Coal seam drilling pressure relief effect detection device and detection method

Abstract

The present application relates to a kind of coal seam borehole pressure relief effect detection equipment, including detector, detector includes cylinder, expansion capsule, piston, telescopic column and vibrating string sensing component, expansion capsule is wrapped in cylinder outside and is set to be able to expand to the hole wall of coal seam borehole abuts, piston is movably arranged in cylinder along the axial direction of cylinder, the distal end of piston is provided with driving slope, telescopic column is matched with driving slope, telescopic column is set to slide along driving slope according to the axial movement of piston, to insert hole wall and be configured to measure base point, vibrating string sensing component includes vibrating string, one end of vibrating string is connected in piston, the other end is connected with telescopic column.The coal seam borehole pressure relief effect detection equipment proposed in the present application is compact in structure, reliable in anchoring, direct in measurement feedback path, solve the technical problem that prior art cannot detect the coal seam expansion deformation in borehole, improve the accuracy and reliability of coal seam borehole pressure relief effect detection.

Description

Technical Field

[0001] This invention belongs to the field of coal mine safety mining technology, specifically relating to a device and method for detecting the pressure relief effect of coal seam drilling. Background Technology

[0002] In coal mine safety production, coal and gas outbursts are extremely serious dynamic disasters. Construction-based pressure relief boreholes are the most commonly used localized outburst prevention measure in outburst-prone coal seam tunneling faces. Currently, most methods evaluate the pressure relief effect by measuring indirect parameters such as the initial gas emission velocity from the borehole and the gas desorption index of drill cuttings. However, these gas parameters are affected by multiple factors such as coal seam permeability, stress state, and gas occurrence, resulting in significant fluctuations and lags. They are difficult to accurately and dynamically reflect the actual structural changes of the coal body under pressure relief. Therefore, existing effectiveness evaluation methods suffer from low accuracy and poor reliability.

[0003] According to the "Detailed Rules for the Prevention and Control of Coal and Gas Outbursts," a maximum expansion deformation exceeding 3‰ is an effective criterion for determining the elimination of outburst risk. This indicates that the maximum expansion deformation of the coal seam can serve as a more intuitive and accurate criterion. However, current technology lacks equipment and methods for directly detecting the expansion deformation of coal seams within boreholes. Traditional mechanical dial gauges or resistance displacement gauges are prone to drifting or failure in high-humidity and strong electromagnetic interference environments underground, and are difficult to adapt to the installation requirements of narrow boreholes such as φ80mm. Vibrating wire sensors cannot simulate the original geostress boundary of the coal seam borehole wall and cannot capture minute radial expansion. Therefore, existing hardware testing equipment cannot detect the expansion deformation of the coal seam. Thus, there is an urgent need for equipment and methods that can accurately measure the expansion deformation of coal seams within boreholes to evaluate the pressure relief effect. Summary of the Invention

[0004] The objective of this invention is to at least solve the technical problem that existing technologies cannot detect the expansion and deformation of coal seams within boreholes. This objective is achieved through the following technical solution: The first aspect of this invention provides a device for detecting the pressure relief effect of coal seam drilling. The device includes a detector, which comprises a cylinder, an expansion capsule, a piston, a telescopic column, and a vibrating wire sensing assembly. The expansion capsule is enclosed outside the cylinder and configured to expand to abut against the borehole wall. The piston is movably disposed within the cylinder along its axial direction. A driving inclined surface is provided at the distal end of the piston. The telescopic column cooperates with the driving inclined surface and is configured to slide along the driving inclined surface according to the axial movement of the piston, thereby inserting into the borehole wall to form a measurement base point. The vibrating wire sensing assembly includes a vibrating wire, one end of which is connected to the piston, and the other end is connected to the telescopic column.

[0005] The coal seam borehole pressure relief effect detection device proposed in this invention simulates the original geostress environment of the coal seam before drilling by setting an expansion capsule outside the cylinder to abut against the borehole wall, eliminating stress release interference caused by drilling and providing stable and realistic stress conditions for subsequent accurate measurement of the micro-expansion deformation after pressure relief in the coal seam borehole. By setting a driving inclined surface at the distal end of the piston to cooperate with the telescopic column, the axial thrust on the piston is converted into the radial displacement of the telescopic column, allowing the telescopic column to be stably and controllably inserted into the borehole wall to form a reliable measurement base point, ensuring that the measurement base does not drift. By connecting a vibrating wire to the telescopic column, the small radial expansion displacement of the borehole wall is converted into a change in the tension of the vibrating wire, thereby calculating the amount of coal seam expansion deformation by measuring the frequency change of the vibrating wire. The coal seam borehole pressure relief effect detection device proposed in this invention has a compact structure, reliable anchoring, and a direct measurement feedback path, solving the technical problem that existing technologies cannot detect the amount of coal seam expansion deformation in boreholes, and improving the accuracy and reliability of coal seam borehole pressure relief effect detection.

