Static expansion fracturing device and method for hard rock on coal mining working face

Abstract

The invention discloses a static expansion fracturing device and method for hard rocks on a coal mining working face, and the device is characterized in that a pressing and plugging pipe and a fracturing pipe are distributed at an interval and are inserted into a plugging bag in the height direction in a penetrating manner, and a plurality of liquid outlet holes are formed in the part, in an inner cavity of the plugging bag, of the pressing and plugging pipe; the positioning mechanism is fixedly connected to the outer side of the lower portion of the pressing and plugging pipe and acts synchronously with the plugging bag. The buffering protection unit comprises a damping supporting body and a telescopic liquid injection pipe. The damping supporting body has axial telescopic deformation capacity, the fixed end of the damping supporting body is connected with the lower end of the pressing-plugging pipe, and the telescopic end of the damping supporting body is fixedly connected with a baffle. The upper end of the telescopic liquid injection pipe is connected with the lower end of the fracturing pipe, and the lower end of the telescopic liquid injection pipe is fixedly inserted into the mounting hole in the baffle. The method comprises the following steps: constructing a drill hole and filling the fracturing capsule; a fracturing device is installed, high-pressure gas or high-pressure liquid is injected through a pressing and plugging pipe, and opening of sealing, positioning and protection states is achieved; and high-pressure water is injected through the fracturing pipe for static fracturing operation. The fracturing effect and the fracturing efficiency can be remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of static expansion fracturing technology, specifically relating to a static expansion fracturing device and method for hard rock in coal mine working faces. Background Technology

[0002] During coal mining, coal mining faces and tunneling faces often encounter geological structures such as fault zones, where the rock mass is often exceptionally hard, making it difficult for coal mining machines and tunneling machines to cut the rock and severely restricting the efficiency of mechanical operations. This not only slows down the mining progress and affects production capacity release, but also exacerbates equipment wear and tear and increases maintenance costs. Traditional blasting or mechanical crushing methods have limitations in terms of safety, environmental protection, and operability, making them difficult to adapt to the complex underground environment.

[0003] While existing static fracturing techniques have addressed some of the drawbacks of traditional blasting, practical applications still suffer from issues such as inadequate borehole sealing, lack of protective buffering mechanisms, and susceptibility of the sealing body to significant slippage due to impact forces, all of which significantly reduce fracturing effectiveness. Before static fracturing of rock mass through the reaction of chemical powders or liquids with high-pressure water to generate gas, incomplete borehole sealing can lead to gas leakage, hindering rapid pressurization within the borehole and thus affecting fracturing efficiency, reducing construction costs, and extending the construction period. Furthermore, inadequate positioning is a major cause of poor sealing. Traditional sealing devices often lack protective buffering mechanisms; during fracturing and pressurization, the generated pressure and shock waves directly act on the sealing body. With inadequate positioning, the impact force can directly push the sealing body outwards, significantly reducing pressure in the fracturing zone and resulting in poor fracturing effectiveness. Additionally, traditional sealing devices are often complex and poorly designed, making them difficult to carry and increasing construction inconvenience. To address the above deficiencies, there is an urgent need for a static expansion fracturing device and method for hard rock in coal mine working faces that offers excellent sealing, protective buffering, and positioning effects, and is easy to carry, so as to effectively ensure fracturing effect and construction efficiency. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a static expansion fracturing device and method for hard rock in coal mine working faces. The device is compact, portable, and possesses sealing, positioning, and protective buffering functions. It simultaneously achieves reliable sealing of the borehole, reliable positioning within the borehole, and effective buffering of shock waves, significantly improving fracturing effect and construction efficiency while reducing fracturing construction costs. The method is simple to implement, low in cost, and has a good safety factor. Through multiple improvements in sealing, positioning, and protective buffering effects, it enhances fracturing effect and efficiency, significantly reducing construction costs.

[0005] To achieve the above objectives, the present invention provides a static expansion fracturing device for hard rock in coal mine working faces, comprising a sealing and positioning unit and a buffer protection unit. The plugging and positioning unit includes a plugging mechanism and a positioning mechanism; the plugging mechanism includes a plugging bladder, a pressure plugging tube, and a fracturing tube; the pressure plugging tube and the fracturing tube are distributed at intervals and are both inserted into the plugging bladder in the height direction, and the pressure plugging tube has multiple liquid outlet holes in the part of the plugging bladder cavity; The positioning mechanism is located below the occlusion bladder and is fixedly connected to the outer side of the lower part of the plugging tube. The positioning mechanism is driven by pneumatic or hydraulic force and moves synchronously with the occlusion bladder. The buffer protection unit is located below the sealing and positioning unit. The buffer protection unit includes a damping support and a telescopic injection tube. The damping support has axial telescopic deformation capability. Its fixed end is connected to the lower end of the plugging tube, and its telescopic end is fixedly connected to a baffle. The upper end of the telescopic injection tube is connected to the lower end of the fracturing tube, and its lower end is fixedly inserted into the mounting hole on the baffle.

[0006] In this invention, a pressure-closing tube is installed throughout the occlusion bladder, and multiple liquid outlet holes are provided on the tube. This facilitates the injection of high-pressure gas or high-pressure liquid into the occlusion bladder via the pressure-closing tube, enabling control of its expansion or contraction. Furthermore, when the positioning mechanism requires pneumatic or hydraulic actuation, the pressure-closing tube provides the necessary pneumatic or hydraulic power, facilitating synchronized drive control between the positioning mechanism and the occlusion bladder. Additionally, when the lower end of the pressure-closing tube connects to the damping support, it allows for the simultaneous supply of high-pressure gas or high-pressure liquid to the damping support, enabling pneumatic or hydraulic actuation of the support, allowing it to reach its maximum elongation and effectively improving its buffering capacity. A positioning mechanism is installed below the plugging bladder, and its operation is synchronized with the plugging bladder. This allows for reliable positioning within the borehole while the plugging bladder seals the borehole, preventing slippage of the plugging material. Especially during fracturing operations, the positioning mechanism effectively counteracts the impact force, ensuring reliable point-to-point plugging and guaranteeing the fracturing effect. Furthermore, this synchronized mechanism allows the positioning mechanism to retract synchronously during the retraction of the plugging bladder, facilitating overall recovery and reuse. A damping support with axial expansion and contraction capability is installed at the lower end of the plugging tube, with a baffle fixedly installed at its expansion and contraction end. This baffle acts as a shock shield, preventing shock waves from directly impacting the positioning mechanism and plugging bladder. The damping support absorbs the impact force, improving borehole positioning and plugging effectiveness. A fracturing tube is synchronously installed within the sealing bladder, with the upper end of the telescopic injection tube connected to the lower end. This allows the telescopic injection tube to extend and retract synchronously with the damping support during its expansion and contraction, preventing movement interference between the two and ensuring the stability and reliability of the high-pressure water injection process. Furthermore, during high-pressure water injection, when an impact force acts on the baffle, the retraction of the telescopic injection tube is subjected to the pressure of the high-pressure water within the cavity, further enhancing its impact resistance. This, combined with the damping support, provides a comprehensive buffering and absorption of impact forces, significantly improving the buffering and protective effects. Therefore, by installing a buffer protection unit in front of the sealing and positioning mechanisms, the impact force generated during fracturing can be effectively absorbed, preventing direct impact on the positioning and sealing mechanisms. This ensures effective positioning and sealing, thereby guaranteeing the fracturing effect in the fracturing section, improving fracturing efficiency, and reducing construction costs. This invention can effectively absorb the impact force generated during the fracturing process, effectively ensure the sealing effect of the plugging bag on the borehole, and at the same time, effectively improve the positioning effect of the positioning mechanism in the hole, thus achieving multiple improvements in sealing, positioning and protective buffering effects.

