A combined support structure for large-section tunneling in coal mines

Abstract

The present invention relates to the technical field of tunnel support, and discloses a combined support structure for large-section tunnels in coal mines, including a plurality of grouting anchor rods driven radially into the surrounding rock, the grouting anchor rods including a rod body with grouting holes and a cylinder body slidably arranged at the tail end of the rod body, a force relief pipe slidably sleeved on the tail end of the rod body is arranged in the cylinder body, a deformable portion with an inner diameter smaller than the outer diameter of the rod is formed on the force relief pipe, an internal resistance slurry plug is slidably arranged in the force relief pipe, and the axial extrusion force on the rod body drives the rod body to push the internal resistance slurry plug to slide so that the deformable portion deforms outward to relieve force. In the present invention, the situation where the extrusion force of the surrounding rock on the grouting anchor rod is greater than the maximum stress of the rod body itself will not occur, thereby not causing the fracture of the rod body, making the grouting anchor rod less likely to fail, and thus less likely to cause the risk of surrounding rock collapse.

Description

Technical Field

[0001] The present invention relates to the technical field of tunnel support, and in particular to a combined support structure for a large-section tunneling tunnel in a coal mine. Background Art

[0002] In coal mining, tunnels are passages drilled between the surface and the ore body for ore transportation, ventilation, drainage, and other purposes. The tunnel's ability to resist deformation directly impacts the safety of miners. This ability relies primarily on the support and protection of a combined support structure. Clearly, the quality of this combined support structure directly impacts the safety and reliability of coal mining.

[0003] The existing support structure mainly adopts the combination of the first concrete shotcrete layer + wire rope net + second concrete shotcrete layer + steel support + anchor rod, so that the entire support system forms a multi-layer support ring. The multi-layer support ring together forms the internal load-bearing support structure of the tunnel to improve the stability and deformation resistance of the tunnel.

[0004] Among them, anchor rods play a very important role in the entire support structure. The high tensile and compressive strength of anchor rods can withstand the axial and radial forces from the inside of the tunnel surrounding rock, and can effectively prevent the top and two sides of the surrounding rock from bulging or even collapsing.

[0005] Existing anchor rods mostly use grouting anchor rods to replace traditional anchor rods, because grouting anchor rods can not only anchor the rod body, but also when the grouting pressure is high, part of the slurry can penetrate into the anchor hole, which plays a role in reinforcing the surrounding rock and making the internal structure of the surrounding rock more compact and firm.

[0006] For example, the Chinese utility model patent with application number CN201821577235.7, authorization announcement number CN208950616U, and name "A shell-expanding prestressed hollow grouting anchor with a grouting plug" discloses a shell-expanding prestressed hollow grouting anchor with a grouting plug, which includes a nut, an exhaust / grouting pipe, a spherical support pad, a grouting plug, an anchor body, an anchor head plastic ring and an expanding shell anchor head. The expanding pressure is formed by the expanding shell anchor head and the rock wall. After the anchor rod is installed, the support force can be quickly formed to control the deformation of the rock mass. At the same time, the setting of the grouting plug ensures that the grouting is more full during the grouting process, thereby enhancing the installation strength of the anchor rod. Moreover, the slurry gradually fills the entire borehole and the rock wall gaps, which can effectively improve the surrounding rock strength.

[0007] Although the hollow grouting anchor provided by the above patent can improve the installation strength between the grouting anchor and the surrounding rock and improve the strength of the surrounding rock itself to a certain extent, due to the influence of mining such as the excavation of the tunnel itself, the excavation of adjacent tunnels, and the transportation of ore bodies, the surrounding rock will produce a force toward the center of the section, causing the section mouth to gradually shrink. At the same time, the reduction of the section will be limited under the support of the steel bracket. At this time, the grouting anchor located inside the surrounding rock will be subjected to a very large extrusion pressure toward the center of the section. The hollow grouting anchor in the above patent is mainly composed of a nut, an exhaust / grouting pipe, a spherical support pad, a slurry plug, an anchor body, an anchor head plastic ring and an expansion shell anchor head. This structure cannot realize the force transfer of the grouting anchor. When the extrusion pressure exerted on the grouting anchor by the surrounding rock is greater than the maximum stress of the grouting anchor itself, the grouting anchor body will be broken, and then the anchoring effect will be lost, which will eventually lead to the risk of surrounding rock collapse. Summary of the Invention

[0008] The purpose of the present invention is to provide a combined support structure for a large-section coal mine tunneling tunnel to solve the above-mentioned deficiencies in the prior art.

[0009] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions: a combined support structure for a large-section tunnel in a coal mine, comprising a plurality of grouting anchor rods radially driven into the surrounding rock, the grouting anchor rods comprising a rod body with a grouting hole and a cylinder body slidably arranged at the tail end of the rod body, a drain pipe slidably sleeved on the tail end of the rod body is arranged in the cylinder body, a deformable portion with an inner diameter smaller than the outer diameter of the rod is formed on the drain pipe, an internal resistance slurry plug is slidably arranged in the drain pipe, and the axial extrusion force applied to the rod body drives the rod body to push the internal resistance slurry plug to slide so that the deformable portion deforms outward to relieve force.

[0010] The above-mentioned combined support structure for large-section tunneling in a coal mine, wherein the deformable part is located in the middle of the pressure relief pipe, and the two ends of the deformable part are sequentially provided with an upward inclined part and a connecting part toward the outside, and the outer wall of the connecting part is fitted with the inner wall of the cylinder, and a deformation space is formed between the outer wall of the deformable part and the outer wall of the upward inclined part and the inner wall of the cylinder.

[0011] The above-mentioned combined support structure for large-section coal mine tunneling, the internal slurry plug includes a pushing part, a transition part and a sliding part arranged in sequence, the outer wall of the pushing part fits with the inner wall of the connecting part, the outer wall of the transition part fits with the inner wall of the upward inclined part close to the rod body, and the outer wall of the sliding part fits with the inner wall of the deformable part.

