A roof hard rock stratum fracturing device based on dynamic load sweep frequency and static load splitting

Abstract

A fracturing device for hard roof rock strata based on dynamic load frequency sweeping and static load splitting belongs to the field of rock mechanics. The device mainly consists of an integrated splitting unit and a hydraulic control unit. During operation, the electrodes of the servo valve input waveforms and frequency sweeping functions to an external servo controller to determine the natural frequency of the coal and rock mass. This causes the electrodes to be alternately energized at a certain frequency, driving the valve core to switch the oil circuit direction. In conjunction with a flow control valve, the oil flow and pressure are adjusted, allowing high-pressure oil to enter the cylinder and drive the piston to reciprocate. This, in turn, causes the wedge to periodically extend and retract, resulting in the expansion and contraction of the blades at a certain frequency, forming a dynamic load excitation with a specific frequency. The coupling effect of this dynamic load and static load splitting force induces rock resonance, significantly improving crack propagation efficiency and rock-breaking effect.

Description

Technical Field

[0001] This invention relates to the field of rock mechanics, and in particular to a fracturing device for hard rock strata in the roof based on dynamic load sweep frequency and static load splitting. Background Technology

[0002] With the continuous development of rock fracturing technology for rock bursts in my country, the types and application scope of rock fracturing technologies have been greatly expanded. Currently, commonly used rock fracturing technologies include hydraulic fracturing, blasting fracturing, and carbon dioxide fracturing. These rock fracturing technologies are characterized by simple operation, low cost, and wide application range. However, they also have many problems such as poor controllability, high risk factor, and environmental pollution. Therefore, hydraulic fracturing devices are mainly used for rock fracturing in underground operations.

[0003] Currently, mainstream hydraulic rock splitting devices mainly adopt the static load splitting principle. They use high-pressure hydraulic oil to drive a wedge block assembly, applying a continuous static splitting force to the rock mass from inside the borehole. Taking advantage of the fact that the tensile strength of rock is much lower than its compressive strength, the rock cracks in a predetermined direction. Although this type of equipment has advantages such as safety, environmental protection, and strong controllability, it suffers from low rock breaking efficiency when dealing with high-strength, dense hard rock, making it difficult to meet the needs of large-scale projects. Therefore, the industry urgently needs a new type of rock breaking device that can introduce a dynamic load resonance mechanism and organically combine it with static load splitting. This device can provide a continuous and stable main splitting force through static load splitting, while using dynamic load resonance to weaken the rock mass strength and accelerate crack propagation, thereby achieving efficient, energy-saving, and reliable hard rock breaking operations.

[0004] To address the aforementioned issues, a fracturing device for hard roof rock strata based on dynamic load sweeping and static load splitting was designed. By inputting a sweeping function within a certain frequency range into the servo controller, the inherent frequency characteristics of the coal and rock mass are determined. Then, by applying a high-frequency, periodic impact load to the splitting head, the propagation and superposition effect of stress waves within the rock mass induces crack initiation and accelerates its propagation. Studies have shown that under resonance conditions close to the inherent frequency of the rock mass, the effective tensile strength of the rock mass can be significantly reduced, thereby greatly improving the rock breaking efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a fracturing device for hard rock strata in the roof based on dynamic load sweeping and static load splitting, which solves the problems of slow crack initiation and propagation speed, long single splitting time, low rock breaking efficiency under pure static load, and small rock breaking range in the prior art. By making the rock mass resonate close to its natural frequency, a large-scale and high-efficiency rock breaking effect is achieved.

[0006] To achieve the above objectives, the present invention provides a fracturing device for hard rock strata in the roof based on dynamic load sweep frequency and static load splitting, including a splitting actuator and a hydraulic servo control unit: the splitting actuator includes an actuator unit including a blade (1), a wedge (2), a return spring (3), a flange (4), a hydraulic cylinder front end cover (6), a pulley (24), a splitter (25), a cylinder body (10), a piston (8), a sealing ring (7), a positioning pin (9), a hydraulic cylinder rear end cover (11), a hex bolt (12), and a handle (26); the hydraulic servo control unit includes an electromagnetic servo valve (including electrode A (17), electrode B (18), an oil inlet (22), an oil outlet (23), a valve core 1 (21),), a flow control valve (14), a valve core 2 (20), a connecting pipe (15), an oil passage block (16), and an oil inlet tank (19).

