Coal mine roof static expansion fracturing equipment and method

Abstract

The application discloses a coal mine roof static expansion fracturing device and method, which comprises a fracturing part, a drill pipe and a drill bit.

Description

Technical Field

[0001] This invention relates to the field of coal mine roof cracking technology, specifically to equipment and methods for static expansion cracking of coal mine roofs. Background Technology

[0002] During coal mining, as the mining depth and intensity increase, the stress in the roof strata gradually increases. The hard roof is difficult to collapse naturally, easily forming large-area overhangs, posing serious safety hazards to underground workers and equipment. Therefore, artificially fracturing the coal mine roof to induce cracks in the roof strata in a predetermined direction and allow for orderly collapse is an important technical means for safe coal mine production.

[0003] Currently, common roof fracturing methods mainly include blasting fracturing, hydraulic fracturing, and static expansion fracturing. Among them, blasting fracturing, although highly efficient, poses safety hazards such as vibration, noise, and harmful gases, and causes significant disturbance to the surrounding rock, making it difficult to precisely control the direction and extent of crack propagation. Hydraulic fracturing requires large equipment such as high-pressure pump stations, resulting in complex systems, high construction costs, and the water-based fracturing fluid has a hydration and softening effect on the coal and rock mass, affecting the stability of the surrounding rock. Static expansion fracturing, by injecting expansion slurry into the borehole, utilizes the volume expansion force generated by the slurry's hydration reaction to cause rock mass cracking, offering advantages such as no vibration, no noise, and no harmful gases.

[0004] However, the existing static expansion cracking technology still has the following shortcomings in practical applications: First, the crack propagation direction is uncontrollable. The expansion grout applies radial pressure uniformly in the borehole, and the crack initiation location and propagation direction are random, making it difficult to achieve directional cracking of the top plate; Second, a single grouting method is difficult to effectively introduce the expansion grout into the depth of the formed crack, and the crack propagation depth and width are limited, resulting in an unsatisfactory cracking effect; Third, after one grouting expansion, the crack propagation is often insufficient, requiring multiple drilling and grouting cycles, resulting in low construction efficiency.

[0005] Therefore, it is necessary to provide equipment and methods for static expansion fracturing of coal mine roofs to solve the problems mentioned in the background art. Summary of the Invention

[0006] To achieve the above objectives, the present invention provides the following technical solution: a static expansion fracturing device for coal mine roof, comprising:

[0007] The fracturing element includes a cylindrical frame, in which multiple fracturing discs are coaxially arranged;

[0008] Drill casing and fracturing components can be alternately arranged and connected to each other;

[0009] A drill bit can be connected with a drill pipe to drill holes in the top plate;

[0010] The sealing seat can be connected to the drill pipe and installed at the outer end of the borehole.

[0011] Preferably, the fracturing disk comprises:

[0012] The second ring disk has two cylindrical cavities arranged coaxially from the inside to the outside in the radial direction. The outer ring wall has a transverse groove that connects to the outer end of the second cylindrical cavity. The transverse groove is parallel to the axial direction of the second ring disk.

[0013] Piston 1 is located inside cylinder cavity 2 and is connected to the outer end of cylinder cavity 2 by spring 1;

[0014] The top column has its inner end connected to the plunger, and its outer end penetrates the outer end of the second column cavity and is equipped with a wedge. The wedge is placed parallel in the transverse groove, and the surface of the second annular disk is provided with a through hole that penetrates the first column cavity vertically. The through hole is used to guide the gas to push the plunger to move towards the outer end of the second column cavity.

[0015] Preferably, the second annular disk has three coaxially arranged cylindrical cavities three, four, and five along the radial direction from the inside to the outside. Cavity three is coaxially arranged with the cylindrical cavities and connected by a straight pipe. The surface of the second annular disk has a through hole three perpendicularly penetrating the cylindrical cavity three and a through hole two perpendicularly penetrating the cylindrical cavity five. Cavity four has a plunger two. The plunger two is connected to the end of the cylindrical cavity four near the through hole three by a spring two. The plunger two has a jacking pipe. The outer end of the jacking pipe passes through the cylindrical cavity three, the straight pipe, the cylindrical cavity one, the plunger one, the jacking pipe, and the wedge in sequence. The jacking pipe wall has an inlet hole. When the plunger two moves to the maximum displacement in the direction of the through hole three, the inlet hole is located in the through hole three, and the outer end of the jacking pipe penetrates the borehole wall. The through hole two is used to guide gas to push the plunger two towards the end of the cylindrical cavity four near the through hole three. When the inlet hole is located in the through hole three, the through hole three can guide the expanding slurry into the jacking pipe.

