Mine earthquake physical simulation test system and method based on microseismic and acoustic emission joint monitoring

Abstract

The present invention discloses a physical simulation test and analysis method for mine earthquakes based on the combined monitoring of microseismic and acoustic emission, including: positioning and drilling a circular hole on a loading plate according to the design positions of an all-fiber microseismic sensor and an acoustic emission sensor, and installing a concentric limiting circular ring outside the plate; pasting a seismic isolation and friction reduction plate on the inner wall of the loading plate; making a model body to the height of the circular hole after layered compaction, inserting a waveguide rod into the limiting circular ring and the circular hole to the specified depth of the model body in sequence, and compacting the filler, and continuing to make the model body; after the loading of the model body is stable, the limiting circular ring is removed, the all-fiber microseismic sensor is connected to the exposed end of the waveguide rod, and the acoustic emission sensor is pasted in the plane of the outer wall of the waveguide rod; and the simulation test is officially started after verification by a knocking positioning test. This method breaks the limitations of traditional model tests to monitor a few conventional physical quantities such as stress, displacement, and strain, introduces the monitoring of rock stratum fracture vibration signals, and lays an experimental foundation for in-depth revelation of the breeding and evolution mechanism of large-energy mine earthquakes.

Description

Technical Field

[0001] The present invention relates to the field of model testing technology for spontaneous dynamic phenomena such as mine tremors in deep mining engineering, and in particular to a large-scale true three-dimensional model testing system and analysis method for spontaneous fracture of high-position thick hard overburden and induction of high-energy mine tremors caused by deep coal seam mining under complex conditions. Background Art

[0002] Coal mining has advanced into deeper areas. The increase in mining depth has led to a more complex geological environment, more intense engineering disturbance responses, and more intense mine earthquake activities. This has caused the mine earthquake problem to evolve from a resource safety mining problem to a social public safety problem. Therefore, in-depth revelation of the mechanism of the incubation and evolution of coal mine earthquakes has become a major scientific and technological problem that needs to be solved urgently. On-site monitoring methods are limited in conditions, huge in cost, and high in risk. Numerical simulation methods are difficult to simulate real disaster processes, and theoretical analysis methods are difficult to break through the influence of complex geological environments. Geomechanical model tests have unique advantages over the aforementioned methods in discovering new phenomena, exploring new laws, and revealing new mechanisms. Therefore, it is necessary to carry out model tests on the incubation and evolution mechanisms of large-energy mine earthquakes under complex conditions. To carry out mine earthquake model tests, it is necessary to have a model test system and test methods for monitoring vibration signals. The current status of related research is as follows:

[0003] Patent CN116448569A discloses a physical simulation device and method for monitoring collapse-type mine earthquake wells, which only considers acoustic emission monitoring and buries the acoustic emission sensor inside a model body of similar material. This method is not convenient for the inspection and replacement of the acoustic emission sensor, and the monitoring of rock stratum vibration signals is limited, and is not suitable for large-scale true three-dimensional mine earthquake model tests.

[0004] The Chinese Journal of Rock Mechanics and Engineering, Volume 40, Issue 3, 2021, introduced a large-scale three-dimensional tunnel rock burst disaster evolution and instability model test system, which is mainly composed of a static loading system, a model casting device, a model transportation device, a blasting dynamic load application system and a data monitoring system. The system cannot simulate spontaneous dynamic phenomena such as mine earthquakes, and cannot monitor the vibration signals generated by rock fracture.

[0005] Patent CN116337628A discloses a method and device for simulating stick-slip seismicity of active faults under three-dimensional stress. The method points out the evolution process of rock crack initiation and expansion and the change law of at least one of the peak acceleration, amplitude and frequency of seismic waves during the monitoring test with microseismic sensors arranged around the model, but no specific implementation method is given.

[0006] In general, the existing model test methods at home and abroad generally have the following problems:

[0007] (1) The existing model test system cannot simulate the high-energy mining earthquake phenomenon induced by spontaneous overburden fracture and cannot automatically collect the vibration signal generated by the fracture of the rock layer inside the model body;

[0008] (2) The existing true three-dimensional loading model test system cannot flexibly adapt to the mining model test of coal seams at different heights. Summary of the invention

[0009] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a mining earthquake physical simulation test and analysis method based on microseismic and acoustic emission combined monitoring, which can monitor the vibration signals generated by the spontaneous fracture of the overlying rock due to coal seam mining, realize the visualization observation of crack expansion and rock formation fracture, adapt to different model coal seam positions and thicknesses and other working conditions, and provide a true three-dimensional ground stress field.

