Top coal structure dynamic identification device and method based on sound-radon monitoring

Abstract

The invention discloses a top coal structure dynamic recognition device and method based on sound-radon monitoring, and relates to the technical field of coal mine underground mining. The device comprises a probe rod main body, a radon detection device and a sound wave detection device, the probe rod main body comprises a first section rod body, a tail section rod body and a plurality of sections of middle rod bodies, and the adjacent rod bodies are detachably and fixedly connected; the radon measuring device comprises a micro electromagnetic valve and a radon measuring instrument; the sound wave detection device comprises a sound wave transmitting probe, a sound wave receiving probe and a sound wave controller. The lengths of the feeler levers can be flexibly combined according to the actual drilling depth, and the requirements for different coal seam thicknesses and working conditions are effectively met; meanwhile, the micro electromagnetic valves are controlled in a segmented mode, radon gas concentration and sound wave signals of all segments are synchronously collected and subjected to fusion analysis, dynamic detection of the top coal structure is effectively achieved, and key technical support is provided for the fully mechanized caving face.

Description

Technical Field

[0001] This invention relates to the field of top coal structure identification technology, specifically to a dynamic identification device and method for top coal structure based on acoustic-radon monitoring. Background Technology

[0002] Fully mechanized top coal mining is one of the important methods for mining thick coal seams. Its principle is to simultaneously mine the lower part of the thick coal seam and use mine pressure to break up the upper roof coal, releasing it through the vent. The top coal structure, especially the identification of the coal-rock transition zone and the location of fracture development zones, directly affects the coal extraction efficiency, coal quality, and resource recovery rate. Therefore, accurately understanding the top coal structure is of great significance for optimizing coal extraction parameters, improving resource recovery rate, and reducing gangue contamination.

[0003] Traditional methods for judging top coal structure mainly rely on worker experience or single detection equipment. However, workers typically make judgments by observing the characteristics of coal and rock flow at the coal outlet and listening to sounds, which is highly subjective, unreliable, labor-intensive, and severely affected by environmental factors such as underground coal dust, light, and noise. Single physical quantity monitoring methods, such as vibration and acoustic emission methods, are greatly affected by vibration interference from mechanical equipment at the working face and have low signal-to-noise ratios; image and visual methods suffer from poor real-time performance due to the harsh underground environment, high dust levels, low visibility, and poor performance; radar, etc. γ The X-ray method requires expensive equipment, poses radiation safety risks, and is difficult to popularize. Therefore, there is an urgent need to invent a device that can resist interference, identify the top coal structure in real time, and accurately, to provide technical support for the safe and efficient mining of fully mechanized longwall faces in coal mines. Summary of the Invention

[0004] To address the aforementioned problems, this invention discloses a dynamic identification device and method for top coal structure based on acoustic-radon monitoring. By measuring the radon concentration in the coal and rock strata and the sound wave propagation speed, the device can grasp the state of the top coal structure and determine the coal-rock interface, significantly improving the accuracy and reliability of top coal structure and coal-rock interface identification.

[0005] According to the present invention, a dynamic identification device for top coal structure based on acoustic-radon monitoring is proposed, comprising a probe body, a radon measuring device, and an acoustic detection device; The probe body includes a first section, a last section, and multiple intermediate sections, with adjacent sections detachably and fixedly connected. Each section is a double-tube structure, including a pressure-bearing outer tube and a venting inner tube. Both the pressure-bearing outer tube and the venting inner tube are hollow tubes, with the venting inner tube coaxially arranged with the pressure-bearing outer tube and detachably and fixedly installed inside the pressure-bearing outer tube. The top of the first section is closed. The radon detection device includes a miniature solenoid valve and a radon detector. Each section of the rod has a first through hole on its pressure-bearing outer tube and a corresponding second through hole on its ventilation inner tube. The miniature solenoid valve is installed on the connecting pipe between the first and second through holes, and multiple miniature solenoid valves are provided for multiple sections of the rod. Multiple miniature solenoid valves are connected to a solenoid valve controller and are opened and closed under the control of the solenoid valve controller. The radon detector is connected to the ventilation inner tube. The acoustic wave detection device includes an acoustic wave probe and an acoustic wave controller. Each section of the rod has an expansion rubber ring fitted at the bottom of its pressure-bearing outer tube. The outer tube wall corresponding to the expansion rubber ring has a wire hole and an air injection opening, which communicates with the air injection port of the expansion rubber ring. The acoustic wave probes are installed around the expansion rubber rings in multiple groups, evenly distributed along the circumference of the expansion rubber rings. Each group of acoustic wave probes includes one acoustic wave emitting probe and multiple acoustic wave receiving probes. One acoustic wave emitting probe is installed around the expansion rubber ring on the tail section of the rod, and multiple acoustic wave receiving probes are correspondingly installed around the expansion rubber rings on the first and middle sections of the rod. The wires of the acoustic wave emitting probe and the acoustic wave receiving probe are led out through the wire hole and connected to the acoustic wave controller.

