Experimental device and method for exciting artificial acoustic signal through mechanical vibration

Abstract

The embodiment of the invention discloses an experimental device and method for exciting an artificial acoustic signal through mechanical vibration, relates to the technical field of mine disaster early warning, and can improve the prediction capability of mine power phenomenon dangerousness. The experimental device comprises a pressure applying unit, an air charging and discharging unit, a mechanical vibration unit and an acoustic signal monitoring unit, the pressure applying unit comprises a cavity and a pressure head, and the pressure head movably penetrates through the cavity and is used for applying pressure to a test sample in the cavity; the inflation and exhaust unit comprises a vacuumizing system, an inflation system and an exhaust system, the vacuumizing system is connected to the cavity to vacuumize the cavity, the inflation system is connected to the cavity to inject specified gas into the cavity, and the exhaust system is connected to the cavity to exhaust the cavity; the mechanical vibration unit comprises an impact mechanism, a pin body and a force measuring element, the pin body movably penetrates through the cavity, the impact mechanism is configured to apply impact acting force to the first end of the pin body, so that the second end of the pin body transmits the impact acting force to a test sample in the cavity, and the force measuring element is arranged at the first end of the pin body to monitor the impact acting force; the acoustic signal monitoring unit comprises a probe and a detector, and the probe abuts against the cavity and is connected with the detector. The method is suitable for scenes of front stress abnormal area identification and dynamic disaster risk identification in the mine excavation process.

Description

Technical Field

[0001] The present application relates to the technical field of mine disaster early warning, and in particular to an experimental device and method for mechanical vibration-induced artificial acoustic signals. Background Art

[0002] As the mining depth of mines increases, the contradiction between the increased danger of mine dynamic phenomena and the high-yield, efficient and rapid advancement of the mining face becomes increasingly prominent. The traditional contact-type non-continuous drilling index prediction method can no longer meet the needs of the complex geological conditions of deep coal mining, the compound danger of dynamic phenomena, and the high-yield, efficient and intelligent mines.

[0003] External vibrations (such as coal cutter operations, tunneling of tunneling machines, artificial blasting construction, etc.) induce frequent coal and gas outburst accidents. The dynamic changes in ground stress near the working face during coal mining machines, coal cutter coal dropping, blasting operations and tunneling of tunneling machines and the characteristics of gas migration are crucial for predicting coal and gas outbursts and warning of the dangers of dynamic phenomena.

[0004] The artificial acoustic signal prediction method is based on the wide-band artificial acoustic vibration (sound) excited by the operating mining equipment (such as the cutting mechanism of the coal mining machine and the coal planer, the drill bit, etc.) in the rock mass near the working face, or the artificially established sound source (such as a sledgehammer hitting the side of the tunnel) to detect the rock mass, and analyze the stress state of the rock mass near the working face according to the amplitude-frequency characteristics of the artificial acoustic signal, predict the danger of coal and gas outburst at the mining working face, or monitor the rock mass state (such as geological damage in front of the working face and the stress state nearby).

[0005] my country's research on the spectral characteristics of artificial acoustic signals is still not perfect. For example, how to use the amplitude-frequency characteristics of artificial acoustic signals to intuitively reflect coal deformation and damage and internal gas migration, as well as the quantitative relationship between the amplitude-frequency characteristics of artificial acoustic signals and mechanical parameters such as coal stress state and gas pressure are still not clear enough. Therefore, it is necessary to carry out analytical research based on artificial acoustic signals to reflect the stress state of coal and rock and predict the hazard of gas outburst. Summary of the invention

[0006] In view of this, the present application provides an experimental device and method for mechanical vibration excitation of artificial acoustic signals to improve the ability to predict the danger of mine dynamic phenomena.

[0007] In a first aspect, an embodiment of the present invention provides an experimental device for mechanical vibration-induced artificial acoustic signals, comprising: a pressure unit, the pressure unit comprising a cavity and a pressure head, the pressure head movably penetrates the cavity and is used to apply pressure to a test sample in the cavity; an inflation and exhaust unit, the inflation and exhaust unit comprising a vacuum system, an inflation system and an exhaust system, the vacuum system is connected to the cavity to evacuate the cavity, the inflation system is connected to the cavity to inject a specified gas into the cavity, and the exhaust system is connected to the cavity to evacuate the cavity. Exhaust; a mechanical vibration unit, the mechanical vibration unit comprising an impact mechanism, a pin body, and a force measuring element, the pin body being movably arranged in the cavity, the impact mechanism being configured to apply an impact force to the first end of the pin body so that the second end of the pin body transmits the impact force to the test sample in the cavity, and the force measuring element being arranged at the first end of the pin body to monitor the impact force; an acoustic signal monitoring unit, the acoustic signal monitoring unit comprising a probe and a detector, the probe being abutted against the cavity and connected to the detector.

