Device and method for detecting rock displacement and damage state in rock breaking by high-voltage electric pulse

Abstract

The application discloses a device and method for detecting rock stratum displacement and damage state in high-voltage electric pulse rock breaking, which comprises a high-voltage electric pulse rock breaking drill bit, a high-voltage electric pulse power supply device, a drilling data ground monitor, a drilling fluid storage and pumping device, a running control device, a flexible drill pipe and a support; the high-voltage electric pulse rock breaking drill bit is connected with the bottom end of the flexible drill pipe, the upper end of the flexible drill pipe is connected with the high-voltage electric pulse power supply device, the drilling data ground monitor and the drilling fluid storage and pumping device; the running control device is connected with the high-voltage electric pulse power supply device and the drilling fluid storage and pumping device; and the flexible drill pipe and the running control device are fixed on the support. The high-voltage electric pulse rock breaking drill bit is connected with the high-voltage electric pulse power supply device through an inner cable of the flexible drill pipe, so that drilling of the rock mass is realized. The application has the advantages of simple structure, fast rock breaking and hole forming, small mechanical abrasion, high working efficiency, adaptability to rock strata with different hardness and temperature, diversified hole forming shape and the like.

Description

Technical Field

[0001] This invention belongs to the field of mining engineering technology, and relates to the detection of displacement of overlying strata in goaf areas. More specifically, it relates to a device and method for detecting strata displacement and failure state during high-voltage electric pulse rock breaking. Background Technology

[0002] In recent years, with the increasing intensity of coal mining, the coal resources in many mining areas with favorable mining conditions have gradually decreased. However, the remaining coal seams above residual mining areas have considerable reserves and good mining value, which can alleviate the problem of insufficient coal reserves in some mining areas and effectively extend the mining life of the mines. However, due to the existence of goaf areas below, the safety issues such as stability assessment during the upward mining process of these residual coal seams are becoming increasingly prominent. To ensure the safe and orderly progress of upward mining, it is necessary to investigate and monitor the damage to the overlying strata caused by the mining of the lower coal seams.

[0003] Currently, commonly used investigation and monitoring methods mainly include on-site monitoring, simulation analysis, and theoretical calculation. On-site monitoring methods primarily include downhole color television systems, surface borehole ultrasonic imaging technology, borehole segmented water injection, sensor monitoring, distributed fiber optic detection, microseismic monitoring, and remote sensing technology. These methods suffer from drawbacks such as reliance on high borehole quality, large measurement errors, limited monitoring range, susceptibility to missed detections, high monitoring costs, and easy instrument damage. Simulation analysis methods involve establishing small-scale experimental platforms in the laboratory to simulate actual excavation conditions and observe the displacement and damage of overlying strata to verify the actual on-site situation. However, laboratory simulation conditions deviate from actual on-site conditions, and the simulation process involves numerous simplifications, failing to accurately reflect the actual on-site situation. Theoretical calculation methods also suffer from parameter simplification, limited judgment factors, and narrow applicability of formulas. Therefore, a new, efficient, and accurate method for determining the damage status of overlying strata is urgently needed.

[0004] In recent years, a number of emerging rock-breaking technologies have emerged: one type is mechanical energy rock breaking (such as Chinese patents CN113982615A and CN114152514A), and the other is thermal energy rock breaking (such as Chinese patents CN114636544A, CN113898287A, and CN109737841A). Among the new mechanical energy rock breaking technologies, high-voltage electric pulse technology has attracted attention both domestically and internationally in recent years and can be widely applied in rock mining, drilling, mechanical descaling, and medical fields. Furthermore, high-voltage electric pulse rock breaking technology is safe and efficient, possessing great development potential. High-voltage electric pulse rock breaking is divided into two categories: electro-rock breaking and hydraulic-electric rock breaking. When the breakdown voltage rise time is less than 500 ns, the breakdown field strength of water is greater than that of rock. When water acts as an insulating fluid, the rock is broken down first, achieving the effect of rock fracturing, which is known as electro-hydraulic rock fracturing. However, when the breakdown voltage rise time is greater than 500 ns, the breakdown field strength of rock is greater than that of water. The high-voltage pulse wave in the water, as well as the generation and collapse of bubbles, damage the rock, achieving the effect of rock fracturing. This rock fracturing method is called electrohydraulic rock fracturing. During high-voltage pulse rock fracturing, the rock fracturing rate, the flow rate of the conductive fluid, and the lithology, porosity, and fracture density of the rock are related. Therefore, high-voltage pulse rock fracturing can be introduced into the monitoring of the overlying strata in the goaf during upward mining. Summary of the Invention

[0005] This invention aims to provide an apparatus and method for detecting rock strata displacement and failure state during high-voltage electric pulse rock breaking. The high-voltage electric pulse rock breaking detection technology provided by this invention can be applied to the detection of displacement and failure state of overlying rock strata in mined coal seams, providing basic data for feasibility assessment of subsequent upward mining.

[0006] This invention provides a device for detecting rock displacement and failure state during high-voltage electric pulse rock breaking, comprising: a high-voltage electric pulse rock breaking drill bit, a high-voltage electric pulse power supply device, a drilling data ground monitoring instrument, a drilling fluid storage and pumping device, an operation control device, a flexible drill pipe, and a support; the high-voltage electric pulse rock breaking drill bit is connected to the bottom end of the flexible drill pipe, and the upper end of the flexible drill pipe is connected to the high-voltage electric pulse power supply device, the drilling data ground monitoring instrument, and the drilling fluid storage and pumping device; the operation control device is connected to the high-voltage electric pulse power supply device and the drilling fluid storage and pumping device; the flexible drill pipe and the operation control device are fixed on the support.

[0007] A high-voltage electric pulse rock-breaking drill bit is connected to the high-voltage electric pulse power supply device via a cable inside the flexible drill rod to achieve drilling into the rock mass. The high-voltage electric pulse rock-breaking drill bit includes a drill bit insulation support, an outer ring low-voltage electrode, and an inner ring high-voltage electrode.

[0008] The drill bit insulation bracket acts as a connector, used to fix the low-voltage and high-voltage electrodes. Its specific shape can be determined according to the requirements of rock-breaking drilling, such as circular, rectangular, or polygonal. The outer ring low-voltage electrode and the inner ring high-voltage electrode are both connected to the lower end of the drill bit insulation bracket. The drill bit insulation bracket has a hollow structure with a drilling fluid channel in the middle for drilling fluid, cuttings, and other materials to be discharged from the bottom of the borehole.

[0009] Preferably, both the outer ring low-voltage electrode and the inner ring high-voltage electrode are composed of multiple sub-electrodes, and the sub-electrodes are needle-shaped, L-shaped, inverted L-shaped, etc. The sub-electrodes are spliced, which makes it easy to replace the severely worn sub-electrode heads, thereby saving electrode materials and costs.

