support steel frame is completed, seamless steel pipes are installed along the entire cross section of the arch wall;

[0027] Grouting reinforcement was carried out using seamless steel pipes. The grouting was done by skip-hole grouting with 1:1 cement grout. The grouting pressure was controlled at 0.5-1 MPa. After reaching the grouting pressure, the pressure was maintained for 10 minutes and then the grouting was stopped.

[0028] S30, Backfill muck under counter-pressure:

[0029] The tunnel arch replacement section is backfilled with caving muck in layers with counter-pressure, and the counter-pressure muck limits the convergence deformation of the tunnel sidewalls on both sides.

[0030] The arch replacement section was reinforced with an additional 5m of counterpressure before and after the arch was replaced, and the two ends were trimmed. The subsequent excavation was carried out using the three-stage method.

[0031] S40. Install advanced small conduit:

[0032] A small guide pipe is installed on the upper part of the arch support steel frame along the radial direction of the tunnel. The upward angle of the small guide pipe is 5-15°. The small guide pipe is arranged circumferentially along the upper part of the arch support steel frame, with a reinforcement range of 120° and a circumferential spacing of 30cm.

[0033] The pre-insertion small guide pipe injects reinforcing grout to solidify the loose and broken surrounding rock, and the tail end of the pre-insertion small guide pipe is mechanically fixed to the arch support steel frame.

[0034] S50, stepped excavation muck:

[0035] After each section of the advanced small guide pipe is installed and reinforced with grout, the caving space between one arch frame is excavated in a step-by-step manner. Then, the next section of the advanced small guide pipe is installed, reinforced with grout, and the caving space between the next arch frame is excavated in a step-by-step manner. This process of excavating caving space continues in this manner.

[0036] S60. Remove the cutting seam:

[0037] After excavating the slag between each arch frame, a diamond butterfly cutter is installed on the boom of the excavator. The diamond butterfly cutter is used to cut the arch wall, and a conical drill bit is used to remove the initial support shotcrete in the cut seam to expose the deformed steel arch frame.

[0038] The undeformed steel arch frame was removed by hand-held pneumatic picks on one side, with only a portion of the concrete removed to leave welding positions, so that the newly replaced arch frame could be welded to the connecting bars and steel mesh of the undeformed steel arch frame to form a whole.

[0039] S70, Replace the deformed steel arch frame:

[0040] Cut the deformed steel arch frame and dismantle it in sections from top to bottom. Install the steel arch frame to be replaced and re-lay the new steel mesh. The steel mesh should be closely attached to the rock surface. After the steel arch frame has been replaced, first remove the locking foot guide pipes and then remove the arch support steel frame.

[0041] S80, sprayed concrete:

[0042] After dismantling the arch support steel frame, the initial support shotcrete work is carried out again, and the concrete spraying sequence is from bottom to top.

[0043] For the replaced steel arch frame, only one side of the normal section is sprayed with concrete. On the other side of the arch to be replaced, the connecting bars and steel mesh are welded to the next steel arch frame after the arch is replaced. The welding position is left unsprayed for the time being. The concrete will be sprayed and compacted together when the next cycle of sprayed concrete is used.

[0044] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0045] 1. Before replacing the arch, the present invention uses a protective arch steel frame for temporary support, installs seamless steel pipes for grouting reinforcement across the entire cross section, and uses the backfilling of the caving muck to support both sides of the arch wall, reducing the open surface and ensuring the safety of the arch replacement.

[0046] 2. The present invention involves installing a pre-excavation guide pipe before excavating the backfill muck, and then excavating a muck section after installing one section of the pre-excavation guide pipe, which effectively prevents the collapse of the surrounding rock of the tunnel arch.

[0047] 3. In this invention, a diamond butterfly cutter and a conical drill bit are used to remove the initial concrete support on the deformed steel arch frame during arch replacement. The removal of concrete is efficient and quick, and will not damage the arch frame, wire mesh, or connecting bars, thus minimizing the impact on the arch wall. Attached Figure Description

[0048] Figure 1 This is a structural diagram of the tunnel arch frame exhibiting large deformation according to the present invention;

[0049] Figure 2 This is a structural diagram of the steel frame structure for the arch support in the tunnel arch replacement section of the present invention;

[0050] Figure 3 These are structural diagrams of each unit of the arch support steel frame of this invention;