[0007] The wedge (2) and the piston (8) inside the cylinder (10) are rigidly connected to ensure the stability of the output load. The flow control module consists of a flow control valve (14) and a valve core 2 (20), with a built-in throttling and one-way control structure, which can accurately regulate the flow rate and pressure of the oil, thereby controlling the output load. The electromagnetic servo valve assembly is connected to an external servo control system for outputting periodic, high-frequency dynamic load excitation.

[0008] Preferably, the blade (1) and the wedge (2) are combined to form a splitting structure. This structure opens the blade (1) by the axial reciprocating thrust of the wedge (2), thereby realizing static load splitting and dynamic load resonance excitation of the rock. The wedge (2) and the piston (8) in the cylinder (10) are an integrated transmission structure. The wedge (2) is embedded in the precision guide groove between the blades (1) and fits tightly with the inner inclined surface of the blade (1). The oil block (19) can ensure that hydraulic oil is injected into the cylinder (10) in advance before formal operation, so as to ensure that the splitting action can be started immediately when hydraulically driven, eliminating the idle stroke, and can also be used for pressure relief.

[0009] Preferably, the cylinder (10) is located in the middle of the device and is made of high-strength alloy material. Its compressive strength is significantly higher than that of the front end cover and the splitter shell, so as to ensure the overall stability of the structure under high pressure conditions and reliably transmit the splitting force. The inner diameter of the front end of the cylinder (10) is slightly smaller than that of the rear end, which not only provides guidance for the initial stroke of the piston (8), but also increases the oil storage space at the rear end to accommodate hydraulic oil and buffer pressure fluctuations. The outer diameters of the front and rear ends of the cylinder are kept consistent to provide sufficient space for the reciprocating motion of the piston, avoid hydraulic oil turbulence from hindering the piston action, and ensure smooth coordination of propulsion and force transmission during the splitting response.

[0010] Preferably, the handle (26) is located on the rear side of the hydraulic cylinder rear end cover (11) and is detachably connected to the rear end cover by hexagonal bolts (12), which enhances the flexibility and portability during operation and avoids the difficulty of drilling insertion due to the overall length of the equipment.

[0011] Preferably, the connecting pipe (15) is arranged between the cylinder body (10) and the electromagnetic servo valve assembly, and there are two pipes in total. They are distributed in parallel and symmetrically along both sides of the device to balance the inflow and outflow of hydraulic oil, provide a stable basis for the pressure supply during the splitting response, and avoid the action delay caused by single-pipe pressure fluctuation.

[0012] Preferably, in the flow control module, the flow control valve (14) is arranged at the oil inlet end of the electromagnetic servo valve. The valve core 2 (20) and the valve body are connected by a cylindrical slide valve clearance fit + guide bearing auxiliary support structure. The flow rate and pressure of the hydraulic oil can be precisely controlled by adjusting the opening degree to ensure the stability of the frequency and amplitude of the dynamic load output.

[0013] Preferably, the inner wall of the oil passage inside the oil block (16) and the interface of the connecting pipe (15) adopt a conical sealing design, which not only ensures the sealing of the high-pressure hydraulic oil, but also avoids pressure leakage caused by excessive gap, and ensures the stability of force transmission and the timeliness of response during the splitting process.

[0014] Preferably, the reset spring (3) is coaxially sleeved between the wedge (2) and the front cover (6) of the hydraulic cylinder, and a guide roller is coaxially arranged inside to form a rolling fit with the end face of the wedge (2). After the hydraulic pressure is released, the wedge (2) and the blade (1) are driven to reset and retract, preparing for the next splitting action.