[0008] In a specific embodiment, the cavity includes a cylinder wall and a base, the pressure head is movably inserted into the first end of the cylinder wall, and a first seal is provided between the pressure head and the first end of the cylinder wall; the base is detachably connected to the second end of the cylinder wall, and a second seal is provided between the base and the second end of the cylinder wall.

[0009] In a specific embodiment, the experimental device also includes a mechanical control system, and the pressure unit also includes a controller and a press, and the controller is configured to set parameters of the controller through the mechanical control system to control the press to apply force to the pressure head.

[0010] In a specific embodiment, the vacuum system includes a vacuum pump, a first pressure gauge and a first valve connected in sequence, and the first valve is connected to the cavity; and / or the inflation system includes a designated gas storage tank, a pressure reducing valve, a second pressure gauge, a stop valve and a second valve connected in sequence, and the second valve is connected to the cavity.

[0011] In a specific embodiment, the impact mechanism includes a bracket, a pendulum, a dial and a pointer, the pendulum is suspended from the bracket and rotatably connected to the bracket, the dial is connected to the pendulum, and the pointer is arranged on the bracket.

[0012] In a specific embodiment, the mechanical vibration unit also includes a data processor, the force measuring element is connected to the data processor, and the data processor is configured to analyze the impact force monitored by the force measuring element and transmit the analysis result to the mechanical control system.

[0013] In a specific embodiment, the acoustic signal monitoring unit also includes a probe fixing device, which includes a first pad, a second pad, and a through rod. The first pad and the second pad are relatively arranged to clamp the probe, and the through rod is passed through and axially limited to the first pad and the second pad.

[0014] In a specific embodiment, a third sealing member is provided at the sliding contact portion of the outer wall of the pin body, and the pin body is configured such that when the pin body moves to a first preset position away from the cavity, the first end of the pin body is limited, and / or when the pin body moves to a second preset position toward a direction close to the cavity, the second end of the pin body is limited.

[0015] In a specific embodiment, the experimental device also includes a base, the cavity of the pressure unit is detachably fixedly connected to the base, and / or the impact mechanism of the mechanical vibration unit is detachably fixedly connected to the base, and / or the probe of the acoustic signal monitoring unit is detachably fixedly connected to the base.

[0016] In a second aspect, an embodiment of the present invention further provides an experimental method for mechanical vibration-induced artificial acoustic signals, the experimental method comprising: installing a pressure unit of an experimental device, and loading a test sample into a cavity of the pressure unit, wherein the experimental device is an experimental device for mechanical vibration-induced artificial acoustic signals as described in any one of the embodiments of the present application; assembling the mechanical vibration unit, acoustic signal monitoring unit and inflation / exhaust unit of the experimental device, and checking the air tightness of the experimental device; evacuating the cavity with the vacuum pumping system, and allowing the test sample to be vacuum-degassed for a first preset time, and then injecting the specified gas into the cavity with the inflation system to a preset air pressure. and make the test sample adsorb the specified gas for a second preset time period; under the preset air pressure, use the pressure head of the pressure-applying unit to apply a preset pressure to the test sample, and under the preset pressure, use the impact mechanism of the mechanical vibration unit to apply a preset impact force to the pin body, and monitor the acoustic test signal under the preset impact force through the acoustic signal monitoring unit; utilize the exhaust system of the inflation and exhaust unit to discharge the specified gas in the cavity to a specified position, disassemble the experimental device, and clean the test sample; analyze the relationship between the acoustic test signal and the preset air pressure, the preset pressure, and the preset impact force.

[0017] The experimental device and method for mechanical vibration excitation of artificial acoustic signals provided in the embodiments of the present invention include: a pressure unit, an inflation and exhaust unit, a mechanical vibration unit, and an acoustic signal monitoring unit; wherein the pressure unit includes a cavity and a pressure head, the pressure head is movably arranged in the cavity, and is used to apply pressure to the test sample in the cavity; the inflation and exhaust unit includes a vacuum system, an inflation system, and an exhaust system, the vacuum system is connected to the cavity to vacuum the cavity, the inflation system is connected to the cavity to inject a specified gas into the cavity, and the exhaust system is connected to the cavity to exhaust the cavity; the mechanical vibration unit includes an impact mechanism, a pin body, and a force measuring element, the pin body is movably arranged in the cavity, the impact mechanism is configured to apply an impact force to the first end of the pin body, so that the second end of the pin body transmits the impact force to the test sample in the cavity, and the force measuring element is arranged at the first end of the pin body to monitor the impact force; the acoustic signal monitoring unit includes a probe and a detector, the probe abuts the cavity and is connected to the detector. The experimental device can analyze the acoustic test signals of the test samples under multiple groups of different stress states, thereby providing a theoretical basis for using artificial acoustic signals at the work site to monitor and warn of the dangers of dynamic phenomena in the coal mining process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A diagram of an experimental device for mechanical vibration excitation of an artificial acoustic signal provided in an embodiment of the present application; Figure 2 A schematic diagram of a cavity of an experimental device for mechanical vibration excitation of an artificial acoustic signal provided in an embodiment of the present application; Figure 3 A partial top view of a pressure unit and a mechanical vibration unit of an experimental device for mechanical vibration excitation of an artificial acoustic signal provided in an embodiment of the present application; Figure 4 A partial side view of a pressure unit and a mechanical vibration unit of an experimental device for mechanical vibration excitation of an artificial acoustic signal provided in an embodiment of the present application.

