A Tunnel TBM excavation earthquake advance prediction receiving device

Abstract

The invention relates to the field of geological survey technology, and discloses a tunnel TBM excavation earthquake advance prediction receiving device, including a source excitation device and a source signal receiving device, two sets of source excitation devices are symmetrically installed at positions near the face of the tunnel in the TBM excavator, and multiple source signal receiving devices are installed at different positions on the inner wall of the tunnel, and the source signal receiving device includes a conical casing, an installation anchor rod and a wireless seismic detector, the conical casing is hollow, and two arc-shaped reinforcement plates are symmetrically arranged in the conical casing, and the end surface of the arc-shaped reinforcement plate close to the inner wall of the conical casing is fixed with a plurality of hollow reinforcement cones, and the side wall of the conical casing is provided with conical holes at positions corresponding to the hollow reinforcement cones, and a conical space for the installation anchor rod to pass through is formed between the two arc-shaped reinforcement plates, and the installation anchor rod passes through the conical space to squeeze the arc-shaped reinforcement plate to move, and the installation anchor rod is connected to the wireless seismic detector. A breakthrough in the advance prediction of earthquake reflection in the shield-type TBM excavation tunnel is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of geological exploration, and in particular to a tunnel TBM excavation earthquake advance prediction receiving device. Background Art

[0002] With the construction of large-scale infrastructure in my country, some tunnels with large burial depth and long mileage are often encountered during construction. The existing geological problems are becoming more and more complex, and the number of geological units crossed is increasing. During the construction of underground tunnels, due to changes in geological conditions, sudden accidents often occur (such as landslides, water gushing, mud bursts, rock bursts, high gas and other geological disasters). Therefore, geological advance prediction during tunnel construction and excavation is particularly important. Through tunnel geological advance prediction, the adverse geological bodies in front of the tunnel face and their properties, locations, scales, occurrences and disaster possibilities can be predicted in time to prevent the occurrence of catastrophic accidents and provide a basis for the correct selection of excavation sections, support design parameters and optimization of construction plans.

[0003] At present, tunnel excavation is generally divided into drilling and blasting method and TBM method, and TBM method is further divided into open TBM excavation and shield TBM excavation. The most common tunnel excavation is the drilling and blasting method. The tunnel face and the tunnel wall are exposed, and the tunnel is relatively open and unobstructed. When conducting seismic reflection advance prediction, the excitation source can use conventional explosion excitation and hammer excitation, and the receiving detector can be directly coupled with the rock tunnel wall; therefore, it is relatively easy to carry out seismic reflection advance prediction on-site operations in tunnels excavated by drilling and blasting method and open TBM. In shield TBM excavation, the tunnel face and the tunnel wall are all closed, the tunnel wall around the tunnel face is closed by the shield, and the excavated tunnel wall is closed by the prefabricated pipe segment. Conventional explosion excitation and hammer excitation cannot be directly implemented, and the receiving detector cannot be directly coupled with the rock tunnel wall; therefore, it is necessary to design an advance prediction excitation receiving device specifically for shield TBM excavation. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a tunnel TBM excavation earthquake advance prediction receiving device, which achieves a breakthrough in carrying out earthquake reflection advance prediction in a shield TBM excavation tunnel.

[0005] The objective of the present invention is achieved through the following technical solutions: a tunnel TBM excavation earthquake advance prediction receiving device, comprising a source excitation device and a source signal receiving device, two groups of the source excitation devices are symmetrically installed at positions near the face of the tunnel in the TBM excavator, and multiple source signal receiving devices are installed at different positions on the inner wall of the tunnel, the source signal receiving device comprises a conical casing, an installation anchor rod and a wireless seismic detector, the conical casing is hollow, and two arc-shaped reinforcement plates are symmetrically arranged in the conical casing, and the end surface of the arc-shaped reinforcement plate close to the inner wall of the conical casing is fixed. A plurality of hollow reinforcing cones are defined, and conical holes are provided on the side walls of the conical sleeve at positions corresponding to the hollow reinforcing cones. A conical space for the installation anchor rod to pass through is formed between the two arc-shaped reinforcing plates, and the installation anchor rod passes through the conical space to squeeze the arc-shaped reinforcing plate to move, so as to make the hollow reinforcing cone pass through the conical hole with interference fit. A casting pipe is connected to one end of the conical sleeve with a large diameter, and the casting pipe is used to connect concrete casting equipment, and the concrete casting equipment is used to inject quick-setting cement into the conical sleeve, and the installation anchor rod passes through the casting pipe to connect to the wireless seismic geophone;

[0006] The seismic source excitation device includes a box, a hammer rod and a lifting leg. The lifting leg is vertically installed on the TBM floor, the box is installed on the lifting leg, the hammer rod is slidably arranged on the box, and the hammer rod moves in the horizontal direction. A plurality of skylight holes are opened on the shields on the left and right sides of the TBM tunneling machine. The hammer rod extends out of the skylight holes and hits the inner wall of the tunnel to generate a seismic signal. The wireless seismic detector is used to receive the seismic signal generated by the seismic source excitation device.

[0007] Furthermore, a driving cavity is provided in the mounting anchor rod, and a plurality of mounting grooves are opened on the side wall of the mounting anchor rod, and the plurality of mounting grooves are evenly distributed around the circumferential direction of the mounting anchor rod, and the mounting grooves are connected to the driving cavity, and a support block is slidably provided in the mounting groove, and an extrusion rod is provided in the driving cavity, and the extrusion rod has the freedom to move along the axial direction of the mounting anchor rod, and a wedge surface is provided at one end of the support block close to the extrusion rod, and the wedge surface is located on the moving path of the extrusion rod, and the support block partially extends from the mounting groove and abuts against the end of the arc-shaped reinforcement plate.

[0008] Furthermore, a circular groove is provided at one end of the mounting anchor rod away from the support block, a threaded hole is provided in the circular groove, a screw is provided in the circular groove, the screw thread is adapted to the threaded hole, the tail of the screw rod is inserted into the driving cavity to connect to the extrusion rod, and the head of the screw rod is located in the circular groove.