[0007] The device is compact and portable, and has sealing, positioning and protective buffering functions. During static fracturing, it can simultaneously achieve reliable sealing of the borehole, reliable positioning inside the hole and effective buffering of impact force, which can significantly improve the fracturing effect and fracturing construction efficiency. At the same time, the device can be reused multiple times, which significantly reduces the fracturing construction cost.

[0008] Furthermore, to significantly improve the buffering and protection capabilities, and simultaneously enhance the positioning and sealing effects, the damping support includes a bottom cylinder, a piston, a piston rod, an outer limiting plate, and a spring. The upper end of the bottom cylinder is fixedly connected to the lower end of the pressure plugging tube, and a guide ring is fixedly connected to the inner side of its lower end. The piston is slidably and sealingly assembled in the inner cavity of the bottom cylinder. The piston rod is slidably assembled inside the guide ring, and its upper end is fixedly connected to the piston. The outer contour of the baffle is circular and is fixedly connected to the lower end of the piston rod. The outer limiting plate is fixedly connected to the outer side of the bottom cylinder. The spring is sleeved on the outside of the bottom cylinder, and its upper and lower ends abut against the outer limiting plate and the baffle, respectively. Because a piston is slidably connected to the bottom cylinder, and the bottom cylinder is connected to the plugging tube, when the plugging bladder expands, high-pressure gas or high-pressure liquid simultaneously enters the bottom cylinder, driving the piston and extending the piston rod outward until it reaches its maximum stroke. This drives the baffle installed at the end of the piston rod to extend towards the bottom of the hole. The guide ring at the lower end of the bottom cylinder not only guides the piston rod during its movement but also limits the piston's stroke. This structure allows for significant support pressure within the bottom cylinder's cavity when the plugging bladder is in its expanded plugging state. When the fracturing body in the target fracturing area breaks and generates a shock wave that acts on the baffle, the piston's retraction compresses the gas or liquid within the bottom cylinder's cavity. The compressed gas or liquid simultaneously acts on the plugging bladder and positioning mechanism, thus providing both enhanced plugging and enhanced positioning during the shock wave action. Simultaneously, this compression process effectively absorbs the impact force, providing effective protection for the plugging and positioning mechanisms and extending their service life. In addition, an outer limiting plate is fixedly installed on the outside of the bottom cylinder, and the two ends of the spring fitted on the outside of the bottom cylinder abut against the outer limiting plate and the baffle respectively. In this way, the spring can act on the baffle through its elastic force. Thus, when the baffle is subjected to impact force, the spring can absorb the impact force through elastic deformation. Furthermore, the spring can work in conjunction with the gas or liquid inside the bottom cylinder to absorb the impact force synchronously, significantly improving the buffering effect and further enhancing the buffering protection, sealing, and positioning effects, which helps to improve the cracking effect in the target area. In addition, this cooperative structure allows the spring's elastic restoring force to push the piston rod and baffle back to the set extension range after the shock wave disappears, which is beneficial for better dealing with intermittent shock wave conditions and thus can achieve good protective buffering function under complex impact conditions.

[0009] Furthermore, to ensure the stability and reliability of the high-pressure water delivery process, the telescopic injection pipe includes an inner connecting pipe and an outer injection pipe. The inner connecting pipe is fixedly connected to the bottom cylinder via a connecting arm, and its upper end is connected to the lower end of the fracturing tube. The outer injection pipe is axially slidably fitted onto the outside of the inner connecting pipe, and its lower end is fixedly inserted into the mounting hole on the baffle. Using the connecting arm to connect the inner connecting pipe to the bottom cylinder ensures the stability of the inner connecting pipe and a reliable connection with the fracturing tube. The sliding fit between the outer injection pipe and the inner connecting pipe, with the lower end of the outer injection pipe inserted into the mounting hole on the baffle, facilitates the supply of high-pressure water delivered through the fracturing tube to the target fracturing section outside the baffle via the telescopic injection pipe. This achieves a stable and reliable high-pressure water delivery process. Simultaneously, during the high-pressure water delivery process, the sliding capability between the outer injection pipe and the inner connecting pipe compresses the high-pressure water in the inner cavity, thereby effectively absorbing impact forces in conjunction with the damping support.

[0010] Furthermore, to achieve efficient and reliable positioning within the borehole, the positioning mechanism includes a flat cylindrical body and radial positioners. The flat cylindrical body is coaxially connected to the outer side of the lower part of the plugging tube through a central mounting hole, and multiple mounting channels are evenly distributed circumferentially on its body. Multiple radial positioners are distributed one-to-one with the multiple mounting channels. Each radial positioner includes a radial cylinder, an anchoring pin, and a tension spring. The radial cylinder is radially fixedly inserted into the positioning channel, with an end plate encapsulated at its inner end, and a connecting hole at the center of the end plate. The anchoring pin is slidably inserted into the radial cylinder, and a piston head that slides and seals with the radial cylinder is fixedly connected to its inner end, with a pointed outer end. The tension spring is located in the radial cylinder, with its two ends connected to the end plate and the piston head, respectively. Connecting the flat cylindrical body to the lower part of the plugging tube ensures effective communication between the plugging tube and the flat cylindrical body, allowing high-pressure gas or high-pressure liquid in the plugging tube to directly enter the inner cavity of the flat cylindrical body. Multiple radial positioners are installed in the circumferential mounting channels of the flat cylinder, facilitating multi-directional positioning and ensuring effective positioning. A connecting hole is provided on the end plate at the inner end of the radial cylinder, and a tension spring is connected between the piston head and the end plate. This allows gas or liquid to be introduced into the radial cylinder through the connecting hole during the entry of high-pressure gas or liquid into the flat cylinder, pushing the piston head to extend the anchor pin radially for positioning. Simultaneously, when the gas or liquid pressure decreases or disappears, the tension spring causes the anchor pin to retract, facilitating timely release of the positioning state and allowing the device to be smoothly withdrawn from the borehole for recycling and reuse.