[0006] Preferably, a positioning bracket is provided between the pressure-bearing outer tube and the ventilation inner tube in each section of the rod, and the pressure-bearing outer tube and the ventilation inner tube are detachably and fixedly connected by the positioning bracket; the positioning bracket includes a C-shaped clamp, a wing bracket and a limiting boss; the C-shaped clamp is clamped onto the ventilation inner tube, the wing bracket is fan-shaped and three are evenly distributed along the circumference of the C-shaped clamp, and the limiting boss is fixedly installed on one fan-shaped surface of the wing bracket; the inner wall of the pressure-bearing outer tube is provided with a groove on the circumference of the groove to cooperate with the limiting boss for limiting, and the limiting boss is embedded in the groove.

[0007] Preferably, two sets of positioning brackets are symmetrically arranged vertically within each section of the rod, and two sets of slots are arranged axially along the pressure-bearing outer tube; a wire harness is also provided on the positioning bracket, and the wire harness is located between the two wing brackets.

[0008] Preferably, the radon measuring device further includes a filter device, which is cylindrical and threadedly connected to the first through hole on the pressure-bearing outer tube. The filter device includes a metal filter screen, a filter element, and a waterproof and breathable membrane arranged in sequence, with the waterproof and breathable membrane located close to the inner venting tube. The filter device is also provided with a solenoid valve interface.

[0009] Preferably, an expansion rubber ring is also fitted at the top of the first section of the rod; a hydraulic expansion ring is also fitted below the expansion rubber ring on the tail section of the rod.

[0010] Preferably, each section of the rod is fitted with an expansion rubber ring at the location where an installation seat is fitted. The installation seat is a hollow annular structure. The expansion rubber ring is located around the installation seat, with its inner side fixedly connected to the installation seat and its outer side expanding to contact the borehole wall.

[0011] Preferably, the acoustic probes are three groups evenly distributed along the circumference of the expansion rubber ring; each expansion rubber ring has three sliding links corresponding to the acoustic emitting probe or acoustic receiving probe, one end of the sliding link is connected to the mounting base, and the other end is connected to the expansion rubber ring, moving radially outward as the expansion rubber ring expands; the end of the sliding link away from the mounting base is attracted to a ring-shaped strong magnetic buckle, and the acoustic emitting probe or acoustic receiving probe is fixedly connected to the sliding link through the strong magnetic buckle.

[0012] Another method disclosed in this invention for identifying top coal structures using the aforementioned acoustic-radon-based dynamic identification device for top coal structures includes the following steps: S1. Modularly pre-assemble segmented poles on the ground and install radon measuring devices and acoustic detection devices on the poles; S2. Based on the thickness of the top coal, drill holes and select the appropriate number of standard length pre-installed segmented rods for installation, placing the first rod at the top and the last rod at the bottom; connect the quick-connect wire of each miniature solenoid valve to the main circuit of the solenoid valve controller, connect the quick-connect wire of each acoustic probe to the main circuit of the acoustic controller; connect the quick-connect air injection pipe of each expansion rubber ring to the main circuit of the air pump; during this process, fix all connecting cables in an orderly manner along the cable bundle on the positioning bracket; S3. Slowly lower the assembled probe rod to the designed depth in the borehole. Use a portable hydraulic pump to inject hydraulic oil into the hydraulic expansion steel ring until it makes stable contact with the borehole wall. Start the air pump and inject gas into the expansion rubber ring through the air injection hole. This causes the ring to expand and drive the sliding connecting rod to move radially outward until the outer side of the expansion rubber ring is tightly attached to the borehole wall. At this time, the acoustic wave transmitting probe and the acoustic wave receiving probe are both attached and fixed to the end of the corresponding sliding connecting rod by strong magnetic fasteners, achieving good acoustic coupling with the coal and rock mass. S4. In the solenoid valve controller and acoustic controller, set the corresponding measurement segment number for each connected segment rod, configure the start-up sequence, single opening duration and data acquisition sampling frequency of each micro solenoid valve, configure the acoustic signal characteristic parameters and the start-up sequence of the three sets of probes evenly distributed along the circumference of the probe rod body. S5. According to the set segment number, the corresponding micro solenoid valve is automatically opened; under negative pressure, radon gas in the coal and rock mass fissures and pores is purified by metal filter screen, filter element and waterproof breathable membrane, and then enters the ventilation inner tube through micro solenoid valve, and is then transported to the radon detector at the orifice to measure its radioactivity specific activity and calculate the concentration; the sound wave controller is started at the same time to control the transmission and reception of sound wave signals and calculate the sound wave velocity; S6. Based on the data of sound wave velocity and radon concentration collected by the sound wave controller and radon meter for each segment, construct the correlation curves of "sound wave velocity and top coal thickness" and "radon concentration and top coal thickness". Overlay the two curves and observe their corresponding trend. Based on the characteristics of radon concentration and sound wave propagation velocity in coal and rock mass under different fracture conditions, dynamically identify and classify the top coal structure type and determine the coal-rock boundary line.