[0010] Preferably, the sub-electrode material is one of pure copper, graphite, and steel; the drill bit insulating support material is one of corundum and polytetrafluoroethylene.

[0011] Preferably, the inner ring high-voltage electrode and the insulating support are connected by a rotatable snap-fit ​​connection, and the drill bit insulating support can be rotated to adjust the distance between the outer ring low-voltage electrode and the inner ring high-voltage electrode sub-electrode.

[0012] Preferably, a grid is provided at the drilling fluid channel opening in the middle of the drill bit insulation support to prevent large pieces of rock from being sucked back into the drilling fluid delivery pipe after breakage, causing blockage. The grid can be directly welded and fixed to the insulation support, with evenly distributed holes in the grid, and the hole diameter is about 2cm.

[0013] Preferably, the high-voltage electric pulse rock-breaking drill bit can be circular, rectangular, polygonal, or the like.

[0014] A high-voltage pulse power supply device is electrically connected to the high-voltage pulse rock-breaking drill bit through a cable in the flexible drill rod, providing high-voltage pulse power to the high-voltage pulse rock-breaking drill bit.

[0015] The drilling fluid storage and pumping device includes a drilling fluid storage tank, a high-pressure water pump, and a settling tank. It provides drilling fluid between the inner high-voltage electrode and the outer low-voltage electrode of the high-voltage electric pulse rock-breaking drill bit during rock breaking, ensuring the circulation of the drilling fluid and carrying away broken rock cuttings. The drilling fluid storage tank delivers the drilling fluid to the downhole via a pipeline (which extends from the storage tank into the drilled well). One end of the high-pressure water pump is connected to a flexible drill pipe via a pipeline to pump the drilling fluid and broken rock cuttings out of the well. The other end of the high-pressure water pump is connected to the settling tank to settle the broken rock cuttings. The settling tank is connected to the drilling fluid storage tank, allowing the treated drilling fluid to be recycled.

[0016] Preferably, the drilling fluid is one of natural groundwater, NaCl solution, NaOH solution, and CaCl2 solution, and the concentration of NaCl solution, NaOH solution, and CaCl2 solution is 0.01~0.5%;

[0017] The flexible drill pipe contains a cable that connects the high-voltage electric pulse rock-breaking drill bit and the high-voltage electric pulse power supply device, serving as a connection, suspension, and guide (the flexible drill pipe can be considered as being fixed and suspended on the support via a flexible drill pipe fixing gripper on the support); it also transmits drilling measurement data from the high-voltage electric pulse rock-breaking drill bit to the drilling data ground monitoring instrument (the flexible drill pipe contains a cable, which generates relevant electromagnetic data through electromagnetic induction, and transmits the data to the ground monitoring instrument via the cable in the flexible drill pipe). The flexible drill pipe consists of an inner cavity, an outer cavity, and a mating end, where the inner cavity is the drilling fluid delivery channel and the outer cavity is the cable placement space;

[0018] Preferably, two adjacent flexible drill rods are connected by a mating end, which contains an electrical connector and an electromagnetic coil to achieve effective transmission of high voltage and high voltage pulses. The flexible drill rod has a certain strength and can support the high voltage pulse rock-breaking drill bit, thereby guiding the high voltage pulse rock-breaking drill bit to change its drilling direction. Each flexible drill rod has a fixed length, and as the drilling depth increases, the flexible drill rod is continuously extended to ensure that the drill bit can be lowered to the predetermined drilling depth.

[0019] Preferably, the drilling angle of the high-voltage electric pulse rock-breaking drill bit is 0-180°, controlled by a flexible drill rod.

[0020] The operation control device is electrically connected to the high-voltage pulse power supply device, drilling fluid storage and pumping device, and support. It is used to control the power supply of the high-voltage pulse power supply device, including power on / off, voltage level, and discharge duration; to control the start / stop of drilling fluid pumping and the flow rate of drilling fluid pumping; and to control the drilling and lifting of flexible drill pipe.

[0021] Control of the high-voltage pulse power supply by the operation control device: First, turn on the power of the high-voltage pulse power supply device via the power switch in the operation control device. Adjust the voltage and discharge duration required during the rock-breaking process according to the rock-breaking needs. After rock breaking is complete, turn off the power of the high-voltage pulse power supply device in the operation control device. Control of the drilling fluid storage and pumping device by the operation control device: Before the high-voltage pulse rock-breaking drill bit begins rock breaking, turn on the drilling fluid storage and pumping device via the control button in the operation control device. Adjust the drilling fluid flow rate to ensure effective circulation of the drilling fluid between the drill bit, the high-voltage pulse rock-breaking drill bit (flexible drill pipe), the drilling fluid storage tank, the high-pressure pump, and the sedimentation tank. After rock breaking is complete, turn off the drilling fluid storage and pumping device via the control button in the operation control device. Device; Control of the support by the operation control device: When it is necessary to add flexible drill pipe, firstly, turn off the high-voltage pulse power supply and the high-pressure water pump of the drilling fluid storage and pumping device by using the power switch of the high-voltage pulse power supply device and the control button of the drilling fluid storage and pumping device in the operation control device. Then, after fixing the high-voltage pulse rock-breaking drill bit or flexible drill pipe by the flexible drill pipe fixing device by using the control button of the support in the operation control device, separate the docking end of the high-voltage pulse rock-breaking drill bit (flexible drill pipe) from the high-voltage pulse power supply. Then, place the flexible drill pipe on the grab lifting device on the rear side of the outer frame of the support by using the control button of the support in the operation control device, so that the grab lifting device grips the flexible drill pipe tightly and aligns the docking end of the flexible drill pipe with the docking end of the high-voltage pulse power supply. Lower the flexible drill pipe to connect and fix it to the high-voltage pulse rock-breaking drill bit (flexible drill pipe). Open the flexible drill pipe fixing device and connect the cable of the flexible drill pipe to the high-voltage pulse power supply.

[0022] The drilling data ground monitoring instrument is used to monitor and collect the drilling angle, drilling azimuth angle, pressure at the bottom of the well, and physical properties of the formation such as resistivity, density, and porosity of the drilled formation by the high-voltage electric pulse rock breaking drill bit.