[0011] Furthermore, to facilitate flexible control of the filling process, a pressure-injecting mechanism is also included. This mechanism is located upstream of the sealing and positioning unit and includes a pressure-injecting pipeline and a valve. The lower end of the pressure-injecting pipeline is connected to the upper end of the pressure-sealing pipe. The valve is connected in series in the middle section of the pressure-injecting pipeline. This allows for the connection of a water pump or air pump to the pressure-injecting pipeline to introduce high-pressure gas or liquid. Connecting the valve in series on the pressure-injecting pipeline facilitates convenient control of the gas or liquid filling process by opening and closing the valve.

[0012] Furthermore, to ensure the sealing effect on the borehole, two sealing and positioning units are used, connected in a cascade manner. The lower end of the pressure plug tube in the upper sealing and positioning unit is fixedly connected to the upper end of the pressure plug tube in the lower sealing and positioning unit, and the lower end of the fracturing tube in the upper sealing and positioning unit is connected to the upper end of the fracturing tube in the lower sealing and positioning unit. Because the inner wall of underground boreholes is prone to unevenness and fracture development due to geological conditions, a single sealing capsule, after expansion, cannot completely conform to the borehole wall. Therefore, multiple sealing capsules can be used simultaneously to seal the borehole, improving the sealing performance. Simultaneously, multiple positioning mechanisms can improve the positioning effect within the borehole. Even if one sealing capsule ruptures or leaks, the other sealing capsules can still ensure the sealing effect, improving the reliability and stability of the sealing. Furthermore, even if one positioning mechanism fails, the remaining positioning mechanisms can still be used to ensure the positioning effect. This solves the problems of high-pressure medium leakage and failure to ensure sealing effect caused by traditional single sealing capsule structure, and positioning failure caused by single positioning mechanism. In addition, this cascaded structure can be quickly combined and replaced through standardized design, and can be flexibly adjusted according to actual engineering needs.

[0013] Furthermore, to facilitate rapid assembly and disassembly, the upper inner side of the plugging tube is provided with an internally threaded connecting section A, and the lower outer side is provided with an externally threaded connecting section A. The upper inner side of the bottom cylinder is provided with an internally threaded connecting section B. The externally threaded connecting section A at the lower end of the plugging tube is inserted into the internally threaded connecting section B at the upper end of the bottom cylinder through threaded engagement. When two adjacent plugging tubes are connected, the externally threaded connecting section A at the lower end of the upper plugging tube is inserted into the internally threaded connecting section A at the upper end of the lower plugging tube through threaded engagement. In this way, when multiple plugging and positioning units are set up simultaneously, the threaded engagement enables rapid assembly and disassembly of the plugging and positioning units, improving the flexibility and convenience of assembly. At the same time, the setting of multiple plugging and positioning units can effectively ensure the plugging and positioning effects.

[0014] Furthermore, to ensure the service life of the occlusion capsule, the occlusion capsule is made of nano-modified rubber material, which is made by adding 5% to 10% nano-silica and 2% to 5% nano-carbon fiber by mass fraction to natural rubber for composite modification.

[0015] Furthermore, to ensure the hardness and anchoring effect of the anchoring pin, the anchoring pin is integrally formed from gradient cemented carbide material. Its pointed structure is made of WC-Co cemented carbide, and the part outside the pointed structure is made of 40CrNiMoA alloy. The WC-Co cemented carbide and the 40CrNiMoA alloy are metallurgically bonded by hot pressing sintering. The Co mass fraction in the WC-Co cemented carbide layer is 12% to 15%.

[0016] This invention also provides a static expansion fracturing method for hard rock in coal mine working faces, employing a static expansion fracturing device for hard rock in coal mine working faces, and the method includes the following steps: Step 1: Drill multiple holes sequentially in the hard rock of the coal mining face or the facing area of ​​the tunneling face, and clean the holes. Step 2: Push the fracturing capsule into the target fracturing zone inside the borehole; Step 3: Push the static expansion fracturing device for hard rock in coal mining face into the borehole; Step 4: Connect an air pump or water pump to the inlet end of the pressure inlet pipeline, open the valve, start the air pump or water pump, and simultaneously inject high-pressure gas or high-pressure liquid into the damping support, positioning mechanism and sealing bladder through the pressure plugging pipe, so that the baffle extends axially, the anchoring pin extends radially and penetrates into the rock mass, and the sealing bladder fully expands and seals the borehole. Step 5: Connect a high-pressure pump to the inlet end of the fracturing tube, start the high-pressure pump, and deliver high-pressure water through the fracturing tube to the target fracturing section via the telescopic injection pipe, causing the fracturing capsule to rupture. At the same time, the chemical powder or liquid in the fracturing capsule comes into full contact with the high-pressure water and reacts, generating a large amount of water-insoluble gas in a short time and forming a high-pressure environment. The continuous expansion pressure causes the rock mass to fracture. At the same time, baffles are used as protective plates against shock waves, and damping supports are used in conjunction with telescopic injection tubes to provide composite buffer support force. Step Six: After completing the static fracturing operation, open the valve and depressurize through the plugging pipe to allow the plugging bladder to retract naturally. Use the tension of the tension spring to detach the anchoring pin from the rock mass and retract it into the radial cylinder, thus completing the recovery operation.

[0017] This invention provides a static expansion fracturing method for hard rock in coal mine working faces. First, a fracturing capsule is inserted into the target fracturing section within the borehole. Then, the static expansion fracturing device for hard rock in coal mine working faces is assembled. Next, high-pressure gas or high-pressure liquid is supplied through a pressure plugging pipe, simultaneously driving the damping support to open its protective buffer state. This drives the multi-diameter radial locator in the positioning mechanism to fully extend and penetrate into the rock mass, achieving reliable positioning of the device within the borehole. The plugging capsule is then fully expanded and inserted into the borehole for sealing. Next, high-pressure ice is delivered to the target fracturing section in front of the baffle using a fracturing pipe and a telescopic injection pipe. The high-pressure impact causes the fracturing capsule to rupture rapidly. Simultaneously, the high-pressure water fully contacts and reacts with the chemical powder and liquid in the fracturing capsule, generating a large amount of water-insoluble gas in a short time, thus quickly creating a high-pressure environment. Under the continuous expansion pressure, static fracturing of the rock mass can be achieved. Through the combined action of the pre-charge pressure within the damping support's internal cavity and the spring, a damping support force can be provided to offset the impact and effectively absorb the impact force. Simultaneously, the compression of the gas or liquid within the damping support's internal cavity during the impact process increases the pressure within the positioning mechanism's internal cavity and the sealing bladder's internal cavity, thus achieving the dual purpose of improving both positioning and sealing effects. Simultaneously, during high-pressure water injection, when the impact force acts on the baffle, it simultaneously compresses the telescopic injection pipe, which in turn compresses the high-pressure water within the pipe. This further effectively absorbs the impact force through the compression process of the high-pressure water, thus providing better buffering and protection in conjunction with the damping support. Finally, simply opening the valve allows for the depressurization process. The sealing bladder retracts due to its own elastic restoring force, and the tension spring causes the anchoring pin to detach from the rock mass and retract, facilitating the recovery of the static expansion fracturing device used in hard rock at coal mine working faces and promoting subsequent reuse.