[0016] Preferably, the column frame includes:

[0017] The first ring disk has fixed holes symmetrically arranged on its disk surface, and the cracking disk has through holes corresponding to the fixed holes.

[0018] The fixing post can pass through the through hole to install multiple fracturing discs, and can be connected and fixed with the fixing hole to fix two ring discs together.

[0019] Preferably, the first ring disk is provided with a channel one corresponding to the first through hole, a channel three corresponding to the third through hole, and a slot corresponding to the second through hole. The first ring disk is provided with a channel two, and the first ring disk is provided with a direct current channel connecting the channel two and the slot. The channel two, channel one and channel three are all close to the ring hole of the first ring disk.

[0020] Preferably, the drill pipe wall is provided with a flow channel one corresponding to the first channel, a flow channel two corresponding to the second channel, and a flow channel three corresponding to the third channel.

[0021] Preferably, the sealing seat is provided with a rotating pipe corresponding to the drill pipe cavity, a pressure supply pipe one corresponding to flow channel one, a pressure supply pipe two corresponding to flow channel two, and a grouting pipe corresponding to flow channel three.

[0022] Preferably, the drill bit is capable of blocking flow channel one and flow channel two, and the drill bit is provided with a side hole that communicates with flow channel three. The end of the side hole near the outer wall of the drill bit is provided with an annular groove, and the outer end of the annular groove is provided with a cap. The cap is connected to the bottom of the annular groove by a spring three, and the inner end of the cap is connected to a flow tube that slides in the side hole.

[0023] A static expansion-induced cracking method for coal mine roof includes the following steps:

[0024] S101: Alternately assemble and connect the drill pipe and the fracturing component, install the drill bit, and insert it into the top plate hole until the bottom of the hole. Then install the sealing seat on the outer end of the hole.

[0025] S102: First, pressure is supplied in a pulse manner through the pressure supply pipe, so that the plunger, the top column and the wedge impact the borehole wall in a pulse manner. The wedge chisels the borehole wall with chisel marks, and the chisel marks are in a straight line structure.

[0026] S103: Pressure is then supplied through the second pressure supply pipe, causing the second plunger and the jacking pipe to move toward the chisel mark until the outer end of the jacking pipe presses against the chisel mark and maintains this state.

[0027] S104: Continue to supply expansion grout through the grouting pipe. The expansion grout flows to the top of the side hole opening cover, flows into the outside of the drill bit and fills the inside of the borehole. When the grouting pipe is about to stop supplying expansion grout, gas is injected into the grouting pipe to drive the expansion grout in the grouting pipe, flow channel three, channel three, through hole three and side hole into the borehole.

[0028] S105: Wait for the expanding grout to expand and cause cracks in the borehole, which will crack the top plate. The cracks in the borehole will preferentially crack along the direction of the chisel marks. Then, pressure is supplied in a pulse manner through the pressure supply pipe, causing the jacking pipe to impact the crack until it is introduced into the crack. The inlet hole is located in the third through hole. At this time, the expanding grout is continuously supplied through the grouting pipe, and the supply pressure is less than the pressure of the top opening cap separating from the outer end of the annular groove. The expanding grout is introduced into the crack again and fills the crack. When the grouting pipe is about to stop supplying the expanding grout, gas is injected into the grouting pipe to drive out the expanding grout in the grouting pipe, flow channel three, channel three, through hole three, and jacking pipe. Wait for the expanding grout to expand and cause cracks in the top plate in the borehole again.

[0029] Compared with the prior art, the present invention provides a static expansion fracturing device and method for coal mine roofs, which has the following beneficial effects:

[0030] 1. In this invention, by setting a wedge and a pulse pressure supply mechanism, straight chisel marks can be pre-formed on the borehole wall to provide directional guidance for crack propagation. This allows cracks generated by the expansion of the slurry to preferentially propagate along the chisel mark direction, thereby achieving directional fracturing of the top rock strata. This improves the accuracy and controllability of fracturing and solves the problem of uncontrollable crack direction in existing static expansion fracturing technology.