[0015] The invention discloses a fracturing device for hard roof rock strata based on dynamic load frequency sweeping and static load splitting. By integrating the splitting head, static load splitting cylinder, dynamic load resonance module, hydraulic control valve group, and power transmission structure into one unit, it effectively solves the problems of traditional static load hydraulic splitting equipment that rely solely on static splitting force acting on the rock mass, such as difficulty in crack initiation, slow propagation speed, low rock breaking efficiency, high energy consumption, excessively high requirements for drilling accuracy, free face conditions, and ultra-high pressure hydraulic systems, and difficulty in detecting the natural frequency of the rock block. During operation, the static load splitting cylinder provides a continuous and stable radial static load splitting force to the splitting head, while simultaneously... The electromagnetic servo valve connected to the servo system generates a high-frequency vibration load adapted to the rock mass characteristics through periodic opening and closing. Under the synergistic effect of static load splitting and dynamic load resonance, the effective tensile strength of the rock mass is reduced, accelerating the initiation and penetration of internal cracks. In conjunction with the hydraulic control valve group, the static and dynamic loads are precisely matched and controlled. It retains the advantages of static load splitting in terms of safety, stability and controllability, while significantly improving rock breaking efficiency and energy utilization. The device has a compact overall structure and reasonable layout, and can adapt to various complex engineering conditions such as mining, tunneling and urban hard rock breaking, making it more practical and reliable.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is a flowchart of the process of the present invention. Figure 2 This is a schematic diagram of the structure of the device for fracturing hard rock strata in the roof based on dynamic load sweeping and static load splitting according to the present invention. Figure 3 This is a schematic diagram of the flow control section. Figure 4 This is a schematic diagram of the device's reset structure; Figure 5 This is a schematic diagram of the oil flow control section. Figure 6 This is a schematic diagram of the actuator structure of the device; Attached Figure

[0018] 1. Blade; 2. Wedge; 3. Return spring; 4. Flange; 5. Spring washer; 6. Hydraulic cylinder front cover; 7. Sealing ring; 8. Piston; 9. Positioning pin; 10. Cylinder body; 11. Hydraulic cylinder rear cover; 12. Hex bolt; 13. Electromagnet; 14. Flow control valve; 15. Connecting pipe; 16. Oil passage block; 17. Electrode A; 18. Electrode B; 19. Oil inlet tank; 20. Valve core 2; 21. Valve core 1; 22. Oil inlet; 23. Oil outlet; 24. Roller; 25. Splitter; 26. Handle Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention. Example