[0018] This method is simple to implement, low in cost, and has a good safety factor. Through multiple improvements in sealing, positioning, and protective buffering effects, it enhances the fracturing effect and efficiency, significantly reducing construction costs. This technology enables the safe and efficient fracturing of hard rock masses using a non-explosive, low-vibration physical method, thereby effectively improving cutting efficiency and ensuring continuous and stable mining operations. It has significant practical implications for promoting safe and efficient coal mine production. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the device portion of the present invention; Figure 2 This is a schematic diagram of a partial structure of the fracturing tube in the device of the present invention; Figure 3 This is a schematic diagram of the internal structure of the sealing bladder in the device of the present invention; Figure 4 This is a cross-sectional schematic diagram of the internal structure of the connecting cylinder in the device part of the present invention; Figure 5 This is a partial structural diagram of the bottom cylinder in the device of the present invention; Figure 6 This is a cross-sectional schematic diagram of the internal structure of the bottom cylinder in the device of the present invention; Figure 7 This is a flowchart of the method portion of the present invention.

[0020] In the diagram: 1. Pressure plugging tube; 2. Sealing bladder; 3. Rupture tube; 4. Quick connector one; 5. Liquid outlet; 6. Pressure inlet mechanism; 7. Flat cylinder; 8. Radial cylinder; 9. Anchor pin; 10. End plate; 11. Tension spring; 12. Bottom cylinder; 13. Piston; 14. Piston rod; 15. Baffle; 16. Spring; 17. External injection pipe; 18. Internal connecting pipe; 19. External limiting plate; 20. Sealing and positioning unit; 21. Buffer protection unit; 22. Sealing mechanism; 23. Positioning mechanism; 24. Connecting arm; 25. Piston head; 26. Damping support body; 27. Telescopic injection pipe; 28. Valve; 29. ​​Pressure inlet pipeline; 30. Internal threaded connection section A; 31. External threaded connection section A; 32. Internal threaded connection section B; 33. Quick connector two. Detailed Implementation

[0021] The invention will now be further described with reference to the accompanying drawings.

[0022] like Figures 1 to 6 As shown, the present invention provides a static expansion fracturing device for hard rock in coal mine working faces, including a sealing and positioning unit 20 and a buffer protection unit 21; The sealing and positioning unit 20 includes a sealing mechanism 22 and a positioning mechanism 23; the sealing mechanism 22 includes a sealing bladder 2, a pressure plugging tube 1, and a fracturing tube 3; the pressure plugging tube 1 and the fracturing tube 3 are distributed at intervals and are both inserted into the sealing bladder 2 in the height direction; the pressure plugging tube 1 has multiple liquid outlet holes 5 in the inner cavity of the sealing bladder 2; as a preferred embodiment, the pressure plugging tube 1 is located at the axis of the sealing bladder 2, and the connection between the pressure plugging tube 1 and the sealing bladder 2 is fixed and sealed; simultaneously, the fracturing tube 3 is eccentrically positioned relative to the axis of the sealing bladder 2, and the connection between the fracturing tube 3 and the sealing bladder 2 is fixed and sealed. The positioning mechanism 23 is located below the sealing bladder 2 and is fixedly connected to the outer side of the lower part of the plugging tube 1. The positioning mechanism 23 is driven by pneumatic or hydraulic force and moves synchronously with the sealing bladder 2. When the sealing bladder 2 expands, it extends radially synchronously and is positioned radially by pressing against the rock wall. When the sealing bladder 2 retracts, it retracts radially synchronously. The buffer protection unit 21 is located below the sealing and positioning unit 20. The buffer protection unit 21 includes a damping support 26 and a telescopic injection tube 27. The damping support 26 has axial telescopic deformation capability. Its fixed end is connected to the lower end of the plugging tube 1, and its telescopic end is fixedly connected to a baffle 15. The upper end of the telescopic injection tube 27 is connected to the lower end of the fracturing tube 3, and its lower end is fixedly inserted into the mounting hole on the baffle 15.

[0023] In this invention, a pressure-closing tube is installed throughout the occlusion bladder, and multiple liquid outlet holes are provided on the tube. This facilitates the injection of high-pressure gas or high-pressure liquid into the occlusion bladder via the pressure-closing tube, enabling control of its expansion or contraction. Furthermore, when the positioning mechanism requires pneumatic or hydraulic actuation, the pressure-closing tube provides the necessary pneumatic or hydraulic power, facilitating synchronized drive control between the positioning mechanism and the occlusion bladder. Additionally, when the lower end of the pressure-closing tube connects to the damping support, it allows for the simultaneous supply of high-pressure gas or high-pressure liquid to the damping support, enabling pneumatic or hydraulic actuation of the support, allowing it to reach its maximum elongation and effectively improving its buffering capacity. A positioning mechanism is installed below the plugging bladder, and its operation is synchronized with the plugging bladder. This allows for reliable positioning within the borehole while the plugging bladder seals the borehole, preventing slippage of the plugging material. Especially during fracturing operations, the positioning mechanism effectively counteracts the impact force, ensuring reliable point-to-point plugging and guaranteeing the fracturing effect. Furthermore, this synchronized mechanism allows the positioning mechanism to retract synchronously during the retraction of the plugging bladder, facilitating overall recovery and reuse. A damping support with axial expansion and contraction capability is installed at the lower end of the plugging tube, with a baffle fixedly installed at its expansion and contraction end. This baffle acts as a shock shield, preventing shock waves from directly impacting the positioning mechanism and plugging bladder. The damping support absorbs the impact force, improving borehole positioning and plugging effectiveness. A fracturing tube is synchronously installed within the sealing bladder, with the upper end of the telescopic injection tube connected to the lower end. This allows the telescopic injection tube to extend and retract synchronously with the damping support during its expansion and contraction, preventing movement interference between the two and ensuring the stability and reliability of the high-pressure water injection process. Furthermore, during high-pressure water injection, when an impact force acts on the baffle, the retraction of the telescopic injection tube is subjected to the pressure of the high-pressure water within the cavity, further enhancing its impact resistance. This, combined with the damping support, provides a comprehensive buffering and absorption of impact forces, significantly improving the buffering and protective effects. Therefore, by installing a buffer protection unit in front of the sealing and positioning mechanisms, the impact force generated during fracturing can be effectively absorbed, preventing direct impact on the positioning and sealing mechanisms. This ensures effective positioning and sealing, thereby guaranteeing the fracturing effect in the fracturing section, improving fracturing efficiency, and reducing construction costs. This invention can effectively absorb the impact force generated during the fracturing process, effectively ensure the sealing effect of the plugging bag on the borehole, and at the same time, effectively improve the positioning effect of the positioning mechanism in the hole, thus achieving multiple improvements in sealing, positioning and protective buffering effects.