[0006] Furthermore, the coal seam borehole pressure relief effect testing device proposed in the embodiments of the present invention may also have the following technical features: In some embodiments of the present invention, the vibrating string sensing component further includes: A spring and a spring fixing plate, wherein the spring fixing plate is disposed inside the piston, one end of the spring is connected to the spring fixing plate, and the other end extends axially along the cylinder towards the distal end and is connected to the vibrating string; A coil fixing plate and an excitation coil are provided. The coil fixing plate is disposed inside the piston and located at the distal end of the spring. The excitation coil is installed in the coil fixing plate and sleeved on the outer periphery of the vibrating string to excite the vibrating string and sense the frequency change signal generated by the vibrating string according to the displacement of the telescopic column.

[0007] In some embodiments of the present invention, multiple telescopic columns are provided, and the multiple telescopic columns are evenly spaced along the circumference of the cylinder. The number of vibrating wires and excitation coils is the same as the number of telescopic columns, and the vibrating wires, excitation coils and telescopic columns are matched one-to-one.

[0008] In some embodiments of the present invention, the detector further includes a circuit board, a signal transmission cable, and a signal acquisition device. The circuit board is disposed inside the piston and is connected to the excitation coil via the signal transmission cable. The signal acquisition device is disposed outside the cylinder and is connected to the circuit board via the signal transmission cable.

[0009] In some embodiments of the present invention, the coal seam borehole pressure relief effect detection device further includes a high-pressure liquid pipeline, a valve disposed on the high-pressure liquid pipeline, and a push tube for carrying the detector. The high-pressure liquid pipeline is used to inject high-pressure liquid into the cylinder to drive the piston to move axially, and the push tube has an opening that cooperates with the high-pressure liquid pipeline.

[0010] In some embodiments of the present invention, the detector further includes a plug disposed at the proximal end of the cylinder, the plug, the piston, and the cylinder forming a sealed cavity, and the plug having a passage for cooperating with the high-pressure liquid pipeline and a through hole for cooperating with the signal transmission cable.

[0011] In some embodiments of the present invention, the two ends of the expansion capsule are connected to the outer surface of the cylinder by clamps, and the side wall of the cylinder is provided with a liquid injection port communicating with the inside of the expansion capsule. The liquid injection port is used to inject high-pressure liquid into the expansion capsule.

[0012] In some embodiments of the present invention, the piston has a plunger section extending axially, the plunger section slidingly sealingly engaging with the inner wall of the cylinder, and the plunger section covering the injection port under initial operating conditions.

[0013] A second aspect of the present invention provides a method for detecting the pressure relief effect of coal seam boreholes using the coal seam borehole pressure relief effect detection equipment proposed in any of the above embodiments, the method comprising the following steps: S1: A measuring borehole is drilled at the coal seam working face, and the depth of the measuring borehole is brought into the stable section of the coal seam. The detector of the coal seam borehole pressure relief effect detection equipment is sent to the set position of the measuring borehole. High-pressure liquid is injected into the detector to move the piston, so that the telescopic column slides along the driving inclined plane and inserts into the borehole wall of the measuring borehole to form a measuring base point. The expansion capsule expands and abuts against the borehole wall of the measuring borehole to simulate the original geostress environment. After the pressure stabilizes, the initial frequency f0 of the vibrating string is read through the signal acquisition device. S2: Construct a pressure relief borehole at a position L away from the measured borehole; S3: Monitor the frequency of the vibrating string, and read the frequency f1 through the signal acquisition device after the frequency stabilizes; S4: Obtain the calibration coefficient k according to the frequency-tension calibration relationship of the vibrating wire, and calculate the radial absolute expansion deformation ΔD of the measured borehole. The calculation formula is: ΔD=k·|f0-f1|; S5: Calculate the relative expansion deformation rate ε between the measuring borehole and the pressure relief borehole. The calculation formula is: ε=ΔD / L; S6: Compare the relative expansion deformation rate ε with the effective pressure relief threshold of 3‰: If ε≥3‰, the pressure relief borehole at the spacing L is deemed to be effective. If ε < 3‰, the pressure relief borehole under the spacing L is deemed invalid. After reducing the spacing, steps S2 to S6 are repeated until ε ≥ 3‰ is satisfied.