[0021] See Figures 2 to 6 This invention is a fracturing device for hard rock strata in the roof based on dynamic load sweeping and static load splitting. The combined hydraulic splitting device includes: Wing (1), Wedge (2), Return Spring (3), Flange (4), Spring Washer (5), Hydraulic Cylinder Front Cover (6), Sealing Ring (7), Piston (8), Positioning Pin (9), Cylinder Body (10), Hydraulic Cylinder Rear Cover (11), Hex Bolt (12), Electromagnet (13), Flow Control Valve (14), Connecting Pipe (15), Oil Passing Block (16), Electrode A (17), Electrode B (18), Oil Inlet Tank (19), Valve Core 1 (20), Valve Core 2 (21), Oil Inlet (22), Oil Outlet (23), Roller (24), Splitter (25), Handle (26) The wedge (2) is embedded in the guide groove between the winglets (1), the return spring (3) is coaxially sleeved between the wedge (2) and the front cover (6) of the hydraulic cylinder, the roller (25) is coaxially arranged inside the return spring (3), and the flange (4) and the front cover (6) of the hydraulic cylinder are fastened together by spring washers (5) and hexagonal bolts (12). The front cover (6) and rear cover (11) of the hydraulic cylinder are respectively connected to both ends of the cylinder body (10). The sealing rings (7) are respectively set on the mating end faces of the cylinder body (10), the front cover (6) and the rear cover (11) of the hydraulic cylinder, and the outer periphery of the piston (8). The positioning pin (9) passes between the piston (8) and the cylinder body (10). The handle (24) is fixed to the rear end cover (11) of the hydraulic cylinder by hexagonal bolts (12), the oil passage block (16) is fixed to the side of the cylinder body (10), and the two ends of the connecting pipe (15) are respectively connected to the oil passage block (16) and the electromagnetic servo valve; Electromagnets (13) are respectively installed at both ends of the electromagnetic servo valve. Electrode A (17) and electrode B (18) are respectively connected to the corresponding side electromagnets (13). Valve core one (21) is located inside the electromagnetic servo valve. Flow control valve (14) is arranged at the oil inlet end of the electromagnetic servo valve. Valve core two (20) is located inside the flow control valve (14) and is threadedly connected to the valve body. Oil inlet (22) and oil outlet (23) are respectively connected to the electromagnetic servo valve. Oil tank (19) is connected to oil outlet (23). Specifically, before this device is put into operation, pre-drilling work must be completed first. After drilling is completed, the inside of the borehole must be thoroughly cleaned. High-pressure air or clean water is used to completely remove rock cuttings, dust and water adhering to the bottom and wall of the hole, ensuring that the hole wall is smooth and without protrusions, the bottom of the hole is flat and without debris, and the hole depth and diameter strictly meet the design parameters, so as to provide reliable basic conditions for the smooth insertion of the subsequent splitting mechanism. Furthermore, after cleaning the borehole, a comprehensive inspection and assembly verification of each core component of the device is required: check the fit between the wing (1) and the wedge (2), repeatedly push and pull the wedge (2) to confirm that it slides between the wing (1) without jamming or abnormal resistance, the wing (1) opens and closes flexibly, and the edges are free from chipping, cracks and excessive wear; check that the reset spring (3) and the roller (24) are properly assembled, the roller (24) rotates smoothly, and there is no jamming or loosening. Further, check the tightness of the connection between the flange (4) and the front cover (6) of the hydraulic cylinder, confirm that the spring washer (5) is not deformed, the hex bolt (12) is pre-tightened in place, and the sealing ring (7) of the mating end face is well assembled and undamaged; check the sealing condition between the cylinder body (10) and the front cover (6) of the hydraulic cylinder and the rear cover (11) of the hydraulic cylinder, confirm that the sealing ring (7) in the annular sealing groove is not detached or aged, the piston (8) fits tightly with the inner wall of the cylinder body (10), the positioning pin (9) is not bent or loose, and can effectively limit the circumferential rotation of the piston (8); Further, check the reliability of the connection between the oil passage block (16) and the cylinder (10), confirm that the connection surface is clean, the gasket is intact, the hex bolts (12) are tightened in place, and there is no risk of loosening; check the docking of the connecting pipe (15) with the oil passage block (16) and the electromagnetic servo valve, the joint is sealed reliably, there is no looseness or damage, and the conical sealing interface of the oil passage block (16) and the connecting pipe (15) fits tightly; Further, check the hydraulic control module and electrical connection parts: confirm that the electromagnetic servo valve and flow control valve (14) are assembled in place, the valve core 1 (21) moves flexibly without jamming, check that the wiring of electrode A (17), electrode B (18) and electromagnet (13) is firm, the control cable and pressure sensor are connected in accordance with regulations, the shielding layer is grounded reliably to avoid signal interference; check that the hydraulic oil level in the oil tank (19) meets the requirements, and there are no impurities or leaks; Furthermore, after completing the inspection of all components, perform no-load pre-testing: start the hydraulic pump station, slowly increase the system pressure to 30% of the rated value, and continuously observe the connecting pipe (15), oil block (16), cylinder (10), electromagnetic servo valve, flow control valve (14) and each joint to confirm that there is no hydraulic oil leakage; observe the reciprocating motion of the piston (8) driving the wedge (2) and vane (1) to ensure that the action is smooth and there is no crawling, shaking and abnormal noise; Furthermore, by adjusting the hydraulic oil flow through the flow control valve (14), the electromagnetic servo valve is controlled to complete multiple reversing actions to verify the response speed and stability of the dynamic load output, ensuring that the valve core 1 (21) reversing is accurate and without delay, and that the expansion and contraction frequency of the vane (1) meets the design requirements. After the no-load debugging is qualified, the operator holds the handle (26) and slowly inserts the assembled splitting head (vane (1) and wedge (2)) into the pre-drilled hole. During the insertion process, the splitting head is kept parallel to the hole axis to avoid hard collision between the vane (1) and the hole wall. Until the splitting mechanism is fully inserted into the hole and the vane (1) is evenly attached to the hole wall, all the preparatory work before the work can be completed, and the device can be started to carry out the formal splitting operation.