[0024] The device is compact and portable, and has sealing, positioning and protective buffering functions. During static fracturing, it can simultaneously achieve reliable sealing of the borehole, reliable positioning inside the hole and effective buffering of impact force, which can significantly improve the fracturing effect and fracturing construction efficiency. At the same time, the device can be reused multiple times, which significantly reduces the fracturing construction cost.

[0025] To significantly improve buffering and protection capabilities, and simultaneously enhance positioning and sealing effects, the damping support 26 includes a bottom cylinder 12, a piston 13, a piston rod 14, an outer limiting plate 19, and a spring 16. The upper end of the bottom cylinder 12 is fixedly connected to the lower end of the pressure plugging pipe 1, and a guide ring is fixedly connected to the inner side of its lower end. The piston 13 is slidably and sealingly assembled in the inner cavity of the bottom cylinder 12. The piston rod 14 is slidably assembled inside the guide ring, and its upper end is fixedly connected to the piston 13. The outer contour of the baffle 15 is circular, and its size is adapted to the size of the drill hole, preferably slightly smaller than the diameter of the drill hole, and it is fixedly connected to the lower end of the piston rod 14. To prevent the baffle from getting stuck in the hole and to facilitate its easy removal from the drill hole during retrieval, the cross-section of the baffle 15 is frustum-shaped, and the outer diameter of the lower end is smaller than the outer diameter of the upper end. The outer limiting plate 19 is fixedly connected to the outside of the bottom cylinder 12. Preferably, the outer limiting plate 19 is annular and is fixedly fitted onto the outside of the bottom cylinder 12 through a central through hole. The spring 16 is sleeved on the outside of the bottom cylinder 12, with its upper and lower ends abutting against the outer limiting plate 19 and the baffle 15, respectively. Since a piston is slidably sealed in the bottom cylinder and the bottom cylinder is connected to the pressure plugging pipe, when the plugging bladder expands, high-pressure gas or high-pressure liquid will enter the bottom cylinder simultaneously and drive the piston to extend the piston rod outward until the maximum stroke is reached. This will drive the baffle installed at the end of the piston rod to extend towards the bottom of the hole. The guide ring at the lower end of the bottom cylinder not only guides the piston rod during its movement but also limits the piston's stroke. This structure allows for significant support pressure within the bottom cylinder cavity when the sealing bladder is in its inflated, sealing state. Based on this, when the fracturing body in the target fracturing area breaks and generates a shock wave that acts on the baffle, the piston's retraction compresses the gas or liquid within the bottom cylinder cavity. This compressed gas or liquid simultaneously acts on the sealing bladder and positioning mechanism, thus achieving a dual effect of enhanced sealing and positioning during the shock wave's action. Furthermore, this compression process effectively absorbs the impact force, providing effective protection for the sealing and positioning mechanisms and extending their service life. In addition, an outer limiting plate is fixedly installed on the outside of the bottom cylinder, and the two ends of the spring fitted on the outside of the bottom cylinder abut against the outer limiting plate and the baffle respectively. In this way, the spring can act on the baffle through its elastic force. Thus, when the baffle is subjected to impact force, the spring can absorb the impact force through elastic deformation. Furthermore, the spring can work in conjunction with the gas or liquid inside the bottom cylinder to absorb the impact force synchronously, significantly improving the buffering effect and further enhancing the buffering protection, sealing, and positioning effects, which helps to improve the cracking effect in the target area. In addition, this cooperative structure allows the spring's elastic restoring force to push the piston rod and baffle back to the set extension range after the shock wave disappears, which is beneficial for better dealing with intermittent shock wave conditions and thus can achieve good protective buffering function under complex impact conditions.

[0026] To ensure the stability and reliability of the high-pressure water delivery process, the telescopic injection pipe 27 includes an inner connecting pipe 18 and an outer injection pipe 17. The inner connecting pipe 18 is fixedly connected to the bottom cylinder 12 via a connecting arm 24, and its upper end is connected to the lower end of the fracturing pipe 3. The outer injection pipe 17 is axially slidably fitted onto the outside of the inner connecting pipe 18, and its lower end is fixedly inserted into the mounting hole on the baffle 15. Using the connecting arm to connect the inner connecting pipe to the bottom cylinder ensures the stability of the inner connecting pipe and a reliable connection with the fracturing pipe. By allowing a sliding fit between the external injection pipe and the internal connecting pipe, and inserting the lower end of the external injection pipe into the mounting hole on the baffle, it is possible to supply high-pressure water transported through the fracturing pipe to the target fracturing section outside the baffle via the telescopic injection pipe. This achieves a stable and reliable high-pressure water transport process. At the same time, during the high-pressure water transport process, the sliding capability between the external injection pipe and the internal connecting pipe can be used to compress the high-pressure water in the inner cavity, thereby working with the damping support to effectively absorb the impact force.

[0027] To achieve efficient and reliable positioning within the borehole, the positioning mechanism 23 includes a flat cylindrical body 7 and radial positioners. The flat cylindrical body 7 is coaxially connected to the outer side of the lower part of the plugging pipe 1 through a central mounting through-hole, and multiple mounting channels are evenly distributed circumferentially on its body. Multiple radial positioners are distributed one-to-one with multiple mounting channels. Each radial positioner includes a radial cylinder 8, an anchoring pin 9, and a tension spring 11. The radial cylinder 8 is radially fixedly inserted into the positioning channel, and its inner end is encapsulated with an end plate 10, with a connecting hole at the center of the end plate 10. The radial cylinder 8 and the flat cylinder 7 are connected by a sealed connection to ensure that gas or liquid does not leak from the connection. The anchoring pin 9 is slidably inserted into the radial cylinder 8, and its inner end is fixedly connected to a piston head 25 that slides and seals with the radial cylinder 8. Its outer end has a pointed structure. Preferably, in order to effectively reduce the embedding resistance, the angle of the pointed structure is preferably 30° to 45°, so as to ensure effective anchoring under low hydraulic / pneumatic pressure. The tension spring 11 is set in the radial cylinder 8, and its two ends are respectively connected to the end plate 10 and the piston head 25. Connecting the flat cylinder in series with the lower part of the pressure plug tube ensures effective communication between the pressure plug tube and the flat cylinder, so that the high-pressure gas or high-pressure liquid in the pressure plug tube can directly enter the inner cavity of the flat cylinder. Installing multiple radial positioners in multiple installation channels in the circumferential direction of the flat cylinder can facilitate positioning in multiple directions in the circumferential direction, which helps to ensure the positioning effect. A connecting hole is provided on the end plate at the inner end of the radial cylinder. At the same time, a tension spring is connected between the piston head and the end plate. In this way, when the flat cylinder is filled with high-pressure gas or high-pressure liquid, the gas or liquid can be introduced into the radial cylinder through the connecting hole to push the piston head and drive the anchor pin to extend radially for radial positioning. At the same time, when the gas or liquid pressure decreases or disappears, the tension spring can cause the anchor pin to retract, so as to release the positioning state in time. This facilitates the smooth withdrawal of the device from the borehole, achieving the purpose of recycling and reuse.