[0023] The support frame includes tracks, an outer frame, a lifting and grappling device, and a flexible drill pipe fixing gripper. It is used for fixing the drilling position and for lifting and lowering the high-voltage pulse rock-breaking drill bit and the flexible drill pipe. The outer frame consists of two slightly inclined columns on the left and right sides, and a connecting beam connecting the two columns, forming a stable trapezoidal body. The lifting and grappling device for the high-voltage pulse rock-breaking drill bit and the flexible drill pipe is located at the rear of the outer frame and includes a vertical fixing plate and a lifting and grappling slider. The vertical fixing plate is fixed to the rear of the outer frame and includes a vertical groove. The lifting and grappling slider is embedded in the groove to achieve vertical movement of the lifting and grappling slider, ensuring the lifting and lowering of the high-voltage pulse rock-breaking drill bit and the flexible drill pipe. The flexible drill pipe fixing gripper is fixed to the lower end of the outer frame and is used to grip and fix the flexible drill pipe. The tracks are located at the lower part of the outer frame, facilitating the positioning and movement of the high-voltage pulse rock-breaking detection rock displacement and breaking device.

[0024] This invention provides a method for detecting rock strata displacement and failure state using the above-mentioned device, comprising the following steps:

[0025] (1) Based on the preliminary basic geological data, including the range of mined goaf, the number and lithology of the overlying strata, and the physical and mechanical properties of the overlying strata, determine the location of the high-voltage electric pulse rock breaking detection point; ensure that the rock breaking detection borehole is located within the planned upstream mining coal seam range, so as to observe the structural characteristics of the overlying strata in different goaf locations.

[0026] (2) Fix the high-voltage electric pulse rock breaking detection device, align the high-voltage electric pulse rock breaking drill bit with the measuring point, and prepare drilling fluid, drilling fluid storage tank and sedimentation tank; set the drilling direction of the high-voltage electric pulse rock breaking drill bit;

[0027] (3) Manually excavate a pilot tunnel with a cross-sectional edge of 10cm and a depth of 0.3~1.0m at the measuring point location, and introduce drilling fluid into the pilot tunnel;

[0028] (4) Lower the high-voltage electric pulse rock breaking drill bit into the pilot pit, connect the high-voltage electric pulse rock breaking drill bit to the high-voltage electric pulse power supply cable; turn on the main switch of the operation control device and start the drilling fluid high-pressure pump to make the drilling fluid circulate between the pilot pit, the drilling fluid storage tank and the sedimentation tank, and then turn on the high-voltage electric pulse power supply to start high-voltage electric pulse rock breaking drilling.

[0029] (5) When the initial rock-breaking drilling depth is 4 / 5 of the height of the high-voltage electric pulse rock-breaking drill bit, turn off the high-voltage electric pulse power supply and the drilling fluid high-pressure pump; after the high-voltage electric pulse rock-breaking drill bit is fixed by the flexible drill rod fixing device, separate the docking end of the high-voltage electric pulse rock-breaking drill bit from the high-voltage electric pulse power supply; place the flexible drill rod one on the grab lifting device on the back side of the outer frame of the support, so that the docking end of the flexible drill rod is aligned with the docking end of the high-voltage electric pulse power supply, lower the flexible drill rod one, so that the flexible drill rod one is connected and fixed to the high-voltage electric pulse rock-breaking drill bit, open the flexible drill rod fixing device, and at the same time connect the cable of the flexible drill rod one to the high-voltage electric pulse power supply;

[0030] (6) Restart the drilling fluid high-pressure pump and the high-voltage electric pulse power supply to put the high-voltage electric pulse rock-breaking drill bit into the rock-breaking drilling state; when the height of the flexible drill rod end above the ground is the distance from the flexible drill rod fixing device to the ground, turn off the high-voltage electric pulse power supply and the drilling fluid pumping high-pressure pump; after the flexible drill rod fixing device fixes the flexible drill rod one, separate the flexible drill rod one from the docking end of the high-voltage electric pulse power supply; place the flexible drill rod two on the grab lifting device on the rear side of the support frame so that the docking end of the flexible drill rod one is connected to the flexible drill rod two. Align the docking ends, lower the second flexible drill rod, and connect and fix the first flexible drill rod to the second flexible drill rod. Open the flexible drill rod fixing device and connect the second flexible drill rod to the cable of the high-voltage electric pulse power supply. Turn on the drilling fluid high-pressure pump and the high-voltage electric pulse power supply again to put the high-voltage electric pulse rock-breaking drill bit into the rock-breaking drilling state. Repeat this process (as the drilling depth increases, add the third flexible drill rod, the fourth flexible drill rod, etc., until the predetermined drilling depth is reached) until the planned rock-breaking drilling depth is reached, and then stop rock-breaking drilling.

[0031] (7) Throughout the rock-breaking drilling process, the drilling fluid pump high-pressure water pump pumps the drilling fluid and the rock cuttings broken by the high-voltage electric pulse rock-breaking drill bit from the bottom of the rock-breaking borehole through the inner cavity of the flexible drill pipe to the sedimentation tank (the drilling fluid and rock cuttings flow out together); the drilling fluid after sedimentation in the sedimentation tank is returned to the drilling fluid storage tank for recycling; at the same time, the drilling parameters of the high-voltage electric pulse rock-breaking drill bit and the formation physical properties parameters are monitored in real time by the drilling data ground monitoring instrument.

[0032] (8) During the rock breaking and drilling process of the high-voltage electric pulse rock breaking drill bit, the drilling fluid inflow and outflow are recorded in real time, the drilling fluid loss rate is calculated, and the rock breaking and drilling rate of the high-voltage electric pulse rock breaking drill bit is recorded at the same time.

[0033] (9) Repeat the above steps to complete the rock breaking detection of all measuring points within the range; based on the length of each measuring point, the drilling fluid loss rate and the rock breaking drilling rate of the high-voltage electric pulse rock breaking drill bit, draw the flow distribution map and the rock breaking drilling rate map of different boreholes respectively, analyze the fracture development characteristics and permeability characteristics at different locations within the length of the rock breaking borehole, and further combine the cumulative continuous leakage section length (i.e. the zero point of leakage change) L1+L2+…Ln… (n=1、2、....、k) to calculate the damage range and damage situation of the rock mass in different spatial ranges, thereby judging the stability of the overlying rock mass and providing basic data for the feasibility judgment of subsequent upward mining.

[0034] The beneficial effects of this invention are:

[0035] (1) The high voltage electric pulse rock breaking detection device of the present invention uses the electric arc energy of high voltage electric pulse to break rocks without the need for other power devices. Compared with the mechanical rock breaking in the prior art, it has a simple structure, can achieve the purpose of rapid rock breaking and hole formation, and has the advantages of low mechanical wear, high working efficiency, adaptability to rock layers of different hardness and temperature, and diverse hole formation shapes.

[0036] (2) During the rock breaking drilling process, the rock breaking tool of the high voltage electric pulse rock breaking detection device of the present invention is not limited by the increase of hole temperature and driving power, and can fully adapt to the drilling of high temperature and high pressure deep wells (holes) and ultra-deep wells (holes). It is a new and efficient rock breaking detection method.