[0013] Preferably, in S5, the formula for calculating the velocity of sound is: In the formula: V' k,i -No. k In a multi-transmitter acoustic probe i Wave velocity, m / s; ΔS i - The spacing between the acoustic probes in each section of the probe rod is the length of each section of the probe rod, in meters; ΔT k,i -No. k The first of the group of one-transmitter-multiple-receiver acoustic probes i Individual and i -1 time difference of signal received by an acoustic wave receiving probe, s; S i -No. i The distance from the sound wave receiving probe to the transmitting probe, in meters; S i-1 -No. i The distance from a sound wave receiving probe to a transmitting probe, in meters (m). T k,i -No. k The first of the group of one-transmitter-multiple-receiver acoustic probes i The time, s, when a sound wave receiving probe receives a sound wave signal; T k,i-1 -No. k The first of the group of one-transmitter-multiple-receiver acoustic probes i The time, in seconds, when a sound wave receiving probe receives a sound wave signal; V i - Among the three sets of single-transmitter, multi-receiver acoustic probes i Average wave velocity per segment, m / s.

[0014] Preferably, in S6, the coal-rock boundary line is located where the sound wave velocity jumps sharply from the lowest to the highest value, and the radon concentration remains at a relatively high level.

[0015] Compared with existing technologies, the advantages of the dynamic identification device and method for top coal structure based on acoustic-radon monitoring disclosed in this invention are: (1) This invention combines radon gas with acoustic detection technology, making full use of the radon gas occurrence characteristics and the sensitivity of radon gas migration to cracks and the response characteristics of acoustic waves to the medium structure, which significantly improves the accuracy and reliability of top coal structure and coal-rock interface identification.

[0016] (2) The present invention adopts a standard length modular design, which is convenient for transportation, quick installation and maintenance. The probe length can be flexibly combined according to the actual drilling depth, effectively adapting to different coal seam thicknesses and working conditions.

[0017] (3) The present invention can realize independent and continuous monitoring of the top coal structure of each segment, and provide real-time feedback on the dynamic changes of the top coal structure during the mining process, providing timely and accurate data support for intelligent decision-making in fully mechanized longwall mining. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the intermediate rod structure.

[0020] Figure 2 This is a cross-sectional view of the pressure-bearing outer pipe.

[0021] Figure 3 This is a schematic diagram of the sealing device at the top of the first section of the rod.

[0022] Figure 4 This is a schematic diagram of the installation of the inner tube and the positioning bracket.

[0023] Figure 5 This is a schematic diagram of the positioning bracket structure.

[0024] Figure 6 This is a schematic diagram of the filtration device.

[0025] Figure 7 This is a diagram showing the installation structure of an acoustic probe.

[0026] Figure 8 This is a schematic diagram of the underground measurement of the top coal structure dynamic identification device.

[0027] Figure 9 This is a schematic diagram of the underground measurement results of the dynamic identification method for top coal structure.

[0028] In the diagram: 1-First section of rod; 11-Plug; 2-Intermediate rod; 21-Pressure-bearing outer tube; 211-Slot; 212-First through hole; 213-Wire passage hole; 214-Air injection opening; 215-Threaded hole; 22-Ventilation inner tube; 221-Second through hole; 23-Positioning bracket; 231-Wing bracket; 232-C-type clamp; 233-Wire harness; 234-Limiting boss; 3-Filter device; 31-Metal filter screen; 3 2-Filter element; 33-Waterproof and breathable membrane; 34-Solenoid valve interface; 4-Miniature solenoid valve; 41-Miniature solenoid valve quick connector; 42-Solenoid valve controller; 5-Sound wave receiving probe; 51-Sound wave controller; 52-Sound wave probe quick connector; 6-Hydraulic expansion steel ring; 7-Expansion rubber ring; 71-Expansion rubber ring quick connector air injection pipe; 72-Sliding connecting rod; 73-Strong magnetic buckle; 74-Mounting base; 8-Air pump; 9-Radon detector. Detailed Implementation

[0029] The specific embodiments of the present invention will be briefly described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] Figures 1-9 A preferred embodiment of the present invention is shown and analyzed in detail.