[0020] Description of main reference numerals: 1- Experimental device for mechanical vibration excitation of artificial acoustic signals; 11- Pressure unit; 110- Cavity; 1101- Cylinder wall; 1102- Base; 111- Pressure head; 112- First seal; 113- Second seal; 114- Controller; 115- Press; 116- Third seal; 12- Inflating and exhausting unit; 121- Vacuuming system; 1211- Vacuum pump; 1212- First pressure gauge; 1213- First valve; 122- Inflating system; 1221- Designated gas storage tank; 1222- Pressure reducing valve; 1223- Second Pressure gauge; 1224-stop valve; 1225-second valve; 13-mechanical vibration unit; 131-impact mechanism; 1311-bracket; 1312-pendulum; 1313-dial; 1314-pointer; 1315-cylindrical pin; 132-pin body; 133-force measuring element; 134-data processor; 14-acoustic signal monitoring unit; 141-probe; 142-detector; 143-probe fixing part; 1431-first pad; 1432-second pad; 1433-through rod; 15-mechanical control system; 16-base. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0022] It should be clear that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] In the prior art, the research on the spectrum characteristics of artificial acoustic signals is still not perfect. For example, how to intuitively reflect the deformation and damage of coal and internal gas migration by means of the amplitude-frequency characteristics of artificial acoustic signals, and the quantitative relationship between the amplitude-frequency characteristics of artificial acoustic signals and mechanical parameters such as the stress state of coal and gas pressure are still not clear enough. Therefore, in order to utilize the spectrum characteristics of artificial acoustic signals to improve the prediction ability of the danger of mine dynamic phenomena, on the one hand, such as Figure 1 As shown, an embodiment of the present invention provides an experimental device 1 for mechanical vibration excitation of artificial acoustic signals. The experimental device 1 may include a pressure application unit 11, an air filling and exhaust unit 12, a mechanical vibration unit 13, and an acoustic signal monitoring unit 14.

[0024] The pressure unit 11 includes a cavity 110 and a pressure head 111. The pressure head 111 is movably disposed in the cavity 110 and is used to apply pressure to the test sample in the cavity 110. The pressure unit 11 is used to place the test sample. For example, in this embodiment, the artificial acoustic signal of the coal mining environment is analyzed, and the test sample is a coal sample. The cavity 110 structure of the pressure unit 11 is convenient for simulating the stress state of the test sample during various field operations, such as the stress changes in the coal mining operation area, the gas pressure, and the mechanical vibration force of the coal mining equipment. In this embodiment, the axial pressure is applied to the test sample coal sample by the pressure head 111 movably disposed in the cavity 110 to simulate the stress changes in the coal mining operation area.

[0025] The inflation and exhaust unit 12 includes a vacuum system 121, an inflation system 122 and an exhaust system. The vacuum system 121 is connected to the cavity 110 to evacuate the cavity 110, the inflation system 122 is connected to the cavity 110 to inject a specified gas into the cavity 110, and the exhaust system is connected to the cavity 110 to exhaust the gas. In order to simulate the gas pressure environment of the coal body in the coal mining operation area, this embodiment creates an air pressure environment inside the cavity 110 by configuring the inflation and exhaust unit 12. Specifically, the vacuum system 121 first evacuates and exhausts the cavity 110, so that the test sample placed in the cavity 110, such as a coal sample, can be fully vacuum degassed, and then the inflation system 122 injects a specified gas simulating the working environment, such as the gas gas in the coal body in the coal mining operation area, into the cavity 110, so that the coal sample in the cavity 110 can fully absorb the gas and be in a simulated working environment formed by the gas. After the experiment is finished, the gas in the chamber 110 can be discharged to a designated location that meets safety requirements, such as a storage tank, by the exhaust system.