[0012] The above-mentioned combined support structure for large-section excavation tunnels in a coal mine, the deformation space is a sealed space, a plurality of slurry inlet holes and a plurality of slurry outlet holes are circumferentially provided on the deformable part, a slurry guide hole connected to the inner cavity of the rod body and a plurality of circumferentially arranged connecting holes connected to the slurry guide holes are provided on the internal resistance slurry plug, the port of the connecting hole is located on the sliding part, when the front end face of the internal resistance slurry plug abuts the rear end face of the rod body, the slurry inlet hole and the internal resistance slurry plug are staggered, and the slurry outlet hole is connected to the connecting hole.

[0013] In the above-mentioned combined support structure for large-section coal mine tunneling, when the outer wall of the transition portion fits with the inner wall of the upward inclined portion close to the rod body, the slurry inlet and outlet holes are simultaneously sealed by the outer wall of the sliding portion.

[0014] The above-mentioned combined support structure for large-section tunneling in coal mines, the cylinder includes a conical cylinder at the front end and a cylindrical cylinder at the rear end, the inner wall of the cylindrical cylinder is slidably fitted with the outer wall of the connecting portion, the inner wall of the port of the conical cylinder is slidably fitted with the outer wall of the rod body, and a flange is provided at the outer end of the outer surface of the rod, and the outer wall of the flange is fitted with the inner wall of the conical cylinder.

[0015] The above-mentioned combined support structure for large-section tunneling in coal mines has a cover with a grouting port screwed to the tail end of the cylinder, the pressure relief pipe is slidably connected to the cylinder, and a compression spring is connected between the tail end surface of the pressure relief pipe and the inner wall of the cover.

[0016] The above-mentioned combined support structure for large-section excavation tunnels in a coal mine is provided with a slurry discharge hole corresponding to the connecting portion away from the rod body on the cylinder body, and a sealed pushing space is enclosed between the conical cylinder, the rod body, the flange and the connecting portion. A slurry overflow hole connected to the pushing space is provided on the rod body, and the slurry entering the slurry overflow hole pushes the drain pipe to move so that the slurry discharge hole and the connecting portion are staggered.

[0017] In the above-mentioned combined support structure for large-section tunneling in a coal mine, when the slurry discharge hole and the connecting portion are staggered, the slurry discharge hole and the connecting hole are staggered so that the slurry discharge hole is sealed by the sliding portion.

[0018] In the above-mentioned combined support structure for large-section tunneling in coal mines, the diameter of the grouting port is not less than the diameter of the sliding portion.

[0019] In the above technical solution, the present invention provides a combined support structure for large-section tunnels in coal mines. By providing a pressure relief pipe and an internal resistance slurry plug slidably disposed in the pressure relief pipe, a resistance is formed between the deformable portion on the pressure relief pipe and the internal resistance slurry plug to limit the support of the rod body. When the extrusion force on the rod body reaches a specific value, the rod body will push the internal resistance slurry plug to move in the deformable portion, causing the deformable portion to deform, thereby transferring the extrusion force on the rod body to the deformable portion, thereby protecting the rod body. Compared with the prior art, the present invention will not cause the extrusion force of the surrounding rock on the grouting anchor rod to be greater than the maximum stress of the rod body itself, thereby preventing the rod body from breaking, making the grouting anchor rod less likely to fail and less likely to cause the risk of surrounding rock collapse, effectively solving the shortcomings of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0021] Figure 1 A front cross-sectional view of a combined support structure for a large-section tunnel in a coal mine provided by an embodiment of the present invention;

[0022] Figure 2 An exploded view of the grouting anchor provided by an embodiment of the present invention after the rod body and the expansion shell anchor head are removed;

[0023] Figure 3 A connection diagram of a grouting anchor provided by an embodiment of the present invention after removing the rod body and the expansion shell anchor head;

[0024] Figure 4 A schematic structural diagram of a pressure relief pipe provided in an embodiment of the present invention;

[0025] Figure 5 A schematic structural diagram of an internal resistance slurry plug provided in an embodiment of the present invention;

[0026] Figure 6 A schematic structural diagram of a cover provided by an embodiment of the present invention;

[0027] Figure 7 A cross-sectional view of a grouting anchor rod in an initial state provided by an embodiment of the present invention;

[0028] Figure 8 A cross-sectional view of a grouting anchor rod during grouting into an anchor hole according to an embodiment of the present invention;

[0029] Figure 9A cross-sectional view of a grouting anchor rod provided in an embodiment of the present invention for preventing the surrounding rock structure from being damaged by the grouting after grouting is completed in the anchor hole;

[0030] Figure 10 A schematic diagram of the enlarged structure of part A provided in an embodiment of the present invention;

[0031] Figure 11 A schematic diagram of the enlarged structure of part B provided in an embodiment of the present invention;

[0032] Figure 12 A schematic diagram of the enlarged structure of part C provided in an embodiment of the present invention;

[0033] Figure 13 A schematic diagram of the enlarged structure of the D portion provided in an embodiment of the present invention;

[0034] Figure 14 A cross-sectional view of an internal resistance slurry plug provided in an embodiment of the present invention.