[0031] The present invention discloses a dynamic identification device for top coal structure based on acoustic-radon monitoring, comprising a probe body, a radon measuring device, and an acoustic wave detection device.

[0032] The probe body consists of a first section 1, a last section, and multiple intermediate sections 2. For example... Figure 1 As shown, each section of the rod has a double-tube structure, including a pressure-bearing outer tube 21 and a ventilation inner tube 22; both the pressure-bearing outer tube 21 and the ventilation inner tube 22 are hollow steel tubes, coaxially arranged, with the ventilation inner tube 22 installed inside the pressure-bearing outer tube 21 via a positioning bracket 23. Figure 4 , 5 As shown, the positioning bracket 23 includes a C-shaped clamp 232, a wing bracket 231, and a limiting boss 234; the C-shaped clamp 232 is clamped onto the venting inner tube 22, the wing bracket 231 is fan-shaped, with three evenly distributed along the circumference of the C-shaped clamp 232, and the limiting boss 234 is fixedly installed on a fan-shaped surface of the wing bracket 231. Figure 2As shown, the inner wall of the pressure-bearing outer tube 21 is provided with a groove 211 on the circumferential direction to cooperate with and limit the positioning boss 234, and the positioning boss 234 is embedded in the groove 211. Two sets of positioning brackets 23 are symmetrically arranged vertically within each section of the rod, and two sets of grooves 211 are also provided along the axial direction of the pressure-bearing outer tube 21. A cable tie 233 is also provided on the positioning bracket 23; this cable tie 233 is arc-shaped and is located between two adjacent wing brackets 231. The venting inner tubes 22 on adjacent sections of the rod are connected by a socket joint and sealed with an O-ring. The connecting ends of the pressure-bearing outer tubes 21 on adjacent sections of the rod are provided with threaded holes 215, and adjacent pressure-bearing outer tubes 21 are connected in series by insertion and screw fixing. Figure 3 As shown, a plug 11 is installed at the top of the first section of the rod 1 to seal the venting inner tube 22 and prevent coal and rock debris from entering the probe body.

[0033] The radon detection device includes a miniature solenoid valve 4, a radon meter 9, and a filter device 3. For example... Figure 1 As shown, each section of the rod has a first through hole 212 in the middle of the pressure-bearing outer tube 21, and a corresponding second through hole 221 in the middle of the ventilation inner tube 22. Miniature solenoid valves 4 are installed on the connecting pipe between the first through hole 212 and the second through hole 221. Multiple miniature solenoid valves 4 are installed for each section of the rod, and all are connected to a single solenoid valve controller 42, opening and closing under the control of the controller 42. A quick-connect cable 41 for the miniature solenoid valve is located inside the cable bundle 233 of the positioning bracket 23, allowing for quick connection to the main line of the solenoid valve controller 42. A radon meter 9 is connected to the ventilation inner tube 22 and is used to measure the radioactive radon specific activity of radon gas and its decay products, calculating the radon concentration. Figure 6 As shown, the filter device 3 is cylindrical and threadedly connected to the first through hole 212 on the pressure-bearing outer pipe 21. The filter device 3 includes a sintered metal filter screen 31, a filter element 32, and an EPTFE waterproof and breathable membrane 33 arranged sequentially. The filter element 32 can be selected with filter media of different precision and materials according to the actual working conditions to remove fine particles, suspended solids, or other specific contaminants from the fluid. The waterproof and breathable membrane 33 is located close to the inner vent pipe 22. The waterproof and breathable membrane 33 material has a microporous structure, which can allow gas to pass through smoothly while effectively blocking the penetration of liquid, water vapor, and fine dust, maintaining the pressure balance inside and outside the system, and enhancing the protective performance of the filter element 32. The filter device 3 is also provided with a solenoid valve interface 34. The connecting pipe for installing the miniature solenoid valve 4 is connected to the solenoid valve interface 34 at one end of the first through hole 212.