[0037] (3) The high voltage pulse rock breaking detection device of the present invention can measure the movement and damage state of rock strata during the rock breaking drilling process without the need to combine other methods. It is simple, convenient, time-saving, labor-saving and cost-saving.

[0038] (4) The drilling fluid carries the rock cuttings from the bottom of the hole through the cavity of the flexible drill pipe and is discharged from the borehole to realize the reverse circulation of the drilling fluid. This can effectively avoid repeated crushing of rock cuttings, improve drilling efficiency, and realize the function of unloading slag. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a high-voltage electric pulse rock-breaking detection device.

[0040] Figure 2 This is a schematic diagram of the structure of a high-voltage electric pulse rock-breaking drill bit;

[0041] Figure 3 for Figure 2 Top view;

[0042] Figure 4 Schematic diagram of flexible drill pipe structure;

[0043] Figure 5 A cross-sectional view of the external end of the flexible drill pipe connector.

[0044] Figure 6 for Figure 5 Top view;

[0045] Figure 7 This is a cross-sectional view of the inner end of the flexible drill pipe connector.

[0046] Figure 8 for Figure 7 Top view;

[0047] In the diagram: 1 is a high-voltage electric pulse rock-breaking drill bit, 2 is a high-voltage electric pulse power supply device, 3 is a drilling data ground monitoring instrument, 4 is an operation control device, 5 is a flexible drill pipe, 6 is a support, 7 is a drill bit insulation support, 8 is an outer ring low-voltage electrode, 9 is an inner ring high-voltage electrode, 10 is a drilling fluid channel, 11 is a grid, 12 is a drilling fluid storage tank, 13 is a high-pressure water pump, 14 is a sedimentation tank, 15 is an inner cavity, 16 is an outer cavity, 17 is a docking end, 18 is an electromagnetic coil, 19 is an electrical connector, 20 is a crawler walking device, 21 is an outer frame, 22 is a grab lifting device, and 23 is a flexible drill pipe fixing gripper. Detailed Implementation

[0048] The present invention will be further illustrated by the following embodiments, but is not limited to the following embodiments. Example 1

[0049] like Figures 1-3 As shown, a device for detecting rock displacement and failure state during high-voltage pulse rock breaking includes: a high-voltage pulse rock breaking drill bit 1, a high-voltage pulse power supply device 2, a drilling data ground monitoring instrument 3, a drilling fluid storage and pumping device, an operation control device 4, a flexible drill rod 5, and a support 6; the high-voltage pulse rock breaking drill bit 1 is connected to the bottom end of the flexible drill rod 5, and the upper end of the flexible drill rod 5 is connected to the high-voltage pulse power supply device 2, the drilling data ground monitoring instrument 3, and the drilling fluid storage and pumping device; the operation control device 4 is connected to the high-voltage pulse power supply device 2 and the drilling fluid storage and pumping device; the flexible drill rod 5 and the operation control device 4 are fixed on the support 6.

[0050] The high-voltage electric pulse rock-breaking drill bit 1 is connected to the high-voltage electric pulse power supply device 2 via a cable inside the flexible drill rod 5 to achieve drilling into the rock mass. The high-voltage electric pulse rock-breaking drill bit 1 includes a drill bit insulating support 7, an outer ring low-voltage electrode 8, and an inner ring high-voltage electrode 9.

[0051] The drill bit insulation support 7 acts as a connector, used to fix the outer ring low-voltage electrode 8 and the inner ring high-voltage electrode 9. Its specific shape can be determined according to the requirements of rock-breaking drilling, such as circular, rectangular, or polygonal. Both the outer ring low-voltage electrode 8 and the inner ring high-voltage electrode 9 are connected to the lower end of the drill bit insulation support 7. The drill bit insulation support 7 has a hollow structure with a drilling fluid channel 10 in the middle for drilling fluid, cuttings, and other materials to be discharged from the bottom of the borehole.

[0052] Preferably, both the outer ring low-voltage electrode 8 and the inner ring high-voltage electrode 9 are composed of multiple sub-electrodes, and the sub-electrodes are needle-shaped, L-shaped, inverted L-shaped, etc. The sub-electrodes are spliced, which makes it easy to replace the severely worn sub-electrode heads, thereby saving electrode materials and costs.

[0053] Preferably, the sub-electrode material is one of pure copper, graphite, and steel; the drill bit insulating support 7 material is one of corundum and polytetrafluoroethylene.

[0054] Preferably, the inner ring high-voltage electrode 9 and the drill bit insulating support 7 are connected by a rotatable snap-fit ​​connection. The drill bit insulating support 7 can rotate to adjust the distance between the outer ring low-voltage electrode and the inner ring high-voltage electrode sub-electrode. (The distance is adjusted as follows: the insulating support is a circle as shown in the figure. When the rotation angle between the insulating support connecting the inner ring high-voltage electrode and the support connecting the outer ring low-voltage electrode is 0, the distance between the two electrodes is a. When rotated by a small angle, the distance between the two electrodes will become b).

[0055] Preferably, a grid 11 is provided at the drilling fluid channel 10 opening in the middle position of the drill bit insulation support 7 to prevent large pieces of rock from being sucked back into the drilling fluid delivery pipe after being broken, causing blockage; the grid 11 can be directly welded and fixed to the insulation support 7, and the holes in the grid 11 are evenly distributed with a hole diameter of about 2cm.

[0056] Preferably, the high-voltage electric pulse rock-breaking drill bit can be circular, rectangular, polygonal, or the like.

[0057] A high-voltage pulse power supply device is electrically connected to the high-voltage pulse rock-breaking drill bit through a cable in the flexible drill rod, providing high-voltage pulse power to the high-voltage pulse rock-breaking drill bit.

[0058] The drilling fluid storage and pumping device includes a drilling fluid storage tank 12, a high-pressure water pump 13, and a settling tank 14. It provides drilling fluid between the inner high-pressure electrode and the outer low-pressure electrode during rock breaking by the high-pressure electric pulse rock-breaking drill bit, ensuring the circulation of the drilling fluid and carrying away broken rock cuttings. The drilling fluid storage tank delivers the drilling fluid to the well via a pipeline (here, an independent pipeline connects the drilling fluid storage tank to the drilled well). One end of the high-pressure water pump is connected to the flexible drill pipe via a pipeline to pump the drilling fluid and broken rock cuttings out of the well. The other end of the high-pressure water pump is connected to the settling tank to settle the broken rock cuttings. The settling tank is connected to the drilling fluid storage tank, allowing the treated drilling fluid to be recycled.

[0059] Preferably, the drilling fluid is one of natural groundwater, NaCl solution, NaOH solution, and CaCl2 solution, and the concentration of the NaCl solution, NaOH solution, and CaCl2 solution in the drilling fluid is 0.01~0.5%.