[0035] Description of reference numerals:

[0036] 1. Surrounding rock; 2. First concrete shotcrete layer; 3. Wire rope mesh; 4. Second concrete shotcrete layer; 5. Steel support; 6. Grouting anchor; 601. Rod body; 60101. Grouting hole; 60102. Relief; 60103. Flange; 60104. Overflow hole; 602. Shell expansion anchor head; 603. External slurry plug; 60301. Vent; 604. Cylinder; 60401. Conical cylinder; 60402. Cylindrical cylinder; 604021. Discharge hole; 605. Drain pipe; 60501. Connection Part; 60502, inclined part; 60503, deformable part; 60504, slurry outlet hole; 60505, slurry inlet hole; 606, tray; 607, nut; 60701, abutment part; 60702, rotating part; 608, internal resistance slurry plug; 60801, connecting hole; 60802, slurry guide hole; 60803, pushing part; 60804, transition part; 60805, sliding part; 609, compression spring; 610, cover body; 61001, grouting port; 7, pushing space; 8, deformation space. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0038] like Figure 1-14As shown, an embodiment of the present invention provides a combined support structure for a large-section tunnel in a coal mine, comprising a plurality of grouting anchor rods 6 radially driven into the surrounding rock 1, wherein the grouting anchor rods 6 comprise a rod body 601 with a grouting hole 60101 and a cylinder body 604 slidably arranged at the tail end of the rod body 601, a drain pipe 605 slidably sleeved on the tail end of the rod body 601 is arranged in the cylinder body 604, a deformable portion 60503 having an inner diameter smaller than the outer diameter of the rod body 601 is formed on the drain pipe 605, an internal resistance slurry plug 608 is slidably arranged in the drain pipe 605, and the axial extrusion force applied to the rod body 601 drives the rod body 601 to push the internal resistance slurry plug 608 to slide so that the deformable portion 60503 deforms outward to relieve force.