[0034] The acoustic wave detection device includes an acoustic wave probe and an acoustic wave controller 51. For example... Figure 2 and Figure 7As shown, each section of the rod has an expansion rubber ring 7 fitted at the bottom of its pressure-bearing outer tube 21, and the first section of the rod 1 also has an expansion rubber ring 7 fitted at its top. The pressure-bearing outer tube 21 corresponding to the expansion rubber ring 7 has multiple through holes 213 and air injection holes 214. The air injection port of the expansion rubber ring 7 communicates with the air injection hole 214 and is connected to the air pump 8 via a quick-connect air injection pipe 71. Each section of the rod also has a mounting base 74 fitted at the location where the expansion rubber ring 7 is fitted. The mounting base 74 has an annular hollow structure, and the expansion rubber ring 7 is positioned around the mounting base 74. Its inner surface is fixedly connected to the mounting base 74, while its outer surface expands and contacts the borehole wall. The acoustic probes are installed around the expansion rubber ring 7 in three groups, evenly distributed around the circumference of the expansion rubber ring 7. Each group of acoustic probes is collinear and includes one acoustic emitting probe and multiple acoustic receiving probes 5. One acoustic emitting probe is installed around the expansion rubber ring 7 on the tail section rod body, and the multiple acoustic receiving probes 5 are correspondingly installed around the expansion rubber ring 7 on the first section rod body 1 and multiple intermediate sections rod body 2. The wires of the acoustic emitting probe and the acoustic receiving probe 5 are led out through the wire hole 213 and connected to the acoustic controller 51. The acoustic controller 51 provides operating power to the acoustic probes, controls the transmission signal, and receives and processes the acoustic signals collected by all the acoustic probes. Each expansion rubber ring 7 has three sliding connecting rods 72 corresponding to the acoustic emitting probe or the acoustic receiving probe 5. One end of the sliding connecting rod 72 is hinged to the mounting base 74, and the other end is fixedly connected to the expansion rubber ring 7. As the expansion rubber ring 7 expands, it moves radially outward, thereby driving the acoustic probe to make close contact with the borehole wall. A ring-shaped strong magnetic buckle 73 is attached to the end of the sliding connecting rod 72 away from the mounting base 74. The acoustic wave transmitting probe or acoustic wave receiving probe 5 is fixedly connected to the sliding connecting rod 72 through the strong magnetic buckle 73. The quick-connect cable 52 of the acoustic wave probe and the quick-connect air injection tube 71 of the expansion rubber ring are set in the cable bundle 233 of the positioning bracket 23 device, which facilitates quick connection and integration on site. A hydraulic expansion steel ring is also fitted below the expansion rubber ring 7 on the tail section rod body. After hydraulic oil is injected into the hydraulic expansion steel ring 6 and it expands, it can make stable contact with the borehole wall, thereby strengthening the fixation of the probe body.

[0035] like Figure 8 As shown, the air pump 8 is connected to the air injection port of the expansion rubber ring 7 and the bottom outlet of the venting inner tube 22. It is used to inject gas into the expansion rubber ring 7 and extract residual radon gas from the venting inner tube 22 to ensure accurate segmented measurement results.

[0036] like Figure 8 As shown, the present invention also discloses a method for identifying top coal structures using the aforementioned acoustic-radon-based dynamic identification device for top coal structures, comprising the following steps: S1. Modularly pre-assemble segmented poles on the ground and install the radon measuring device and acoustic wave detection device on the poles. Specifically, the C-shaped clamp 232 on the positioning bracket 23 is fitted onto the outer wall of the venting inner pipe 22, and the upper limit boss 234 of the positioning bracket 23 is engaged with the slot 211 on the pressure-bearing outer pipe 21 to ensure that the pressure-bearing outer pipe 21 and the venting inner pipe 22 in each segment of the pole are firmly connected and aligned; the filter device 3 is rotatably connected to the first through hole 212 on the pressure-bearing outer pipe 21, and the miniature solenoid valve 4 is connected to the solenoid valve interface 34 on the filter device 3 and the second through hole 221 on the venting inner pipe 22; the expansion rubber ring 7 is fitted onto the mounting base 74 on each segment of the pressure-bearing outer pipe 21, so that the air injection port of the expansion rubber ring 7 is connected to the air injection opening 214 on the pressure-bearing outer pipe 21; the quick-connect wire 52 of the acoustic wave probe is passed through the wire hole 213 on the pressure-bearing outer pipe 21, and coupling agent is applied to the acoustic wave probe.

[0037] S2. Based on the thickness of the top coal, drill holes and select the appropriate number of standard length pre-assembled segmented rods for installation, placing the first rod 1 at the top and the last rod at the bottom; connect the quick-connect wire 41 of each miniature solenoid valve to the main line of the solenoid valve controller 42, and connect the quick-connect wire 52 of each acoustic probe to the main line of the acoustic controller 51; connect the quick-connect air injection pipe 71 of each expansion rubber ring to the main line of the air pump 8; during this process, fix all connecting cables in an orderly manner along the cable tie 233 on the positioning bracket 23; install a plug 11 at the top of the first rod 1 to seal the probe, install an O-ring seal at the inlet of each section of the venting inner pipe 22, connect each section of the pressure-bearing outer pipe 21 and the venting inner pipe 22 in sequence, and install fastening screws on the threaded holes 215 of each section of the pressure-bearing outer pipe 21 to assemble the probe of the required length; fit the hydraulic expansion steel ring 6 onto the tail end of the last rod.