[0022] The following describes a single use of the present invention with reference to the accompanying drawings: See Figures 2 to 6 This invention is a device for fracturing hard rock strata in the roof based on dynamic load sweeping and static load splitting. The following describes the usage process of this invention with reference to the accompanying drawings: After the inspection and preparation of the device for fracturing hard rock strata in the roof based on dynamic load sweeping and static load splitting is completed, when the splitting operation is carried out, the static load related parameters are set by the control system, and the operator holds the handle (26) and inserts the device into the pre-drilled hole. According to the uniaxial compressive strength of the rock and the preset splitting direction, the position of the device is precisely adjusted so that the target rock strata form initial cracks, providing good preliminary conditions for subsequent dynamic load splitting.

[0023] The hydraulic pump starts and outputs high-pressure hydraulic oil. The hydraulic oil enters the cylinder body (10) through the oil inlet (22) of the electromagnetic servo valve. After passing through the preset oil circuit, it returns to the external cylinder through the oil outlet (23), ensuring that the hydraulic system forms a complete cycle and providing stable power support for the operation of the device.

[0024] Precisely set the hydraulic oil flow range on the flow control valve (14) to ensure stable flow output and meet operational requirements; at the same time, input the sweep frequency function (i.e., the signal whose frequency changes with time, as shown in Table 1) into the control unit of the electromagnetic servo valve, and through precise parameter control, ensure that the propagation direction of the dynamic load stress wave is consistent with the natural joint surface or designed splitting surface of the rock, thereby maximizing the splitting efficiency. After starting the dynamic load output, the operator needs to closely monitor the system pressure curve and the real-time response status of the rock. When the hydraulic pump oil pressure corresponding to a set of dynamic load frequencies drops sharply, it means that the dynamic load sweep frequency operation is completed. If abnormal situations such as a sudden increase in system pressure, increased equipment noise, or deviation of the rock splitting direction from the design preset value occur during the splitting process, the hydraulic supply must be cut off immediately through the electromagnetic servo valve. After the system pressure is completely released, check the status of each component of the equipment and the stress on the rock, promptly investigate and eliminate faults, and continue the splitting operation only after confirming that there are no safety hazards.

[0025] At this time, a static carrier wave with a constant amplitude is input to the servo controller, causing the vane (1) to generate an instantaneous, impactful radial static load, which causes the rock block to develop initial cracks. Then, the device is reset by controlling the servo system, and the servo controller is set to a dynamic carrier wave (sine wave, cosine wave, square wave, frequency sweep function, etc.). The natural frequency of the rock block determined during the frequency sweep process is used as the setting reference, and the hydraulic splitting device actuator (vane (1) and wedge (2)) is fixed. The hydraulic pump switch is turned on, allowing high-pressure oil to enter the inlet (22).