[0031] 2. In this invention, by setting up a jacking mechanism, after the wedge cutter forms a chisel mark, the jacking pipe extends along the chisel mark and penetrates the crack under the drive of high-pressure gas. The hollow structure of the jacking pipe provides a direct channel for the subsequent expanding grout to reach the depth of the crack, enabling the grout to effectively fill the deep area of ​​the crack, significantly increasing the crack's expansion depth and width, and enhancing the cracking effect. Simultaneously, the design of the jacking pipe's entry structure and the through-hole three ensures that during secondary grouting, the grout is injected into the crack only through the jacking pipe and does not enter the main borehole area, achieving precise grout delivery.

[0032] 3. The present invention adopts a two-stage grouting and cracking process: the first grouting fills the entire borehole with expanding grout, and uses the volume expansion force of the grout to form a preliminary crack in the borehole, while driving out gas and removing residual grout in the pipeline; the second grouting injects the expanding grout directly into the depth of the formed crack through the jacking pipe, and expands the crack a second time. The two cracking processes work together to improve the sufficiency and uniformity of cracking in the top plate.

[0033] 4. The present invention incorporates a gas-driven structure in the grouting pipeline and flow channel. Before the end of each grouting operation, compressed gas is introduced into the pipeline to discharge all the remaining expanding grout in the grouting pipe, flow channel, duct, and side hole into the borehole or crack. This reduces the waste of expanding grout and prevents the grout from solidifying in the pipeline, thus ensuring the reusability of the equipment.

[0034] 5. The drill pipe and fracturing element of the present invention adopt an alternating series modular assembly structure, which can flexibly adjust the quantity and arrangement order of the drill pipe and fracturing element according to the drilling depth. It is suitable for drilling coal mine roofs of different depths and different fracturing requirements, and has the advantages of strong versatility and good adaptability. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the static expansion cracking device for coal mine roof according to the present invention.

[0036] Figure 2 This is a schematic diagram of the drill pipe structure of the present invention;

[0037] Figure 3 This is a schematic diagram of the crack-inducing component structure of the present invention;

[0038] Figure 4 This is a schematic diagram of the column frame structure of the present invention;

[0039] Figure 5 This is a partial cross-sectional view of the fracture-inducing disk structure of the present invention;

[0040] Figure 6 This is a schematic cross-sectional view of the fracture-inducing disk structure of the present invention;

[0041] Figure 7 This is a schematic diagram of the drill bit structure of the present invention;

[0042] In the diagram: 1. Drill pipe; 2. Fracturing element; 3. Drill bit; 4. Sealing seat; 11. Flow channel one; 12. Flow channel two; 13. Flow channel three; 21. Column frame; 22. Fracturing disc; 23. Through hole; 211. Ring disc one; 212. Channel one; 213. Channel two; 214. Channel three; 215. Fixing hole; 216. Fixing post; 2131. Groove; 2132. Straight channel; 221. Ring disc two; 222. Cavity one; 223. Cavity two; 224. Piston one; 225. Top post; 226. 227. Spring 1; 228. Horizontal groove; 229. Wedge; 220. Through hole 1; 2210. Column cavity 3; 2211. Column cavity 4; 2212. Straight pipe; 2213. Column cavity 5; 2214. Through hole 2; 2215. Piston 2; 2216. Jacking pipe; 2217. Spring 2; 2218. Inlet hole; 2219. Through hole 3; 31. Side hole; 32. Annular groove; 33. Cover; 34. Spring 3; 35. Flow tube; 41. Rotary pipe; 42. Pressure supply pipe 1; 43. Pressure supply pipe 2; 44. Grouting pipe. Detailed Implementation