[0038] S3. Slowly lower the assembled probe rod to the designed depth in the borehole. Use a portable hydraulic pump to inject hydraulic oil into the hydraulic expansion steel ring 6 until it makes stable contact with the borehole wall. Start the air pump 8 and inject gas into all the expansion rubber rings 7 through the air injection opening 214. This causes them to expand and drive the sliding connecting rod 72 to move outward radially until the outer side of the expansion rubber ring 7 is tightly attached to the borehole wall. At this time, the acoustic wave transmitting probe and the acoustic wave receiving probe 5 are both attached and fixed to the end of the corresponding sliding connecting rod 72 by the strong magnetic buckle 73, achieving good acoustic coupling with the coal and rock mass.

[0039] S4. In the solenoid valve controller 42 and the acoustic wave controller 51, set the corresponding measurement segment number for each connected segment rod, configure the start-up sequence, single opening duration and data acquisition sampling frequency of each micro solenoid valve 4, configure the acoustic wave signal characteristic parameters and the start-up sequence of the three sets of probes evenly distributed along the circumference of the probe rod body.

[0040] S5. According to the set segment number, the corresponding micro solenoid valve 4 is automatically opened; under negative pressure, radon gas in the coal and rock mass fissures and pores is purified by the metal filter screen 31, filter element 32 and EPTFE waterproof and breathable membrane 33, and then enters the ventilation inner pipe 22 through the micro solenoid valve 4, and is then transported to the radon detector 9 at the orifice to measure its radioactivity specific activity and calculate the concentration; after each collection, the air pump 8 is started to flush the residual gas in the pipeline. The acoustic wave controller 51 is started simultaneously to control the transmission and reception of acoustic wave signals and calculate the acoustic wave velocity; The formula for calculating the velocity of sound is: In the formula: V' k,i -No. k In a multi-transmitter acoustic probe i Wave velocity, m / s; ΔS i - The spacing between the acoustic probes in each section of the probe rod is the length of each section of the probe rod, in meters; ΔT k,i -No. k The first of the group of one-transmitter-multiple-receiver acoustic probes i Individual and i -1 acoustic wave receiving probe receives 5 signals with time difference, s; S i -No. i The distance from the sound wave receiving probe 5 to the transmitting probe, in meters; S i-1 -No. i The distance from one acoustic receiving probe 5 to the transmitting probe, in meters (m). T k,i -No. k The first of the group of one-transmitter-multiple-receiver acoustic probes i The time, s, when the acoustic wave receiving probe 5 receives the acoustic wave signal; T k,i-1 -No. k The first of the group of one-transmitter-multiple-receiver acoustic probes i The time, in seconds, when one acoustic wave receiving probe 5 receives the acoustic wave signal; V i - Among the three sets of single-transmitter, multi-receiver acoustic probes i Average wave velocity per segment, m / s.

[0041] S6. Based on the data of sound wave velocity and radon concentration collected by the sound wave controller 51 and the radon meter 9, the data are spatiotemporally synchronized with a ground computer via wired or wireless transmission; correlation curves between "sound wave velocity and top coal thickness" and "radon concentration and top coal thickness" are constructed, such as... Figure 9 As shown, the two curves are overlaid and analyzed to observe their corresponding trends. Based on the radon concentration and sound wave propagation velocity characteristics of coal and rock masses under different fracture conditions, the top coal structure type is dynamically identified and classified, and the coal-rock boundary line is determined. Specifically, the coal-rock boundary line is located where the sound wave velocity jumps sharply from its lowest to its highest value, while the radon concentration remains at a relatively high level.