[0028] To ensure effective positioning while minimizing structural complexity and manufacturing costs, the radial positioner is configured as four units.

[0029] To facilitate flexible control of the filling process, a pressure-injecting mechanism 6 is also included. The pressure-injecting mechanism 6 is located upstream of the sealing and positioning unit 20 and includes a pressure-injecting pipeline 29 and a valve 28. The lower end of the pressure-injecting pipeline 29 is connected to the upper end of the pressure-sealing pipe 1. The valve 28 is connected in series in the middle section of the pressure-injecting pipeline 29. In this way, a water pump or air pump can be connected to the pressure-injecting pipeline to introduce high-pressure gas or high-pressure liquid. Connecting the valve in series in the pressure-injecting pipeline allows for convenient control of the gas or liquid filling process by opening and closing the valve.

[0030] To ensure effective sealing of the pores, two sealing and positioning units 20 are used, connected in a cascaded manner. The lower end of the pressure plugging tube 1 in the upper sealing and positioning unit 20 is fixedly connected to the upper end of the pressure plugging tube 1 in the lower sealing and positioning unit 20, and the lower end of the fracturing tube 3 in the upper sealing and positioning unit 20 is connected to the upper end of the fracturing tube 3 in the lower sealing and positioning unit 20. Preferably, the number of sealing and positioning units 20 can be greater than two, and the specific number can be flexibly determined according to the specific fracturing conditions. Because the inner walls of underground boreholes are prone to unevenness and fractures due to geological conditions, a single sealing capsule, after expansion, cannot completely conform to the borehole wall. Therefore, multiple sealing capsules can be used simultaneously to seal the borehole, improving sealing performance. Simultaneously, multiple positioning mechanisms enhance the positioning effect within the borehole. This ensures that even if one sealing capsule ruptures or leaks, the others can still maintain the sealing effect, improving reliability and stability. Furthermore, even if one positioning mechanism fails, the remaining mechanisms can still ensure positioning effectiveness. This solves the problems of high-pressure medium leakage and inability to guarantee sealing effectiveness caused by traditional single sealing capsule structures, as well as the potential for positioning failure due to a single positioning mechanism. In addition, this cascaded structure allows for rapid assembly and replacement through standardized design, facilitating flexible adjustments based on actual engineering needs.

[0031] To facilitate rapid assembly and disassembly, the upper inner side of the plugging tube 1 is provided with an internally threaded connecting section A30, and the lower outer side is provided with an externally threaded connecting section A31. The upper inner side of the bottom cylinder 12 is provided with an internally threaded connecting section B32. The externally threaded connecting section A31 at the lower end of the plugging tube 1 is threadedly inserted into the internally threaded connecting section B32 at the upper end of the bottom cylinder 12. When two adjacent plugging tubes 1 are connected, the externally threaded connecting section A31 at the lower end of the upper plugging tube 1 is threadedly inserted into the internally threaded connecting section A30 at the upper end of the lower plugging tube 1. This not only facilitates the rapid assembly and disassembly process between two adjacent plugging tubes 1, but also facilitates the rapid assembly and disassembly between the plugging tube 1 and the bottom cylinder 12. Therefore, when multiple plugging and positioning units are set up simultaneously, the threaded connection enables the rapid assembly and disassembly of the plugging and positioning units, improving the flexibility and convenience of assembly. At the same time, the setting of multiple plugging and positioning units can effectively ensure the plugging and positioning effects.

[0032] To ensure the service life of the sealing bladder, the sealing bladder 2 is made of nano-modified rubber material. This nano-modified rubber material is made by adding 5%–10% nano-silica and 2%–5% nano-carbon fiber by mass to natural rubber for composite modification. The addition of nano-carbon fiber creates a three-dimensional network reinforcement structure, significantly improving the fatigue resistance and dynamic mechanical properties of the sealing bladder, making it less prone to permanent deformation during repeated pressurization-depressurization cycles. The surface-modified nanoparticles have a higher interfacial bonding strength with the rubber matrix, synergistically improving the material's chemical corrosion resistance and resisting the erosion of the bladder by acidic water and slag leachate commonly encountered in underground engineering. Simultaneously, this composite modified material maintains good elasticity while ensuring high strength, allowing the sealing bladder to tightly conform to the inner wall of boreholes of different diameters after pressurization, significantly improving sealing performance and effectively preventing high-pressure medium leakage.

[0033] To ensure the hardness and anchoring effect of the anchor pin, the anchor pin 9 is integrally formed from a gradient cemented carbide material. Its pointed portion is made of WC-Co cemented carbide, while the portion outside the pointed portion is made of 40CrNiMoA alloy. The WC-Co cemented carbide and 40CrNiMoA alloy are metallurgically bonded through hot-pressing sintering. The Co content in the WC-Co cemented carbide layer is 12%–15% by mass. Using high-cobalt-content WC-Co cemented carbide for the pointed portion of the anchor pin 9 fully utilizes the advantages of its ultra-high hardness and wear resistance. When extended radially under pressure, it can easily embed into the rock mass inside the borehole, forming a reliable anchoring point and preventing displacement of the device under fracturing impact. Using 40CrNiMoA alloy for the portion outside the pointed portion allows the main support to possess both high strength and excellent toughness, which helps buffer the impact load during fracturing and prevents the anchor pin from breaking due to excessive rigidity. Metallurgical bonding achieved through hot pressing and sintering can eliminate interface defects between the two layers of materials, ensuring that the head and tail form an integral load-bearing structure, preventing delamination and detachment during repeated expansion and contraction, thus ensuring anchoring reliability and extending its service life, and meeting the long-term use requirements under complex geological conditions in underground engineering.

[0034] To facilitate quick connection and disconnection, quick-connect couplings 4 are connected to both the upper and lower ends of the fracturing tube 3. This allows for connection between the two fracturing tubes 3 via quick-connect couplings 4. High-pressure fittings, such as high-pressure hoses, can also be used to connect the two fracturing tubes 3. Alternatively, quick-connect coupling 33 is connected to the upper end of the inner connecting tube 18, allowing for quick connection between the fracturing tube 3 and the inner connecting tube 18 using high-pressure fittings. Both quick-connect couplings 4 and 33 are existing technologies, such as common pipeline quick-connect couplings.