[0043] Reference Figures 1-7 This invention provides a technical solution: a static expansion fracturing device for coal mine roof, comprising a drill pipe 1, fracturing components 2, a drill bit 3, and a sealing seat 4. The drill pipe 1 is a tubular structure used to transmit rotational torque and transport pressurized fluid. The fracturing component 2 includes a columnar frame 21, in which multiple fracturing discs 22 are coaxially mounted. These discs are arranged side-by-side along the axial direction of the columnar frame 21 to simultaneously fracture multiple sections of the borehole wall. The drill bit 3 is installed at the front end of the drill pipe 1 and is used to drill fracturing holes in the coal mine roof. The sealing seat 4 is installed at the outer end of the borehole to seal it and provide interfaces for various pressure pipelines. The drill pipe 1 and the fracturing component 2 can be alternately assembled and connected, meaning multiple drill pipes 1 and multiple fracturing components 2 can be alternately connected in series along the axial direction to flexibly adjust the total length of the device according to the borehole depth. Furthermore, the sections are interconnected by threads or snap-fit ​​mechanisms to ensure connection strength and sealing.

[0044] like Figure 5 and Figure 6As shown, the fracturing disk 22 includes a second annular disk 221, which has an annular disk-shaped structure. Inside, from the inside out, there are two coaxially arranged cylindrical cavities: a first cylindrical cavity 222 and a second cylindrical cavity 223. The first cylindrical cavity 222 is located on the inner side of the second annular disk 221 near the center, and the second cylindrical cavity 223 is located on the outer side near the annular wall. The two cavities are connected. A transverse groove 227 is formed on the outer annular wall of the second annular disk 221. The transverse groove 227 is parallel to the axial direction of the second annular disk 221 and is connected to the outer end of the second cylindrical cavity 223. A plunger 224 is provided inside the second cylindrical cavity 223. A spring 226 is connected between the plunger 224 and the outer end of the second cylindrical cavity 223. The spring 226 applies an elastic restoring force to the plunger 224 towards the center of the second annular disk 221. The inner end of a top post 225 is fixedly connected to the plunger 224, and the outer end of the top post 225 penetrates the second cylindrical cavity 223. At the outer end of 23, a wedge cutter 228 is installed at the outer end of the top post 225. The wedge cutter 228 is placed parallel to the transverse groove 227, and the cutting edge of the wedge cutter 228 faces the outer direction of the second ring disk 221, so that the wedge cutter 228 can move in the radial direction of the second ring disk 221 under the guidance of the transverse groove 227. The second ring disk 221 has a through hole 229 on its surface. The through hole 229 penetrates the first column cavity 222 vertically and is used to introduce high-pressure gas. The high-pressure gas enters the second column cavity 223 through the first column cavity 222, pushing the plunger 224 to move towards the outer end of the second column cavity 223 against the elastic force of the spring 226. This causes the top post 225 and the wedge cutter 228 to move outward synchronously, so that the wedge cutter 228 impacts the borehole wall. When the pressure supply stops, the spring 226 resets and pulls the plunger 224, the top post 225 and the wedge cutter 228 back to the initial position.

[0045] Further as Figure 5 and Figure 6As shown, the annular disk 221 further includes three coaxially arranged cylindrical cavities 2210, 2211, and 2213 arranged radially from the inside out. Cavity 2210 is coaxially arranged with cavity 222, and the two are connected by a straight tube 2212, which is fixedly installed inside the annular disk 221. The surface of the annular disk 221 has a through hole 2219 perpendicularly penetrating cavity 2210 and a through hole 2213 perpendicularly penetrating cavity 2213. 214; A plunger 2215 is provided inside the fourth column cavity 2211. A spring 2217 is connected between the plunger 2215 and the end of the fourth column cavity 2211 near the through hole 2219. The spring 2217 applies an elastic restoring force to the plunger 2215 in the direction away from the through hole 2219. A jacking tube 2216 is fixedly installed on the plunger 2215. The jacking tube 2216 is a hollow tubular structure. The outer end of the jacking tube 2216 passes through the third column cavity 2210 in sequence. The components include a straight pipe 2212, a cylindrical cavity 222, a plunger 224, a jacking rod 225, and a wedge 228. The jacking pipe 2216 can slide axially relative to the above components. An inlet hole 2218 is provided on the wall of the jacking pipe 2216, penetrating the wall to connect the cavity to the outside. During operation, a through hole 2214 is used to introduce high-pressure gas, which pushes the plunger 2215 towards the cylindrical cavity 2211 via the cylindrical cavity 2213. The movement of the near-through hole 2219 causes the jacking pipe 2216 to extend outward. When the plunger 2215 moves to its maximum displacement, the outer end of the jacking pipe 2216 extends beyond the wedge 228 and pierces the borehole wall. At this time, the inlet hole 2218 is located at the position of the near-through hole 2219, allowing the near-through hole 2219 to introduce expansion slurry. The expansion slurry enters the interior of the jacking pipe 2216 through the inlet hole 2218 and is injected into the cracks in the borehole wall through the jacking pipe 2216.