[0026] At this time, a control signal is sent through the electromagnetic servo system to alternately energize the electromagnets (13) at both ends of the electromagnetic servo valve, thereby controlling the valve core 1 (21) inside the electromagnetic servo valve to move left and right, causing oil port 1 and oil port 2 to perform periodic opening and closing actions. When the electromagnet (13) at the right end of the electromagnetic servo valve is energized, as... Figure 2 As shown, the high-pressure hydraulic oil output by the hydraulic pump enters the cylinder (10) through the inlet (22) of the electromagnetic servo valve. After flowing through the preset oil circuit, it returns to the external cylinder through the outlet (23). At this time, the piston (8) inside the cylinder (10) slides to the left axially under the action of hydraulic thrust. The wedge (2) rigidly connected to the piston (8) moves to the left in sync, thereby pushing the vane (1) to expand radially upward and apply a continuous static load splitting force to the rock. When the electromagnet (13) at the left end of the electromagnetic servo valve is energized, as Figure 3 As shown, the high-pressure hydraulic oil output by the hydraulic pump enters the cylinder (10) through the inlet (22) of the electromagnetic servo valve, flows through the preset oil circuit (corresponding to oil circuit 1), and returns to the oil cylinder through the outlet (23). At this time, the piston (8) inside the cylinder (10) slides to the right axially under the action of hydraulic thrust, the wedge (2) moves to the right synchronously, and the vane (1) retracts radially inward under the assistance of the return spring (3), completing one splitting cycle. The periodic opening and closing action of the oil port 1 and the oil port 2 causes the piston to generate periodic reciprocating motion, thereby causing the vane (1) to generate multiple splitting cycles, so that the initial crack generated by static load gradually expands.

[0027] Table 1 shows the dynamic load forms that the splitting device can output.

[0028] Table 1 Load corresponding to servo controller waveforms Serial Number Control function type Regulation principle Output load illustrate Features 1 Sine / Cosine Periodic Function The controller outputs a continuous and smooth sine / cosine periodic signal to drive the valve core (21) of the electromagnetic servo valve to perform a reciprocating motion, so that the valve opening increases and decreases periodically with a sine law, and the opening changes continuously without abrupt changes, corresponding one-to-one with the signal waveform. The periodic dynamic load is of constant amplitude, continuous and stable, with a fixed frequency and no impact, and can be precisely matched with the natural frequency of the rock strata. In the servo control system, the curves are continuous and smooth waveforms. The waveforms of the control signal, servo valve opening, and output load are consistent, without abrupt changes, which intuitively reflects the periodic matching relationship. The output load is stable and shock-free, and the frequency is precisely controllable. It can achieve directional, low-damage periodic fracturing and is suitable for medium-hard to hard intact rock strata, thick sandstone / limestone roofs, dense rock strata with undeveloped fractures, and deep high-stress roadway roof fracturing scenarios where the stability of the surrounding rock is required. 2 Square wave / rectangular wave function The controller outputs a step signal that switches rapidly between high and low levels. When the level is high, it drives the valve core (21) of the electromagnetic servo valve to move to the maximum stroke, and the valve port is fully open. When the level is low, the valve core is reset, the valve port is close to closed, and the opening degree changes abruptly between the maximum and minimum. The sudden change impact dynamic load has an instantaneous jump in load amplitude, strong impact, and the frequency is determined by the level switching speed, making it suitable for high-frequency impact rock breaking. In the servo control system, the signal curve is a rectangular step shape, the servo valve opening curve changes synchronously in a step shape, and the load waveform is steep, clearly showing the correspondence between the sudden change in opening and the load impact. With strong load impact and fast response speed, it can generate instantaneous high stress concentration, accelerate the rapid initiation and penetration of cracks, and greatly improve the efficiency of hard rock splitting. It is suitable for extremely hard and dense rock strata, high-hardness granite / basalt roof, deep high-stress hard rock tunnels, as well as working conditions that pursue rock breaking efficiency such as rapid tunneling and roof pre-splitting and pressure relief. It can achieve efficient fracturing of hard rock with high-frequency impact. 3 Triangular wave / sawtooth wave function The controller outputs a linearly changing signal, and the voltage rises at a constant speed over time (sawtooth wave) or rises and then falls at a constant speed (triangular wave), driving the valve core (21) to move linearly. The valve opening increases or decreases linearly with the signal, and the opening rate changes uniformly. A dynamic load with uniform gradient change has no violent impact, and its amplitude increases or decreases linearly with time, allowing for precise control of the stress change rate. In the servo control system, the signal and servo valve opening curves are broken lines composed of sloping straight line segments, and the load curve changes synchronously and linearly, intuitively showing the correspondence between the gradual change in opening and the load gradient. The stress change rate is controllable and the loading process is stable, making it easy to accurately control the loading rate and stress gradient; it is suitable for medium-hard rock strata, sandstone / shale strata with well-developed bedding, and areas with general integrity of the top rock structure. 4 Chirp function The controller outputs a sinusoidal signal whose frequency changes continuously over time (from low frequency to high frequency or in the opposite direction), which drives the valve core (21) to reciprocate according to the sinusoidal law. However, the reciprocating frequency increases synchronously with the signal frequency, the valve opening changes at a gradually faster frequency, and the opening amplitude remains stable. Wideband continuous frequency sweep dynamic load, with continuously adjustable frequency and stable amplitude, can quickly cover the target frequency band and locate the resonant frequency of rock strata. In the servo control system, the waveform period gradually shortens over time, the frequency of servo valve opening changes increases synchronously, and the load frequency increases continuously, clearly showing the matching relationship between opening and load during the frequency sweep process. It can quickly scan and lock onto the sensitive frequency band of rock strata resonance, achieving efficient energy coupling fracturing; it is suitable for geologically complex, unknown, hard rock strata and deep, thick, hard tops. During dynamic load resonance splitting, the device must be kept in a fixed position. The operator must closely monitor the response state of the rock strata and the crack propagation. By observing the extension speed and range of the cracks on the rock surface, the splitting effect can be judged. When the rock cracks have fully expanded and reached the preset splitting requirements, the splitting work is considered to be over.