[0009] Furthermore, both ends of the pouring pipe are provided with internal threads, and the pouring pipe thread is sleeved on the conical sleeve, a sealing plate is fixed in the pouring pipe, and a switching disk is rotatably arranged on the sealing plate, and through holes are penetrated in the middle of the sealing plate and the middle of the switching disk, and the mounting anchor rod passes through the through hole, and a plurality of first slurry inlet holes are penetrated around the through hole on the sealing plate, and a plurality of second slurry inlet holes are penetrated around the through hole on the switching disk, and the switching disk is rotated to make the plurality of first slurry inlet holes correspond one by one with the plurality of second slurry inlet holes.

[0010] Furthermore, an annular groove is provided on the inner wall of the pouring pipe, the annular groove is coaxially arranged with the pouring pipe, and the switching disk is rotatably adapted to the annular groove.

[0011] Furthermore, the mounting anchor rod is connected to an extension rod, one end of the extension rod is threadedly adapted in the circular groove, and an installation plate is fixed to one end of the extension rod away from the mounting anchor rod, and the installation plate is mounted on the housing of the wireless seismic detector by screws.

[0012] Furthermore, the seismic source excitation device also includes a hook-tooth lever, a large spring and a small spring. A plurality of the large springs are arranged around the hammer rod in the box, one end of the large spring is connected to the hammer rod, and the other end is connected to the inner wall of the box. The hook-tooth lever is arranged below the hammer rod and eccentrically hinged on the box. A hook tooth is formed at the short arm end of the hook-tooth lever, and a groove is provided at the bottom of the hammer rod. The small spring is arranged below the hook-tooth lever, one end of the small spring is connected to the long arm of the hook-tooth lever, and the other end is connected to the inner bottom wall of the box, and the small spring is always in a stretched state.

[0013] Furthermore, a locking hydraulic cylinder is horizontally installed in the box body, and the telescopic shaft of the locking hydraulic cylinder is connected to a locking block, and the locking hydraulic cylinder is perpendicular to the hook tooth lever, and a locking groove is provided on a side of the long arm section of the hook tooth lever close to the locking block. When the hook tooth is adapted in the groove, the locking groove is located on the moving path of the locking block, and the top wall of the groove is a plane, and the side wall of the groove away from the hook tooth lever is an abutment plane, and the side wall of the groove close to the hook tooth lever is a wedge-shaped surface, the top of the hook tooth is an inclined contact surface, and one end of the hook tooth close to the groove is an inclined abutment surface, and when the hook tooth is deflected upward into the groove, the inclined contact surface is deflected to a horizontal state and contacts with the plane, and the inclined abutment surface is deflected to be parallel to the abutment plane, and when the inclined abutment surface contacts the abutment plane, the locking hydraulic cylinder drives the locking block to adapt to the locking groove.

[0014] Furthermore, a rack is fixed on the top of the hammer rod along its length direction, a large gear is rotatably arranged in the box body, the large gear meshes with the rack, a motor is installed in the box body, the output shaft of the motor is connected with a small gear, the small gear meshes with the large gear, a distance sensor is installed on the inner wall of the box body, the detection light path of the distance sensor is parallel to the rack, one end of the rack is located on the detection light path of the distance sensor, a vibration trigger switch is arranged on the hammer rod, and the vibration trigger switch is connected to the wireless seismic detector.

[0015] The gear is connected to the gear box through a driving shaft, and the gear is slidably mounted on the driving shaft through a spline, and the gear is engaged with or separated from the rack by movement, and a driving plate is gap-mounted on the driving shaft, and an outer diameter of the driving plate is larger than an outer diameter of the gear. A bearing groove is provided on the end face of the driving plate close to the gear, and the bearing groove is coaxially arranged with the driving plate. A bearing is arranged in the bearing groove, and an outer wall of the bearing is connected to the driving plate. A hollow shaft is coaxially fixed to the end face of the gear close to the driving plate, and the hollow shaft is connected to the inner ring of the bearing. A switching cylinder is installed in the housing, and the switching cylinder is parallel to the driving shaft. The telescopic shaft of the switching cylinder is connected to a gear shifting rod, and the gear shifting rod is located above the driving plate. Two limiting teeth are fixed on the bottom wall of the gear shifting rod at intervals, and the driving plate is limited between the two limiting teeth.

[0016] The beneficial effects of the present invention are:

[0017] 1. The hammer rod extends out of the skylight hole and hits the tunnel wall to generate a source signal. The seismic signal is received by the wireless seismic detector. The wireless seismic detector collects multi-layer reflection signals and performs three-dimensional inversion calculations on the dielectric bodies of each layer in the tunnel. A three-dimensional result map within a range of about 100m in front of the tunnel face is obtained, and the data is analyzed for geological advance prediction, which solves the problem that the existing tunnel TBM excavation machine cannot perform earthquake advance prediction and achieves a breakthrough in conducting earthquake reflection advance prediction in shield TBM excavation tunnels.

[0018] 2. Insert the conical casing into the gravel between the surrounding rock and the prefabricated pipe segment, so that the end of the conical casing contacts the surrounding rock to isolate the influence of the gravel, install the anchor rod and insert it into the conical casing, and squeeze the arc reinforcement plate by installing the anchor rod to move the arc reinforcement plate. The arc reinforcement plate allows the hollow reinforcement cone to penetrate from the conical hole and embed into the gravel. Finally, pour quick-setting cement into the conical casing to improve the installation strength of the seismic source signal receiving device and ensure that it remains stable under the seismic source signal and will not fall off. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1It is a schematic diagram of the arrangement of a source signal receiving device in a tunnel TBM excavation earthquake advance prediction receiving device of the present invention;

[0020] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0021] Figure 3 for Figure 2 Enlarged view of point B in the middle;

[0022] Figure 4 for Figure 2 Enlarged view of point C in the middle;

[0023] Figure 5 It is a schematic diagram of the arrangement of a source excitation device in a tunnel TBM excavation earthquake advance prediction receiving device of the present invention;

[0024] Figure 6 A partial schematic diagram of a box in a tunnel TBM excavation earthquake advance prediction receiving device of the present invention Figure 1 ;

[0025] Figure 7 A partial schematic diagram of a box in a tunnel TBM excavation earthquake advance prediction receiving device of the present invention Figure 2 ;

[0026] Figure 8 It is a schematic diagram of the assembly of a large gear and a driving plate in a tunnel TBM excavation earthquake advance prediction receiving device of the present invention;

[0027] Fig. 9 It is a schematic diagram of the arrangement of the source point and the receiving point in a device for receiving earthquake advance prediction for tunnel TBM excavation according to the present invention;