[0039] The combined support structure for a large-section coal mine tunnel provided in this embodiment is used to support and protect the large-section tunnel, preventing tunnel collapse during tunneling and mining. The terms "front end," "tail end," "front," and "rear" used in this embodiment refer to the direction in which the grouting anchor 6 is inserted into the surrounding rock 1, i.e., the front end is defined as the depth inside the surrounding rock 1, and the tail end is defined as the inner wall of the surrounding rock 1. Specifically, an embodiment of the present invention provides a combined support structure for a large-section coal mine tunnel, which also includes a first concrete sprayed layer 2, a wire rope net 3, and a second concrete sprayed layer 4 laid in sequence from the inner wall of the surrounding rock 1 to the center of the section. The inner wall of the second concrete sprayed layer is provided with a plurality of steel supports 5 arranged along the depth direction of the tunnel (the first concrete sprayed layer 1, the wire rope net 2, the second concrete sprayed layer 3, and the steel supports 5 are all prior art and will not be described in detail here). In the prior art, in order to improve the firmness of the connection between the grouting anchor rod 6 and the anchor hole in the surrounding rock 1, an expansion shell anchor head 602 is usually provided at the front end of the grouting anchor rod 6 (the structure of the expansion shell anchor head 602 is prior art and will not be described in detail here). When grouting, the high pressure of the slurry can be used to flush the expansion shell anchor head 602 open and then squeeze it against the inner wall of the anchor hole, thereby improving the firmness of the connection between the rod body 601 and the anchor hole. The grouting anchor rod 6 is inserted into the surrounding rock 1 from the inner wall side of the surrounding rock 1, and the tail end of the grouting anchor rod 6 is exposed in the surrounding rock 1 (that is, the front half of the cylinder 604 is located in the surrounding rock 1, and the rear half is located outside the surrounding rock 1). The cylinder 604 is slidably sleeved on the tail end of the rod body 601, and a tray 606 and a nut 607 are sleeved on the cylinder 604. The tray 606 is slidably sleeved with the cylinder 604, and the tray 606 is located at the front end of the nut 607. The outer surface of the cylinder 604 is provided with an external thread. The nut 607 is threadedly connected to the cylinder 604 using the external thread. The tray 606 can be used to extrude the wire rope net, and at the same time, rivets or expansion screws can be passed through the tray 606 and inserted into the surrounding rock 1, so that the tray 606 is more firmly connected to the surrounding rock 1, the first concrete spraying layer and the wire rope net, thereby achieving a firm connection between the tail end of the grouting anchor rod 6 (that is, the cylinder 604) and the surrounding rock 1. In order to allow the slurry to enter the cracks of the anchor hole, it is usually necessary to improve the sealing of the anchor hole to prevent the slurry from flowing out of the anchor hole before it fully enters the cracks. For this purpose, an external slurry plug 603 is provided on the cylinder 604. The external slurry plug 603 is made of elastic rubber material. The inner wall of the external slurry plug 603 fits the outer wall of the cylinder 604. The outer wall of the external slurry plug 603 fits the inner wall of the anchor hole. At the same time, in order to achieve ventilation during grouting, a plurality of ventilation holes 60301 are provided on the external slurry plug 603, which are used to discharge the air in the anchor hole during grouting, so that the slurry fills the entire anchor hole. The pressure relief pipe 605 is slidably set in the cylinder 604, and the pressure relief pipe 605 is limited in the cylinder 604 (the limiting method is detailed below). The front end of the inner cavity of the pressure relief pipe 605 is slidably sleeved on the tail end of the rod body 601.The deformable portion 60503 is located at the rear of the intersection of the pressure relief tube 605 and the cylinder 604. An internal resistance slurry plug 608 is slidably disposed within the pressure relief tube 605, located on the side of the pressure relief tube 605 close to the rod body 601. Initially, a gap remains between the internal resistance slurry plug 608 and the rod body 601. At this point, the pressure relief tube 605 is sealed, and the grouting anchor 6 is non-conductive. In this invention, the internal resistance slurry plug 608 has two functions: first, to switch the grouting anchor 6 on and off; second, to compress the inner wall of the deformable portion 60503, causing it to deform outward. In the combined support structure for large-section tunneling of coal mines provided by the present invention, the working principle of the grouting anchor rod 6 is as follows: first, the external slurry plug 603, the tray 606 and the nut 607 are sleeved on the cylinder 604, and then the cylinder 604 is slid from the front end to the rear end of the rod body 601 until it is sleeved on the tail end of the rod body 601 (the position where the cylinder 604 is sleeved on the tail end of the rod body 601 is a specific position, and the specific implementation method is described in detail below), and then the pressure relief pipe 605 is slid from the tail end of the cylinder 604 into the cylinder 604 until it is inserted to the limit state (a specific position for each insertion of the pressure relief pipe 605), and then The expansion shell anchor head 602 is installed to the front end of the rod body 601, and then the grouting anchor rod 6 is inserted into the anchor hole until it is inserted to the limit position. During this process, the relative position of the cylinder 604 and the rod body 601 remains unchanged. At this time, the outer slurry plug 603 is located in the anchor hole near the port. The elasticity of the outer slurry plug 603 itself is used to make the outer wall of the outer slurry plug 603 fit with the inner wall of the anchor hole and have an extrusion force. Then the position of the tray 606 is adjusted so that the side of the tray 606 also fits the inner wall of the surrounding rock 1, and by turning the nut 607 (the nut 607 includes an integrally connected abutment near the tray 606), The structure of the nut 607 is the prior art and will not be described here in detail), so that the abutting portion 60701 abuts against and squeezes the tray 606, so that the tray 606 presses the inner wall of the surrounding rock 1, and can be inserted into the surrounding rock 1 after passing through the tray 606 with rivets or expansion screws, so that the tray 606 is firmly connected to the surrounding rock 1, the first concrete spraying layer and the wire rope net, thereby achieving the preliminary fixation of the grouting anchor rod 6, and then the input port of the grouting pump is connected to the tail end of the cylinder 604, and the slurry is input into the inner cavity of the cylinder 604 by starting the grouting pump. Under the high pressure of the slurry, the internal resistance slurry plug 608 is pushed to slide in the direction of the rod body 601 until the side surface of the internal resistance slurry plug 608 abuts against the tail end surface of the rod body 601. At this time, the internal resistance slurry plug 608 stops sliding, and the pressure relief pipe 605 is turned on, so that the grouting anchor rod 6 is turned on. The slurry flows into the cavity of the rod body 601 after passing through the internal resistance slurry plug 608, and flows into the anchor hole through the grouting hole 60101 until the slurry fills the anchor hole and penetrates into the cracks of the anchor hole. The slurry under high pressure will flush the expansion shell anchor head 602 and then squeeze it against the inner wall of the anchor hole, thereby improving the firmness of the connection between the rod body 601 and the anchor hole.The air in the anchor hole is discharged through the vent hole 60301 opened on the outer resistance slurry plug 603. When slurry flows out of the anchor hole, the injection of slurry can be stopped. After the grouting pump is turned off, the pressure at the tail end of the inner resistance slurry plug 608 disappears instantly. At this time, the pressure value in the cavity of the rod body 601 is relatively large. Under the action of the pressure difference, the slurry pushes the inner resistance slurry plug 608 to slide toward the rear end until the inner resistance slurry plug 608 is reset. At this time, the slurry also fills the gap between the inner resistance slurry plug 608 and the rod body 601 during the flow, and the pressure relief pipe 605 is again opened. The rod 601 is sealed by the internal resistance slurry plug 608 to prevent the slurry in the anchor hole from leaking. Then other support work in the existing technology is completed. After the combined support is completed, when the surrounding rock 1 is affected by mining such as the excavation of the tunnel itself, the excavation of adjacent tunnels, and the transportation of ore bodies, the force acting toward the center of the section is generated, causing the section opening to gradually shrink. The rod body 601 located inside the surrounding rock 1 will be subjected to a very large extrusion pressure toward the center of the section. This extrusion pressure continuously squeezes the rod body 601 and the shell anchor head 602. When the extrusion pressure on the rod body 601 reaches a specific value, it will push The movable rod 601 together with the shell anchor head 602 breaks through the cohesive force of the concrete (because at this time the cylinder 604 is firmly connected to the inner wall of the surrounding rock 1 under the action of the tray 606, so that the cylinder 604 does not move toward the center of the cross section relative to the inner wall of the surrounding rock 1), so that the rod 601 together with the shell anchor head 602 begins to move toward the rear end of the cylinder 604. During the movement, the rod 601 will squeeze and push the concrete between the internal resistance slurry plug 608 and the rod 601, so that the concrete is separated from the inner wall of the pressure relief pipe 605, and push the internal resistance slurry plug 608 to 08 slides toward the rear end of the pressure relief tube 605, causing the deformable portion 60503 on the pressure relief tube 605 to deform outward (the cylinder 604, the pressure relief tube 605 and the internal resistance slurry plug 608 are all made of metal). During the deformation process, the squeezing force of the surrounding rock 1 on the rod body 601 is relieved, so that the squeezing force borne by the rod body 601 is transferred to the pressure relief tube 605. The force required for the deformable portion 60503 to deform outward is less than the maximum stress value of the rod body 601, thereby protecting the rod body 601 from being broken and thus not losing its anchoring effect. The grouting anchor in the prior art is mainly composed of a nut, an exhaust / grouting pipe, a spherical support pad, a grouting plug, an anchor body, a plastic ferrule of the anchor head, and an expansion shell anchor head. This structure cannot achieve the force transfer of the grouting anchor. When the extrusion pressure exerted on the grouting anchor by the surrounding rock 1 is greater than the maximum stress of the grouting anchor itself, the grouting anchor body will be broken, and the anchoring effect will be lost, which will eventually lead to the risk of collapse of the surrounding rock 1. The main innovation of the present invention is that when the extrusion pressure of the surrounding rock 1 on the rod body 601 reaches a preset value, the pressure value can be transferred and released through the pressure relief pipe 605, thereby preventing the rod body 601 from breaking and losing its anchoring effect, and preventing the surrounding rock 1 from collapsing.