[0060] The flexible drill rod contains a cable that connects the high-voltage electric pulse rock-breaking drill bit and the high-voltage electric pulse power supply device, serving as a connection and guide (the flexible drill rod is fixed and suspended on the support by the flexible drill rod fixing gripper on the support); at the same time, it transmits (the flexible drill rod contains a cable, and through the electromagnetic induction of the cable, relevant electromagnetic data is generated, and the data is transmitted to the ground monitoring instrument through the cable in the flexible drill rod) the drilling measurement data of the high-voltage electric pulse rock-breaking drill bit to the drilling data ground monitoring instrument.

[0061] The flexible drill pipe consists of an inner cavity 15, an outer cavity 16, and a mating end 17. The inner cavity 15 serves as a drilling fluid delivery channel, and the outer cavity 16 is a space for cable placement. Figures 4-8 A schematic diagram of the flexible drill pipe structure is shown; wherein, Figure 4 The diagram shows the joint end of two flexible drill pipes after splicing and the cross-sectional structure of the flexible drill pipes. Figure 5-8 This is a schematic diagram of the external and internal ends of a flexible drill pipe joint, along with its top view. Figure 7 The small protrusion on the internal end passes through Figure 5 The "L"-shaped groove in the external end allows the mating ends of the two flexible drill pipes to be rotated and fixed, and... Figure 7 The electrical connector on the internal terminal "pops in". Figure 5 The connection between the two flexible drill rods is completed in the groove of the electrical connector at the external end. Figure 6 yes Figure 5 Top view of the external end. Figure 8 yes Figure 7 Top view of the internal terminal.

[0062] Preferably, two adjacent flexible drill rods 5 are connected by a mating end 17, which contains an electromagnetic coil 18 and an electrical connector 19 to achieve effective transmission of high voltage and high voltage pulses. The flexible drill rod has a certain strength and can support the high voltage pulse rock-breaking drill bit, thereby guiding the high voltage pulse rock-breaking drill bit to change its drilling direction. Each flexible drill rod has a fixed length, and as the drilling depth increases, the flexible drill rod is continuously extended to ensure that the drill bit can be lowered to the predetermined drilling depth.

[0063] Preferably, the drilling angle of the high-voltage electric pulse rock-breaking drill bit is 0-180°, controlled by a flexible drill rod.

[0064] The operation control device is electrically connected to the high-voltage pulse power supply, drilling fluid storage and pumping device, and support frame. It controls the power supply, voltage, and discharge duration of the high-voltage pulse power supply; it controls the start / stop of drilling fluid pumping and the flow rate; and it controls the drilling and lifting of the flexible drill pipe. The operation control device controls the high-voltage pulse power supply as follows: First, the power supply is turned on via the power switch in the operation control device. Based on the rock-breaking requirements, the voltage and discharge duration of each discharge are adjusted. After rock breaking is complete, the power supply is turned off in the operation control device. The operation control device also controls the drilling fluid storage and pumping device as follows: Before the high-voltage pulse rock-breaking drill bit begins rock breaking, the drilling fluid storage and pumping device is turned on via the control button in the operation control device. The drilling fluid flow rate is adjusted to ensure proper flow of drilling fluid between the drill bit (flexible drill pipe), the drilling fluid storage tank, and the high-pressure pump. An effective circulation is formed between the sedimentation tank and the drilling fluid storage and pumping device. After rock breaking is completed, the drilling fluid storage and pumping device is shut off via the control button in the operation control device. The operation control device controls the support as follows: When a flexible drill pipe needs to be added, first, the high-voltage pulse power supply and the high-pressure water pump are shut off via the power switch of the high-voltage pulse power supply device and the control button of the drilling fluid storage and pumping device in the operation control device. Then, the flexible drill pipe fixing device secures the high-voltage pulse rock breaking drill bit or... After the flexible drill rod is installed, separate the high-voltage pulse rock-breaking drill bit (flexible drill rod) from the docking end of the high-voltage pulse power supply. Using the control button on the support in the operation control device, place the flexible drill rod on the grabbing and lifting device on the rear side of the outer frame of the support, so that the grabbing and lifting device grips the flexible drill rod tightly and aligns the docking end of the flexible drill rod with the docking end of the high-voltage pulse power supply. Lower the flexible drill rod to connect and fix it to the high-voltage pulse rock-breaking drill bit (flexible drill rod). Open the flexible drill rod fixing device and connect the cable of the flexible drill rod to the high-voltage pulse power supply.

[0065] The drilling data ground monitoring instrument is used to monitor and collect the drilling angle, drilling azimuth angle, pressure at the bottom of the well, and physical properties of the formation such as resistivity, density, and porosity of the drilled formation by the high-voltage electric pulse rock breaking drill bit.

[0066] The support frame includes a tracked walking device 20, an outer frame 21, a grabbing and lifting device 22, and a flexible drill pipe fixing gripper 23, used for fixing the drilling position and lifting and lowering the high-voltage electric pulse rock-breaking drill bit and flexible drill pipe. The outer frame 21 consists of two columns with a slight inclination on the left, two columns with a slight inclination on the right, and a connecting beam connecting the two columns, forming a stable trapezoidal body. The grabbing and lifting device 22 for the high-voltage electric pulse rock-breaking drill bit and flexible drill pipe is located on the rear side of the outer frame of the support frame and includes a vertical fixing mechanism. The system includes a vertical fixing plate fixed to the rear side of the outer frame and containing a vertical groove. The lifting slider is embedded in the groove to enable vertical movement of the lifting slider, ensuring the lifting and lowering of the high-voltage electric pulse rock-breaking drill bit and the flexible drill rod. The flexible drill rod fixing gripper 23 is fixed to the lower end of the outer frame of the support for gripping and fixing the flexible drill rod. The tracked walking device 20 is located at the lower part of the outer frame, facilitating the positioning and movement of the high-voltage electric pulse rock-breaking detection rock displacement and the breaking device.

[0067] This invention provides a method for detecting rock strata displacement and failure state using the above-mentioned device, comprising the following steps:

[0068] (1) Based on the preliminary basic geological data, including the range of mined goaf, the number and lithology of the overlying strata, and the physical and mechanical properties of the overlying strata, determine the location of the high-voltage electric pulse rock breaking detection point; ensure that the rock breaking detection borehole is located within the planned upstream mining coal seam range, so as to observe the structural characteristics of the overlying strata in different goaf locations.