[0028] Fig.10 It is a three-dimensional top view of the tunnel of the present invention;

[0029] Fig.11 It is a three-dimensional stereogram of the tunnel of the present invention;

[0030] In the figure, 1-conical casing, 2-installation anchor rod, 3-wireless seismic detector, 4-arc reinforcement plate, 5-hollow reinforcement cone, 6-conical hole, 7-casting pipe, 8-box, 9-hammer rod, 10-lifting leg, 11-skylight hole, 12-driving cavity, 13-installation groove, 14-support block, 15-extrusion rod, 16-wedge surface, 17-circular groove, 18-threaded hole, 19-screw, 20-sealing plate, 21-switching plate, 22-through hole, 23-first slurry inlet hole, 24-second slurry inlet hole, 25-annular groove, 26-extension rod, 27-installation sheet , 28-hook tooth lever, 29-large spring, 30-small spring, 31-hook tooth, 32-groove, 33-locking hydraulic cylinder, 34-locking block, 35-locking groove, 36-abutment plane, 37-wedge surface, 38-inclined contact surface, 39-inclined abutment surface, 40-rack, 41-large gear, 42-motor, 43-small gear, 44-distance sensor, 45-vibration trigger switch, 46-drive shaft, 47-drive disk, 48-bearing groove, 49-bearing, 50-hollow shaft, 51-switching cylinder, 52-gear lever, 53-limiting tooth. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0032] like Figures 1 to 8As shown, a tunnel TBM excavation earthquake advance prediction receiving device includes a source excitation device and a source signal receiving device. Two sets of source excitation devices are symmetrically installed near the face of the tunnel in the TBM excavator, and multiple source signal receiving devices are installed at different positions on the inner wall of the tunnel. The source signal receiving device includes a conical casing 1, an installation anchor 2 and a wireless seismic detector 3. The conical casing 1 is hollow, and two arc-shaped reinforcement plates 4 are symmetrically arranged in the conical casing 1. A plurality of hollow reinforcement cones 5 are fixed to the end surface of the arc-shaped reinforcement plate 4 close to the inner wall of the conical casing 1. Conical holes 6 are opened at the positions of the side walls of the conical casing 1 corresponding to the hollow reinforcement cones 5. A hole for the installation anchor 2 to pass through is formed between the two arc-shaped reinforcement plates 4. The cone-shaped space is penetrated by the installation anchor rod 2 to squeeze the arc-shaped reinforcement plate 4 to move, so as to make the hollow reinforcement cone 5 interfere and pass through the cone hole 6. The end of the cone casing 1 with a large diameter is connected with a pouring pipe 7, and the pouring pipe 7 is used to connect the concrete pouring equipment. The concrete pouring equipment is used to inject quick-setting cement into the cone casing 1. The installation anchor rod 2 passes through the pouring pipe 7 to connect the wireless seismic detector 3. After the TBM is excavated, the surrounding rock will be installed on the tunnel wall, and the prefabricated pipe segment will be installed on the inner side of the surrounding rock. The space between the prefabricated pipe segment and the surrounding rock is filled with gravel. When installing the seismic source signal receiving device, a drilling rig is used to drill an installation hole on the prefabricated pipe segment, and then the cone casing 1 is inserted from the installation hole. The cone-shaped cone casing 1 can be easily inserted into the gravel and pass through The installation hole is blocked by the conical casing 1 to prevent gravel from falling from the installation hole under the action of the seismic source signal. The end of the conical casing 1 contacts the surrounding rock. The installation anchor rod 2 is inserted into the conical casing 1. Since a conical space is formed between the two arc-shaped reinforcement plates 4, the installation anchor rod 2 will squeeze the arc-shaped reinforcement plate 4 during the insertion of the conical casing 1, so that the arc-shaped reinforcement plate 4 moves close to the inner wall of the conical casing 1. The arc-shaped reinforcement plate 4 drives the hollow reinforcement cone 5 to extend out of the conical hole 6. The hollow reinforcement cone 5 is embedded in the gravel to stabilize the position of the conical casing 1. Then, the casting pipe 7 is installed on the conical casing 1, and quick-setting cement is poured into the casting pipe 7 through concrete pouring equipment. The quick-setting cement flows into the conical casing 1, and part of the quick-setting cement is poured into the conical casing 1. The quick-setting cement flows out from the end of the tapered casing 1, so that the quick-setting cement connects the surrounding rock and the tapered casing 1. The quick-setting cement also flows into the gravel from the hollow reinforcing cone 5, so that the tapered casing 1 is wrapped with the quick-setting cement. The quick-setting cement connects the tapered casing 1 to the gravel, thereby greatly improving the connection strength of the tapered casing 1. At the same time, the installation anchor 2 is fixed in the tapered casing 1 by the quick-setting cement, and the connection strength between the installation anchor 2 and the tapered casing 1 is strengthened. Finally, the infinite seismic detector 3 is installed at the end of the installation anchor 2, so that the tapered casing 1 and the installation anchor 2 have strong seismic resistance, ensuring that they will not fall off under the vibration generated by the source excitation device, so that the infinite seismic detector 3 can normally receive seismic signals;The source excitation device includes a box 8, a hammer rod 9 and a lifting leg 10. The lifting leg 10 is vertically installed on the TBM floor, the box 8 is installed on the lifting leg 10, and the hammer rod 9 is slidably set on the box 8. The hammer rod 9 moves in the horizontal direction. A plurality of skylight holes 11 are opened on the shields on the left and right sides of the TBM tunneling machine. The hammer rod 9 extends from the skylight holes 11 and hits the inner wall of the tunnel to generate seismic signals. The wireless seismic detector 3 is used to receive the seismic signals generated by the source excitation device. The wireless seismic detector 3 collects multi-layer reflection signals and performs three-dimensional inversion calculations on each layer of the medium in the tunnel to obtain a three-dimensional result map within a range of about 100m in front of the tunnel face, and analyzes the data for geological advance prediction, which solves the problem that the existing tunnel TBM tunneling machine cannot perform earthquake advance prediction, and achieves a breakthrough in conducting earthquake reflection advance prediction in the shield TBM tunneling tunnel. ;