[0042] The above description of the disclosed embodiments enables those skilled in the art to make and use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit and scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dynamic identification device for top coal structure based on acoustic-radon monitoring, characterized in that, It includes the probe body, radon detection device, and acoustic detection device; The probe body includes a first section (1), a last section, and multiple intermediate sections (2), with adjacent sections being detachably and fixedly connected. Each section is a double-tube structure, including a pressure-bearing outer tube (21) and a ventilation inner tube (22). Both the pressure-bearing outer tube (21) and the ventilation inner tube (22) are hollow tubes. The ventilation inner tube (22) is coaxially arranged with the pressure-bearing outer tube (21) and is detachably and fixedly installed inside the pressure-bearing outer tube (21). The top of the first section (1) is closed. The radon measuring device includes a miniature solenoid valve (4) and a radon meter (9). Each section of the rod has a first through hole (212) on its pressure-bearing outer tube (21) and a corresponding second through hole (221) on its ventilation inner tube (22). The miniature solenoid valve (4) is installed on the connecting pipe between the first through hole (212) and the second through hole (221). Multiple miniature solenoid valves (4) are provided for multiple sections of the rod. Multiple miniature solenoid valves (4) are connected to a solenoid valve controller (42) and are opened and closed under the control of the solenoid valve controller (42). The radon meter (9) is connected to the ventilation inner tube (22). The acoustic detection device includes an acoustic probe and an acoustic controller (51); each section of the rod has an expansion rubber ring (7) fitted at the bottom of the pressure-bearing outer tube (21), and the wall of the pressure-bearing outer tube (21) corresponding to the expansion rubber ring (7) is provided with a wire hole (213) and an air injection hole (214), and the air injection hole (214) is connected to the air injection port of the expansion rubber ring (7); the acoustic probe is installed around the expansion rubber ring (7), and there are multiple groups evenly distributed along the circumference of the expansion rubber ring (7). Each group of acoustic probes includes an acoustic emitting probe and multiple acoustic receiving probes (5). One acoustic emitting probe is installed around the expansion rubber ring (7) on the tail section of the rod, and multiple acoustic receiving probes (5) are installed around the expansion rubber ring (7) on the first section of the rod (1) and the middle section of the rod (2), respectively. The wires of the acoustic emitting probe and the acoustic receiving probe (5) are led out through the wire hole (213) and connected to the acoustic controller (51).

2. The dynamic identification device for top coal structure based on acoustic-radon monitoring according to claim 1, characterized in that, A positioning bracket (23) is provided between the pressure-bearing outer tube (21) and the ventilation inner tube (22) in each section of the rod, and the pressure-bearing outer tube (21) and the ventilation inner tube (22) are detachably and fixedly connected by the positioning bracket (23); the positioning bracket (23) includes a C-shaped clamp (232), a wing bracket (231) and a limiting boss (234); the C-shaped clamp (232) is clamped on the ventilation inner tube (22), the wing bracket (231) is fan-shaped, and three are evenly distributed along the circumference of the C-shaped clamp (232), and the limiting boss (234) is fixedly installed on a fan-shaped surface of the wing bracket (231); the inner wall of the pressure-bearing outer tube (21) is provided with a groove (211) that cooperates with the limiting boss (234) for limiting, and the limiting boss (234) is embedded in the groove (211).

3. The dynamic identification device for top coal structure based on acoustic-radon monitoring according to claim 2, characterized in that, Two sets of positioning brackets (23) are symmetrically arranged in the upper and lower parts of each rod body, and two sets of slots (211) are arranged along the axial direction of the pressure-bearing outer tube (21); a wire bundler (233) is also provided on the positioning bracket (23), and the wire bundler (233) is located between the two wing brackets (231).

4. The dynamic identification device for top coal structure based on acoustic-radon monitoring according to claim 1, characterized in that, The radon measuring device also includes a filter device (3), which is cylindrical and threadedly connected to the first through hole (212) on the pressure-bearing outer tube (21). The filter device (3) includes a metal filter screen (31), a filter element (32), and a waterproof and breathable membrane (33) arranged in sequence. The waterproof and breathable membrane (33) is located close to the ventilation inner tube (22). The filter device (3) is also provided with a solenoid valve interface (34).

5. A dynamic identification device for top coal structure based on acoustic-radon monitoring according to claim 1, characterized in that, The top of the first section rod (1) is also fitted with an expansion rubber ring (7); a hydraulic expansion ring is also fitted below the expansion rubber ring (7) on the tail section rod.

6. A dynamic identification device for top coal structure based on acoustic-radon monitoring according to claim 5, characterized in that, At the position where the expansion rubber ring (7) is fitted on each section of the rod, a mounting seat (74) is also fitted. The mounting seat (74) is a ring-shaped hollow structure. The expansion rubber ring (7) is set on the periphery of the mounting seat (74), and its inner side is fixedly connected to the mounting seat (74). Its outer side expands and contacts the borehole wall.