[0026] The mechanical vibration unit 13 includes an impact mechanism 131, a pin body 132, and a force measuring element 133. The pin body 132 is movably arranged in the cavity 110. The impact mechanism 131 is configured to apply an impact force to the first end of the pin body 132, so that the second end of the pin body 132 transmits the impact force to the test sample in the cavity 110. The force measuring element 133 is arranged at the first end of the pin body 132 to monitor the impact force. In order to simulate the mechanical vibration in the coal mining operation area, such as the effects of coal mining machines, coal cutting machines dropping coal, blasting operations and tunneling of tunneling machines, this embodiment configures the impact mechanism 131 to generate an impact force on the pin body 132, and transmits the impact force to the coal sample in the cavity 110, and monitors and records the magnitude of the impact force through the force measuring element 133.

[0027] The acoustic signal monitoring unit 14 includes a probe 141 and a detector 142. The probe 141 is in contact with the cavity 110 and connected to the detector 142. In the environment of axial pressure, gas pressure, and mechanical vibration impact force simulated for the test sample coal sample, different axial pressures, gas pressures, and impact forces can be set, and the corresponding acoustic test signals can be recorded by the acoustic signal monitoring unit 14. In this way, the collected artificial acoustic signal data, mechanical vibration data, and mechanical data can be sorted and analyzed to establish a quantitative relationship between coal sample stress-strain, gas pressure, and artificial acoustic signal spectrum-amplitude.

[0028] An experimental device 1 for mechanical vibration excitation of artificial acoustic signals provided in an embodiment of the present invention comprises: a pressure unit 11, an inflation and exhaust unit 12, a mechanical vibration unit 13, and an acoustic signal monitoring unit 14; wherein the pressure unit 11 comprises a cavity 110 and a pressure head 111, the pressure head 111 is movably arranged in the cavity 110, and is used to apply pressure to the test sample in the cavity 110; the inflation and exhaust unit 12 comprises a vacuum system 121, an inflation system 122, and an exhaust system, the vacuum system 121 is connected to the cavity 110 to evacuate the cavity 110, and the inflation system 122 is connected to the cavity 110 to inject a specified gas into the cavity 110, The exhaust system is connected to the cavity 110 to exhaust the cavity 110; the mechanical vibration unit 13 includes an impact mechanism 131, a pin body 132, and a force measuring element 133. The pin body 132 is movably arranged in the cavity 110. The impact mechanism 131 is configured to apply an impact force to the first end of the pin body 132, so that the second end of the pin body 132 transmits the impact force to the test sample in the cavity 110. The force measuring element 133 is arranged at the first end of the pin body 132 to monitor the impact force; the acoustic signal monitoring unit 14 includes a probe 141 and a detector 142. The probe 141 abuts against the cavity 110 and is connected to the detector 142. The experimental device 1 can analyze the acoustic test signals of the test sample under multiple groups of different stress states, thereby providing a theoretical basis for monitoring and warning the danger of dynamic phenomena in the coal mining process using artificial acoustic signals at the operation site.

[0029] Optional, such as Figure 2 As shown, in one embodiment of the present invention, the cavity 110 includes a cylinder wall 1101 and a base 1102, the pressure head 111 is movably arranged at the first end of the cylinder wall 1101, and a first sealing member 112 is arranged between the pressure head 111 and the first end of the cylinder wall 1101; the base 1102 is detachably connected to the second end of the cylinder wall 1101, and a second sealing member 113 is arranged between the base 1102 and the second end of the cylinder wall 1101.

[0030] The cylinder wall 1101 and the base 1102 constitute a detachable structure of the cavity 110, which is not only convenient for processing and installation, but also convenient for placing the test sample and cleaning the test sample after the experiment is completed. The base 1102 and the cylinder wall 1101 can be detachably connected by bolts. The cylinder wall 1101 can be a structure with open ends at both ends. The first end of the cylinder wall 1101 is matched with the pressure head 111. The pressure head 111 is penetrated at the first end of the cylinder wall 1101 and can move axially to apply axial pressure to the test sample in the cavity 110. The second end of the cylinder wall 1101 is matched with the base 1102. Considering the sealing performance of the cavity 110, a first sealing member 112 is provided at the fitting connection between the first end of the cylinder wall 1101 and the pressure head 111, for example, by opening a groove and embedding a tightly fitting "O" type sealing ring, so as to construct a sealing protection for the sliding contact part. At the same time, a second sealing member 113 is provided at the fitting connection between the second end of the cylinder wall 1101 and the base 1102, for example, by also opening a groove and embedding a tightly fitting "O" type sealing ring, so as to construct a sealing protection for the contact part, thereby ensuring that the required vacuum environment and gas pressure environment can be formed in the cavity 110.