[0051] Figure 4 This is a cross-sectional view of the arch support steel frame installed in the tunnel arch replacement section of the present invention. Figure 2 (See Figure AA in the middle);

[0052] Figure 5 This is a diagram of the backfilling and counter-pressure slag in the tunnel arch replacement section of this invention;

[0053] Figure 6 This is a structural diagram of the advanced small guide pipe arrangement in the tunnel arch replacement section of the present invention;

[0054] Figure 7 This is a radial structural diagram of the advanced small guide pipe in the tunnel arch replacement section of the present invention. Figure 6 (Chinese BB diagram);

[0055] Figure 8 This is a diagram of the step-by-step excavation structure for the counter-pressure muck section of the tunnel according to the present invention;

[0056] Figure 9 This is a structural diagram of the cut seams on both sides of the deformed steel arch frame of the present invention;

[0057] Figure 10 This is a schematic diagram of the connection between the replaced arch frame and the arch frame to be replaced in the tunnel arch replacement section of the present invention;

[0058] Figure 11 This is a structural diagram of the diamond butterfly cutting tool of the present invention fixed on the modified boom of an excavator;

[0059] Figure 12 This is a front view of the connection between the diamond butterfly cutting tool and the cutting tool main unit of the present invention;

[0060] Figure 13 This is a side view of the connection between the diamond butterfly cutting tool and the cutting tool main unit of the present invention;

[0061] Figure 14 This is a structural diagram of the connection between the hydraulic breaker vibrator and the conical drill bit of the present invention.

[0062] The components include: 1. Surrounding rock; 2. Reinforced anchor bolts; 3. Deformed steel arch frame; 4. Initial support shotcrete; 5. Arch wall; 6. Deformed section of arch frame; 7. Deformed bulge of initial support concrete; 8. Arch protection steel frame; 9. Locking foot guide pipe; 10. Seamless steel pipe; 11. Positioning reinforcement; 12. Muck; 13. Advance guide pipe; 14. Reinforcement grout; 15. Cutting joint; 16. Connecting reinforcement; 17. Undeformed steel arch frame; 18. Replaced steel arch frame; 19. Steel arch frame to be replaced; 20. Cutting knife main unit box; 21. Diamond butterfly cutting knife; 22. Spindle; 23. Concrete breaker hammer joint; 24. Breaker hammer vibrator; 25. Conical drill bit. Detailed Implementation

[0063] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0064] Those skilled in the art should understand that, in the disclosure of this application, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on this application.

[0065] The invention will not elaborate on the following: tunnel lining structure, construction method of anchor pipe, construction technology of seamless steel pipe, manufacturing process and on-site installation technical requirements of deformed steel arch frame, construction process of backfilling of tunnel muck, installation process and grouting process of advanced anchor pipe, dismantling process of deformed steel arch frame and installation process of new arch frame, welding technical requirements of various steel plates, etc. The focus of this invention is to describe the implementation method of the structure.

[0066] Example 1

[0067] like Figure 1 As shown, the large deformation surrounding rock control structure of this deep-buried water-rich karst tunnel includes surrounding rock 1, reinforcing anchor bolts 2, deformed steel arch frame 3, initial support shotcrete 4, arch wall 5, arch frame deformation section 6, and initial support concrete deformation bulge 7. Water inflow in surrounding rock 1 causes deformation of the steel arch frame, forming deformed steel arch frame 3. There are multiple arch frame deformation sections 6 on the deformed steel arch frame 3, resulting in multiple initial support concrete deformation bulges 7.

[0068] like Figure 2-4As shown in the diagram, the arch replacement section of the tunnel is equipped with a steel frame structure for arch support, including a deformable steel arch frame 3, an arch wall 5, a steel frame for arch support 8, a foot-locking guide pipe 9, and a seamless steel pipe 10. The deformable steel arch frame 3 is temporarily reinforced on both sides by the steel frame for arch support 8, which is closely attached to the arch wall 5 to provide support for the arch wall 5. The foot-locking guide pipe 9 is installed on both sides of the arch support 8 and along the arch riser line to improve the overall load-bearing performance of the steel frame for arch support 8. Seamless steel pipes 10 are installed along the entire section of the arch wall 5 for grouting reinforcement. Cement grout is injected into the foot-locking guide pipe 9 and the seamless steel pipe 10 for reinforcement. The water-cement ratio of the cement grout is 1:1, and the grouting pressure is 0.5 to 1 MPa.