[0046] like Figure 3 and Figure 4 As shown, the column frame 21 includes two annular discs 211 and two fixing posts 216. The annular disc 211 has an annular disc structure with two fixing holes 215 symmetrically arranged on its disc surface. The fixing holes 215 are evenly distributed along the circumference of the annular disc 211. The fracturing disc 22 has through holes 23 corresponding to the positions of the fixing holes 215, and the through holes 23 penetrate the disc surface of the fracturing disc 22. The fixing posts 216 are elongated column structures that can pass through the through holes 23 to connect multiple fracturing discs 22 together. The two ends of the fixing posts 216 are respectively connected and fixed to the fixing holes 215 of the two annular discs 211, thereby clamping and fixing multiple fracturing discs 22 between the two annular discs 211 to form an integral column frame 21 structure. During installation, the number and spacing of the fracturing discs 22 can be adjusted as needed to adapt to drilling holes of different lengths and fracturing requirements.

[0047] like Figure 4As shown, the annular disk 211 is provided with a first channel 212, a second channel 213, a third channel 214, and a groove 2131; wherein, the first channel 212 corresponds to the through hole 229 on the fracturing disk 22 and is used to introduce pressurized gas into the through hole 229; the third channel 214 corresponds to the through hole 2219 on the fracturing disk 22 and is used to introduce expanding slurry into the through hole 2219; the groove 2131 corresponds to the through hole 2214 on the fracturing disk 22. The pressure gas introduced into the through hole 2214 should be introduced into the annular disk 211. The annular disk 211 is provided with a direct current channel 2132, which connects the channel 213 and the slot 2131, so that the pressure gas introduced into the channel 213 can enter the through hole 2214 through the direct current channel 2132 and the slot 2131. The channel 213, channel 1 212 and channel 3 214 are all set near the central annular hole of the annular disk 211 to facilitate docking with the flow channels on the drill pipe 1.

[0048] like Figure 2 As shown, the drill pipe 1 has flow channels 11, 12, and 13 inside its wall. Flow channel 11 extends axially along the drill pipe 1 and corresponds to the hole 212 on the annular plate 211. It is used to transport pressurized gas supplied by the pressure supply pipe 42 to the hole 212. Flow channel 212 corresponds to the hole 213 and is used to transport pressurized gas supplied by the pressure supply pipe 43 to the hole 213. Flow channel 13 corresponds to the hole 214 and is used to transport the expanding slurry supplied by the grouting pipe 44 to the hole 214. Each flow channel has a sealing joint at the end of the drill pipe 1 to ensure reliable sealing when connected to the corresponding hole on the annular plate 211.

[0049] like Figure 1 As shown, the sealing seat 4 is equipped with a rotating pipe 41, a first pressure supply pipe 42, a second pressure supply pipe 43, and a grouting pipe 44. The rotating pipe 41 is connected to the cavity of the drill pipe 1 and is used to transmit rotational motion during drilling, so that the drill pipe 1 and the fracturing element 2 can rotate synchronously with the drilling rig. The first pressure supply pipe 42 is connected to the first flow channel 11 of the drill pipe 1 and is used to supply pulsed high-pressure gas to the first flow channel 11. The second pressure supply pipe 43 is connected to the second flow channel 12 of the drill pipe 1 and is used to supply continuous or pulsed high-pressure gas to the second flow channel 12. The grouting pipe 44 is connected to the third flow channel 13 of the drill pipe 1 and is used to supply expanding slurry to the third flow channel 13. Each pipe is equipped with a control valve for independently controlling the on / off state and pressure of each pipe.