[0031] To facilitate the pressure setting and control of the pressure applying unit 11, optionally, Figure 1 As shown, in one embodiment of the present invention, the experimental device 1 further includes a mechanical control system 15, and the pressure unit 11 further includes a controller 114 and a press 115. The controller 114 is configured to set parameters of the controller 114 through the mechanical control system 15 to control the press 115 to apply a force to the pressure head 111. For example, the press 115 can be a rock direct shear / triaxial compression composite testing machine, and the mechanical control system 15 is operated to set relevant parameters in the controller 114, and the rock direct shear / triaxial compression composite testing machine is operated to apply axial pressure to the pressure head 111, and the mechanical data is digitally recorded.

[0032] Optional, such as Figure 1As shown, in one embodiment of the present invention, the vacuum system 121 includes a vacuum pump 1211, a first pressure gauge 1212 and a first valve 1213 connected in sequence, and the first valve 1213 is connected to the cavity 110; and / or the gas filling system 122 includes a designated gas storage tank 1221, a pressure reducing valve 1222, a second pressure gauge 1223, a stop valve 1224 and a second valve 1225 connected in sequence, and the second valve 1225 is connected to the cavity 110. In this embodiment, the first port and the second port, a mechanical vibration force transmission port and an artificial acoustic signal monitoring portion can be processed in the circumferential direction of the cavity 110 respectively, wherein the first port and the second port are opposite to each other and are respectively connected to the first valve 1213 of the vacuum system 121 and the second valve 1225 of the gas filling system 122, and the cavity 110 is vacuumed or filled with designated gas through the switch valve control of the first valve 1213 and the second valve 1225. When the gas in the cavity 110 needs to be discharged at the end of the experiment, the exhaust system can be connected to the first valve 1213 or the second valve 1225, or a third port can be separately provided in the cavity 110 and a third valve can be configured to connect to the exhaust system to achieve exhaust.

[0033] There are many optional mechanisms for achieving mechanical impact, such as Figure 3 , Figure 4 As shown, in one embodiment of the present invention, the impact mechanism 131 includes a bracket 1311, a pendulum 1312, a dial 1313 and a pointer 1314. The pendulum 1312 is suspended from the bracket 1311 and is rotatably connected to the bracket 1311. The dial 1313 is connected to the pendulum 1312, and the pointer 1314 is arranged on the bracket 1311. The suspension connection between the pendulum 1312 and the bracket 1311 can be rotatably connected by passing a cylindrical pin 1315 and setting grease. When the pendulum 1312 is in a static state, the indicated position of the pointer 1314 is matched and aligned with the zero scale of the dial 1313. In this way, when the pendulum 1312 falling at different angles is used for impact each time, the free swing angle of the pendulum 1312 and its corresponding mechanical energy can be determined by the reading of the dial 1313. Specifically, the dial 1313 can be detachably fixedly connected to the pendulum 1312 by bolts, nuts, etc. As another optional solution, the dial 1313 can also be fixedly connected to the bracket 1311, and the angle of the pendulum 1312 and the corresponding mechanical energy can be determined by the reading of the pendulum 1312's swing arm, such as a suspension rod or a cable connected to the bracket 1311 relative to the dial 1313.

[0034] Optional, such as Figure 1As shown, in one embodiment of the present invention, the mechanical vibration unit 13 further includes a data processor 134, and the force measuring element 133 is connected to the data processor 134. The data processor 134 is configured to analyze the impact force monitored by the force measuring element 133 and transmit the analysis result to the mechanical control system 15. Specifically, a gasket can be fixed to the outer surface of the pin body 132 penetrating the cavity 110 with bolts, and then the force measuring element 133, such as a pressure sensor, can be fixed between the two gaskets with gaskets and bolts of the same specifications. The force measuring element 133 is connected to the data processor 134 and can be connected to the mechanical control system 15 to achieve communication connection and transmit monitoring data, analysis results, etc.

[0035] Optional, such as Figure 1 , Figure 3 As shown, in one embodiment of the present invention, the acoustic signal monitoring unit 14 also includes a probe fixing member 143, the probe fixing member 143 includes a first pad 1431, a second pad 1432, and a through rod 1433, the first pad 1431 and the second pad 1432 are relatively arranged to clamp the probe 141, and the through rod 1433 is passed through and axially limited at the first pad 1431 and the second pad 1432. In this embodiment, the probe 141 of the acoustic signal monitoring unit 14 can be fixed by a penetration rod 1433, a first pad 1431, and a second pad 1432. The penetration rod 1433 can be a threaded rod. For example, three threaded rods can be used to penetrate the first pad 1431 and the second pad 1432, and are axially limited by nuts at the first pad 1431 and the second pad 1432. The probe 141 is adjusted to ensure that the surface of the probe 141 does not contact the threaded rod, and the end of the probe 141 is in close contact with the cavity 110. At the same time, the probe 141 is connected to a detector 142, such as a seismic detector 142, through a communication line to monitor and collect artificial acoustic signals generated when the pendulum 1312 mechanically vibrates and strikes the coal sample.