[0014] In some embodiments of the present invention, in step S6, after determining that the pressure relief is effective, steps S2 to S6 are repeated by increasing the spacing L to obtain the maximum spacing value L that satisfies the condition for effective pressure relief. max , will the L max This serves as the upper limit for the spacing of pressure relief boreholes.

[0015] The coal seam borehole pressure relief effect detection method according to the embodiments of the present invention has the same advantages as the coal seam borehole pressure relief effect detection equipment proposed in any of the above embodiments, solves the technical problem that the prior art cannot detect the amount of coal seam expansion and deformation in the borehole, and improves the accuracy and reliability of coal seam borehole pressure relief effect detection. Attached Figure Description

[0016] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 A schematic diagram of a coal seam borehole pressure relief effect testing device; Figure 2 for Figure 1 A cross-sectional view along the AA direction; Figure 3 A schematic diagram of the detector in a coal seam borehole pressure relief effect testing device; Figure 4 for Figure 3 Main view of the detector Figure 5 for Figure 3 Left view of the detector; Figure 6 for Figure 4 Cross-sectional view along the BB direction; Figure 7 for Figure 5 A cross-sectional view along the CC direction; Figure 8 for Figure 3 Schematic diagram of the structure of the expansion capsule; Figure 9 for Figure 3 Schematic diagram of the middle cylinder; Figure 10 for Figure 3 Schematic diagram of the piston structure; Figure 11 for Figure 3 Front view of the telescopic column; Figure 12 for Figure 11 Top view of the telescopic column shown; Figure 13 for Figure 3 Schematic diagram of the structure of the middle plug; Figure 14 A schematic diagram of a borehole used in a method for detecting the pressure relief effect of coal seam boreholes. Figure 15 for Figure 14 A cross-sectional view along the DD direction; Figure 16 for Figure 15 Enlarged diagram of point E in the middle.

[0017] The markings in the attached diagram are as follows: 100. Equipment for testing the pressure relief effect of coal seam drilling; 101. Detector; 102. High-pressure liquid pipeline; 103. Valve; 104. Push tube; 10. Cylinder; 11. Injection port; 12. Through hole; 20. Expansion capsule; 21. Clamp; 30. Piston; 31. Drive ramp; 32. Plunger section; 33. Groove; 40. Telescopic column; 41. Connecting part; 42. Mating ramp; 51. Vibrating string; 52. Spring; 53. Spring fixing plate; 54. Excitation coil; 55. Coil fixing plate; 60. Circuit board; 70. Signal transmission cable; 80. Plug; 81. Liquid passage; 91. Measuring borehole; 92. Pressure relief borehole. Detailed Implementation

[0018] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0019] In this invention, the end of the cylinder inserted deep into the borehole is defined as the distal end, and the end of the cylinder near the borehole opening is defined as the proximal end.

[0020] like Figures 1 to 16As shown in the figure, this embodiment of the invention proposes a coal seam borehole pressure relief effect testing device 100. The coal seam borehole pressure relief effect testing device 100 includes a detector 101, which includes a cylinder 10, an expansion capsule 20, a piston 30, a telescopic column 40, and a vibrating wire 51 sensing assembly. The expansion capsule 20 is wrapped around the cylinder 10 and is configured to expand to abut against the borehole wall of the coal seam borehole. The piston 30 is movably disposed inside the cylinder 10 along the axial direction. A driving inclined surface 31 is provided at the distal end of the piston 30. The telescopic column 40 cooperates with the driving inclined surface 31 and is configured to slide along the driving inclined surface 31 according to the axial movement of the piston 30 to insert into the borehole wall to form a measurement base point. The vibrating wire 51 sensing assembly includes a vibrating wire 51, one end of which is connected to the piston 30 and the other end is connected to the telescopic column 40.