[0069] (2) Fix the high-voltage electric pulse rock breaking detection device, align the high-voltage electric pulse rock breaking drill bit with the measuring point, and prepare drilling fluid, drilling fluid storage tank and sedimentation tank; set the drilling direction of the high-voltage electric pulse rock breaking drill bit;

[0070] (3) Manually excavate a pilot tunnel with a cross-sectional edge of 10cm and a depth of 0.3~1.0m at the measuring point location, and introduce drilling fluid into the pilot tunnel;

[0071] (4) Lower the high-voltage electric pulse rock breaking drill bit into the pilot pit, connect the high-voltage electric pulse rock breaking drill bit to the high-voltage electric pulse power supply cable; turn on the main switch of the operation control device and start the drilling fluid high-pressure pump to make the drilling fluid circulate between the pilot pit, the drilling fluid storage tank and the sedimentation tank, and then turn on the high-voltage electric pulse power supply to start high-voltage electric pulse rock breaking drilling.

[0072] (5) When the initial rock-breaking drilling depth is 4 / 5 of the height of the high-voltage electric pulse rock-breaking drill bit, turn off the high-voltage electric pulse power supply and the drilling fluid high-pressure pump; after the high-voltage electric pulse rock-breaking drill bit is fixed by the flexible drill rod fixing device, separate the docking end of the high-voltage electric pulse rock-breaking drill bit from the high-voltage electric pulse power supply; place the flexible drill rod one on the grab lifting device on the back side of the outer frame of the support, so that the docking end of the flexible drill rod is aligned with the docking end of the high-voltage electric pulse power supply, lower the flexible drill rod one, so that the flexible drill rod one is connected and fixed to the high-voltage electric pulse rock-breaking drill bit, open the flexible drill rod fixing device, and at the same time connect the cable of the flexible drill rod one to the high-voltage electric pulse power supply;

[0073] (6) Restart the drilling fluid high-pressure pump and the high-voltage electric pulse power supply to put the high-voltage electric pulse rock-breaking drill bit into the rock-breaking drilling state; when the height of the flexible drill rod end above the ground is the distance from the flexible drill rod fixing device to the ground, turn off the high-voltage electric pulse power supply and the drilling fluid pumping high-pressure pump; after the flexible drill rod fixing device fixes the flexible drill rod one, separate the flexible drill rod one from the docking end of the high-voltage electric pulse power supply; place the flexible drill rod two on the grab lifting device on the rear side of the support frame so that the docking end of the flexible drill rod one is connected to the flexible drill rod two. Align the docking ends, lower the second flexible drill rod, and connect and fix the first flexible drill rod to the second flexible drill rod. Open the flexible drill rod fixing device and connect the second flexible drill rod to the cable of the high-voltage electric pulse power supply. Turn on the drilling fluid high-pressure pump and the high-voltage electric pulse power supply again to put the high-voltage electric pulse rock-breaking drill bit into the rock-breaking drilling state. Repeat this process (as the drilling depth increases, add the third flexible drill rod, the fourth flexible drill rod, etc., until the predetermined drilling depth is reached) until the planned rock-breaking drilling depth is reached, and then stop rock-breaking drilling.

[0074] (7) Throughout the rock-breaking drilling process, the drilling fluid pump high-pressure water pump pumps the drilling fluid and the rock cuttings broken by the high-voltage electric pulse rock-breaking drill bit from the bottom of the rock-breaking borehole through the inner cavity of the flexible drill pipe to the sedimentation tank (the drilling fluid and rock cuttings flow out together); the drilling fluid after sedimentation in the sedimentation tank is returned to the drilling fluid storage tank for recycling; at the same time, the drilling parameters of the high-voltage electric pulse rock-breaking drill bit and the formation physical properties parameters are monitored in real time by the drilling data ground monitoring instrument.

[0075] (8) During the rock breaking and drilling process of the high-voltage electric pulse rock breaking drill bit, the drilling fluid inflow and outflow are recorded in real time, the drilling fluid loss rate is calculated, and the rock breaking and drilling rate of the high-voltage electric pulse rock breaking drill bit is recorded at the same time.

[0076] (9) Repeat the above steps to complete the rock breaking detection of all measuring points within the range; based on the length of each measuring point, the drilling fluid loss rate and the rock breaking drilling rate of the high-voltage electric pulse rock breaking drill bit, draw the flow distribution map and the rock breaking drilling rate map of different boreholes respectively, analyze the fracture development characteristics and permeability characteristics at different locations within the length of the rock breaking borehole, and further combine the cumulative continuous leakage section length (i.e. the zero point of leakage change) L1+L2+…Ln… (n=1、2、....、k) to calculate the damage range and damage situation of the rock mass in different spatial ranges, thereby judging the stability of the overlying rock mass and providing basic data for the feasibility judgment of subsequent upward mining.

[0077] In this embodiment, the above steps are repeated to complete the rock breaking detection of all measuring points within the range; taking a coal mine in Datong, Shanxi as an example, the length of measuring point 1 in the goaf area of ​​coal seam No. 22 is 149m, and the lithology of the overlying strata and the drilling fluid loss rate from top to bottom are shown in Table 1.

[0078] Table 1. Statistics on lithology of overlying strata and drilling fluid loss rate at measuring point No. 1

[0079]

[0080] As shown in Table 1, the first soil layer has higher permeability than the rock, with a permeability range (drilling fluid loss section) of 54m. The third silty mudstone layer has a drilling fluid loss section of 4m, the fourth fine sandstone layer has a drilling fluid loss section of 2m, the fifth No. 16-2 coal seam has a drilling fluid loss section of 2m, the sixth sandy mudstone layer has a drilling fluid loss section of 2m, the eighth No. 19 coal seam has a drilling fluid loss section of 3m, the ninth sandy mudstone layer has a drilling fluid loss section of 11m, and the tenth fine sandstone layer has a drilling fluid loss section of 10m. Therefore, the total continuous leakage section length of the entire borehole at measuring point 1 is 54+4+2+2+2+3+11+10=88m. The main rock mass damage is concentrated in the mined No. 16-2 coal seam and its roof and floor, as well as the fine sandstone of the roof of the No. 22 coal seam. Meanwhile, the drilling fluid loss rate in the fine sandstone section of the No. 22 coal seam roof is relatively small, and the stability of the fine sandstone can be further determined by combining the rock fracture theory, thus providing basic data for the feasibility assessment of subsequent upward mining.