7. A dynamic identification device for top coal structure based on acoustic-radon monitoring according to claim 6, characterized in that, The acoustic probes are three sets evenly distributed around the circumference of the expansion rubber ring (7); each expansion rubber ring (7) has three sliding rods (72) corresponding to the acoustic emitting probe or acoustic receiving probe (5). One end of the sliding rod (72) is connected to the mounting base (74), and the other end is connected to the expansion rubber ring (7). The sliding rod (72) moves outward radially as the expansion rubber ring (7) expands. The end of the sliding rod (72) away from the mounting base (74) is attached with a ring-shaped strong magnet buckle (73). The acoustic emitting probe or acoustic receiving probe (5) is fixedly connected to the sliding rod (72) through the strong magnet buckle (73).

8. A method for identifying top coal structure using the acoustic-radon monitoring-based dynamic identification device for top coal structure according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Modularly pre-assemble segmented poles on the ground and install radon measuring devices and acoustic detection devices on the poles; S2. Based on the thickness of the top coal, drill holes and select the corresponding number of standard length pre-installed segmented rods for installation. Place the first rod (1) at the top and the last rod at the bottom. Connect each segment of the miniature solenoid valve quick-connect wire (41) to the main line of the solenoid valve controller (42) and connect each segment of the acoustic probe quick-connect wire (52) to the main line of the acoustic controller (51). Connect each segment of the expansion rubber ring quick-connect air injection pipe (71) to the main line of the air pump (8). During this process, fix all connecting cables in an orderly manner along the cable tie (233) on the positioning bracket (23). S3. Slowly lower the assembled probe into the designed depth in the borehole. Use a portable hydraulic pump to inject hydraulic oil into the hydraulic expansion steel ring (6) until it is in stable contact with the borehole wall. Start the air pump (8) and inject gas into the expansion rubber ring (7) through the air injection hole (214) to make it expand and drive the sliding connecting rod (72) to move outward radially until the outer side of the expansion rubber ring (7) is tightly attached to the borehole wall. At this time, the acoustic wave transmitting probe and the acoustic wave receiving probe (5) are both attached and fixed to the end of the corresponding sliding connecting rod (72) by strong magnetic buckle (73) to achieve good acoustic coupling with the coal and rock mass. S4. In the solenoid valve controller (42) and the acoustic wave controller (51), set the corresponding measurement segment number for each connected segment rod, configure the start-up sequence, single opening duration and data acquisition sampling frequency of each micro solenoid valve (4), configure the acoustic wave signal characteristic parameters and the start-up sequence of the three sets of probes evenly distributed along the circumference of the probe rod body. S5. According to the set segment number, the corresponding micro electromagnetic valve (4) is automatically opened; under negative pressure, the radon gas in the coal and rock mass fissures and pores is purified by the metal filter (31), filter element (32) and waterproof breathable membrane (33), and then enters the ventilation inner tube (22) through the micro electromagnetic valve (4), and is then transported to the radon detector (9) at the orifice to measure its radioactivity specific activity and calculate the concentration; the sound wave controller (51) is started at the same time to control the transmission and reception of sound wave signals and calculate the sound wave velocity; S6. Based on the data of sound wave velocity and radon concentration collected by the sound wave controller (51) and the radon meter (9) for each segment, construct the correlation curves of "sound wave velocity and top coal thickness" and "radon concentration and top coal thickness". Overlay the two curves and observe their trend correspondence. Based on the characteristics of radon concentration and sound wave propagation speed of coal and rock mass under different fracture conditions, dynamically identify and classify the top coal structure type and determine the coal-rock boundary line.

9. The method according to claim 8, characterized in that, In S5, the formula for calculating the velocity of sound waves is: In the formula: V' k,i -No. k In a multi-transmitter acoustic probe i Wave velocity, m / s; ΔS i - The spacing between the acoustic probes in each section of the probe rod is the length of each section of the probe rod, in meters; ΔT k,i -No. k The first of the group of one-transmitter-multiple-receiver acoustic probes i Individual and i -1 acoustic wave receiving probe (5) received the signal time difference, s; S i -No. i The distance from the acoustic receiving probe (5) to the transmitting probe is m; S i-1 -No. i The distance from one acoustic receiving probe (5) to the transmitting probe, in meters; T k,i -No. k The first of the group of one-transmitter-multiple-receiver acoustic probes i The moment, s, when the acoustic wave receiving probe (5) receives the acoustic wave signal; T k,i-1 -No. k The first of the group of one-transmitter-multiple-receiver acoustic probes i The moment, s, when a sound wave receiving probe (5) receives a sound wave signal; V i - Among the three sets of single-transmitter, multi-receiver acoustic probes i Average wave velocity per segment, m / s.

10. The method according to claim 8, characterized in that, In S6, the coal-rock boundary line is located where the sound wave velocity jumps sharply from the lowest to the highest value, while the radon concentration remains at a relatively high level.

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