[0021] The coal seam borehole pressure relief effect testing device 100 proposed in this embodiment of the invention simulates the original geostress environment of the coal seam before drilling by setting an expansion capsule 20 outside the cylinder 10 to abut against the borehole wall, thus eliminating the stress release interference caused by drilling and providing stable and realistic stress conditions for subsequent accurate measurement of the micro-expansion deformation of the coal seam after pressure relief. By setting a driving inclined surface 31 at the far end of the piston 30 to cooperate with the telescopic column 40, the axial thrust of the piston 30 is converted into the radial displacement of the telescopic column 40, so that the telescopic column 40 can be stably and controllably inserted into the borehole wall to form a reliable measurement base point, ensuring that the measurement base does not drift. By connecting the vibrating wire 51 to the telescopic column 40, the small radial expansion displacement of the borehole wall is converted into the tension change of the vibrating wire 51, so that the amount of coal seam expansion deformation can be calculated by the frequency change of the vibrating wire 51. The coal seam borehole pressure relief effect detection device 100 proposed in this embodiment of the invention has a compact structure, reliable anchoring, and direct measurement feedback path. It solves the technical problem that the existing technology cannot detect the amount of coal seam expansion and deformation in the borehole, and improves the accuracy and reliability of coal seam borehole pressure relief effect detection.

[0022] like Figure 1 and Figure 2As shown, the coal seam borehole pressure relief effect detection device 100 proposed in this embodiment of the invention includes a detector 101. In some embodiments of the invention, the coal seam borehole pressure relief effect detection device 100 further includes a high-pressure liquid pump, a high-pressure liquid pipeline 102, and a valve 103 disposed on the high-pressure liquid pipeline 102. The high-pressure liquid pump is connected to the detector 101 through the high-pressure liquid pipeline 102 and is used to inject high-pressure liquid into the detector 101, thereby pushing the piston 30 inside the cylinder 10 to move axially and driving the expansion capsule 20 to expand. The valve 103 is disposed on the high-pressure liquid pipeline 102. When the detector 101 is sent to the designated position of the coal seam borehole, the high-pressure liquid can be delivered by opening the valve 103. When the expansion capsule 20 expands to a tight contact with the borehole wall and the pressure inside the expansion capsule 20 reaches a set value, the pressure inside the expansion capsule 20 can be kept stable by closing the valve 103.

[0023] For further information, please refer to [link / reference]. Figure 1 and Figure 2 Based on the above embodiments, the coal seam borehole pressure relief effect detection device 100 further includes a push tube 104, which carries the detector 101 and transports the detector 101 to a set position in the coal seam borehole. For example, in this embodiment, the push tube 104 is cylindrical, and an opening is provided axially from the proximal end of the push tube 104 for inserting a high-pressure liquid pipeline 102. The distal end of the push tube 104 is connected to the cylinder 10 of the detector 101. For example, the outer surface of the cylinder 10 may be provided with external threads, thereby connecting it to the inner wall of the push tube 104 via threads.

[0024] Continue reading Figures 3 to 7 The detector 101 includes a cylinder 10, an expansion capsule 20, a piston 30, a telescopic column 40, and a vibrating wire 51 sensing assembly. When the detector 101 is working, the piston 30 moves to drive the telescopic column 40 to insert into the inner wall of the coal seam borehole. The displacement change of the telescopic column 40 can reflect the radial expansion of the coal seam. The vibrating wire 51 sensing assembly can calculate the displacement change of the telescopic column 40 through the frequency change of the vibrating wire 51, thereby accurately detecting the radial expansion amount.

[0025] In some embodiments of the present invention, in conjunction with reference to [reference] Figure 2 , Figure 3 , Figure 7 and Figure 8 The expansion capsule 20 is wrapped around the outer surface of the cylinder 10. Specifically, both ends of the expansion capsule 20 are connected to the outer surface of the cylinder 10 via clamps 21 to ensure reliable connection. Figure 9As shown, the side wall of the cylinder 10 is provided with an injection port 11 communicating with the interior of the expansion capsule 20. The injection port 11 is used to inject high-pressure liquid into the expansion capsule 20. In an optional embodiment, the number of injection ports 11 can be multiple, for example, three. The three injection ports 11 can be evenly arranged along the circumference of the cylinder 10 to ensure the uniformity of the injected liquid and the stability of the subsequent expansion of the expansion capsule 20. Furthermore, the distal end of the cylinder 10 is provided with a tapered slope to facilitate insertion into the borehole. Near the proximal end of the cylinder 10, a through hole 12 is also provided for the extension of the telescopic column 40.