[0040] In this embodiment, by providing a pressure relief tube 605 and an internal resistance slurry plug 608 slidably disposed within the pressure relief tube 605, a resistance force is formed between the deformable portion 60503 on the pressure relief tube 605 and the internal resistance slurry plug 608 to provide positional support for the rod body 601. When the extrusion force on the rod body 601 reaches a specific value, the rod body 601 pushes the internal resistance slurry plug 608 to move within the deformable portion 60503, causing the deformable portion 60503 to deform, thereby transferring the extrusion force on the rod body 601 to the deformable portion 60503, thereby protecting the rod body 601. Compared with the prior art, the present invention prevents the situation where the extrusion force of the surrounding rock 1 on the grouting anchor rod 6 exceeds the maximum stress of the rod body 601 itself, thereby preventing the rod body 601 from breaking, making the grouting anchor rod 6 less likely to fail and, in turn, less likely to cause the risk of collapse of the surrounding rock 1.

[0041] In this embodiment, the deformable part 60503 is located in the middle of the pressure relief tube 605, and the two ends of the deformable part 60503 are sequentially provided with an upward inclined part 60502 and a connecting part 60501 toward the outside. The outer wall of the connecting part 60501 is in contact with the inner wall of the cylinder 604, and the outer walls of the two connecting parts 60501 are slidably arranged with the inner wall of the cylinder 604, providing support for the pressure relief tube 605 in the cylinder 604. A deformation space 8 is formed between the outer wall of the deformable part 60503 and the outer wall of the upward inclined part 60502 and the inner wall of the cylinder 604. The deformation space 8 provides the deformable part 60503 with the activity space required for deformation. When squeezed by the rod body 601, the internal resistance slurry plug 608 moves the deformable part 60503 outward into the deformation space 8 during the process of moving toward the rear end.

[0042] In this embodiment, the internal resistance slurry plug 608 includes a pushing portion 60803, a transition portion 60804 and a sliding portion 60805 arranged in sequence. The outer wall of the pushing portion 60803 is in contact with the inner wall of the connecting portion 60501, the outer wall of the transition portion 60804 is in contact with the inner wall of the inclined portion 60502 close to the rod body 601, and the outer wall of the sliding portion 60805 is in contact with the inner wall of the deformable portion 60503. The sliding fit between the outer wall of the pressing portion 60803 and the inner wall of the connecting portion 60501, and the outer wall of the sliding portion 60805 and the inner wall of the deformable portion 60503, enables the internal resistance slurry plug 608 to slide within the pressure relief tube 605 (whether in the initial state or the grouting state, the internal resistance slurry plug 608 maintains the sliding fit between the outer wall of the pressing portion 60803 and the inner wall of the connecting portion 60501, and the outer wall of the sliding portion 60805 and the inner wall of the deformable portion 60503). During the pressure relief process, the compression of the deformable portion 60503 by the internal resistance slurry plug 608 is the result of the transition portion 60804 and the pressing portion 60803 sequentially compressing the inner wall of the deformable portion 60503.

[0043] In this embodiment, the internal resistance slurry plug 608 realizes whether the grouting anchor rod 6 is conductive. Specifically, the deformation space 8 is a sealed space. The deformable portion 60503 is provided with a plurality of slurry inlet holes 60505 and a plurality of slurry outlet holes 60504 in the circumferential direction. The slurry inlet holes 60505 are located at the rear side of the slurry outlet holes 60504. Figure 11 、 12 , 13, it can be observed that the slurry inlet hole 60505 and the slurry outlet hole 60504 are both connected to the deformation space 8, the internal resistance slurry plug 608 is provided with a slurry guide hole 60802 connected to the inner cavity of the rod body 601 and a plurality of circumferentially arranged connecting holes 60801 connected to the slurry guide hole 60802, the port of the connecting hole 60801 is located on the sliding part 60805, when the front end face of the internal resistance slurry plug 608 abuts the rear end face of the rod body 601, the slurry inlet hole 60505 and the internal resistance slurry plug 608 are staggered, and the slurry outlet hole 60504 is connected to the connecting hole 60801. With the above structure, when the slurry is injected, the high-pressure slurry pushes the front end surface of the internal resistance slurry plug 608 to abut against the rear end surface of the rod body 601. At this time, the slurry enters the deformation space 8 through each slurry inlet hole 60505 and enters the communication hole 60801 through each slurry outlet hole 60504. Then, the slurry enters the inner cavity of the rod body 601 through the slurry guide hole 60802, thereby achieving conduction of the grouting anchor rod 6.

[0044] Furthermore, when the outer wall of the transition portion 60804 is in contact with the inner wall of the upwardly inclined portion 60502 close to the rod body 601, the pulp inlet 60505 and the pulp outlet 60504 are simultaneously sealed by the outer wall of the sliding portion 60805. Figure 11 When the grouting is completed, the internal resistance slurry plug 608 is pushed by the slurry in the rod body 601 to continuously move backward until it is reset. At this time, the outer wall of the transition part 60804 is re-fitted with the inner wall of the upward inclined part 60502 close to the rod body 601, and the slurry inlet hole 60505 and the slurry outlet hole 60504 are sealed by the outer wall of the sliding part 60805 at the same time, so that the slurry cannot flow out, thereby achieving the non-conduction of the grouting anchor rod 6.