[0010] To achieve the above object, the present invention discloses the following technical solution:

[0011] In the first aspect, the present invention provides a mining earthquake physical simulation test system based on the combined monitoring of microseismic and acoustic emissions, including a combined visual reaction force combined stand device, a hydraulic jack is arranged on the inner wall of the combined visual reaction force combined stand device, which acts on the loading plate to apply a load to the model body, and also includes a waveguide rod, the embedded end of the waveguide rod is inserted into the model body, and the exposed end extends to the outside of the loading plate, the exposed end is connected to an all-fiber microseismic sensor, and an acoustic emission sensor is also adhered to the plane of the outer wall of the exposed waveguide rod; the all-fiber microseismic sensor is connected to the all-fiber microseismic monitoring system, and the acoustic emission sensor is connected to the acoustic emission system; stress, strain, and displacement monitoring elements are also arranged in the model body, and the stress, strain, and displacement monitoring elements are connected to the test system.

[0012] As a further technical solution, the loading plate includes a sliced ​​steel loading plate, a block steel loading plate and an integral steel loading plate.

[0013] As a further technical solution, the integral steel loading plate is located at the bottom of the model body, the sliced ​​steel loading plates are located at the left, right and rear sides of the model body, and the block steel loading plates are located at the top surface of the model body.

[0014] As a further technical solution, the positions of the all-fiber microseismic sensor and the acoustic emission sensor in space cannot be coplanar, and there is no requirement for their layout positions, but they must cover the research object as comprehensively as possible.

[0015] As a further technical solution, a seismic isolation and friction reduction plate is arranged on the inner wall of the steel loading plate to isolate the mutual interference of the vibration waves in the model body and the steel loading plate.

[0016] As a further technical solution, round holes are drilled in the steel loading plate, and a detachable limiting ring concentric with the round holes is arranged on the outer surface of the steel loading plate and fixed by a limiting bolt. The waveguide rod is sequentially inserted into the limiting ring and the round hole of the loading plate to a specified depth inside the model body.

[0017] As a further technical solution, the waveguide rod is a regular prism, and the width of a single outer side surface is greater than the diameter of the acoustic emission sensor. The exposed end of the regular prism waveguide rod is processed into a thread matching the all-fiber microseismic sensor.

[0018] As a further technical solution, one side of the combined visual reaction force combined bench device is provided with a visual acrylic plate and a coal-blocking acrylic plate spliced together, and the acrylic plate is closely attached to the surface of the model body.

[0019] As a further technical solution, the front wall of the combined visual reaction force device includes a lattice steel beam with a split middle hollow and closed ends connected by bolts, a pull-out reaction force bench front wall, and an acrylic plate. The lattice steel beam is used for free combination to adapt to the coal seam mining model test under different similarity scales; a pull-out reaction force bench front wall is arranged inside the steel beam, and the pull-out reaction force bench front wall provides passive constraint for the model body and reserves an operation space for coal seam mining; an acrylic plate is arranged in the groove of the steel beam, which is used to provide passive constraint for the model body and realize the visual observation of overlying rock fracture.

[0020] In the second aspect, based on the test method of the mine earthquake physical simulation test system based on microseismic acoustic emission joint monitoring, as follows:

[0021] Select the coordinate origin and establish a space rectangular coordinate system;

[0022] Taking the space rectangular coordinate system as a reference system, design the space layout scheme of the all-fiber microseismic sensor and the acoustic emission sensor and determine the three-dimensional coordinates of the two sensors;

[0023] Based on the space layout scheme of the all-fiber microseismic sensor and the acoustic emission sensor, drill round holes in the loading plate, install a detachable limiting ring concentric with the round holes outside the plate and fix it with a limiting bolt;

[0024] When the model body is made to the height of the round hole by the layered compaction and air-drying method, insert the regular prism waveguide rod into the limiting ring and the round hole of the steel loading plate to a specified depth inside the model body in sequence, and fill and compact the material;

[0025] The acoustic emission sensor is pasted at a specified position in the plane of the outer side wall of the regular prism waveguide rod, and the all-fiber microseismic sensor is connected with the regular prism waveguide rod by a thread;

[0026] Based on the knocking positioning test, judging whether the microseismic-acoustic emission positioning error meets the accuracy requirement;

[0027] If the accuracy requirements are met, the mine earthquake model test will continue to be carried out, and microseismic and acoustic emission events will be monitored and collected in real time. Otherwise, the all-fiber microseismic monitoring system, acoustic emission system and corresponding sensors will need to be repaired and the knock positioning test will be carried out again until the positioning accuracy meets the requirements.