[0026] In some embodiments of the present invention, in conjunction with reference to [reference] Figure 7 , Figure 10 The piston 30 has a plunger section 32 extending axially, which slides and seals with the inner wall of the cylinder 10, such as... Figure 13 As shown, in some embodiments of the present invention, the detector 101 further includes a plug 80, which is disposed at the proximal end of the cylinder 10 and fills the cylinder 10. The plug 80, piston 30 and cylinder 10 enclose a sealed cavity. The plug 80 is provided with a liquid passage 81 that cooperates with the high-pressure liquid pipeline 102. Thus, when the high-pressure liquid is injected into the cylinder 10, it enters the sealed cavity and pushes the piston 30 to move axially.

[0027] See also Figures 3 to 6 as well as Figure 10 The distal end of the piston 30 is provided with a driving ramp 31 and a groove 33 formed on the driving ramp 31, such as Figure 11 and Figure 12 As shown, the end of the telescopic column 40 is provided with a connecting part 41, which cooperates with the groove 33. The two sides of the connecting part 41 are provided with a cooperating inclined surface 42 that cooperates with the driving inclined surface 31. Thus, the telescopic column 40 is inserted into the far end of the piston 30 and cooperates with the driving inclined surface 31. In the initial state, both the piston 30 and the telescopic column 40 are located inside the cylinder 10. The telescopic column 10 is restricted by the inner wall of the cylinder 10 and is partially compressed in the piston 30. When the piston 30 moves axially to the position of the through hole 12 of the cylinder 10 under the push of the high-pressure liquid, the telescopic column 40 is driven by the inclined surface to slide, and at the same time extends radially from the through hole 12 and inserts into the coal body of the coal seam borehole, thus forming a stable deformation measurement base point.

[0028] Furthermore, in this embodiment, multiple telescopic columns 40 are provided, and the multiple telescopic columns 40 are evenly distributed along the circumference of the cylinder 10. For example, three can be provided. The three telescopic columns 40 can measure three directions, thereby ensuring the comprehensiveness of the borehole radial deformation measurement results.

[0029] See also Figure 7Based on the above implementation method, the plunger section 32 covers the injection port 11 on the side wall of the cylinder 10 under initial operating conditions. It should be noted that the initial operating conditions refer to the state before high-pressure liquid is injected and before the piston 30 moves to the distal end. The injection port 11 is located on the side wall of the cylinder 10 near the proximal end and is covered by the plunger section 32. After high-pressure liquid is injected, the piston 30 moves to the distal end under force, gradually exposing the injection port 11, allowing the high-pressure liquid to enter the expansion capsule 20. The expansion capsule 20 expands under force, achieving tight contact with the borehole wall of the coal seam, thereby simulating the original geostress environment of the coal seam. This embodiment, through the above-mentioned hydraulic sequential structure design, ensures the order of first anchoring the telescopic column 40 and then expanding the capsule 20 to simulate stress, thus ensuring the accuracy and reliability of the measurement benchmark construction and geostress state recovery.

[0030] like Figure 7 As shown, in some embodiments of the present invention, the vibrating wire 51 sensing assembly includes a vibrating wire 51, a spring 52, a spring fixing plate 53, a coil fixing plate 55, and an excitation coil 54. The spring fixing plate 53 is disposed within the piston 30. One end of the spring 52 is connected to the spring fixing plate 53, and the other end extends axially towards the distal end of the cylinder 10. One end of the vibrating wire 51 is connected to the telescopic column 40, and the other end is connected to the spring 52. The coil fixing plate 55 is disposed within the piston 30 and located at the distal end of the spring 52. The excitation coil 54 is installed in the coil fixing plate 55 and sleeved around the outer periphery of the vibrating wire 51 to excite the vibrating wire 51 and sense the frequency change signal generated by the vibrating wire 51 according to the displacement of the telescopic column 40. When the telescopic column 40 undergoes radial micro-movement due to coal depressurization, it causes a change in the tension of the vibrating wire 51, enabling the excitation coil 54 to excite the vibrating wire 51 and sense its frequency change signal. In this embodiment, the number of vibrating wires 51 and excitation coils 54 is the same as the number of telescopic columns 40. The three correspond one-to-one to achieve multi-point synchronous measurement. For example, there are three telescopic columns 40, three vibrating wires 51, and three excitation coils 54.