[0036] To further ensure the sealing performance of the cavity 110, optionally, as Figure 1As shown, in one embodiment of the present invention, a third sealing member 116 is provided at the sliding contact portion of the outer wall of the pin body 132, and the pin body 132 is configured such that when the pin body 132 moves to a first preset position in a direction away from the cavity 110, the first end of the pin body 132 is limited, and / or when the pin body 132 moves to a second preset position in a direction close to the cavity 110, the second end of the pin body 132 is limited. It can be understood that the provision of the third sealing member 116 at the sliding contact portion of the pin body 132 relative to the cavity 110 can further improve the sealing performance of the sliding contact portion of the pin body 132, and prevent the vacuum environment or air pressure environment in the cavity 110 from causing gas leakage or pressure relief due to the matching clearance of the sliding contact portion of the pin body 132. In addition, in order to improve the displacement reliability of the pin body 132 when the pendulum 1312 hits it and avoid the occurrence of overtravel and the like, the first end of the pin body 132 is designed as a T-shaped structure in this embodiment, and the outer diameter of the T-shaped structure is larger than the outer diameter of the sliding contact portion of the pin body 132, so that when the pin body 132 moves to the first preset position away from the cavity 110, the first end of the pin body 132 is limited, and a disc-shaped structure is provided at the second end of the pin body 132, and the outer diameter of the disc-shaped structure is larger than the outer diameter of the sliding contact portion of the pin body 132, so that when the pin body 132 moves to the second preset position toward the cavity 110, the second end of the pin body 132 is limited, thereby improving the movement reliability and safety of the pin body 132 when it is hit.

[0037] To improve the integrity and motion accuracy of the experimental components, optional Figure 1 , Figure 4 As shown, in one embodiment of the present invention, the experimental device 1 further includes a base 16, and the cavity 110 of the pressure unit 11 is detachably fixedly connected to the base 16, and / or the impact mechanism 131 of the mechanical vibration unit 13 is detachably fixedly connected to the base 16, and / or the probe 141 of the acoustic signal monitoring unit 14 is detachably fixedly connected to the base 16. It can be understood that the experimental components such as the cavity 110, the impact mechanism 131, and the probe 141 are detachably fixedly connected to the base 16 by bolts and nuts, which is not only convenient for installation and disassembly, but also allows the cavity 110, the impact mechanism 131, and the probe 141 to be relatively fixed to the base 16 at the same time. When the base 16 is used as the same reference object, the cavity 110, the impact mechanism 131, and the probe 141 have higher experimental accuracy and data accuracy, avoid systematic errors in the test data, and improve the accuracy and credibility of the experimental results.

[0038] In a second aspect, an embodiment of the present invention also provides an experimental method for mechanical vibration excitation of artificial acoustic signals, which can improve the ability to predict the danger of mine dynamic phenomena.

[0039] The experimental method of mechanical vibration excitation artificial acoustic signal provided in the embodiment of the present application may include: S21, installing the pressure unit 11 of the experimental device, and placing the test sample in the cavity 110 of the pressure unit 11, wherein the experimental device is any of the experimental devices 1 for mechanical vibration excitation of artificial acoustic signals described in the embodiments of the present application.

[0040] Before loading the test sample, such as the coal sample of the present embodiment, a tightly fitting "O"-ring can be placed in the groove of the base 1102 of the cavity 110, and the base 1102 can be tightly connected to the wall 1101 of the cavity 110 by bolts, and the assembled cavity 110 can be fixed to the base 16 by fixing bolts.

[0041] S22 , assemble the mechanical vibration unit 13 , the acoustic signal monitoring unit 14 , and the inflation and exhaust unit 12 of the experimental device 1 , and check the airtightness of the experimental device 1 .