[0033] Furthermore, if Figures 1 to 4 As shown, a driving cavity 12 is provided in the installation anchor rod 2, and a plurality of installation grooves 13 are provided on the side wall of the installation anchor rod 2. The plurality of installation grooves 13 are evenly distributed around the circumferential direction of the installation anchor rod 2. The installation grooves 13 are connected to the driving cavity 12. A support block 14 is slidably provided in the installation groove 13. An extrusion rod 15 is provided in the driving cavity 12. The extrusion rod 15 has the freedom to move along the axial direction of the installation anchor rod 2. A wedge surface 16 is provided at one end of the support block 14 close to the extrusion rod 15. The wedge surface 16 is located on the moving path of the extrusion rod 15. The support block 14 partially extends out of the installation groove 13 and abuts against the end of the arc-shaped reinforcement plate 4. A circular groove 17 is provided at one end of the installation anchor rod 2 away from the support block 14. A threaded hole 18 is provided in the circular groove 17. A screw 19 is provided in the circular groove 17. The thread of the screw 19 is adapted to the threaded hole 18. The tail of the screw 19 is inserted into the driving cavity 12 to connect the extrusion rod 15. The head of the screw 19 is located in the circular groove 17. The installation anchor rod 2 is inserted into the tapered sleeve 1 until the end of the installation anchor rod 2 passes through the arc reinforcing plate 4 and contacts the tapered sleeve 1. Then the screw 19 is tightened. The screw 19 drives the extrusion rod 15 to move close to the support block 14. The extrusion rod 15 squeezes the wedge surface 16 of the support block 14. Under the guidance of the wedge surface 16, the support block 14 extends out of the installation groove 13, so that the distance between the end of the support block 14 away from the installation anchor rod 2 and the center of the installation anchor rod 2 is greater than the minimum diameter of the conical space, so that the support block 14 contacts the end of the arc reinforcing plate 4, so that the installation anchor rod 2 will not fall out of the tapered sleeve 1, which is convenient for installing the pouring pipe 7 to pour quick-setting cement.

[0034] Furthermore, if Figures 2 to 4As shown, both ends of the pouring pipe 7 are provided with internal threads, and the pouring pipe 7 is threadedly sleeved on the conical sleeve 1. A sealing plate 20 is fixed in the pouring pipe 7, and a switching disk 21 is rotatably arranged on the sealing plate 20. A through hole 22 is penetrated in the middle of the sealing plate 20 and the middle of the switching disk 21, and the mounting anchor 2 passes through the through hole 22. A plurality of first slurry inlet holes 23 are penetrated around the through hole 22 on the sealing plate 20, and a plurality of second slurry inlet holes 24 are penetrated around the through hole 22 on the switching disk 21. The switching disk 21 rotates to make the plurality of first slurry inlet holes 23 correspond to the plurality of second slurry inlet holes 24 one by one. An annular groove 25 is provided on the inner wall of the pouring pipe 7, and the annular groove 25 is coaxially arranged with the pouring pipe 7. The switching disk 21 rotatably adapts to the annular groove 25. The pouring pipe 7 docks with the conical sleeve 1 and the pipeline of the concrete pouring equipment, and the pouring pipe 7 is quickly connected in a threaded manner. On the tapered sleeve 1, the end of the pouring pipe 7 away from the tapered sleeve 1 is connected to the pipeline by means of a thread or a flange. The concrete pouring equipment can pass the quick-setting cement into the tapered sleeve 1 through a mud pump. At this time, the first slurry inlet hole 23 and the second slurry inlet hole 24 correspond coaxially, so that the quick-setting cement flows into the tapered sleeve 1 through the first slurry inlet hole 23 and the second slurry inlet hole 24. After the quick-setting cement is poured, the concrete pouring equipment is removed, and a tool is used to act on the second slurry inlet hole 24 of the switching disk 21 to drive the switching disk 21 to rotate, so that the second slurry inlet hole 24 is staggered with the first slurry inlet hole 23, so that the first slurry inlet hole 23 and the second slurry inlet hole 24 are blocked by the staggered arrangement of the switching disk 21 and the sealing plate 20, so that the cement in the tapered sleeve 1 will not overflow, and the quick-setting cement can solidify normally, so as to complete the connection between the tapered sleeve 1 and the installation anchor rod 2.

[0035] Furthermore, the installation anchor rod 2 is connected to an extension rod 26, one end of the extension rod 26 is threadedly adapted in the circular groove 17, and a mounting plate 27 is fixed to the end of the extension rod 26 away from the installation anchor rod 2, and the mounting plate 27 is mounted on the housing of the wireless seismic detector 3 by screws. After the above-mentioned quick-setting cement is poured, the wireless seismic detector 3 is installed, the extension rod 26 is threadedly connected to the installation anchor rod 2, and then the wireless seismic detector 3 is connected through the mounting plate 27. After the conical casing 1 is connected, the large diameter end of the conical casing 1 is flush with the inner wall of the prefabricated pipe segment to ensure that the conical casing 1 does not affect the withdrawal of the tunnel boring machine. The extension rod 26 enables the wireless seismic detector 3 to be installed in the tunnel to ensure that the wireless seismic detector 3 has sufficient installation space. When the forecasting operation is completed, the wireless seismic detector 3 and the extension rod 26 can be removed without removing the conical casing 1 and the installation anchor rod 2. At the same time, the conical casing 1 continues to block the mounting hole drilled in the prefabricated pipe segment, thereby reducing the workload of disassembling the source signal receiving device.

[0036] Furthermore, if Figures 5 to 8As shown, the seismic source excitation device also includes a hook-tooth lever 28, a large spring 29 and a small spring 30. A plurality of large springs 29 are arranged around the hammer rod 9 in the box body 8. One end of the large spring 29 is connected to the hammer rod 9, and the other end is connected to the inner wall of the box body 8. The hook-tooth lever 28 is arranged below the hammer rod 9 and is eccentrically hinged on the box body 8. A hook tooth 31 is formed at the short arm end of the hook-tooth lever 28. A groove 32 is provided at the bottom of the hammer rod 9. The small spring 30 is arranged below the hook-tooth lever 28. One end of the small spring 30 is connected to the long arm of the hook-tooth lever 28, and the other end is connected to the inner bottom wall of the box body 8. The small spring 30 is always in a stretched state. The lifting leg 10 adjusts the height of the hammer rod 9 so that the hammer rod 9 can extend from the skylight hole 11 at different heights to generate a seismic signal. It is connected to the lower part of the long arm of the hook-tooth lever 28, and the small spring 30 is always in a stretched state, so that the small spring 30 pulls the hook-tooth lever 28 downward to deflect, so that the hook tooth 31 on the hook-tooth lever 28 deflects upward, and the hook tooth 31 always contacts the bottom surface of the hammer rod 9, and the hammer rod 9 moves close to the center of the shield, so that the groove 32 on the hammer rod 9 moves close to the hook-tooth lever 28 until the hook tooth 31 fits in the groove 32, and the hook-tooth lever 28 stops moving. At this time, the large spring 29 is in a stretched state, and then the hook-tooth lever 28 deflects, so that the hook tooth 31 deflects downward and disengages from the groove 32, thereby unlocking the motion state of the hammer rod 9. The hammer rod 9 moves away from the center of the shield under the reaction of the large spring 29, so that the hammer rod 9 extends out of the skylight hole 11 and hits the rock wall of the tunnel to generate a seismic signal.