[0031] In some embodiments of the present invention, the detector 101 further includes a circuit board 60, a signal transmission cable 70, and a signal acquisition device. The circuit board 60 is disposed inside the piston 30 and is connected to the excitation coil 54 via the signal transmission cable 70. The signal acquisition device is disposed outside the cylinder 10 and is connected to the circuit board 60 via the signal transmission cable 70. Furthermore, the plug 80 is provided with a through hole that mates with the signal transmission cable 70, and the opening on the push tube 104 is also used to accommodate the signal transmission cable 70.

[0032] In summary, this embodiment of the invention utilizes the sequential action of the expansion capsule 20 and the piston 30 to achieve the orderly triggering of the anchoring of the telescopic column 40 and the simulated ground stress environment, effectively eliminating stress release interference caused by drilling construction and providing a stable and accurate stress benchmark for measurement. The sliding engagement between the distal drive inclined surface 31 of the piston 30 and the telescopic column 40 converts the axial thrust of the piston 30 into the radial displacement of the telescopic column 40, forming a stable measurement base point. The vibrating string 51 is connected at both ends to springs 52 and the telescopic column 40, respectively. The pre-tensioning of the springs 52 keeps the vibrating string 51 taut. Combined with the installation of the excitation coil 54, this allows for the direct measurement of minute radial expansion displacements of the coal body. The signal is converted into a high-precision frequency change signal, with strong anti-interference ability and high measurement accuracy. The three telescopic columns 40 are evenly distributed around the circumference and correspond one-to-one with the three sets of vibrating wires 51 and excitation coils 54, which can realize synchronous deformation monitoring of the borehole wall in multiple directions, and comprehensively and accurately reflect the stress state of the borehole wall. The integrated design of the push tube 104, plug 80, high-pressure liquid pipeline 102, valve 103 and signal transmission cable 70 channels takes into account the convenience of installation in narrow boreholes (such as φ80mm) and the high-pressure sealing reliability, so that the equipment can operate stably for a long time. It provides a direct, reliable and accurate physical deformation measurement tool for the evaluation of the effect of pressure relief drilling in coal mines.

[0033] The second aspect of the present invention provides a method for detecting the pressure relief effect of coal seam drilling using the coal seam drilling pressure relief effect detection device 100 proposed in any of the above embodiments, in conjunction with the following references. Figures 14 to 16 The method for detecting the pressure relief effect of coal seam boreholes includes the following steps: S1: A measuring borehole 91 is constructed at the coal seam working face, and the depth of the measuring borehole 91 is brought into the stable section of the coal seam. The detector 101 of the coal seam borehole pressure relief effect detection equipment 100 is sent to the set position of the measuring borehole 91. By injecting high-pressure liquid into the detector 101, the piston 30 is moved, and the telescopic column 40 slides along the driving inclined surface 31 and inserts into the borehole wall of the measuring borehole 91 to form a measuring base point. The expansion capsule 20 is expanded and abuts against the borehole wall of the measuring borehole 91 to simulate the original ground stress environment. After the pressure stabilizes, the initial frequency f0 of the vibrating wire 51 is read through the signal acquisition device. S2: Construct a pressure relief borehole 92 at a distance L from the measuring borehole 91; S3: Monitor the frequency of the vibrating string 51, and read the frequency f1 through the signal acquisition device after the frequency stabilizes; S4: Obtain the calibration coefficient k based on the frequency-tension calibration relationship of the vibrating wire 51, and calculate the radial absolute expansion deformation ΔD of the borehole 91. The calculation formula is: ΔD=k·|f0-f1|. The process of obtaining the calibration coefficient k in this step includes: before the detector 101 leaves the factory, a known radial displacement δ is applied to the telescopic column 40 using a high-precision displacement stage, and the corresponding frequency change Δf of the vibrating wire 51 is recorded through the excitation coil 54. By linear fitting of multiple sets of data, the frequency-deformation calibration coefficient k=δ / Δf of the detector 101 can be obtained. This k value is only valid for the current physical structure of the detector 101 and can be directly substituted into the actual downhole measurement.

[0034] S5: Calculate the relative expansion deformation rate ε between the measurement borehole 91 and the pressure relief borehole 92. The calculation formula is: ε=ΔD / L; S6: Compare the relative expansion deformation rate ε with the effective pressure relief threshold of 3‰: If ε≥3‰, the pressure relief borehole 92 at the distance L is deemed to be effective in relieving pressure. If ε < 3‰, the pressure relief borehole 92 under the spacing L is deemed invalid. After reducing the spacing, steps S2 to S6 are repeated until ε ≥ 3‰ is satisfied.