Claims

1. A device for detecting rock displacement and failure state during high-voltage electric pulse rock breaking, characterized in that: include: High-voltage electric pulse rock-breaking drill bit, high-voltage electric pulse power supply device, drilling data ground monitoring instrument, drilling fluid storage and pumping device, operation control device, flexible drill pipe and support; The high-voltage electric pulse rock-breaking drill bit is connected to the bottom end of the flexible drill rod, and the upper end of the flexible drill rod is connected to the high-voltage electric pulse power supply device, the drilling data ground monitoring instrument, and the drilling fluid storage and pumping device; the operation control device is connected to the high-voltage electric pulse power supply device and the drilling fluid storage and pumping device; the flexible drill rod and the operation control device are fixed on the support. A high-voltage electric pulse rock-breaking drill bit is connected to the high-voltage electric pulse power supply device via a flexible drill rod internal cable to achieve drilling of the rock mass. The high-voltage electric pulse rock-breaking drill bit includes a drill bit insulating support, an outer ring low-voltage electrode, and an inner ring high-voltage electrode. The drill bit insulating support is used to fix the outer ring low-voltage electrode and the inner ring high-voltage electrode, and the distance between the outer ring low-voltage electrode and the inner ring high-voltage electrode is adjustable. The drill bit insulating support has a hollow structure with a drilling fluid channel in the middle. A high-voltage pulse power supply device is electrically connected to the high-voltage pulse rock-breaking drill bit through a cable in the flexible drill rod, providing high-voltage pulse power to the high-voltage pulse rock-breaking drill bit. The drilling fluid storage and pumping device includes a drilling fluid storage tank, a high-pressure water pump, and a settling tank. It provides drilling fluid between the inner high-pressure electrode and the outer low-pressure electrode during rock breaking by the high-pressure electric pulse rock-breaking drill bit. The drilling fluid storage tank transports the drilling fluid downhole through pipelines. One end of the high-pressure water pump is connected to a flexible drill pipe through a pipeline to pump the drilling fluid and broken rock cuttings out of the well. The other end of the high-pressure water pump is connected to the settling tank to settle the broken rock cuttings. The settling tank is connected to the drilling fluid storage tank, allowing the treated drilling fluid to be recycled. The flexible drill pipe contains a cable connecting the high-voltage pulse rock-breaking drill bit and the high-voltage pulse power supply device, serving to connect, support, and guide the drill bit's drilling direction; it also transmits drilling measurement data from the high-voltage pulse rock-breaking drill bit to the drilling data ground monitoring instrument. The flexible drill pipe consists of an inner cavity, an outer cavity, and a connecting end, where the inner cavity is the drilling fluid delivery channel and the outer cavity is the cable placement space. The device includes several flexible drill pipes, with adjacent flexible drill pipes connected by a connecting end containing an electrical connector and an electromagnetic coil to achieve high-voltage and high-voltage... Effective transmission of electrical pulses; the flexible drill rod has a certain strength, which can support the high-voltage electrical pulse rock-breaking drill bit and guide it to change its drilling direction; each flexible drill rod has a fixed length, and as the drill bit's drilling depth increases, the flexible drill rod is continuously extended to ensure that the drill bit can be lowered to the predetermined drilling depth; the drilling angle of the high-voltage electrical pulse rock-breaking drill bit is controlled from 0 to 180° through the flexible drill rod; the high-voltage electrical pulse rock-breaking drill bit is circular or polygonal in shape; the drill bit insulation support is circular or polygonal in shape. The operation control device is electrically connected to the high-voltage pulse power supply device, drilling fluid storage and pumping device, and support, and is used to control the power supply of the high-voltage pulse power supply device to turn on and off, the voltage level, and the discharge duration. Used for controlling the start and stop of drilling fluid pumping, controlling the flow rate of drilling fluid pumping, and controlling the drilling and lifting of flexible drill pipe; The drilling data ground monitoring instrument is used to monitor and collect the drilling angle, drilling azimuth angle, pressure at the bottom of the well, and physical properties of the formation such as resistivity, density, and porosity of the drilled formation by the high-voltage electric pulse rock breaking drill bit. The support frame includes tracks, an outer frame, a lifting and grappling device, and a flexible drill pipe fixing gripper. It is used for fixing the drilling position and for lifting and lowering the high-voltage pulse rock-breaking drill bit and the flexible drill pipe. The outer frame consists of two columns on the left and two columns on the right, and a connecting beam connecting the two columns. The upper parts of the columns on both sides are inclined inwards, forming a stable trapezoidal shape. The lifting and grappling device for the high-voltage pulse rock-breaking drill bit and the flexible drill pipe is located at the rear of the outer frame and includes a vertical fixing plate and a lifting and grappling slider. The vertical fixing plate is fixed to the rear of the outer frame and includes a vertical groove. The lifting and grappling slider is embedded in the groove to achieve vertical movement of the lifting and grappling slider, ensuring the lifting and lowering of the high-voltage pulse rock-breaking drill bit and the flexible drill pipe. The flexible drill pipe fixing gripper is fixed to the lower end of the outer frame and is used to grip and fix the flexible drill pipe. The tracks are located at the lower part of the outer frame, facilitating the positioning and movement of the high-voltage pulse rock-breaking detection rock displacement and breaking device. Both the outer ring low-voltage electrode and the inner ring high-voltage electrode are composed of multiple sub-electrodes. The sub-electrodes are needle-shaped, L-shaped, or inverted L-shaped. The sub-electrodes are spliced ​​to facilitate the replacement of severely worn sub-electrode heads. The sub-electrodes are made of pure copper, graphite, or steel.

2. The device for detecting rock displacement and failure state during high-voltage electric pulse rock breaking according to claim 1, characterized in that: A grid is installed at the drilling fluid passage opening in the middle of the drill bit insulation support to prevent larger pieces of rock from being sucked back into the drilling fluid delivery pipe after breakage, causing blockage.

3. The device for detecting rock displacement and failure state during high-voltage electric pulse rock breaking according to claim 2, characterized in that: The drill bit insulation support is made of either corundum or polytetrafluoroethylene; the grid is directly welded and fixed to the insulation support, and the holes in the grid are evenly distributed with a diameter of 2cm.

4. The device for detecting rock displacement and failure state during high-voltage electric pulse rock breaking according to claim 1, characterized in that: Both the outer ring low-voltage electrode and the inner ring high-voltage electrode are connected to the lower end of the drill bit insulation support; the connection between the inner ring high-voltage electrode and the insulation support is a rotating snap-fit ​​connection, and the drill bit insulation support can be rotated to adjust the distance between the sub-electrodes of the outer ring low-voltage electrode and the inner ring high-voltage electrode.

5. The device for detecting rock displacement and failure state during high-voltage electric pulse rock breaking according to claim 1, characterized in that: The drilling fluid is one of the following: natural groundwater, NaCl solution, NaOH solution, and CaCl2 solution, wherein the concentration of NaCl solution, NaOH solution, and CaCl2 solution is 0.01%~0.5%.