[0037] Furthermore, if Figure 6 and Figure 7As shown, a locking hydraulic cylinder 33 is horizontally installed in the box body 2, and a locking block 34 is connected to the telescopic shaft of the locking hydraulic cylinder 33. The locking hydraulic cylinder 33 is perpendicular to the hook tooth lever 28. A locking groove 35 is provided on the side of the long arm section of the hook tooth lever 28 close to the locking block 34. When the hook tooth 31 is adapted in the groove 32, the locking groove 35 is located on the moving path of the locking block 34. To ensure that the hammer rod 9 can smoothly extend from the skylight hole 11 after being released, the initial state of the hammer rod 9 installed in the shield is a power storage state, that is, the hook tooth 31 is adapted in the groove 32 to limit the movement of the hammer rod 9, so that the source excitation device does not interfere with the shield. At the same time, when released, it has enough length to extend from the skylight hole 11 to hammer on the rock wall of the tunnel. To ensure the locking stability of the hammer rod 9, avoid the hammer rod 9 from being pressed In case of accidental launch due to the force of the hook tooth lever 28, after the hook tooth 31 is engaged in the groove 32, the locking hydraulic cylinder 33 extends to drive the locking block 34 to be inserted into the locking groove 35 of the hook tooth lever 28, and the hook tooth lever 28 is locked by hydraulic means, thereby locking the state of the hammer bar 9; the top wall of the groove 32 is a plane, the side wall of the groove 32 away from the hook tooth lever 28 is an abutment plane 36, the side wall of the groove 32 close to the hook tooth lever 28 is a wedge-shaped surface 37, the top of the hook tooth 31 is an inclined contact surface 38, and the end of the hook tooth 31 close to the groove 32 is an inclined abutment surface 39. When the hook tooth 31 is deflected upward into the groove 32, the inclined contact surface 38 is deflected to a horizontal state and contacts with the plane, and the inclined abutment surface 39 is deflected to be parallel to the abutment plane 36. When the abutting surface 39 contacts the abutting plane 36, the locking hydraulic cylinder 33 drives the locking block 34 to adapt to the locking groove 35. A rack 40 is fixed on the top of the hammer rod 9 along its own length direction. A large gear 41 is rotatably arranged in the box body 8, and the large gear 41 engages with the rack 40. A motor 42 is installed in the box body 8. The output shaft of the motor 42 is connected to a small gear 43, and the small gear 43 engages with the large gear 41. A distance sensor 44 is installed on the inner wall of the box body 8. The detection light path of the distance sensor 44 is parallel to the rack 40. One end of the rack 40 is located on the detection light path of the distance sensor 44. A vibration trigger switch 45 is arranged on the hammer rod 9. The vibration trigger switch 45 is connected to the wireless seismic detector 3. Since the source excitation device is installed in the shield, it cannot be operated by personnel and needs In order for the source excitation device to automatically start multiple hammer strikes to generate source signals, the motor 42 drives the small gear 42 to rotate, the small gear 42 drives the large gear 41 to rotate, and the large gear 41 drives the rack 40 to move, so that the rack 40 drives the hammer rod 9 to move close to the hook-tooth lever 28. It should be noted that when the hook-tooth lever 28 is in a normal state (the hook tooth 31 contacts the bottom surface of the hammer rod 9), the inclined contact surface 38 and the inclined abutment surface 39 are both inclined, and the inclined contact surface 38 is perpendicular to the inclined abutment surface 39, and the inclination angle is equal to the deflection angle of the hook-tooth lever 28 deflected and adapted to the groove 32. When the hammer rod 9 moves to the hook tooth 31 corresponding to the groove 32, under the action of the small spring 30, the hook-tooth lever 28 is deflected upward and adapted to the groove 32. At this time,The inclined contact surface 38 of the hook tooth 31 deflects to a horizontal state to match the top wall of the groove 32, and then the hammer rod 9 continues to move until the inclined abutting surface 39 of the hook tooth 31 contacts the abutting plane 36. Since the inclined abutting surface 39 is in vertical contact with the abutting plane 36, the freedom of the hammer rod 9 to continue to move in the direction close to the center of the shield is limited. At this time, the hammer rod 9 stops moving, and the feedback time of the distance sensor 44 is set within the overload range of the motor 42. When the distance sensor 44 detects that the distance of the rack 40 no longer changes within the set time, the feedback signal of the distance sensor 44 causes the locking hydraulic cylinder 33 to drive the locking block 34 to adapt to the locking groove 35, thereby locking the state of the hook tooth lever 28, and the motor 42 stops at the same time, thereby protecting the motor 42 and automatically enabling The hammer rod 9 switches to the source excitation state, and then the locking hydraulic cylinder 33 drives the lock block 34 to disengage from the lock groove 35. At this time, the hammer rod 9 moves away from the center of the shield under the reaction of the large spring 29, so that the hook tooth 31 contacts the wedge surface 37. Since the reaction force generated by the multiple large springs 29 is much greater than the force generated by the small springs 30, plus the guiding effect of the wedge surface 37, the hammer rod 9 can press down the short arm of the hook tooth lever 28, so that the hook tooth lever 28 is disengaged from the groove 32, and then the hammer rod 9 extends from the skylight hole 11 to act on the tunnel wall to generate a source signal, and the vibration trigger switch 45 is activated. The vibration trigger switch 45 activates the wireless seismic detector 3 to receive the source signal. Repeat the above process to generate multiple seismic signals, or generate seismic signals at different source points.