[0035] In some embodiments of the present invention, in step S6, after determining that the pressure relief is effective, steps S2 to S6 are repeated by increasing the spacing L to obtain the maximum spacing value L that satisfies the condition for effective pressure relief. max , will L max This serves as the upper limit for the spacing of the pressure relief borehole 92.

[0036] The coal seam borehole pressure relief effect detection method proposed in this embodiment is simple to operate. It only requires using the push tube 104 to send the detector 101 into a conventional φ80mm borehole, and can be implemented with the help of an external high-pressure liquid pump and a signal acquisition device. By constructing a pressure relief borehole 92 at a distance of 91L from the measuring borehole and calculating the relative expansion rate ε, a closed-loop process of "construction-measurement-judgment" is formed. When ε < 3‰, the spacing L is reduced and iterative testing is repeated until the criterion is met, which can quickly determine the ineffective pressure relief area. When ε ≥ 3‰, the spacing L is increased and the test is repeated to obtain the maximum spacing value L that meets the criterion. max (i.e., effective radius of influence). This embodiment provides a precise quantitative basis for determining the optimal borehole parameters on site through a stepwise approximation optimization, avoiding the waste of engineering work caused by conservative parameters or the safety hazards caused by aggressive parameters. It enhances the scientific nature and engineering guidance value of on-site outburst prevention design, has strong adaptability, and has broad prospects for promotion in coal mines.

[0037] The coal seam borehole pressure relief effect detection method proposed in this invention directly uses the macroscopic physical expansion deformation of the coal body as the evaluation basis. It incorporates the "3‰" criterion stipulated in the "Detailed Rules for the Prevention and Control of Coal and Gas Outbursts" into the effect assessment of pressure relief borehole 92, resulting in objective, accurate, and authoritative evaluation results. This embodiment effectively eliminates stress release interference caused by borehole construction by first anchoring the expansion column 40 and then using the expansion capsule 20 to simulate the original ground stress. This allows the sensor to measure under stable stress boundary conditions, and, in conjunction with the calibration coefficient k, accurately calculates the absolute expansion deformation ΔD. This method can sensitively capture minute deformations on the order of a few thousandths, significantly improving measurement accuracy. It solves the technical problem that existing technologies cannot detect the expansion deformation of coal seams within boreholes, thus improving the accuracy and reliability of coal seam borehole pressure relief effect detection.

[0038] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “” used herein may also mean including the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof.

[0039] Although terms such as first, second, third, etc., may be used in this document to describe multiple elements, components, regions, layers, and / or segments, these elements, components, regions, layers, and / or segments should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Unless the context clearly indicates otherwise, terms such as "first," "second," and other numerical terms used herein do not imply order or sequence. Therefore, the first element, component, region, layer, or segment discussed below may be referred to as the second element, component, region, layer, or segment without departing from the teachings of the exemplary embodiments.

[0040] For ease of description, spatial relative terms may be used in the text to describe the relationship of one element or feature relative to another element or feature, as shown in the figure. These relative terms include, for example, "inside," "outside," "middle," "outer," "below," "below," "above," "over," etc. Such spatial relative terms are intended to include different orientations of the device in use or operation, other than those depicted in the figure. For example, if the device in the figure is flipped, an element described as "below other elements or features" or "below other elements or features" would subsequently be oriented as "above other elements or features" or "above other elements or features." Therefore, the example term "below" can include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions), and the spatial relative descriptors used in the text will be interpreted accordingly.

[0041] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A device for testing the pressure relief effect of coal seam drilling, characterized in that, The coal seam borehole pressure relief effect testing equipment includes a detector, which includes a cylinder, an expansion capsule, a piston, a telescopic column, and a vibrating wire sensing assembly. The expansion capsule is wrapped around the cylinder and configured to expand to abut against the borehole wall. The piston is movably disposed within the cylinder along its axial direction. A driving inclined surface is provided at the distal end of the piston. The telescopic column cooperates with the driving inclined surface and is configured to slide along the driving inclined surface according to the axial movement of the piston to insert into the borehole wall and form a measurement base point. The vibrating wire sensing assembly includes a vibrating wire, one end of which is connected to the piston and the other end is connected to the telescopic column.