[0050] like Figure 7As shown, the drill bit 3 is installed at the front end of the drill pipe 1. The rear end face of the drill bit 3 can seal the ports of flow channel 11 and flow channel 2 12 to prevent fluid leakage from the rear end of the drill bit 3. The drill bit 3 has a side hole 31 that communicates with flow channel 3 13 inside. The side hole 31 extends radially or obliquely to the vicinity of the outer wall of the drill bit 3. An annular groove 32 is provided at one end of the side hole 31 near the outer wall of the drill bit 3. The annular groove 32 is an annular groove, and a cap 33 is provided at its outer end opening. The cap 33 is connected to the bottom of the annular groove 32 by a spring 34. The spring 34 applies an inward pulling force to the cap 33, so that the cap 33... 3. Under natural conditions, the outer end opening of the annular groove 32 is closed; the inner end of the cover 33 is connected to the flow tube 35, which is slidably installed in the side hole 31. The flow tube 35 has a porous or mesh structure to allow fluid to pass through; when the grouting pipe 44 supplies the expanding grout, the grout enters the side hole 31 through the flow channel 313, pushing the flow tube 35 and the cover 33 to move outward against the elastic force of the spring 34. The cover 33 opens, and the grout flows out from the side wall of the drill bit 3 through the flow tube 35 and enters the borehole; when the grout supply stops and the gas driving is completed, the spring 34 resets, and the cover 33 re-closes the outer end opening of the annular groove 32.

[0051] The specific implementation includes the following steps:

[0052] S101: First, according to the drilling depth, multiple drill pipes 1 and multiple fracturing components 2 are alternately assembled and connected, that is, one section of drill pipe 1, one fracturing component 2, another section of drill pipe 1, and another fracturing component 2 are alternately connected to form an integral drill string structure; the drill bit 3 is installed at the front end, and the assembled equipment is inserted into the hole in the top plate until the drill bit 3 reaches the bottom of the hole; then the sealing seat 4 is installed at the outer end of the hole, and the rotating pipe 41 on the sealing seat 4 is connected to the cavity of the drill pipe 1, and the pressure supply pipe 1 42, pressure supply pipe 2 43 and grouting pipe 44 are respectively connected to the corresponding flow channels;

[0053] S102: First, high-pressure gas is supplied in a pulsed manner through pressure supply pipe 42. The high-pressure gas enters the column cavity 222 through flow channel 11, orifice 212, and through hole 229, pushing plunger 224 to overcome the elastic force of spring 226 and move towards the outer end of column cavity 223. This causes the top column 225 and wedge 228 to pulse outward, and the wedge 228 chisels the borehole wall, forming straight chisel marks. The pulsed pressure supply causes the wedge 228 to repeatedly impact the borehole wall, deepening the chisel mark depth. The direction of the chisel mark is determined by the orientation of the wedge 228 and can be adjusted according to the stress direction of the top rock layer.

[0054] S103: High-pressure gas is supplied through pressure supply pipe 2 43. The high-pressure gas enters the column cavity 5 2213 through flow channel 2 12, orifice 2 213, direct flow channel 2132, groove 2131, and through hole 2 2214. This pushes the plunger 2 2215 to move closer to the through hole 3 2219, causing the jacking pipe 2216 to extend outward until the outer end of the jacking pipe 2216 is pressed against the chisel mark. This state is maintained to prepare for subsequent crack introduction.

[0055] S104: Expanding grout is continuously supplied through grouting pipe 44. The expanding grout enters the side hole 31 through flow channel 3 13, hole 3 214, and through hole 3 2219, pushing the flow tube 35 and the cap 33 to open. The grout flows from the side wall of the drill bit 3 into the borehole and fills the borehole. When the grouting pipe 44 is about to stop supplying expanding grout, compressed gas is injected into the grouting pipe 44. The gas is used to drive the remaining expanding grout in the grouting pipe 44, flow channel 3 13, hole 3 214, through hole 3 2219 and side hole 31, so that it is all discharged into the borehole, reducing grout waste and pipeline blockage.