[0042] Grease is evenly applied to the cylindrical pin 1315 at the connection between the bracket 1311 and the pendulum 1312, and the dial 1313 is fixed to the swing arm of the pendulum 1312 by fixing the nut, and the zero scale line of the dial 1313 is aligned with the pointer 1314 fixed to the bracket 1311; the force measuring element 133 pressure sensor is tightly connected to the pin body 132 penetrated on one side of the cavity 110 through a gasket by using bolts; the bracket 1311 and the base 16 are fixed by bolts and nuts; the probe fixing part 143 can be fixedly connected to the base 16 in a detachable manner, and the through rod 1433 of the probe fixing part 143, such as three threaded rods, is passed through the first pad 1431 and the second pad 1432, and the probe 141 is placed in the space surrounded by the three threaded rods and fixed with nuts, so that the probe 141 does not contact the three threaded rods, and the end of the probe 141 is in close contact with the barrel wall 1101 of the cavity 110.

[0043] S23, using the vacuum system 121 to evacuate the cavity 110 and allow the test sample to be vacuum degassed for a first preset time, then using the inflation system 122 to inject a specified gas into the cavity 110 to a preset pressure, and allowing the test sample to adsorb the specified gas for a second preset time.

[0044] After checking that the air tightness of the experimental device 1 meets the experimental requirements, the mechanical control system 15 can be operated for preloading so that the pressure head 111 fits the top surface of the coal sample in the cavity 110, and then the cavity 110 is evacuated by the vacuum system 121 for a first preset time, for example, 10 hours, to degas the coal sample; then, a specified gas, such as methane or other gas, is injected into the cavity 110 to a preset pressure through the inflation system 122, so that the coal sample in the cavity 110 is inflated and adsorbed with methane for a second preset time, for example, 12 hours.

[0045] S24. Under a preset air pressure, use the pressure head 111 of the pressure-applying unit 11 to apply a preset pressure to the test sample, and under the preset pressure, use the impact mechanism 131 of the mechanical vibration unit 13 to apply a preset impact force to the pin body 132, and monitor the acoustic test signal under the preset impact force through the acoustic signal monitoring unit 14.

[0046] After the coal sample reaches gas adsorption equilibrium, use the mechanical control system 15 to set relevant parameters for the controller 114, and operate the rock direct shear / triaxial compression composite testing machine to apply axial pressure to the pressure head 111. Under different axial pressures, the pendulum 1312 is placed at different angles to swing freely to hit the force measuring element 133. The interval between each strike should be no less than 10 seconds, and the probe 141 monitors and collects the artificial acoustic signals during each strike.

[0047] S25. Use the exhaust system of the charging and exhaust unit 12 to exhaust the specified gas in the cavity 110 to a specified position, disassemble the experimental device 1, and clean the test sample.

[0048] After the impact test, the exhaust system can be connected to the valve on one side of the cavity 110 to discharge the gas in the cavity 110 to a designated location such as a storage container, the assembled cavity 110 can be disassembled and separated, and the base 1102 of the cavity 110 can be opened to clean the internal coal sample.

[0049] S26. Analyze the relationship between the acoustic test signal and the preset air pressure, the preset pressure, and the preset impact force.

[0050] Through the test, multiple groups of acoustic test signals under different preset air pressures, preset pressures, and preset impact forces were obtained. The axial pressure parameter data, acoustic test signals, and mechanical vibration impact force data collected after each group of experiments were sorted and analyzed to obtain the quantitative relationship between different axial stress magnitudes, different mechanical vibration impact force magnitudes, different gas pressures, and artificial acoustic signals. The study of rock stress-strain state based on acoustic detection results can refer to the following principles: resonance occurs in each rock layer from the free surface to the weakened contact surface, and the thickness of the rock layer in which the resonance occurs is h and resonant frequency f р The following relationship exists: ; In the formula, V represents the phase velocity of the shear wave, m / s.

[0051] Relative stress coefficient K , which is equal to the ratio of the sum of the amplitudes of the high-frequency part of the spectrum to the sum of the amplitudes of the low-frequency part of the spectrum: ; In the formula, A BRepresents the sum of the amplitudes of the high-frequency part of the acoustic signal spectrum; A H Represents the sum of the amplitudes of the low-frequency part of the acoustic signal spectrum.

[0052] By changing the axial stress, mechanical vibration impact force (pendulum 1312 free swing angle), and gas pressure of gas-containing coal samples during the experiment, the quantitative relationship between coal sample stress-strain, gas pressure, mechanical vibration impact force and artificial acoustic signal spectrum-amplitude can be obtained.