2. The coal seam borehole pressure relief effect testing equipment according to claim 1, characterized in that, The vibrating wire sensing component also includes: A spring and a spring fixing plate, wherein the spring fixing plate is disposed inside the piston, one end of the spring is connected to the spring fixing plate, and the other end extends axially along the cylinder towards the distal end and is connected to the vibrating string; A coil fixing plate and an excitation coil are provided. The coil fixing plate is disposed inside the piston and located at the distal end of the spring. The excitation coil is installed in the coil fixing plate and sleeved on the outer periphery of the vibrating string to excite the vibrating string and sense the frequency change signal generated by the vibrating string according to the displacement of the telescopic column.

3. The coal seam borehole pressure relief effect testing equipment according to claim 2, characterized in that, Multiple telescopic columns are provided, and the multiple telescopic columns are evenly spaced along the circumference of the cylinder. The number of vibrating wires and excitation coils is the same as the number of telescopic columns, and the vibrating wires, excitation coils and telescopic columns are matched one-to-one.

4. The coal seam borehole pressure relief effect testing equipment according to claim 2, characterized in that, The detector also includes a circuit board, a signal transmission cable, and a signal acquisition device. The circuit board is disposed inside the piston and is connected to the excitation coil via the signal transmission cable. The signal acquisition device is disposed outside the cylinder and is connected to the circuit board via the signal transmission cable.

5. The coal seam borehole pressure relief effect testing equipment according to claim 4, characterized in that, The coal seam borehole pressure relief effect detection equipment also includes a high-pressure liquid pipeline, a valve installed on the high-pressure liquid pipeline, and a push tube for carrying the detector. The high-pressure liquid pipeline is used to inject high-pressure liquid into the cylinder to drive the piston to move axially, and the push tube has an opening that cooperates with the high-pressure liquid pipeline.

6. The coal seam borehole pressure relief effect testing equipment according to claim 5, characterized in that, The detector also includes a plug, which is located at the near end of the cylinder. The plug, the piston, and the cylinder together form a sealed cavity. The plug has a passage for cooperating with the high-pressure liquid pipeline and a through hole for cooperating with the signal transmission cable.

7. The coal seam borehole pressure relief effect testing equipment according to claim 6, characterized in that, The two ends of the expansion capsule are connected to the outer surface of the cylinder by clamps. The side wall of the cylinder is provided with a liquid injection port that communicates with the inside of the expansion capsule. The liquid injection port is used to inject high-pressure liquid into the expansion capsule.

8. The coal seam borehole pressure relief effect testing equipment according to claim 7, characterized in that, The piston has a plunger section extending axially, which slides and seals with the inner wall of the cylinder, and the plunger section covers the injection port under initial operating conditions.

9. A method for detecting the pressure relief effect of coal seam drilling using the coal seam drilling pressure relief effect detection equipment according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1: A measuring borehole is drilled at the coal seam working face, and the depth of the measuring borehole is brought into the stable section of the coal seam. The detector of the coal seam borehole pressure relief effect detection equipment is sent to the set position of the measuring borehole. High-pressure liquid is injected into the detector to move the piston, so that the telescopic column slides along the driving inclined plane and inserts into the borehole wall of the measuring borehole to form a measuring base point. The expansion capsule expands and abuts against the borehole wall of the measuring borehole to simulate the original geostress environment. After the pressure stabilizes, the initial frequency f0 of the vibrating string is read through the signal acquisition device. S2: Construct a pressure relief borehole at a position L away from the measured borehole; S3: Monitor the frequency of the vibrating string, and read the frequency f1 through the signal acquisition device after the frequency stabilizes; S4: Obtain the calibration coefficient k according to the frequency-tension calibration relationship of the vibrating wire, and calculate the radial absolute expansion deformation ΔD of the measured borehole. The calculation formula is: ΔD=k·|f0-f1|; S5: Calculate the relative expansion deformation rate ε between the measuring borehole and the pressure relief borehole. The calculation formula is: ε=ΔD / L; S6: Compare the relative expansion deformation rate ε with the effective pressure relief threshold of 3‰: If ε≥3‰, the pressure relief borehole at the spacing L is deemed to be effective. If ε < 3‰, the pressure relief borehole under the spacing L is deemed invalid. After reducing the spacing, steps S2 to S6 are repeated until ε ≥ 3‰ is satisfied.

10. The method for detecting the pressure relief effect of coal seam drilling according to claim 9, characterized in that, In step S6, after determining that the pressure relief is effective, steps S2 to S6 are repeated by increasing the spacing L to obtain the maximum spacing value L that satisfies the effective pressure relief condition. max , will the L max This serves as the upper limit for the spacing of pressure relief boreholes.

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