[0069] like Figure 5 As shown, the diagram shows the backfilling and counter-pressure of the tunnel arch replacement section, including the arch wall 5 and the tunnel muck 12. The tunnel muck 12 backfilled in the section where the initial support deformation occurred applies counter-pressure to the arch wall 5, and the tunnel muck 12 is backfilled in layers under counter-pressure.

[0070] like Figure 6-7 The diagram shows the layout of the pre-cast guide pipes in the tunnel arch replacement section, including surrounding rock 1, arch support steel frame 8, muck 12, pre-cast guide pipes 13, and reinforcing grout 14. Pre-cast guide pipes 13 are installed before the excavation of the muck 12, and the reinforcing grout 14 injected into the pre-cast guide pipes 13 solidifies the surrounding rock 1. The tail of the pre-cast guide pipe 13 is mechanically fixed to the arch support steel frame 8.

[0071] like Figure 8-9 The diagram shows the stepped excavation structure of the counter-pressure muck section in the tunnel arch replacement phase. It includes deformed steel arch frame 3, muck 12, and advance guide pipe 13. Each section of the advance guide pipe 13 is installed before excavating a section of muck 12. The counter-pressure muck 12 is excavated in a stepped manner. The deformed steel arch frame 3 is replaced promptly after each section is excavated. The cutting seams 15 are made using diamond butterfly cutter 21 and are located on both sides of the deformed steel arch frame 3.

[0072] like Figure 11-13 As shown in the diagram, the diamond butterfly cutter is fixed to the excavator modified boom structure, including the cutter main unit 20, the diamond butterfly cutter 21, the rotating shaft 22, etc. The width of the cutting slit 15 is the distance between the two diamond butterfly cutters 21. The diamond butterfly cutter 21 is fixed to the cutter main unit 20 through the rotating shaft 22. The cutter main unit 20 is fixed to the boom modified from the excavator.

[0073] like Figure 14 As shown in the diagram, the connection structure between the hydraulic breaker vibrator and the conical drill bit is as follows: the conical drill bit 25 is installed on the hydraulic breaker vibrator 24, and the hydraulic breaker vibrator 24 is fixed on the concrete breaker joint 23. The concrete breaker joint 23 can also be installed on the boom of an excavator. The conical drill bit 25 is used to chisel away the concrete of the cutting joint 15.

[0074] like Figure 9-10As shown, the diagram illustrates the connection between the replaced arch frame and the arch frame to be replaced in the tunnel arch replacement section. It includes the deformed steel arch frame 3, the arch support steel frame 8, the cutting joint 15, etc. After the concrete in the cutting joint 15 is removed, the deformed steel arch frame 3 is dismantled and replaced with a new steel arch frame. After the deformed steel arch frame 3 is replaced, the arch support steel frame 8 is removed.

[0075] Example 2

[0076] Based on Example 1, this example also provides a construction method for the large deformation surrounding rock control structure of a deep-buried water-rich karst tunnel, including the following steps:

[0077] S00, Initial support deformation inspection:

[0078] A full-length inspection was conducted on the water-rich karst section of the tunnel. The number of arch frame deformation sections 6 and initial support concrete deformation bulges 7 that occurred during the initial support were counted. The loosening of the reinforcing anchor rods 2 was checked, and corresponding deformed steel arch frames 3 were marked on the arch wall 5.

[0079] S10, Supporting the arch steel frame 8:

[0080] Supporting arch steel frames 8 are erected on both sides of the arch wall at mark 5. The supporting arch steel frames 8 are made of I20a I-beams, spaced 1.0m apart, and consist of 7 units (3 A units, 2 B units, and 2 C units). The units are connected by bolts, and each unit is positioned using positioning ribs 11. Channel steel is welded at the arch foot. Each supporting arch steel frame 8 is constructed at both arch footes and along both arch rise lines. The locking foot guide pipe 9 improves the overall load-bearing performance of the arch support. The locking foot guide pipe 9 is 4.5m long. After the locking foot guide pipe 9 is installed, grouting reinforcement is carried out in time. The grout is cement grout with a water-cement ratio of 1:1. The grouting pressure is 0.5-1MPa. The grouting is stopped after maintaining the pressure for 10 minutes.