[0045] In order to achieve the above-mentioned position that the position of the cylinder 604 is sleeved on the tail end of the rod body 601 each time is a specific position, and the position of the relief tube 605 is also a specific position each time it slides from the tail end of the cylinder 604 into the cylinder 604, in this embodiment, the cylinder 604 includes a conical cylinder 60401 at the front end and a cylindrical cylinder 60402 at the rear end, the inner wall of the cylindrical cylinder 60402 slides and fits with the outer wall of the connecting part 60501, the inner wall of the port of the conical cylinder 60401 slides and fits with the outer wall of the rod body 601, and the outer end of the outer surface of the rod body 601 is provided with a flange 60103, the flange 60103 is a hollow cone connected or welded to the rod body 601 as a whole, and the outer wall of the flange 60103 fits with the inner wall of the conical cylinder 60401. By utilizing the abutment cooperation between the flange 60103 and the inner wall of the conical cylinder 60401, the flange 60103 and the inner wall of the conical cylinder 60401 will abut each time the cylinder 604 is sleeved on a specific position at the tail end of the rod body 601, thereby achieving a specific position each time the cylinder 604 is sleeved on the tail end of the rod body 601; at the same time, due to the shape characteristics of the conical cylinder 60401, when the pressure relief tube 605 slides from the tail end of the cylinder 604 to the front end of the pressure relief tube 605 located at the connection between the cylindrical cylinder 60402 and the conical cylinder 60401, the pressure relief tube 605 will be limited by the conical cylinder 60401. At this time, the pressure relief tube 605 slides to the extreme state, that is, the specific position, thereby achieving a specific position each time the pressure relief tube 605 slides from the tail end of the cylinder 604 to the position of the cylinder 604.

[0046] In this embodiment, the outer surface of the rod body 601 is provided with a convex groove 60102, and the tail end of the rod body 601 does not have the convex groove 60102. The specific position of the convex groove 60102 at the tail end of the rod body 601 is that when the cylinder body 604 reaches a specific position, the tail end of the convex groove 60102 abuts or nearly abuts the front end of the cylinder body 604. The convex groove 60102 can be an external thread, which is a prior art. The use of the convex groove 60102 can improve the firmness of the connection between the slurry (i.e., concrete) and the rod body 601 when it solidifies, thereby improving the firm connection between the grouting anchor rod 6 and the surrounding rock 1. In this embodiment, the convex groove 60102 also has a prompt function to determine whether the cylinder body 604 is located at a specific position. Specifically, when the assembled grouting anchor rod 6 is inserted into the anchor hole, the grouting anchor rod 6 needs to be inserted to the deepest part of the anchor hole and the external grouting plug 603 needs to be inserted into the anchor hole. When inserting the grouting anchor rod 6, the convex groove 60102 can be inserted into the anchor hole. At the last moment of the grouting anchor rod 6, a thrust is applied to the cylinder 604. Due to the presence of the expansion shell anchor head 602, there is a large friction resistance between the rod body 601 and the inner wall of the anchor hole, which causes the cylinder 604 to slide toward the front end until the tail end of the rod body 601 abuts against the end face of the internal resistance slurry plug 608, and the internal resistance slurry plug 608 is limited by the pressure relief pipe 605, so that the grouting anchor rod 6 can be inserted into the deepest part of the anchor hole and the external resistance slurry plug 603 can be inserted into the anchor hole, which will cause the cylinder 604 to slide to the front end until the tail end of the rod body 601 abuts against the end face of the internal resistance slurry plug 608. The internal resistance slurry plug 608 is limited by the pressure relief pipe 605, so that the grouting anchor rod 6 can be inserted into the deepest part of the anchor hole and the external resistance slurry plug 603 can be inserted into the anchor hole, which will cause the cylinder 60 4 is no longer in the specific position (at this time, the front end of the cylinder 604 covers part of the convex groove 60102), and the cylinder 604 needs to be pulled back to the specific position. During the process of pulling the cylinder 604, due to the presence of the expansion shell anchor head 602, there is a greater friction resistance between the rod 601 and the anchor hole during the movement of the cylinder 604, so that the rod 601 will not be pulled out. By utilizing the convex groove 60102, during the process of pulling the cylinder 604, the front end of the cylinder 604 will vibrate when passing through the convex groove 60102, and the vibration is transmitted to the hand. When the cylinder 604 moves to the specific position, the cylinder 604 will no longer pass through the convex groove 60102, and no more vibration will occur. In this way, it can be sensed that the cylinder 604 has reached the specific position. Combined with the change in resistance during the process of pulling the cylinder 604 (the resistance will greatly increase after reaching the specific position), it can be more certain whether the cylinder 604 has reached the specific position, and then the position of the tray 606 and the nut 607 can be adjusted.

[0047] In this embodiment, in order to achieve the above-mentioned pressure relief tube 605 being limited in the cylinder 604, the specific limiting method is that the tail end of the cylinder 604 is screwed with a cover body 610 with a grouting port 61001, and the grouting port 61001 is used to connect to the input end of the grouting pump to achieve grouting. The pressure relief tube 605 is slidably connected to the cylinder 604, and a compression spring 609 is connected between the tail end face of the pressure relief tube 605 and the inner wall of the cover body 610. There are multiple compression springs 609, which are circumferentially arranged at equal angles on the tail end face of the pressure relief tube 605. One end of the compression spring 609 is fixedly connected to the tail end face of the pressure relief tube 605, and the other end is a free end, which is squeezed against the cover body 610. Under the action of the cover body 610 and the conical cylinder 60401, the pressure relief tube 605 is limited in the cylinder 604; under the action of the compression spring 609, the pressure relief tube 605 is automatically located at a specific position.