[0038] Furthermore, if Figures 6 to 8As shown, the large gear 41 is rotatably connected to the housing 8 through the driving shaft 46. The large gear 41 is slidably sleeved on the driving shaft 46 through a spline. The large gear 41 meshes with or separates from the rack 40 by movement. A driving disk 47 is gap-fitted on the driving shaft 46. The outer diameter of the driving disk 47 is larger than the outer diameter of the large gear 41. A bearing circular groove 48 is provided on the end face of the driving disk 47 close to the large gear 41. The bearing circular groove 48 is coaxially arranged with the driving disk 47. A bearing 49 is arranged in the bearing circular groove 47. The outer wall of the bearing 49 is connected to the driving disk 47. A hollow shaft 50 is coaxially fixed to the end face of the large gear 41 close to the driving disk 47. The shaft 50 is connected to the inner ring of the bearing 49, and a switching cylinder 41 is installed in the box body 8. The switching cylinder 51 is parallel to the driving shaft 46. The telescopic shaft of the switching cylinder 51 is connected to a gear lever 52. The gear lever 52 is located above the driving disk 47. Two limiting teeth 53 are fixed at intervals on the bottom wall of the gear lever 52. The driving disk 47 is limited between the two limiting teeth 53. In order to protect the motor 42 and ensure that the earthquake signal generated by the hammer rod 9 does not interfere with the output shaft of the motor 42, the self-locking ability of the motor 42 also does not affect the movement of the hammer rod 9, ensuring that the hammer rod 9 smoothly generates earthquake signals. For this reason, when the hammer rod 9 is in the power storage state, In the state, before the locking block 34 is not disengaged from the locking groove 35, the transmission between the motor 42 and the hammer rod 9 is first cut off to ensure that when the hammer rod 9 is released, the hammer rod 9 and the motor 42 will not affect each other. Specifically, the switching cylinder 51 drives the driving disk 47 to move away from the hammer rod 9. Since the large gear 41 is connected to the bearing 49 through the hollow shaft 50, the driving disk 47 will drive the large gear 41 to move away from the rack 40, so that the large gear 41 is separated from the rack 40, and the motor 42 engages the large gear 41 through the small gear 43, thereby indirectly cutting off the transmission between the motor 42 and the hammer rod 9, ensuring that the hammer rod 9 will not affect each other when the seismic signal is released. It will interact with the motor 42. At the same time, the setting of the bearing 49 enables the large gear 41 and the driving disk 47 to rotate relative to each other, and does not affect the transmission of the large gear 41 and the small gear 43. When the hammer rod 9 generates a seismic signal, the switching cylinder 51 pushes the driving disk 47 to move close to the hammer rod 9, so that the driving disk 47 drives the large gear 41 to move close to the rack 40, so that the large gear 41 is reset and moves with the rack 40 again, so that the motor 42 drives and connects to the hammer rod 9. The motor 42 starts, so that the hammer rod 9 moves close to the center of the shield, and the hammer rod 9 returns to the shield and is in a power storage state again, waiting for the next start.

[0039] In summary, if Fig. 9 As shown, a method for performing advance prediction using a tunnel TBM excavation earthquake advance prediction receiving device includes the following steps:

[0040] S1. Install a seismic source excitation device on the left and right sides of the TBM near the tunnel face, and open a plurality of skylight holes 11 on the left and right shields of the TBM. The skylight holes 11 are used for the hammer rod 9 to extend and hit the tunnel wall to excite seismic waves.

[0041] S2, the impact position of the hammer rod 9 is the source point, and the source signal receiving device is arranged 20m behind the excitation point, and at least four groups of receiving sections are arranged, and the distance between two adjacent groups of receiving sections is 5m. Two or three source signal receiving devices are arranged on the receiving section, and the signal receiving position of the source signal receiving device is the receiving point;

[0042] S3, measure the relative coordinates of all earthquake source points and all receiving points; measure the relative coordinates of earthquake source points and receiving points with the help of laser rangefinder, tape measure and other tools;

[0043] S4, the source excitation device is activated to excite the seismic signal at the source point, and the source signal receiving device at the receiving point receives the seismic reflection wave signal;

[0044] S5. The source excitation device is powered off, and the source signal receiving devices and other auxiliary devices at each receiving point are recovered;

[0045] S6. Through data processing and calculation of reflection coefficient, a three-dimensional result map within a range of about 100m in front of the tunnel face is obtained, and the data is analyzed for geological advance forecasting.

[0046] In step S2, four groups of receiving sections are arranged, and two adjacent groups of receiving sections are respectively provided with two seismic source signal receiving devices and three seismic source signal receiving devices, the two seismic source signal receiving devices are respectively arranged on the left and right side walls of the prefabricated pipe segment, and the three seismic source signal receiving devices are respectively arranged on the top arch and the left and right side walls; in step S2, two skylight holes 11 are opened on each of the left and right sides to form four seismic source points.

[0047] The specific measurement method of step S3 is as follows:

[0048] Three seismic signal receiving devices are set up at the last group of receiving sections away from the tunnel face. The origin of the relative coordinate system is set at the center of the arc formed by the three receiving points of the receiving section. The direction from the origin to the tunnel face is the positive direction of the X axis, the direction from the origin to the right side of the tunnel face is the positive direction of the Y axis, and the direction from the origin upward is the positive direction of the Z axis. After the prefabricated segments of the TBM are installed, it is a circular tunnel model. Dongjing is a fixed value, recorded as Y0;

[0049] Use measuring tools (laser rangefinder, tape measure, etc.) to measure the relative coordinates X of each source point and receiving point, or calculate the difference in the number of rings of the prefabricated segments where the source point and the receiving point are located relative to the coordinate origin. Since the size of the prefabricated segment is known, the relative coordinates X of the source point and the receiving point can be calculated based on the length of the prefabricated segment;

[0050] Y coordinate: for the receiving point, since the source signal receiving device is installed on the surrounding rock of the prefabricated segment, the distance from the inner surface of the prefabricated segment to the surrounding rock surface is first measured, which is recorded as Y1. The horizontal distance of the inner surface of the prefabricated segment where the wireless seismic detector 3 receiving point in the source signal receiving device is measured relative to the coordinate origin is recorded as Y2, Y=Y1+Y2. The source point is measured in the same way, that is, the horizontal distance of the hammer position of the hammer rod 9 relative to the coordinate origin;

[0051] The Z coordinate is calculated based on triangular geometry. The Z coordinates of each source point and receiving point are calculated in turn.