[0081] S20, full-section seamless steel pipe 10 grouting reinforcement:

[0082] After the arch support steel frame 8 is completed, seamless steel pipes 10 are installed along the entire cross section of the arch wall 5. The length of the seamless steel pipes 10 is L = 4.5m, and the circumferential longitudinal spacing is 150*150cm. Grouting reinforcement is carried out through the seamless steel pipes 10. The grouting uses 1:1 cement grout for skip-hole grouting. The grouting pressure is controlled at 0.5-1Mpa. After reaching the grouting pressure, the pressure is maintained for 10 minutes and then the grouting is stopped.

[0083] S30, Backfill muck 12:

[0084] The tunnel arch replacement section was backfilled with caving muck in layers using the backfill muck 12, which limited the convergence deformation of the tunnel sidewalls on both sides. An additional 5m of backfill was applied before and after the arch replacement section, and the ends were trimmed. The subsequent excavation was carried out using the three-stage method.

[0085] S40, Install 13 advanced small catheters:

[0086] A pre-installed small guide pipe 13 is installed on the upper part of the arch support steel frame 8 along the radial direction of the tunnel. The pre-installed small guide pipe 13 has an upward angle of 5 to 15° and a length of 4.5m. The pre-installed small guide pipe 13 is arranged circumferentially on the upper part of the arch support steel frame 8, with a reinforcement range of 120 degrees and a circumferential spacing of 30cm. The pre-installed small guide pipe 13 is injected with reinforcement grout 14 to solidify the loose and broken surrounding rock 1. The tail of the pre-installed small guide pipe 13 is mechanically fixed to the arch support steel frame 8.

[0087] S50, stepped excavation muck 12:

[0088] After each section of the advanced small guide pipe 13 is installed and reinforced with grout, the caving 12 of the spacing between one arch frame is excavated in a step-by-step manner. After the next section of the advanced small guide pipe 13 is installed and reinforced with grout, the caving 12 of the spacing between the next arch frame is excavated in a step-by-step manner, and so on, excavating the caving 12.

[0089] S60, Remove the cutting seam 15:

[0090] After excavating the burial muck 12 at the interval of each arch frame, a diamond butterfly cutter 21 is installed on the boom of the excavator. The diamond butterfly cutter 21 is used to cut the arch wall 5, and a conical drill bit 25 is used to remove the initial support shotcrete 4 in the cut seam 15 to expose the deformed steel arch frame 3. When removing the concrete of the first deformed steel arch frame 3, try to avoid damaging the connecting bar 16 and steel mesh on the side of the undeformed steel arch frame 17. If necessary, a hand-held pneumatic pick can be used to remove the undeformed steel arch frame 17 side, removing only part of the concrete to leave a welding position so that the newly replaced arch frame can be welded to the connecting bar 16 and steel mesh of the undeformed steel arch frame 17 to form a whole.

[0091] S70, Replacement of deformed steel arch frame 3:

[0092] Cut the deformed steel arch frame 3 and dismantle it in sections from top to bottom. Install a new steel arch frame and re-lay a new steel mesh. The steel mesh should be as close to the rock surface as possible. After the steel arch frame 18 has been replaced, first remove the locking foot guide pipe 9, and then remove the arch protection steel frame 8.

[0093] S80, sprayed concrete:

[0094] After dismantling the arch support steel frame 8, the initial support shotcrete 4 is applied again, with the shotcrete applied sequentially from bottom to top. To ensure the connection effect and integrity between the subsequent steel arch frames, only one side of the normal section of the replaced steel arch frame 18 is shotcreted. The other side, towards the direction of the arch to be replaced, needs to be welded to the next steel arch frame 19 after the arch replacement, including the connecting bars 16 and steel mesh. Therefore, the welding positions need to be left unsprayed for the time being, and the shotcrete will be applied together and compacted during the next shotcrete cycle.

[0095] The parts not described in detail in this application are prior art, and therefore are not described in detail in this application.

[0096] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0097] Although this document uses a significant amount of technical terminology, the possibility of using other terms is not excluded. These terms are used merely to facilitate the description and explanation of the nature of this application; interpreting them as any additional limitation would be contrary to the spirit of this application.

[0098] This application is not limited to the above-described preferred embodiments. Anyone can derive other products in various forms under the guidance of this application. However, regardless of any changes made to their shape or structure, any technical solution that is the same as or similar to that of this application falls within the protection scope of this application.