[0028] The present invention has the following significant technical advantages:

[0029] (1) The present invention can realistically simulate the evolution process of high-energy mine earthquake events induced by spontaneous breaking of high-position thick and hard overburden under coal seam recovery by setting a waveguide rod. At the same time, the all-fiber microseismic monitoring system and the acoustic emission system can capture all vibration signals generated by overburden breaking to the maximum extent, and the positioning results can be mutually verified to ensure that the test results are true and reliable. In addition, since the sensors are installed outside the model body, the installation, disassembly, testing and maintenance of the two sensors are very convenient.

[0030] (2) The front wall of the combined visualized reaction force device of the present invention comprises a segmented lattice steel beam connected by bolts and having a hollow middle and closed ends, which can be used for free combination to adapt to coal seam mining model tests under different similar scales; a pull-out reaction force stand front wall is arranged inside the steel beam, which provides passive constraints for the model body and reserves operating space for coal seam mining. By adjusting the position of the pull-out reaction force stand front wall, coal seam mining at different heights can be simulated; an acrylic plate is arranged in the groove of the steel beam, which can directly observe the expansion of model cracks and rock fracture while ensuring the horizontal displacement constraint of the model body.

[0031] (3) The present invention also has broad application value in the physical simulation and disaster mechanism research of spontaneous dynamic disasters such as rock burst, rock burst, coal and gas outburst in deep geotechnical engineering such as hydropower, transportation, energy, mining and national defense. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0033] Figure 1 This is a layout diagram of the all-fiber microseismic sensor and acoustic emission sensor of the present invention;

[0034] Figure 2 A diagram showing the installation of the all-fiber microseismic sensor and the acoustic emission sensor of the present invention;

[0035] Figure 3 It is a schematic diagram of the interior of the combined visual reaction force stand of the present invention in the front view (front);

[0036] Figure 4 It is a schematic diagram of the installation of the microseismic and acoustic emission sensors of the present invention;

[0037] Figure 5 It is a top view of the front wall of the combined visualization reaction force stand and the visualization acrylic plate of the present invention in a separated state;

[0038] Figure 6 It is a front view of the combined visual reaction force stand front wall and the visual acrylic plate of the present invention in a disassembled state;

[0039] Figure 7 It is a three-dimensional design diagram of the interior of the combined visual reaction force stand device of the present invention;

[0040] Figure 8 It is a design diagram of the guide frame structure of the present invention;

[0041] Fig. 9 It is a three-dimensional design drawing of the combined visual reaction force stand of the present invention;

[0042] Among them: 1. All-fiber microseismic monitoring system, 2. Acoustic emission system, 3. High-precision test system, 4. Combined visual reaction force stand device, 5. Hydraulic servo loading control system, 6. Regular prism waveguide rod, 7. Regular prism waveguide rod exposed end head screw, 8. All-fiber microseismic sensor, 9. Acoustic emission sensor, 10. Limiting ring, 11. Hydraulic jack, 12. Table-type thruster plate, 13. Sliced ​​steel loading plate, 14. Guide frame, 15. Model body, 16. Stress, strain and displacement monitoring elements, 17. Connectors, 18. Front wall of combined visual reaction bench, 19. Front wall of pull-out reaction bench, 20. Visible acrylic plate, 21. Coal-blocking acrylic plate, 22. Optical cable, 23. Electric cable, 24. Oil line, 25. Limit bolts, 26. Isolation and friction reduction plate, 27. Block steel loading plate, 28. Integral steel loading plate. DETAILED DESCRIPTION

[0043] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0044] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0045] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0046] like Figure 3 As shown, the mining earthquake physical simulation test system based on the combined monitoring of microseismic and acoustic emissions proposed in this embodiment includes an all-fiber microseismic monitoring system 1, an acoustic emission system 2, a high-precision testing system 3, a combined visual reaction force combination stand device 4 and a hydraulic servo loading control system 5; the model test system can accommodate a large-scale model body with a thickness, length and width similar to that of the model body, and can apply true three-dimensional non-uniform loads to all its outer sides to truly simulate the initial ground stress field.