[0029] After the hydraulic splitting operation is completed, the splitting effect needs to be evaluated. The frequency characteristics of the coal and rock mass are measured using equipment such as a Doppler vibration meter, and the safety factor of the coal and rock mass is calculated using empirical formulas. When the calculated safety factor is low, it means that the internal cracks of the coal and rock mass have fully expanded under dynamic load, meeting the construction requirements.

[0030] After the splitting operation is completed, the electromagnetic servo valve is operated to send a reset signal, causing the wedge (2) to slowly reset and the blade (1) to retract synchronously, thus relieving the force on the borehole wall. After the piston (8) has completely retracted into the cylinder (10), the hydraulic pump station is shut off, the oil passage block (16) and the system pressure relief valve are opened to drain the residual pressure in the hydraulic system, preventing the residual pressure from damaging the equipment or causing safety hazards to the operators. Then the connecting pipe (15) is disassembled and properly stored to avoid leakage of residual hydraulic oil into the pipe, which could pollute the working environment. After disassembly, the operator holds the handle (26) and smoothly pulls the splitting head (blade (1), wedge (2), splitter housing) out of the borehole, avoiding collision between the blade (1) and the borehole wall during the extraction process, which could cause damage to the components. After extraction, use a brush and compressed air to thoroughly clean the blades (1), wedges (2), and rock debris and oil stains adhering to the surface of the splitter housing. Conduct a comprehensive inspection of the wear, deformation, and sealing of each component. Replace any parts with cracks, deformation, or sealing failures in a timely manner to prevent malfunctions in subsequent operations. At the same time, clean and rust-proof the surfaces of the cylinder body (10), electromagnetic servo valve, and flow control valve (14), apply a special rust inhibitor, and properly store all components to make full preparations for the next splitting operation.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A fracturing device for hard rock strata in the roof based on dynamic load sweep frequency and static load splitting, comprising a splitting actuator and a hydraulic servo control unit, characterized in that: The splitting actuator includes a blade (1), a wedge (2), and a hydraulic cylinder that drives the wedge (2) to move axially. The wedge-shaped inclined surface of the wedge (2) cooperates with the inner guide inclined surface of the blade (1) to drive the blade (1) to open outward when the wedge (2) moves axially. The hydraulic servo control unit is connected to the hydraulic cylinder through a connecting pipe (15) to control the flow direction of hydraulic oil and realize dynamic load sweeping and static load splitting.