Claims

1. A large deformation surrounding rock control structure for a deep-buried, water-rich karst tunnel, comprising surrounding rock (1), reinforcing anchors (2) and arch walls (5) within the surrounding rock (1), a deformed steel arch frame (3) caused by water inrush within the surrounding rock (1), and a deformation bulge (7) in the initial support concrete caused by the deformation section (6) of the deformed steel arch frame (3), characterized in that, It also includes arch support steel frame (8), foot locking small guide pipe (9), seamless steel pipe (10), positioning rib (11), caving debris (12), advanced small guide pipe (13), reinforcing grout (14), cutting seam (15), connecting rib (16), replaced steel arch frame (18), steel arch frame to be replaced (19), cutting knife main unit box (20), diamond butterfly cutting knife (21), rotating shaft (22), concrete breaker hammer joint (23), breaker hammer vibrator (24), and conical drill bit (25). The deformed steel arch frame (3) is temporarily reinforced on both sides by the arch support steel frame (8). The arch feet and arch rise line on both sides of the arch support steel frame (8) are provided with locking foot guide pipes (9), and the arch support steel frame (8) is positioned by positioning ribs (11) to improve the overall load-bearing performance of the arch support steel frame (8). The steel arch frame to be replaced (19) is used to replace the deformed steel arch frame (3) to obtain the replaced steel arch frame (18). The connecting ribs (16) are used to weld the steel arch frame to be replaced (19). The entire arch wall (5) is fitted with seamless steel pipes (10) and reinforced by grouting; The initial support deformation section of the tunnel is backfilled with slag (12) and counter-pressured by the arch wall (5). The slag (12) is backfilled in layers by counter-pressure. Before excavating the caving muck (12) of the counter-pressure body, advanced small guide pipes (13) are installed and the surrounding rock (1) is reinforced by reinforcing grout (14). The tail of the advanced small guide pipes (13) is fixedly connected to the arch support steel frame (8). The caving muck (12) of the counter-pressure body is excavated in a step-by-step manner. Each time an advanced small guide pipe (13) is installed, a section of caving muck (12) is excavated in a step-by-step manner. The deformed steel arch frame (3) is replaced in time after each section is excavated. The cutting seam (15) is located on both sides of the deformed steel arch frame (3). The width of the cutting seam (15) is the distance between the two diamond butterfly cutting blades (21). The cutting seam (15) is cut using diamond butterfly cutting blades (21). The initial support shotcrete (4) of the cutting seam (15) is removed using a conical drill bit (25). The diamond butterfly cutting blade (21) is fixed on the cutting blade main unit box (20) via a rotating shaft (22). The cutting blade main unit box (20) is fixed on the boom of the excavator. The conical drill bit (25) is installed on the vibrating breaker. On the device (24), the breaker vibrator (24) is fixed on the concrete breaker joint (23), which can also be installed on the boom of the excavator; the diamond butterfly cutter (21) precisely cuts two cutting seams (15) on both sides of the deformed steel arch frame (3) to cut off the stress transmission path, and then the tapered drill bit (25) is used in conjunction with the breaker vibrator (24) to locally and slightly remove the initial support shotcrete (4) within the cutting seam (15) to expose the deformed steel arch frame (3).

2. The large deformation surrounding rock control structure for deep-buried water-rich karst tunnels according to claim 1, characterized in that, The arch support steel frame (8) is close to the arch wall (5) and provides support for the arch wall (5).

3. The rock mass control structure for large deformation surrounding rocks in deep-buried water-rich karst tunnels according to claim 1, characterized in that, Cement grout is injected into both the locking foot guide tube (9) and the seamless steel pipe (10) for reinforcement. The water-cement ratio of the cement grout is 1:1 and the grouting pressure is 0.5~1MPa.

4. The construction method for the large deformation surrounding rock control structure of a deep-buried water-rich karst tunnel as described in any one of claims 1-3, characterized in that, Includes the following steps: S00, Initial support deformation inspection: A full-length inspection of the water-rich karst section of the tunnel was carried out. The number of arch frame deformation sections (6) and initial support concrete deformation bulges (7) that occurred during the initial support were counted. The loosening of the reinforcing anchor rods (2) was checked. The corresponding deformed steel arch frames (3) were marked on the arch wall (5). S10, Erecting the arch support steel frame (8): A protective arch steel frame (8) is installed on both sides of the arch wall (5) mark. Each protective arch steel frame (8) is fitted with a locking foot guide pipe (9) at the arch feet on both sides and the arch rise line on both sides. After the installation of the locking foot small guide pipe (9) is completed, it is reinforced by grouting with reinforcing grout (14) in a timely manner. The grout is cement grout with a water-cement ratio of 1:

1. The grouting pressure is 0.5~1MPa. The grouting is stopped after 10 minutes of continuous pressure stabilization. S20, full-section seamless steel pipe (10) grouting reinforcement: After the arch support steel frame (8) is completed, seamless steel pipes (10) are installed on the entire cross section of the arch wall (5). Grouting reinforcement was carried out through seamless steel pipe (10). Grouting was carried out by skip-hole grouting with 1:1 cement grout. The grouting pressure was controlled at 0.5~1Mpa. After reaching the grouting pressure, the pressure was stabilized for 10 minutes and then the grouting was stopped. S30, Backfill muck (12): The tunnel arch replacement section is backfilled with slag in layers (12) to limit the convergence deformation of the tunnel sidewalls on both sides through the slag in the back pressure body (12); The arch replacement section was reinforced with an additional 5m of counterpressure before and after the arch was replaced, and the two ends were trimmed. The subsequent excavation was carried out using the three-stage method. S40, Installing a pre-implanted small catheter (13): A small guide pipe (13) is installed on the upper part of the arch support steel frame (8) along the radial direction of the tunnel. The upward angle of the small guide pipe (13) is 5~15°. The small guide pipe (13) is arranged circumferentially on the upper part of the arch support steel frame (8). The reinforcement range is 120° and the circumferential spacing is 30cm. The pre-conducting small guide pipe (13) injects the reinforcing grout (14) to solidify the loose and broken surrounding rock (1), and the tail of the pre-conducting small guide pipe (13) is mechanically fixed to the arch support steel frame (8); S50, stepped excavation of muck (12): After each section of the advanced small guide pipe (13) is installed and reinforced with grout, the caving muck (12) between the spans of one arch frame is excavated in a step-by-step manner. After the next section of the advanced small guide pipe (13) is installed and reinforced with grout, the caving muck (12) between the spans of one arch frame is excavated in a step-by-step manner. This process is repeated to excavate the caving muck (12). S60, Remove the cutting seam (15): After excavating the slag (12) between each arch frame, a diamond butterfly cutter (21) is installed on the boom of the excavator. The diamond butterfly cutter (21) is used to cut the arch wall (5). The cutting seams (15) are cut on both sides of the deformed steel arch frame (3) to cut off the stress transmission path. A tapered drill bit (25) installed on the excavator boom is used in conjunction with a breaker hammer vibrator (24) to perform localized micro-removal only in the cutting seams (15). The initial support shotcrete (4) in the cutting seams (15) is removed to expose the deformed steel arch frame (3). The undeformed steel arch frame (17) was chipped away by hand-held pneumatic picks. Only part of the concrete was chipped away to leave a welding position so that the newly replaced arch frame could be welded to the connecting bar (16) and steel mesh of the undeformed steel arch frame (17) to form a whole. S70, Replace the deformed steel arch frame (3): Cut the deformed steel arch frame (3) and dismantle it in sections from top to bottom. Install the steel arch frame to be replaced (19), and re-lay the new steel mesh. The steel mesh is closely attached to the rock surface. After the steel arch frame (18) has been replaced, first remove the locking foot guide pipe (9), and then remove the arch protection steel frame (8). S80, sprayed concrete: After dismantling the arch support steel frame (8), the initial support shotcrete (4) is carried out again. The shotcrete is sprayed from bottom to top. The steel arch frame (18) that has been replaced is sprayed on one side of the normal section. The other side of the arch to be replaced is connected to the steel arch frame (19) to be replaced. After the arch is replaced, the connecting bar (16) and the steel mesh are welded. The welding position is left unsprayed for the time being. When the next cycle of sprayed concrete is used, it will be sprayed together to make it dense.

5. The construction method for the large deformation surrounding rock control structure of a deep-buried water-rich karst tunnel according to claim 4, characterized in that, In step S10, the arch support steel frame (8) is made of I20a I-beams. The arch support steel frame (8) is spaced 1.0m apart. The arch support steel frame (8) is composed of 7 units. Each unit is connected by bolts. Each unit is equipped with positioning ribs (11) for positioning. The arch foot is padded with channel steel and welded.

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