[0047] The four corners of the combined reaction platform device 4 are all equipped with connecting pieces 17, which are used to improve the rigidity of the reaction platform. The hydraulic jacks 11 are installed on the upper, lower, left, right and rear inner walls of the combined reaction platform device 4, and each hydraulic jack 11 is connected to the table-type thruster plate 12; a guide frame 14 is arranged in the combined reaction platform device 4, an integral steel loading plate 28 is arranged at the bottom of the guide frame 14, and a piece-type steel loading plate 13 is arranged on the left, right and rear sides; a block-type steel loading plate 27 is arranged on the top; the front part is overlapped on the front wall 18 of the combined visual reaction platform (see for details) Figure 7 , Figure 8 ); the sliced ​​steel loading plate 13, the block steel loading plate 27 and the integral steel loading plate 28 move within the range surrounded by the guide frame 14 to eliminate the "corner effect" of true three-dimensional loading, so as to achieve that the loading plates move on each surface of the model body without interfering with each other. The hydraulic loading control system 5 applies load to the hydraulic jack 11 through 8 oil circuits 24. The sliced ​​steel loading plate 13 is divided into three pieces along the height direction on the left, right and rear of the model body and a gradient load is applied to achieve true three-dimensional gradient non-uniform loading on the model body. The top block steel loading plate 27 is divided into blocks to achieve the sinking of the top surface of the model while still servo-loading the top load.

[0048] Furthermore, the all-fiber microseismic monitoring system 1 is connected to the all-fiber microseismic sensor 8 installed in the model body 15 through the optical cable 22, and the all-fiber microseismic monitoring system 1 can effectively capture the high-energy low-frequency vibration signal of the internal rupture of the model body 15; the acoustic emission system 2 is connected to the acoustic emission sensor installed in the model body 15 through the cable 23, and the acoustic emission system 2 can effectively capture the low-energy high-frequency vibration signal of the internal rupture of the model body 15. The combined use of the all-fiber microseismic monitoring system 1 and the acoustic emission system 2 can capture all vibration signals of the internal rupture of the model body 15. The high-precision test system 3 is connected to the stress, strain, and displacement monitoring element 16 pre-buried in the model body 15 through the optical cable, and the multi-source monitoring information inside the model body 15 is captured and recorded during the test.

[0049] like Figure 4 As shown, the inner walls of the sliced ​​steel loading plate 13, the block steel loading plate 27 and the integral steel loading plate 28 are pasted with seismic isolation and friction reduction plates 26 to isolate the model body 15 and the interference of vibration signals inside the sliced ​​steel loading plate 13, the block steel loading plate 27 and the integral steel loading plate 28.

[0050] Circular holes can be drilled on the sliced ​​steel loading plate 13, the block steel loading plate 27 and the integral steel loading plate 28, and a limiting ring 10 concentric with the circular hole is installed outside the loading plate and fixed by a limiting bolt 25. The regular prism waveguide rod 6 passes through the circular hole of the loading plate to a certain depth inside the model body 15 through the limiting ring 10. After the loading of the model body is stable, the limiting ring 10 is removed to ensure that the regular prism waveguide rod 6 and the sliced ​​steel loading plate 13, the block steel loading plate 27 and the integral steel loading plate 28 are not in contact throughout the entire process of the mine earthquake model test, so as to isolate the interference of the vibration signal between the regular prism waveguide rod 6 and the sliced ​​steel loading plate 13, the block steel loading plate 27 and the integral steel loading plate 28.

[0051] Connect the all-fiber microseismic sensor 8 to the exposed end 7 of the regular prism waveguide rod, and paste the acoustic emission sensor 9 at the specified position in the outer wall plane of the regular prism waveguide rod 6. After connecting the sensor, carry out the knocking positioning test. If the positioning error is within the allowable range, the mine earthquake model test will be formally carried out; otherwise, it is necessary to overhaul the all-fiber microseismic monitoring system 1, the all-fiber microseismic sensor 8, the acoustic emission system 2, and the acoustic emission sensor 9 until the positioning error reaches the allowable range.