[0035] like Figure 7 As shown, the present invention also provides a static expansion fracturing method for hard rock in coal mine working faces, employing a static expansion fracturing device for hard rock in coal mine working faces, and the method includes the following steps: Step 1: Drill multiple holes sequentially in the hard rock of the coal mining face or the facing area of ​​the tunneling face, and clean the holes; when drilling multiple holes, the distance between adjacent holes is 0.5 to 1.5m, and the hole depth is 0.8 to 1.6m. Step 2: Push the fracturing capsule (using a glass or plastic bottle, containing chemical powder or liquid for fracturing) into the target fracturing section inside the borehole; Step 3: Push the static expansion fracturing device for hard rock in coal mining face into the borehole, while simultaneously stopping the baffle 15 at the outside of the target fracturing section. Step 4: Connect an air pump or water pump to the inlet end of the pressure inlet pipe 29, open valve 28, start the air pump or water pump, and simultaneously inject high-pressure gas or high-pressure liquid into the damping support 26, positioning mechanism 23 and sealing bladder 2 through the pressure plugging pipe 1, so that the baffle 15 extends axially, the anchoring pin 9 extends radially and penetrates into the rock mass, and the sealing bladder 2 fully expands and seals the borehole; Specifically, high-pressure gas or high-pressure liquid is used to push piston 13, which drives piston rod 14 and baffle 15 to extend axially. High-pressure gas or high-pressure liquid is used to push piston head 25, which drives anchor pin 9 to extend radially. High-pressure gas or high-pressure liquid is used to fully expand sealing bladder 2. When the injection pressure reaches the predetermined pressure state, valve 28 is closed and air pump or water pump is turned off. At this time, piston rod 14 and baffle 15 reach the maximum extension state and the maximum protection and buffer state. Anchor pin 9 reaches the maximum extension state and penetrates into the rock mass. Sealing bladder 2 reaches the fully expanded state and completely seals the borehole. Step 5: Connect a high-pressure pump to the inlet end of the fracturing pipe 3, start the high-pressure pump to supply high-pressure water, and deliver the high-pressure water to the target fracturing section through the fracturing pipe 3 and the telescopic injection pipe 27. The high-pressure impact causes the fracturing capsule to rupture. At the same time, the chemical powder or liquid in the fracturing capsule comes into full contact with the high-pressure water and reacts. A large amount of water-insoluble gas is generated in the target fracturing section in a short time and a high-pressure environment is formed. The continuous expansion pressure causes the rock mass to fracture, thus achieving static fracturing of the rock mass. Simultaneously, the shock wave generated during the fracturing process acts synchronously on the baffle 15, using the baffle 15 as a protective plate against the shock wave. The damping support 26, in conjunction with the telescopic injection pipe 27, provides a composite buffer support force. Specifically, the pressure of the gas or liquid inside the bottom cylinder 12, in conjunction with the spring 16, provides a damping support force to counteract the shock wave. As the shock wave pushes the baffle 15 to retract, it simultaneously compresses the gas or liquid inside the bottom cylinder 12, increasing the gas or liquid pressure in the positioning mechanism 23 and the sealing bladder 2. At the same time, it simultaneously compresses the inner connecting pipe 18 and the outer injection pipe 17, thereby compressing the high-pressure water inside the telescopic injection pipe 27. This allows the pressure of the high-pressure water to further enhance the effect of absorbing the shock force, thus achieving multiple effects of simultaneously increasing sealing, positioning, and protective buffering. Step Six: After completing the static fracturing operation, open valve 28 and depressurize through the plugging pipe 1, allowing the plugging bladder 2 to retract naturally under elastic recovery. Use the tension of tension spring 11 to detach the anchoring pin 9 from the rock mass and retract it into the radial cylinder 8. Remove the static expansion fracturing device used for hard rock in coal mining faces and complete the recovery operation.

[0036] This invention provides a static expansion fracturing method for hard rock in coal mine working faces. First, a fracturing capsule is inserted into the target fracturing section within the borehole. Then, the static expansion fracturing device for hard rock in coal mine working faces is assembled. Next, high-pressure gas or high-pressure liquid is supplied through a pressure plugging pipe, simultaneously driving the damping support to open its protective buffer state. This drives the multi-diameter radial locator in the positioning mechanism to fully extend and penetrate into the rock mass, achieving reliable positioning of the device within the borehole. The plugging capsule is then fully expanded and inserted into the borehole for sealing. Next, high-pressure ice is delivered to the target fracturing section in front of the baffle using a fracturing pipe and a telescopic injection pipe. The high-pressure impact causes the fracturing capsule to rupture rapidly. Simultaneously, the high-pressure water fully contacts and reacts with the chemical powder and liquid in the fracturing capsule, generating a large amount of water-insoluble gas in a short time, thus quickly creating a high-pressure environment. Under the continuous expansion pressure, static fracturing of the rock mass can be achieved. Through the combined action of the pre-charge pressure within the damping support's internal cavity and the spring, a damping support force can be provided to offset the impact and effectively absorb the impact force. Simultaneously, the compression of the gas or liquid within the damping support's internal cavity during the impact process increases the pressure within the positioning mechanism's internal cavity and the sealing bladder's internal cavity, thus achieving the dual purpose of improving both positioning and sealing effects. Simultaneously, during high-pressure water injection, when the impact force acts on the baffle, it simultaneously compresses the telescopic injection pipe, which in turn compresses the high-pressure water within the pipe. This further effectively absorbs the impact force through the compression process of the high-pressure water, thus providing better buffering and protection in conjunction with the damping support. Finally, simply opening the valve allows for the depressurization process. The sealing bladder retracts due to its own elastic restoring force, and the tension spring causes the anchoring pin to detach from the rock mass and retract, facilitating the recovery of the static expansion fracturing device used in hard rock at coal mine working faces and promoting subsequent reuse.

[0037] This method is simple to implement, low in cost, and has a good safety factor. Through multiple improvements in sealing, positioning, and protective buffering effects, it enhances the fracturing effect and efficiency, significantly reducing construction costs. This technology enables the safe and efficient fracturing of hard rock masses using a non-explosive, low-vibration physical method, thereby effectively improving cutting efficiency and ensuring continuous and stable mining operations. It has significant practical implications for promoting safe and efficient coal mine production.

Claims

1. A static expansion fracturing device for hard rock in coal mine working faces, comprising a sealing and positioning unit (20), characterized in that, It also includes a buffer protection unit (21); The sealing and positioning unit (20) includes a sealing mechanism (22) and a positioning mechanism (23); the sealing mechanism (22) includes a sealing bladder (2), a pressure plug (1) and a rupture tube (3); the pressure plug (1) and the rupture tube (3) are distributed at intervals and are inserted into the sealing bladder (2) through the height direction; the pressure plug (1) has multiple liquid outlet holes (5) in the part of the sealing bladder (2) cavity. The positioning mechanism (23) is located below the occlusion bladder (2) and is fixedly connected to the outer side of the lower part of the plugging tube (1). The positioning mechanism (23) is driven by pneumatic or hydraulic force and moves synchronously with the occlusion bladder (2). The buffer protection unit (21) is located below the sealing and positioning unit (20). The buffer protection unit (21) includes a damping support (26) and a telescopic injection tube (27). The damping support (26) has axial telescopic deformation capability. Its fixed end is connected to the lower end of the plugging tube (1), and its telescopic end is fixedly connected to a baffle (15). The upper end of the telescopic injection tube (27) is connected to the lower end of the fracturing tube (3), and its lower end is fixedly inserted into the mounting hole on the baffle (15).