[0048] In this embodiment, the outer slurry plug 603 is sleeved onto the outer surface of the conical cylinder 60401. The inclination of the inner wall of the outer slurry plug 603 is the same as the inclination of the outer wall of the conical cylinder 60401, thereby achieving a close fit between the inner wall of the outer slurry plug 603 and the outer wall of the conical cylinder 60401. The vent hole 60301 is located away from the center of the outer slurry plug 603 and close to the outer edge of the outer slurry plug 603. The aperture of the vent hole 60301 can be appropriately adjusted according to needs. With this structure, the outer slurry plug 603 can automatically adjust the sealing degree of the anchor hole, thereby smoothly exhausting the air in the anchor hole in the early stage of grouting, thereby increasing the grouting speed; and continuously increasing the pressure in the anchor hole in the later stage of grouting, so that the slurry can more thoroughly and fully enter the cracks in the anchor hole. Specifically, in the initial stage of grouting, the outer slurry plug 603 is located on the front half of the outer surface of the conical cylinder 60401. At this time, the outer slurry plug 603 is subjected to a smaller extrusion force from the inner wall of the anchor hole and the outer wall of the conical cylinder 60401. The aperture of the vent hole 60301 is larger. When the slurry is poured into the anchor hole, the air in the anchor hole can be squeezed out very smoothly by the slurry and discharged through the vent hole 60301. In this process, the slurry is injected more smoothly due to the smooth discharge of air. As the slurry increases, it will gradually accumulate in the anchor hole. When the slurry reaches the position of the outer resistance slurry plug 60, the slurry will first block the vent 60301 located at the lower half of the outer resistance slurry plug 603. At this time, the exhaust speed of air slows down, and the internal pressure of the anchor hole continues to increase with the injection of slurry. After continuing to inject slurry, the amount of slurry accumulated and the height of the slurry reaching the outer resistance slurry plug 603 gradually increase. At this time, under the action of the accumulated slurry and high pressure, the outer resistance slurry plug 603 moves along the cone. The outer wall of the conical cylinder 60401 gradually slides backward, which causes the squeezing force on the outer slurry plug 603 from the inner wall of the anchor hole and the outer wall of the conical cylinder 60401 to increase continuously, resulting in the continuous reduction of the aperture size of the vent hole 60301, thereby making the air circulation slower (since the vent hole 60301 is mainly for the outflow of air and water, the aperture of the vent hole 60301 should not be too large, so that the amount of slurry flowing out during the whole process is extremely small), and the pressure value in the anchor hole is also getting smaller and smaller. The larger the size, when the anchor hole is completely occupied by the slurry, as the slurry pushes the external slurry plug 603, the aperture of the vent hole 60301 will be close to zero, making it impossible for the slurry to pass through. Through the above-mentioned grouting process, as the amount of injected slurry increases, the external slurry plug 603 will continue to move toward the rear end, causing the aperture of the vent hole 60301 to become smaller, thereby increasing the internal pressure of the anchor hole, thereby ensuring that the slurry can enter the cracks of the anchor hole more thoroughly and fully.

[0049] Furthermore, there are multiple air holes 60301, and they are located in the rear half of the rod body 601, so that during grouting, the slurry will gradually accumulate from the inside of the anchor hole to the outside, thereby allowing the air in the anchor hole to be discharged more smoothly and completely, and there will be no situation where the air is blocked by slurry before it is discharged.

[0050] In this embodiment, since the air vent 60301 will be completely blocked in the final stage of grouting, the air, water and slurry will not be able to be discharged as the slurry enters again. Therefore, when grouting continues, the pressure value in the anchor hole is huge. If the pressure cannot be effectively relieved or even if the grouting is stopped, the surrounding rock 1 structure will be destroyed by the slurry, and even the rod body 601 will burst.

[0051] In order to solve the above technical problems, further, a slurry discharge hole 604021 corresponding to the connecting part 60501 away from the rod body 601 is provided on the cylinder 604. There can be multiple slurry discharge holes 604021 to increase the flow rate of the slurry. The conical cylinder 60401, the rod body 601, the flange 60103 and the connecting part 60501 are enclosed to form a sealed pushing space 7. A slurry overflow hole 60104 connected to the pushing space 7 is provided on the rod body 601. The slurry entering the overflow hole 60104 pushes the relief pipe 605 to move so that the slurry discharge hole 604021 is staggered with the connecting part 60501; when the slurry discharge hole 604021 is staggered with the connecting part 60501, the slurry outlet hole 60504 is staggered with the connecting hole 60801 so that the slurry outlet hole 60504 is sealed by the sliding part 60805. Through the above structural design, when the vent hole 60301 is completely blocked, as the slurry is injected, the slurry will continue to enter the pushing space 7 through the overflow hole 60104. Since the pressure relief pipe 605 is slidably arranged in the cylinder 604, and the tail end of the pressure relief pipe 605 is connected to the cover body 610 through the compression spring 609, the slurry that continuously enters the pushing space 7 will push the pressure relief pipe 605 to overcome the elastic force of the compression spring 609 and make the pressure relief pipe 605 slide to the rear side. Figure 13As shown, when the pressure relief pipe 605 slides to the rear side, the internal resistance slurry plug 608 is always pushed by the slurry, so that the internal resistance slurry plug 608 will not move. As the pressure relief pipe 605 continues to slide to the rear side, the slurry hole 604021 and the connecting part 60501 are offset, causing the slurry hole 604021 to be connected with the deformation space 8. At the same time, the slurry outlet hole 60504 and the connecting hole 60801 are offset so that they are sealed by the sliding part 60805 of the slurry outlet hole 60504. Therefore, in this state, when the slurry is continued to be injected, the slurry will not be able to continue to enter the cavity of the rod body 601, but will be discharged through the slurry outlet hole 604021, which can effectively prevent the pressure value in the rod body 601 and the anchor hole from being too large. When a large amount of slurry is observed to be discharged from the slurry outlet hole 604021, a signal to stop grouting can be obtained, and the grouting can be stopped immediately. It can be seen that this design not only solves the technical problem of the surrounding rock 1 structure being destroyed by the slurry and even causing the rod body 601 to burst, but also provides a signal for when to stop grouting.

[0052] After the grouting is stopped, most of the slurry remaining in the deformation space 8 will be discharged through the slurry discharge hole 604021 located at the bottom, and only a small amount of slurry will remain in the deformation space 8, which will not affect the deformation of the deformable part 60503.