2. The device for fracturing hard rock strata in the roof based on dynamic load sweeping and static load splitting according to claim 1, characterized in that: The hydraulic cylinder includes a cylinder body (10), a piston (8), a front cover (6) of the hydraulic cylinder and a rear cover (11) of the hydraulic cylinder. The wedge (2) is connected to the piston (8) by a positioning pin (9) or is configured as an integral structure. A combined sealing ring (7) is provided between the piston (8) and the cylinder body (10).

3. The device for fracturing hard rock strata in the roof based on dynamic load sweeping and static load splitting according to claim 2, characterized in that: A return spring (3) is coaxially sleeved on the outside of the guide shaft section of the wedge (2). One end of the return spring (3) is fixed to the inner contour surface of the splitter (25), and the other end is fixed to the stepped end face of the wedge (2). A guide roller is coaxially arranged inside the return spring (3). The axle of the guide roller is fixedly connected to the front end cover (6) of the hydraulic cylinder. The outer circular surface of the guide roller is in rolling cooperation with the guide shaft section of the wedge (2).

4. The device for fracturing hard rock strata in the roof based on dynamic load sweeping and static load splitting according to claim 2, characterized in that: The flange (4) and the front cover (6) of the hydraulic cylinder are fastened together by bolts and spring washers (5). The mating end faces of the two adopt a stepped stop structure, and an O-ring seal is provided in the stop. The flange (4) is locked to the connection end of the splitter (25) by high-strength bolts.

5. The device for fracturing hard rock strata in the roof based on dynamic load sweeping and static load splitting according to claim 2, characterized in that: The cylinder body (10) is provided with an oil passage block (16) on its side. A section of the connecting pipe (15) is embedded inside the oil passage block (16) and forms a sealed oil passage. The connecting pipe (15) is symmetrically arranged on both sides of the cylinder body (10), and the interface between the connecting pipe (15) and the oil passage inside the oil passage block (16) adopts a conical sealing structure.

6. The device for fracturing hard rock strata in the roof based on dynamic load sweeping and static load splitting according to claim 1, characterized in that: The hydraulic servo control unit includes an electromagnetic servo valve assembly and a flow control module. The electromagnetic servo valve assembly includes an electromagnet (13), a valve core 1 (21), an oil inlet (22), and an oil outlet (23). The flow control module includes a flow control valve (14) and a valve core 2 (20). The flow control valve (14) is located at the oil inlet end of the electromagnetic servo valve assembly.

7. The device for fracturing hard rock strata in the roof based on dynamic load sweeping and static load splitting according to claim 6, characterized in that: The electromagnets (13) are respectively located at the left and right ends of the electromagnetic servo valve assembly, and electrodes A (17) and B (18) are respectively connected to the electromagnets (13) on the left and right sides; the valve core 1 (21) is connected to the driving end of the electromagnet (13), and the oil inlet (22) and oil outlet (23) are opened on the upper end face of the electromagnetic servo valve assembly and communicate with the valve passage of the valve core 1 (21).

8. The device for fracturing hard rock strata in the roof based on dynamic load sweeping and static load splitting according to claim 6, characterized in that: The oil outlet of the flow control valve (14) is connected to the hydraulic cylinder through a pipeline. The valve core 2 (20) and the valve body adopt a cylindrical slide valve clearance fit and are supported by a guide bearing.

9. The device for fracturing hard rock strata in the roof based on dynamic load sweeping and static load splitting according to claim 1, characterized in that: The handle (26) is detachably connected to the rear end cover (11) of the hydraulic cylinder; the hydraulic servo control unit is configured to output hydraulic pulses with adjustable alternating frequency through an electromagnetic servo valve to apply dynamic load sweeping action to the hard rock strata on the top plate.

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