2. The static expansion fracturing device for hard rock in coal mine working faces according to claim 1, characterized in that, The damping support (26) includes a bottom cylinder (12), a piston (13), a piston rod (14), an outer limiting plate (19), and a spring (16). The upper end of the bottom cylinder (12) is fixedly connected to the lower end of the pressure plug (1), and a guide ring is fixedly connected to the inner side of its lower end. The piston (13) is slidably and sealingly assembled in the inner cavity of the bottom cylinder (12). The piston rod (14) is slidably assembled inside the guide ring, and its upper end is fixedly connected to the piston (13). The outer contour of the baffle (15) is circular, and it is fixedly connected to the lower end of the piston rod (14). The outer limiting plate (19) is fixedly connected to the outer side of the bottom cylinder (12). The spring (16) is sleeved on the outside of the bottom cylinder (12), and its upper and lower ends abut against the outer limiting plate (19) and the baffle (15), respectively.

3. The static expansion fracturing device for hard rock in coal mine working faces according to claim 1, characterized in that, The telescopic injection tube (27) includes an inner connecting tube (18) and an outer injection tube (17); the inner connecting tube (18) is fixedly connected to the bottom cylinder (12) through a connecting arm (24), and its upper end is connected to the lower end of the fracturing tube (3); the outer injection tube (17) is axially slidably fitted outside the inner connecting tube (18), and its lower end is fixedly inserted into the mounting hole on the baffle (15).

4. A static expansion fracturing device for hard rock in coal mine working faces according to claim 1, characterized in that, The positioning mechanism (23) includes a flat cylinder (7) and a radial positioner; the flat cylinder (7) is coaxially connected to the outer side of the lower part of the pressure plug tube (1) through the central mounting through hole, and multiple mounting channels are evenly opened around its cylinder body; multiple radial positioners are distributed one-to-one with multiple mounting channels; the radial positioner includes a radial cylinder (8), an anchor pin (9) and a tension spring (11); the radial cylinder (8) is radially fixedly inserted into the positioning channel, and its inner end is encapsulated with an end plate (10), and the center of the end plate (10) is provided with a connecting hole; the anchor pin (9) is slidably inserted into the radial cylinder (8), and its inner end is fixedly connected to a piston head (25) that slides and seals with the radial cylinder (8), and its outer end is a pointed structure; the tension spring (11) is set in the radial cylinder (8), and its two ends are respectively connected to the end plate (10) and the piston head (25).

5. A static expansion fracturing device for hard rock in coal mine working faces according to claim 1, characterized in that, It also includes a pressure feeding mechanism (6); The pressure inlet mechanism (6) is located upstream of the plugging and positioning unit (20). The pressure inlet mechanism (6) includes a pressure inlet pipeline (29) and a valve (28). The lower end of the pressure inlet pipeline (29) is connected to the upper end of the plugging pipe (1). The valve (28) is connected in series in the middle section of the pressure inlet pipeline (29).

6. A static expansion fracturing device for hard rock in coal mine working faces according to claim 1, characterized in that, The number of the sealing and positioning units (20) is two. The two sealing and positioning units (20) are connected in a cascade manner. The lower end of the pressure plug (1) in the upper sealing and positioning unit (20) is fixedly connected to the upper end of the pressure plug (1) in the lower sealing and positioning unit (20). The lower end of the rupture tube (3) in the upper sealing and positioning unit (20) is connected to the upper end of the rupture tube (3) in the lower sealing and positioning unit (20).

7. A static expansion fracturing device for hard rock in coal mine working faces according to claim 3, characterized in that, The upper inner side of the pressure plug (1) is provided with an internal threaded connection section A (30), and the lower outer side is provided with an external threaded connection section A (31). The upper inner side of the bottom cylinder (12) is provided with an internal threaded connection section B (32). The external threaded connection section A (31) at the lower end of the pressure plug (1) is inserted into the internal threaded connection section B (32) at the upper end of the bottom cylinder (12) through threaded engagement. When two adjacent pressure plugs (1) are connected, the external threaded connection section A (31) at the lower end of the upper pressure plug (1) is inserted into the internal threaded connection section A (30) at the upper end of the lower pressure plug (1) through threaded engagement.

8. A static expansion fracturing device for hard rock in coal mine working faces according to claim 1, characterized in that, The occlusion capsule (2) is made of nano-modified rubber material, which is made by adding 5% to 10% nano-silica and 2% to 5% nano-carbon fiber by mass fraction to natural rubber for composite modification.

9. A static expansion fracturing device for hard rock in coal mine working faces according to claim 1, characterized in that, The anchoring pin (9) is integrally formed from gradient hard alloy material. Its pointed structure is made of WC-Co hard alloy, and the part outside the pointed structure is made of 40CrNiMoA alloy. The WC-Co hard alloy and the 40CrNiMoA alloy are metallurgically bonded by hot pressing sintering. The Co mass fraction in the WC-Co hard alloy layer is 12% to 15%.

10. A static expansion fracturing method for hard rock in coal mine working faces, employing the static expansion fracturing device for hard rock in coal mine working faces as described in claim 1, characterized in that... The method includes the following steps: Step 1: Drill multiple holes sequentially in the hard rock of the coal mining face or the facing area of ​​the tunneling face, and clean the holes. Step 2: Push the fracturing capsule into the target fracturing zone inside the borehole; Step 3: Push the static expansion fracturing device for hard rock in coal mining face into the borehole; Step 4: Connect an air pump or water pump to the inlet end of the pressure inlet pipe (29), open the valve (28), start the air pump or water pump, and simultaneously inject high-pressure gas or high-pressure liquid into the damping support (26), positioning mechanism (23) and sealing bladder (2) through the pressure plug pipe (1), so that the baffle (15) extends axially, the anchoring pin (9) extends radially and penetrates into the rock mass, so that the sealing bladder (2) fully expands and seals the borehole; Step 5: Connect a high-pressure pump to the inlet end of the fracturing pipe (3), start the high-pressure pump, and deliver high-pressure water through the fracturing pipe (3) to the target fracturing section via the telescopic injection pipe (27), and cause the fracturing capsule to rupture. At the same time, the chemical powder or liquid in the fracturing capsule comes into full contact with the high-pressure water and reacts, generating a large amount of water-insoluble gas in a short time and forming a high-pressure environment. The rock mass is fractured by the pressure of continuous expansion. At the same time, the baffle (15) is used as a protective plate to protect against shock waves, and the damping support (26) is used in conjunction with the telescopic injection tube (27) to provide composite buffer support force; Step 6: After completing the static fracturing operation, open the valve (28), depressurize through the plugging pipe (1), and let the plugging bladder (2) retract naturally. Use the tension of the tension spring (11) to make the anchor pin (9) detach from the rock mass and retract into the radial cylinder (8) to complete the recovery operation.

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