[0052] Through data processing, the reflection coefficient is calculated, and a three-dimensional result map within 100m of the tunnel face is obtained, and the data is analyzed for geological advance prediction. The specific step S7 is as follows: when the seismic wave passes through the two adjacent geological interfaces, the reflection and transmission phenomena occur due to the difference in wave impedance between the geological bodies. The reflected seismic wave is received by the wireless seismic detector 3, and the transmitted seismic wave enters the geological body in front and continues to propagate until it encounters the geological interface again and reflects and transmits. In this way, the seismic wave can form multi-layer reflection signals at the geological interfaces of each layer of the tunnel. The wireless seismic detector 3 collects multi-layer reflection signals and performs three-dimensional inversion calculation on each layer of the medium in the tunnel to obtain a three-dimensional geological image of the tunnel. The reflection coefficient and transmission coefficient calculation formula are:

[0053]

[0054] Where: R is the reflection coefficient, T is the transmission coefficient, ρ1 and ρ2 are the densities of the rock medium before and after the geological interface, V1 and V2 are the propagation velocities of seismic waves in the rock medium before and after the geological interface.

[0055] It can be seen from the formula that the strength of reflection and transmission of seismic waves is directly related to the rock and soil properties of the geological bodies before and after the interface, that is, when the seismic wave enters the hard rock layer from the soft rock layer, the reflection coefficient is positive, otherwise, the reflection coefficient is negative; when the wave impedance between the rock bodies at the interface is very different, the reflection is strong and the transmission is weak. On the contrary, the reflection is weak and the transmission is strong. The study of these laws is helpful to comprehensively judge the lithology characteristics in the tunnel detection area.

[0056] like Fig.10 and Fig.11 As shown, according to the implementation case of the above-mentioned advance forecasting device and forecasting method:

[0057] The total length of the Q tunnel is about 5540m, and the maximum burial depth of the tunnel is about 650m. The inner diameter of the tunnel is 8.1m, and the excavation diameter is 9.13m. The first 150m of the tunnel (pile number K0~K0+200) is excavated by manual drilling and blasting, and the subsequent tunnel section is excavated by shield TBM construction. Due to the closed structure formed by the TBM shield and prefabricated segments, the rock mass is isolated, not only is it difficult to arrange and implement the excitation and receiving profiles, but the locations of the source excitation points and receiving points are easily blocked by various equipment, making it difficult to measure the geodetic coordinates of each point with measurement equipment.

[0058] The Q tunnel used the device and method proposed in the present invention to carry out advance prediction in the TBM excavation section. In this tunnel, the system problem of being unable to carry out excitation, reception and coordinate measurement due to the full closure of the tunnel body in the shield TBM excavation tunnel was overcome, and a breakthrough in carrying out advance prediction of seismic reflection in the shield TBM excavation tunnel was achieved.

[0059] Table 1 is a comparison table of the advance prediction and actual excavation of the Q tunnel. It can be seen that the geological conditions of the section predicted in advance are basically consistent with the geological conditions revealed by the actual excavation. The prediction error within 100m is within 5m. It is sensitive to the fracture structure and has a high prediction accuracy. Therefore, the device and method proposed in the present invention are feasible for conducting seismic reflection advance prediction in shield TBM tunneling tunnels, and the effect is good.

[0060] Table 1 Comparison between advance prediction and actual excavation of Q tunnel

[0061]

Claims

1. A tunnel TBM excavation earthquake advance prediction receiving device, characterized in that: The invention comprises a seismic source excitation device and a seismic source signal receiving device. Two groups of the seismic source excitation devices are symmetrically installed at positions near the face of the tunnel in a TBM tunneling machine. A plurality of the seismic source signal receiving devices are installed at different positions on the inner wall of the tunnel. The seismic source signal receiving device comprises a conical casing (1), an installation anchor rod (2) and a wireless seismic detector (3). The conical casing (1) is hollow. Two arc-shaped reinforcement plates (4) are symmetrically arranged inside the conical casing (1). A plurality of hollow reinforcement cones (5) are fixed to the end surface of the arc-shaped reinforcement plate (4) close to the inner wall of the conical casing (1). The side wall of the conical casing (1) corresponds to the hollow reinforcement cones (5). A conical hole (6) is provided at the position of the cone (5); a conical space for the installation anchor rod (2) to pass through is formed between the two arc-shaped reinforcement plates (4); the installation anchor rod (2) passes through the conical space to squeeze the arc-shaped reinforcement plate (4) to move, so as to make the hollow reinforcement cone (5) pass through the conical hole (6) with interference fit; a casting pipe (7) is connected to the end with a large diameter of the conical sleeve (1); the casting pipe (7) is used to connect to a concrete casting device; the concrete casting device is used to inject quick-setting cement into the conical sleeve (1); the installation anchor rod (2) passes through the casting pipe (7) to connect to the wireless seismic detector (3); The seismic source excitation device comprises a box (8), a hammer rod (9) and a lifting leg (10), wherein the lifting leg (10) is vertically mounted on a TBM floor, the box (8) is mounted on the lifting leg (10), the hammer rod (9) is slidably mounted on the box (8), and the hammer rod (9) moves in a horizontal direction. A plurality of skylight holes (11) are provided on the shields on the left and right sides of the TBM tunneling machine, and the hammer rod (9) extends out from the skylight holes (11) and strikes the inner wall of the tunnel to generate a seismic signal. The wireless seismic detector (3) is used to receive the seismic signal generated by the seismic source excitation device.

2. The device for receiving earthquake advance prediction during tunnel TBM excavation according to claim 1, characterized in that: A driving cavity (12) is provided in the mounting anchor rod (2), and a plurality of mounting grooves (13) are provided on the side wall of the mounting anchor rod (2). The plurality of mounting grooves (13) are evenly distributed around the circumferential direction of the mounting anchor rod (2), and the mounting grooves (13) are connected to the driving cavity (12). A support block (14) is slidably provided in the mounting groove (13), and an extrusion rod (15) is provided in the driving cavity (12). The extrusion rod (15) has the freedom to move along the axial direction of the mounting anchor rod (2). A wedge surface (16) is provided at one end of the support block (14) close to the extrusion rod (15), and the wedge surface (16) is located on the moving path of the extrusion rod (15). The support block (14) partially extends from the mounting groove (13) to abut against the end of the arc-shaped reinforcement plate (4).