[0052] like Figure 5 , Figure 6As shown, the front wall 18 in the combined visual reaction bench device 4 is composed of lattice steel beams with different heights and hollowed out in the middle and closed at both ends, which are installed on the combined visual reaction bench device 4 by high-strength bolts, and the inner wall thereof is grooved so that it can accommodate an acrylic plate with a thickness of 20 mm. The acrylic plate is composed of a visible acrylic plate 20 and a coal-blocking acrylic plate 21. The acrylic plate is closely attached to the surface of the model body 15, constraining the horizontal displacement of the model body 15 and applying a passive load to the model body 15. The crack development and overburden fracture of the model body 15 during the test can also be observed in real time through the front wall 18 of the combined visual reaction bench and the acrylic plate. The lattice steel beams with different heights and hollowed-out ends and closed in the middle of the combined reaction bench front wall 18 and the pull-out reaction bench front wall 19 can be freely adjusted and spliced ​​in the vertical direction, so that the pull-out reaction bench front wall 19 can be flexibly adjusted in height. The pull-out reaction bench front wall 19 has the same shape as the coal-blocking acrylic plate 21. Before the coal seam mining simulation is officially started, the pull-out reaction bench front wall 19 is first pulled out, and then the coal-blocking acrylic plate 21 is taken out to provide an operating space for coal seam mining. Therefore, the present invention can be applied to mining test conditions of coal seams at different heights.

[0053] Optionally, the more blocks the block-type top steel loading plate has, the better. Six blocks are used as an example in this application. The block-type top steel loading plate is used to independently servo-control the initial vertical geostress field of the block area. The blocks of the block-type top steel loading plate move vertically without interference, and each block is independently controlled by the oil cylinder connected thereto.

[0054] Furthermore, there is no clear requirement for the spatial distribution of the all-fiber microseismic sensors and acoustic emission sensors, but they cannot be coplanar and need to cover the research object as comprehensively as possible, such as the key layer in this example.

[0055] Furthermore, the circular hole drilled on the side steel loading plate is concentric with the circular hole of the limiting ring, and the diameter of the circular hole drilled on the side steel loading plate is larger than the inner diameter of the limiting ring, and the inner diameter of the limiting ring is larger than the outer diameter of the regular prism waveguide rod. In addition, the limiting ring needs to be removed after the loading of the model body is stable, and then the acoustic emission sensor is pasted and the all-fiber microseismic sensor is installed. The purpose is to ensure that the regular prism waveguide rod always remains out of contact with the loading plate during the mine earthquake model test, so as to isolate the interference from the vibration signal in the loading plate.

[0056] Furthermore, the waveguide rod is designed as a regular prism and the width of a single outer side surface is greater than the diameter of the acoustic emission sensor, and the exposed end of the regular prism waveguide rod is processed into a thread matching the all-fiber microseismic sensor. The purpose of designing the waveguide rod as a regular prism is to provide a uniform medium and surface for vibration wave propagation and to facilitate the attachment of the acoustic emission sensor.

[0057] Furthermore, before the mine earthquake model test officially begins, a knocking positioning test needs to be carried out to verify that the positioning accuracy meets the requirements. The inner wall of the steel loading plate of the model test system is pasted with a seismic isolation and friction reduction plate to isolate the mutual interference between the model body and the vibration waves in the steel loading plate.

[0058] Furthermore, the steel loading plates in the model test system are designed in different layouts according to their different spatial positions. The top steel loading plate is designed as a block type, and the top steel loading plate is divided into nine blocks in the horizontal direction. Each block can move independently and each block is independently controlled by the hydraulic jack connected to it, and the more blocks there are, the better the physical simulation effect; the side steel loading plate is designed as a slice type, and the side steel loading plate is divided into three pieces in the vertical direction, each piece corresponds to three hydraulic jacks, which are used to perform gradient loading on the model body, and the more slices there are, the better the physical simulation effect; the bottom steel loading plate is designed as an integral type, characterized in that the six hydraulic jacks at the bottom act together on the bottom steel loading plate to jointly apply uniform initial ground stress to the bottom of the model body.

[0059] Furthermore, the combined visual reaction force front wall includes a lattice steel beam with closed ends in the middle hollow, a pull-out reaction force stand front wall and a coal-blocking acrylic plate connected by bolts. The lattice steel beam with closed ends in the middle hollow can be freely combined to adapt to the coal seam mining model test under different similar scales. The pull-out reaction force stand front wall is connected to the lattice steel beam with closed ends in the middle hollow by bolts, which provides passive constraints for the model body on the one hand, and can realize mining at different heights of the model by adjusting the position of the pull-out reaction force stand front wall on the other hand, that is, after the pull-out reaction force stand front wall is pulled out, this position is used as the mining position of the model, and the coal-blocking acrylic plate provides passive constraints for the model body and realizes the visual observation of the overburden fracture. The heights of the lattice steel beam with closed ends in the middle hollow of the lattice are different, and the needs of different test schemes can be met by arbitrary combination in the height direction. The overlapping area of ​​the coal-blocking acrylic plate and the pull-out reaction force stand front wall is the same in shape. The acrylic plate should be thick rather than thin, and the thickness of the acrylic plate can be flexibly designed according to the needs of the test.