[0056] S105: Wait for the expanding grout to expand in the borehole, and apply uniform radial expansion pressure to the borehole wall. Since there are pre-set chisel marks on the borehole wall, the crack will preferentially expand along the chisel mark direction, achieving directional fracturing. At the same time, pressure is supplied in a pulse manner through pressure supply pipe 23, causing the jacking pipe 2216 to repeatedly impact the crack, guiding the crack to expand further until the jacking pipe 2216 is gradually introduced into the depth of the crack. At this time, the inlet hole 2218 is located in the through hole 3 2219, providing a channel for secondary grouting. Expanding grout is continuously supplied again through grouting pipe 44. This time, the supply pressure is less than that of the jacking pipe. The pressure required for the cover 33 to disengage from the outer end of the annular groove 32 is required, so the cover 33 remains closed. The grout enters the cavity of the jacking pipe 2216 through the through hole 2219 and the inlet hole 2218, and is injected into the formed crack through the outer end of the jacking pipe 2216, so that the crack is filled with grout. When the grouting pipe 44 is about to stop supplying the expanding grout, gas is injected again to drive out the residual grout in the grouting pipe 44, the flow channel 13, the channel 214, the through hole 2219 and the jacking pipe 2216, so that it all enters the crack. Then wait for the expanding grout to expand again, and complete the static expansion cracking of the top plate in the borehole.

[0057] The above description is merely a preferred embodiment of the invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A static expansion fracturing device for coal mine roof, characterized in that, It includes: The fracturing component (2) includes a column frame (21) in which multiple fracturing disks (22) are coaxially arranged. The drill pipe (1) and the fracturing element (2) can be alternately arranged and connected to each other; The drill bit (3) can be connected with the drill pipe (1) to drill holes in the top plate; The sealing seat (4) can be connected to the drill pipe (1) and installed at the outer end of the borehole.

2. The static expansion fracturing device for coal mine roof as described in claim 1, characterized in that, The fracturing disk (22) includes: The second ring disk (221) has two cylindrical cavities (222 and 223) arranged coaxially from the inside to the outside in the radial direction. The outer ring wall is provided with a transverse groove (227) that connects to the outer end of the second cylindrical cavity (223). The transverse groove (227) is parallel to the axial direction of the second ring disk (221). A plunger (224) is located inside a cylinder cavity (223) and is connected to the outer end of the cylinder cavity (223) by a spring (226); The top column (225) is connected to the plunger (224) at its inner end and its outer end passes through the outer end of the column cavity (223) and is equipped with a wedge (228). The wedge (228) is placed parallel in the transverse groove (227). The surface of the ring disk (221) is provided with a through hole (229) that penetrates the column cavity (222) vertically. The through hole (229) is used to guide the gas to push the plunger (224) towards the outer end of the column cavity (223).

3. The static expansion fracturing device for coal mine roof as described in claim 2, characterized in that, The annular disk two (221) has three coaxially arranged cylindrical cavities three (2210), four (2211), and five (2213) arranged radially from the inside to the outside. Cavity three (2210) is coaxially arranged with cylinder one (222) and connected by a straight tube (2212). The surface of the annular disk two (221) has a through hole three (2219) that penetrates cylinder three (2210) vertically and a through hole two (2214) that penetrates cylinder five (2213) vertically. Cavity four (2211) has a plunger two (2215). The plunger two (2215) is connected to one end of cylinder four (2211) near the through hole three (2219) by a spring two (2217). The plunger two (2215) has a top tube (2216) on it. The outer end of the top tube (2216) is sequentially The jacking pipe (2216) is connected to the three-stage jacking chamber (2210), the straight pipe (2212), the first-stage jacking chamber (222), the first-stage plunger (224), the jacking pipe (225), and the wedge (228). The jacking pipe (2216) has an inlet hole (2218) on its wall. When the second-stage plunger (2215) moves to the maximum displacement in the direction of the third-stage through hole (2219), the inlet hole (2218) is located in the third-stage through hole (2219). The outer end of the jacking pipe (2216) is inserted into the borehole wall. The second-stage through hole (2214) is used to guide the gas to push the second-stage plunger (2215) towards the end of the fourth-stage jacking chamber (2211) close to the third-stage through hole (2219). When the inlet hole (2218) is located in the third-stage through hole (2219), the third-stage through hole (2219) can guide the expansion slurry into the jacking pipe (2216).