3. The device for receiving earthquake advance prediction during tunnel TBM excavation according to claim 2, characterized in that: A circular groove (17) is formed at one end of the mounting anchor rod (2) away from the support block (14), a threaded hole (18) is formed in the circular groove (17), a screw rod (19) is arranged in the circular groove (17), a thread of the screw rod (19) is adapted to fit in the threaded hole (18), a tail end of the screw rod (19) penetrates into the driving cavity (12) to connect to the extrusion rod (15), and a head end of the screw rod (19) is located in the circular groove (17).

4. The device for receiving earthquake advance prediction during tunnel TBM excavation according to claim 3 is characterized in that: Both ends of the pouring pipe (7) are provided with internal threads. The pouring pipe (7) is threadedly sleeved on the conical sleeve (1). A sealing plate (20) is fixed inside the pouring pipe (7). A switching disk (21) is rotatably arranged on the sealing plate (20). A through hole (22) is penetrated through the middle of the sealing plate (20) and the middle of the switching disk (21). The mounting anchor rod (2) passes through the through hole (22). A plurality of first slurry inlet holes (23) are penetrated around the through hole (22) on the sealing plate (20). A plurality of second slurry inlet holes (24) are penetrated around the through hole (22) on the switching disk (21). The switching disk (21) is rotated to make the plurality of first slurry inlet holes (23) correspond one to one with the plurality of second slurry inlet holes (24).

5. The device for receiving earthquake advance prediction during tunnel TBM excavation according to claim 4, characterized in that: An annular groove (25) is provided on the inner wall of the pouring tube (7), the annular groove (25) is coaxially arranged with the pouring tube (7), and the switching disk (21) is rotatably adapted to fit into the annular groove (25).

6. The device for receiving earthquake advance prediction during tunnel TBM excavation according to claim 3, characterized in that: The mounting anchor rod (2) is connected to an extension rod (26), one end of the extension rod (26) is threadedly adapted in the circular groove (17), and an installation plate (27) is fixed to one end of the extension rod (26) away from the mounting anchor rod (2), and the installation plate (27) is mounted on the housing of the wireless seismic detector (3) by means of screws.

7. The device for receiving earthquake advance prediction during tunnel TBM excavation according to claim 1, characterized in that: The seismic source excitation device further comprises a hook-tooth lever (28), a large spring (29) and a small spring (30). A plurality of the large springs (29) are arranged around the hammer rod (9) in the box (8). One end of the large spring (29) is connected to the hammer rod (9), and the other end is connected to the inner wall of the box (8). The hook-tooth lever (28) is arranged below the hammer rod (9) and is eccentrically hinged on the box (8). A hook tooth (31) is formed at the short arm end of the hook-tooth lever (28). A groove (32) is provided at the bottom of the hammer rod (9). The small spring (30) is arranged below the hook-tooth lever (28). One end of the small spring (30) is connected to the long arm of the hook-tooth lever (28), and the other end is connected to the inner bottom wall of the box (8). The small spring (30) is always in a stretched state.

8. The device for receiving earthquake advance prediction during tunnel TBM excavation according to claim 7, characterized in that: A locking hydraulic cylinder (33) is horizontally installed in the box body (8); a telescopic shaft of the locking hydraulic cylinder (33) is connected to a locking block (34); the locking hydraulic cylinder (33) is perpendicular to the hook tooth lever (28); a locking groove (35) is provided on a side of the long arm end of the hook tooth lever (28) close to the locking block (34); when the hook tooth (31) is fitted into the groove (32), the locking groove (35) is located on the moving path of the locking block (34); the top wall of the groove (32) is a plane; the side wall of the groove (32) away from the hook tooth lever (28) is an abutting plane (36); and the groove (32) close to the hook tooth The side wall of the lever (28) is a wedge-shaped surface (37), the top of the hook tooth (31) is an inclined contact surface (38), and one end of the hook tooth (31) close to the groove (32) is an inclined abutment surface (39). When the hook tooth (31) deflects upward into the groove (32), the inclined contact surface (38) deflects to a horizontal state and contacts with the top wall of the groove (32), and the inclined abutment surface (39) deflects to be parallel to the abutment plane (36). When the inclined abutment surface (39) contacts the abutment plane (36), the locking hydraulic cylinder (33) drives the locking block (34) to fit into the locking groove (35).

9. The device for receiving earthquake advance prediction during tunnel TBM excavation according to claim 8, characterized in that: A rack (40) is fixed on the top of the hammer rod (9) along its length direction; a large gear (41) is rotatably arranged in the box (8), and the large gear (41) meshes with the rack (40); a motor (42) is installed in the box (8), and the output shaft of the motor (42) is connected to a small gear (43), and the small gear (43) meshes with the large gear (41); a distance sensor (44) is installed on the inner wall of the box (8), and the detection light path of the distance sensor (44) is parallel to the rack (40); one end of the rack (40) is located on the detection light path of the distance sensor (44); a vibration trigger switch (45) is arranged on the hammer rod (9), and the vibration trigger switch (45) is connected to the wireless seismic detector (3).

10. The device for receiving earthquake advance prediction during tunnel TBM excavation according to claim 9, characterized in that: The large gear (41) is rotatably connected to the housing (8) via a drive shaft (46); the large gear (41) is slidably mounted on the drive shaft (46) via a spline; the large gear (41) engages with or separates from the rack (40) by movement; a drive disk (47) is gap-mounted on the drive shaft (46); the outer diameter of the drive disk (47) is larger than the outer diameter of the large gear (41); a bearing groove (48) is provided on the end surface of the drive disk (47) close to the large gear (41); the bearing groove (48) is coaxially arranged with the drive disk (47); a bearing (49) is arranged in the bearing groove (48); the bearing (49) is provided in the bearing groove (48); The outer wall of the gear (49) is connected to the driving disk (47), a hollow shaft (50) is coaxially fixed to the end face of the large gear (41) close to the driving disk (47), the hollow shaft (50) is connected to the inner ring of the bearing (49), a switching cylinder (51) is installed in the box body (8), the switching cylinder (51) is parallel to the driving shaft (46), the telescopic shaft of the switching cylinder (51) is connected to a gear lever (52), the gear lever (52) is located above the driving disk (47), two limiting teeth (53) are fixed at intervals on the bottom wall of the gear lever (52), and the driving disk (47) is limited between the two limiting teeth (53).

Images