[0053] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0054] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0055] In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0056] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. An experimental device for mechanical vibration excitation of artificial acoustic signals, characterized in that: include: A pressure unit, the pressure unit comprising a cavity and a pressure head, the pressure head is movably arranged in the cavity and is used to apply pressure to the test sample in the cavity; An inflation and exhaust unit, the inflation and exhaust unit comprising a vacuum system, an inflation system and an exhaust system, the vacuum system being connected to the cavity to evacuate the cavity, the inflation system being connected to the cavity to inject a specified gas into the cavity, and the exhaust system being connected to the cavity to exhaust the cavity; A mechanical vibration unit, the mechanical vibration unit comprising an impact mechanism, a pin body, and a force measuring element, the pin body being movably arranged in the cavity, the impact mechanism being configured to apply an impact force to a first end of the pin body so that a second end of the pin body transmits the impact force to a test sample in the cavity, and the force measuring element being arranged at the first end of the pin body to monitor the impact force; An acoustic signal monitoring unit comprises a probe and a detector. The probe abuts against the cavity and is connected to the detector.

2. The experimental device for mechanical vibration excitation of artificial acoustic signals as claimed in claim 1, characterized in that: The cavity includes a cylinder wall and a base. The pressure head is movably arranged at the first end of the cylinder wall, and a first sealing member is arranged between the pressure head and the first end of the cylinder wall. The base is detachably connected to the second end of the cylinder wall, and a second sealing member is arranged between the base and the second end of the cylinder wall.

3. The experimental device for mechanical vibration excitation of artificial acoustic signals as claimed in claim 1, characterized in that: It also includes a mechanical control system, and the pressure-applying unit also includes a controller and a press, and the controller is configured to set parameters of the controller through the mechanical control system to control the press to apply force to the pressure head.

4. The experimental device for mechanical vibration excitation of artificial acoustic signals as claimed in claim 1, characterized in that: The vacuum system comprises a vacuum pump, a first pressure gauge and a first valve connected in sequence, wherein the first valve is connected to the cavity; and / or The inflation system includes a designated gas storage tank, a pressure reducing valve, a second pressure gauge, a stop valve and a second valve which are connected in sequence, and the second valve is connected to the cavity.

5. The experimental device for mechanical vibration excitation of artificial acoustic signals as claimed in claim 1, characterized in that: The impact mechanism includes a bracket, a pendulum, a dial and a pointer. The pendulum is suspended from the bracket and rotatably connected to the bracket. The dial is connected to the pendulum, and the pointer is arranged on the bracket.

6. The experimental device for mechanical vibration excitation of artificial acoustic signals as claimed in claim 3, characterized in that: The mechanical vibration unit further includes a data processor, the force measuring element is connected to the data processor, and the data processor is configured to analyze the impact force monitored by the force measuring element and transmit the analysis result to the mechanical control system.

7. The experimental device for mechanical vibration excitation of artificial acoustic signals as claimed in claim 1, characterized in that: The acoustic signal monitoring unit also includes a probe fixing member, which includes a first pad, a second pad, and a through rod. The first pad and the second pad are relatively arranged to clamp the probe, and the through rod is passed through and axially limited by the first pad and the second pad.

8. The experimental device for mechanical vibration excitation of artificial acoustic signals as claimed in claim 1, characterized in that: A third sealing member is provided at the sliding contact portion of the outer wall of the pin body, and the pin body is configured such that when the pin body moves to a first preset position away from the cavity, the first end of the pin body is limited, and / or when the pin body moves to a second preset position toward a direction close to the cavity, the second end of the pin body is limited.

9. The experimental device for mechanical vibration excitation of artificial acoustic signals as claimed in claim 1, characterized in that: It also includes a base, the cavity of the pressure unit is detachably fixedly connected to the base, and / or the impact mechanism of the mechanical vibration unit is detachably fixedly connected to the base, and / or the probe of the acoustic signal monitoring unit is detachably fixedly connected to the base.

10. An experimental method for mechanical vibration excitation of artificial acoustic signals, characterized in that: include: Installing a pressure unit of an experimental device, and placing a test sample in a cavity of the pressure unit, wherein the experimental device is an experimental device for mechanical vibration excitation of an artificial acoustic signal according to any one of claims 1 to 9; Assembling the mechanical vibration unit, the acoustic signal monitoring unit and the inflation and exhaust unit of the experimental device, and checking the air tightness of the experimental device; Using the vacuum system to evacuate the cavity and allow the test sample to be vacuum degassed for a first preset time, then using the inflation system to inject the specified gas into the cavity to a preset pressure and allow the test sample to adsorb the specified gas for a second preset time; Under the preset air pressure, use the pressure head of the pressure-applying unit to apply a preset pressure to the test sample, and under the preset pressure, use the impact mechanism of the mechanical vibration unit to apply a preset impact force to the pin body, and monitor the acoustic test signal under the preset impact force through the acoustic signal monitoring unit; Using the exhaust system of the inflation and exhaust unit, the specified gas in the cavity is exhausted to a specified position, and the experimental device is disassembled to clean the test sample; Analyze the relationship between the acoustic test signal and the preset air pressure, the preset pressure, and the preset impact force.

Images