[0053] Furthermore, the diameter of the grouting port 61001 is not less than the diameter of the sliding portion 60805, and when the internal resistance grouting plug 608 moves into the grouting port 61001 under the pushing action of the rod body 601, the pushing portion 60803 is not offset from the deformable portion 60503. This structural design can provide a signal for re-anchoring the surrounding rock 1. Specifically, the position of the internal resistance grouting plug 608 is observed through the grouting port 61001. When the tail end of the internal resistance grouting plug 608 is located in the grouting port 61001 or protrudes from the grouting port 61001, it indicates that the rod body 601 has moved a large distance and the internal resistance grouting plug 608 is about to lose its protective function for the rod body 601. The rod body 601 is also about to lose its ability to resist the squeezing force inside the surrounding rock 1. At this time, the surrounding rock 1 can be re-anchored in a timely manner, effectively preventing the grouting anchor rod 6 from losing its anchoring function and achieving a preventive measure.

[0054] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A combined support structure for a large-section tunnel in a coal mine, comprising a plurality of grouting anchor rods (6) radially driven into the surrounding rock (1), characterized in that: The grouting anchor rod (6) comprises a rod body (601) provided with a grouting hole (60101) and a cylinder body (604) slidably arranged at the tail end of the rod body (601); a force relief tube (605) slidably sleeved on the tail end of the rod body (601) is arranged in the cylinder body (604); a deformable portion (60503) whose inner diameter is smaller than the outer diameter of the rod body (601) is formed on the force relief tube (605); an internal resistance slurry plug (608) is slidably arranged in the force relief tube (605); the axial extrusion force applied to the rod body (601) drives the rod body (601) to push the internal resistance slurry plug (608) to slide so that the deformable portion (60503) deforms outwards to relieve force; The deformable portion (60503) is located in the middle of the pressure relief tube (605), and the two ends of the deformable portion (60503) are sequentially provided with an upwardly inclined portion (60502) and a connecting portion (60501) toward the outside, and the outer wall of the connecting portion (60501) is in contact with the inner wall of the cylinder (604), and a deformation space (8) is formed between the outer wall of the deformable portion (60503) and the outer wall of the upwardly inclined portion (60502) and the inner wall of the cylinder (604). The internal resistance slurry plug (608) includes a pushing portion (60803), a transition portion (60804) and a sliding portion (60805) arranged in sequence, the outer wall of the pushing portion (60803) fits with the inner wall of the connecting portion (60501), the outer wall of the transition portion (60804) fits with the inner wall of the inclined portion (60502) close to the rod body (601), and the outer wall of the sliding portion (60805) fits with the inner wall of the deformable portion (60503).

2. The combined support structure for large-section tunneling in a coal mine according to claim 1 is characterized in that: The deformation space (8) is a sealed space. The deformable portion (60503) is provided with a plurality of slurry inlet holes (60505) and a plurality of slurry outlet holes (60504) circumferentially. The internal resistance slurry plug (608) is provided with a slurry guide hole (60802) connected to the inner cavity of the rod body (601) and a plurality of circumferentially arranged connecting holes (60801) connected to the slurry guide hole (60802). The port of the connecting hole (60801) is located on the sliding portion (60805). When the front end face of the internal resistance slurry plug (608) abuts the rear end face of the rod body (601), the slurry inlet hole (60505) is staggered with the internal resistance slurry plug (608), and the slurry outlet hole (60504) is connected to the connecting hole (60801).

3. The combined support structure for large-section tunneling in a coal mine according to claim 2 is characterized in that: When the outer wall of the transition portion (60804) fits with the inner wall of the upwardly inclined portion (60502) close to the rod body (601), the pulp inlet hole (60505) and the pulp outlet hole (60504) are simultaneously sealed by the outer wall of the sliding portion (60805).

4. The combined support structure for large-section tunneling in a coal mine according to claim 3 is characterized in that: The cylinder (604) includes a conical cylinder (60401) located at the front end and a cylindrical cylinder (60402) located at the rear end, the inner wall of the cylindrical cylinder (60402) is slidably fitted with the outer wall of the connecting portion (60501), the inner wall of the port of the conical cylinder (60401) is slidably fitted with the outer wall of the rod body (601), and the outer end of the outer surface of the rod body (601) is provided with a flange (60103), and the outer wall of the flange (60103) is fitted with the inner wall of the conical cylinder (60401).

5. The combined support structure for large-section tunneling in a coal mine according to claim 4 is characterized in that: The rear end of the cylinder (604) is screwed with a cover (610) having a grouting port (61001), the pressure relief tube (605) is slidably connected to the cylinder (604), and a compression spring (609) is connected between the rear end surface of the pressure relief tube (605) and the inner wall of the cover (610).

6. The combined support structure for large-section tunneling in a coal mine according to claim 5 is characterized in that: The cylinder (604) is provided with a slurry discharge hole (604021) corresponding to the connecting portion (60501) away from the rod body (601); the conical cylinder (60401), the rod body (601), the flange (60103) and the connecting portion (60501) together form a sealed pushing space (7); the rod body (601) is provided with a slurry overflow hole (60104) connected to the pushing space (7); the slurry entering the slurry overflow hole (60104) pushes the drain pipe (605) to move so that the slurry discharge hole (604021) and the connecting portion (60501) are staggered.

7. The combined support structure for large-section tunneling in a coal mine according to claim 6 is characterized in that: When the slurry discharge hole (604021) and the connecting part (60501) are offset, the slurry outlet hole (60504) and the connecting hole (60801) are offset so that the slurry outlet hole (60504) is sealed by the sliding part (60805).

8. The combined support structure for large-section tunneling in a coal mine according to claim 7 is characterized in that: The diameter of the grouting port (61001) is not less than the diameter of the sliding portion (60805).

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