4. The static expansion fracturing device for coal mine roof as described in claim 3, characterized in that, The column frame (21) includes: The first ring disk (211) has a fixing hole (215) symmetrically provided on its disk surface, and the cracking disk (22) has a through hole (23) corresponding to the fixing hole (215); The fixing post (216) can pass through the through hole (23) for installing multiple fracturing discs (22) and can be connected and fixed with the fixing hole (215) to fix the two ring discs (211).

5. The static expansion fracturing device for coal mine roof as described in claim 4, characterized in that, The first ring disk (211) is provided with a channel one (212) corresponding to the first through hole (229), a channel three (214) corresponding to the third through hole (2219), and a slot (2131) corresponding to the second through hole (2214). The first ring disk (211) is provided with a channel two (213). The first ring disk (211) is provided with a direct current channel (2132) connecting the channel two (213) and the slot (2131). The channel two (213), channel one (212) and channel three (214) are all close to the ring hole of the first ring disk (211).

6. The static expansion fracturing device for coal mine roof as described in claim 5, characterized in that, The wall of the drill pipe (1) is provided with flow channel one (11) corresponding to channel one (212), flow channel two (12) corresponding to channel two (213), and flow channel three (13) corresponding to channel three (214).

7. The static expansion fracturing device for coal mine roof as described in claim 6, characterized in that, The sealing seat (4) is provided with a rotating pipe (41) corresponding to the borehole of the drill pipe (1), a pressure supply pipe (42) corresponding to the first flow channel (11), a pressure supply pipe (43) corresponding to the second flow channel (12), and a grouting pipe (44) corresponding to the third flow channel (13).

8. The static expansion fracturing device for coal mine roof as described in claim 7, characterized in that, The drill bit (3) can block the first flow channel (11) and the second flow channel (12), and the drill bit (3) is provided with a side hole (31) that communicates with the third flow channel (13). The side hole (31) is provided with an annular groove (32) at one end near the outer wall of the drill bit (3), and a cover (33) is provided at the outer end of the annular groove (32). The cover (33) is connected to the bottom of the annular groove (32) by a spring (34), and a flow tube (35) that slides in the side hole is connected to the inner end of the cover (33).

9. A method for static expansion fracturing of coal mine roof, comprising using the static expansion fracturing equipment for coal mine roof as described in claim 8, characterized in that, It includes the following steps: S101: Alternately assemble and connect the drill pipe (1) and the fracturing element (2) and install the drill bit (3), insert it into the top plate hole until the bottom of the hole, and then install the sealing seat (4) on the outer end of the hole; S102: First, pressure is supplied in a pulse manner through the pressure supply pipe (42), so that the plunger (224), the top column (225) and the wedge (228) pulse impact the borehole wall, and the wedge (228) chisels the borehole wall with chisel marks, and the chisel marks are in a straight line structure. S103: Pressure is supplied through the second pressure supply pipe (43) to make the second plunger (2215) and the jacking pipe (2216) move towards the chisel mark until the outer end of the jacking pipe (2216) presses against the chisel mark and maintains this state. S104: Continue to supply expansion grout through grouting pipe (44). The expansion grout flows to the side hole (31) to open the cap (33), flows into the outside of the drill bit (3) and fills the inside of the borehole. When the grouting pipe (44) is about to stop supplying expansion grout, gas is injected into the grouting pipe (44) to drive the expansion grout in the grouting pipe (44), flow channel three (13), hole three (214), through hole three (2219) and side hole (31) into the borehole. S105: Wait for the expansion grout to expand and crack the top plate in the borehole. The crack in the borehole will preferentially crack along the direction of the chisel marks. Then, pressure is supplied in a pulse manner through the pressure supply pipe 2 (43) so that the jacking pipe (2216) impacts the crack until it is introduced into the crack. The inlet hole (2218) is located in the through hole 3 (2219). At this time, the expansion grout is continuously supplied through the grouting pipe (44), and the supply pressure is less than the pressure of the top opening cap (33) leaving the outer end of the ring groove (32). The expansion grout is introduced into the crack again and fills the crack. When the grouting pipe (44) is about to stop supplying the expansion grout, gas is injected into the grouting pipe (44) to drive out the expansion grout in the grouting pipe (44), the flow channel 3 (13), the channel 3 (214), the through hole 3 (2219) and the jacking pipe (2216). Wait for the expansion grout to expand and crack the top plate in the borehole again.

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