6. The device for detecting rock displacement and failure state during high-voltage electric pulse rock breaking according to claim 1, characterized in that: Control of the high-voltage pulse power supply by the operation control device: First, turn on the power of the high-voltage pulse power supply device via the power switch in the operation control device. Adjust the voltage and discharge duration required during the rock-breaking process according to the rock-breaking needs. After rock breaking is complete, turn off the power of the high-voltage pulse power supply device in the operation control device. Control of the drilling fluid storage and pumping device by the operation control device: Before the high-voltage pulse rock-breaking drill bit begins rock breaking, turn on the drilling fluid storage and pumping device via the control button in the operation control device. Adjust the drilling fluid flow rate to ensure effective circulation of the drilling fluid between the drill bit, the high-voltage pulse rock-breaking drill bit, the drilling fluid storage tank, the high-pressure pump, and the sedimentation tank. After rock breaking is complete, turn off the drilling fluid storage and pumping device via the control button in the operation control device. And pumping device; control of the support by the operation control device: When it is necessary to add flexible drill pipe, firstly, turn off the high-voltage pulse power supply and the high-pressure water pump of the drilling fluid storage and pumping device by using the power switch of the high-voltage pulse power supply device and the control button of the drilling fluid storage and pumping device in the operation control device. Then, after fixing the high-voltage pulse rock-breaking drill bit or flexible drill pipe by the flexible drill pipe fixing device by using the control button of the support in the operation control device, separate the docking end of the high-voltage pulse rock-breaking drill bit from the high-voltage pulse power supply. Then, place the flexible drill pipe on the grab lifting device on the rear side of the outer frame of the support by using the grab lifting device to grip the flexible drill pipe tightly and align the docking end of the flexible drill pipe with the docking end of the high-voltage pulse power supply. Lower the flexible drill pipe to connect and fix it to the high-voltage pulse rock-breaking drill bit. Open the flexible drill pipe fixing device and connect the cable of the flexible drill pipe to the high-voltage pulse power supply.

7. A method for detecting rock strata displacement and failure state during high-voltage electric pulse rock breaking, comprising using the apparatus for detecting rock strata displacement and failure state during high-voltage electric pulse rock breaking as described in any one of claims 1 to 6, characterized in that... Includes the following steps: (1) Based on the preliminary basic geological data, including the range of mined goaf, the number and lithology of the overlying strata, and the physical and mechanical properties of the overlying strata, determine the location of the high-voltage electric pulse rock breaking detection point; ensure that the rock breaking detection borehole is located within the planned upstream mining coal seam range, so as to observe the structural characteristics of the overlying strata in goaf at different locations; (2) Fix the high-voltage electric pulse rock breaking detection device, align the high-voltage electric pulse rock breaking drill bit with the measuring point, and prepare drilling fluid, drilling fluid storage tank and sedimentation tank; set the drilling direction of the high-voltage electric pulse rock breaking drill bit; (3) Manually excavate a pilot tunnel with a cross-sectional edge of 10cm and a depth of 0.3m to 1.0m at the measuring point location, and introduce drilling fluid into the pilot tunnel; (4) Lower the high-voltage electric pulse rock breaking drill bit into the pilot tunnel and connect the high-voltage electric pulse rock breaking drill bit to the cable of the high-voltage electric pulse power supply. Turn on the main switch of the operation control device and start the drilling fluid high-pressure pump to make the drilling fluid circulate between the pilot tunnel, the drilling fluid storage tank and the sedimentation tank. Then turn on the high-voltage electric pulse power supply to start the high-voltage electric pulse rock breaking drilling. (5) When the initial rock-breaking drilling depth is 4 / 5 of the height of the high-voltage electric pulse rock-breaking drill bit, turn off the high-voltage electric pulse power supply and the drilling fluid high-pressure pump; after the high-voltage electric pulse rock-breaking drill bit is fixed by the flexible drill rod fixing device, separate the docking end of the high-voltage electric pulse rock-breaking drill bit from the high-voltage electric pulse power supply; place the flexible drill rod one on the grab lifting device on the back side of the outer frame of the support, so that the docking end of the flexible drill rod is aligned with the docking end of the high-voltage electric pulse power supply, lower the flexible drill rod one, so that the flexible drill rod one is connected and fixed to the high-voltage electric pulse rock-breaking drill bit, open the flexible drill rod fixing device, and at the same time connect the cable of the flexible drill rod one to the high-voltage electric pulse power supply; (6) Restart the drilling fluid high-pressure pump and the high-voltage electric pulse power supply to put the high-voltage electric pulse rock-breaking drill bit into the rock-breaking drilling state; when the height of the flexible drill rod end above the ground is the distance from the flexible drill rod fixing device to the ground, turn off the high-voltage electric pulse power supply and the drilling fluid pumping high-pressure pump; after the flexible drill rod fixing device fixes the flexible drill rod one, separate the flexible drill rod one from the docking end of the high-voltage electric pulse power supply; place the flexible drill rod two on the grab lifting device on the back side of the support frame, align the docking end of the flexible drill rod one with the docking end of the flexible drill rod two, lower the flexible drill rod two, connect and fix the flexible drill rod one and the flexible drill rod two, open the flexible drill rod fixing device, and at the same time connect the cable of the flexible drill rod two to the high-voltage electric pulse power supply; restart the drilling fluid high-pressure pump and the high-voltage electric pulse power supply to put the high-voltage electric pulse rock-breaking drill bit into the rock-breaking drilling state, repeat this process until the planned rock-breaking drilling depth is reached, and then stop rock-breaking drilling; (7) Throughout the rock-breaking drilling process, the drilling fluid pump high-pressure water pump pumps the drilling fluid and the rock cuttings broken by the high-voltage electric pulse rock-breaking drill bit from the bottom of the rock-breaking borehole through the inner cavity of the flexible drill pipe to the sedimentation tank; the drilling fluid after sedimentation in the sedimentation tank is returned to the drilling fluid storage tank for recycling; at the same time, the drilling parameters of the high-voltage electric pulse rock-breaking drill bit and the formation physical properties parameters are monitored in real time by the drilling data ground monitoring instrument. (8) During the rock breaking and drilling process of the high-voltage electric pulse rock breaking drill bit, the drilling fluid inflow and outflow are recorded in real time, the drilling fluid loss rate is calculated, and the rock breaking and drilling rate of the high-voltage electric pulse rock breaking drill bit is recorded at the same time. (9) Repeat steps (2) to (8) above to complete the rock breaking detection of all measuring points within the range; according to the length of each measuring point, the drilling fluid loss rate and the rock breaking drilling rate of the high-voltage electric pulse rock breaking drill bit, draw the flow distribution map and rock breaking drilling rate map of different boreholes respectively, analyze the fracture development characteristics and permeability characteristics of different locations within the length of the rock breaking borehole, and further combine the cumulative continuous leakage section length L1+L2+…Ln…, n=1、2、....、k to calculate the damage range and damage situation of the rock mass in different spatial ranges, thereby judging the stability of the overlying rock mass and providing basic data for the feasibility judgment of subsequent upward mining.

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