[0060] This embodiment also provides a test and analysis method for a mining earthquake physical simulation test system based on microseismic and acoustic emission joint monitoring, comprising the following steps:

[0061] Select the coordinate origin and establish a spatial rectangular coordinate system;

[0062] Taking the spatial rectangular coordinate system as a reference system, designing a spatial layout plan of the all-fiber microseismic sensor and the acoustic emission sensor and determining the three-dimensional coordinates of the two sensors;

[0063] Based on the spatial arrangement scheme of the all-fiber microseismic sensor and the acoustic emission sensor, a circular hole is drilled on the loading plate, and a limiting circular ring concentric with the circular hole is installed outside the plate and fixed with a limiting bolt;

[0064] When the model body is made to the height of the circular hole by the layered compaction and air-drying method, the regular prism waveguide rod is sequentially inserted into the limit ring and the circular hole of the loading plate to the specified depth inside the model body, the filler is compacted, and the model body is continued to be made;

[0065] The acoustic emission sensor is pasted at a designated position in the plane of the outer wall of the regular prism waveguide rod, and the all-fiber microseismic sensor is connected to the exposed end of the regular prism waveguide rod through a threaded connection;

[0066] Based on the knocking positioning test, judging whether the microseismic-acoustic emission positioning error meets the accuracy requirement;

[0067] If the accuracy requirements are met, the mine earthquake model test will continue to be carried out, and microseismic and acoustic emission events will be monitored and collected in real time. Otherwise, the all-fiber microseismic monitoring system, acoustic emission system and corresponding sensors will need to be repaired and the knock positioning test will be carried out again until the positioning accuracy meets the requirements.

[0068] Furthermore, the coordinate origin and the spatial rectangular coordinate system are selected based on the principle of convenience of calculation.

[0069] This application can realize the monitoring of cover and fracture signals based on the vibration signal monitoring method. At the same time, the positioning results of microseismic and acoustic emission can verify each other, ensuring the reliability of the test results. Since the sensors are installed outside the model body, the installation, disassembly, testing and maintenance of the two sensors are very convenient.

[0070] The front wall of the combined visualization reaction bench in this application is designed as a lattice steel frame with different heights and hollowed out in the middle and closed at both ends, which can be applied to model test schemes of different models and different coal seam heights of the same model under various working conditions. At the same time, the front wall is equipped with acrylic plates, which can directly observe the expansion of model cracks and rock fracture while ensuring the horizontal displacement constraint of the model body.

[0071] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made on the basis of the technical solution of the present invention without the need for creative labor by those skilled in the art are still within the scope of protection of the present invention.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A mining earthquake physical simulation test system based on the combined monitoring of microseismic and acoustic emissions, characterized in that: It comprises a combined visualized reaction force combined bench device, the inner wall of which is provided with a hydraulic jack, which acts on the loading plate to apply a load to the model body, and is characterized in that it also comprises a waveguide rod, the embedded end of the waveguide rod is inserted into the interior of the model body, the exposed end extends to the outside of the loading plate, the end of the exposed end is connected to an all-fiber microseismic sensor, and an acoustic emission sensor is also adhered to a specified position in the plane of the outer wall of the exposed waveguide rod; the all-fiber microseismic sensor is connected to the all-fiber microseismic monitoring system, and the acoustic emission sensor is connected to the acoustic emission system; the positions of the all-fiber microseismic sensor and the acoustic emission sensor in space are not coplanar; the all-fiber microseismic monitoring system and the acoustic emission system are used together, the all-fiber microseismic monitoring system and the acoustic emission system can capture all vibration signals generated by the overburden fracture to the maximum extent, and the positioning results can be mutually verified to ensure that the test results are true and reliable; stress, strain, and displacement monitoring elements are also arranged in the model body, and the stress, strain, and displacement monitoring elements are connected to the high-precision test system; The loading plate is made by cutting uniform and flat thick steel plates, including a sliced ​​steel loading plate, a block steel loading plate and an integral steel loading plate; the integral steel loading plate is located at the bottom of the model body, the sliced ​​steel loading plate is located on the left, right and rear sides of the model body, and the block steel loading plate is located on the top surface of the model body.

2. The mining earthquake physical simulation test system based on microseismic and acoustic emission joint monitoring as claimed in claim 1 is characterized in that: A seismic isolation and friction reduction plate is arranged on the inner wall of the loading plate.

3. The mining earthquake physical simulation test system based on microseismic and acoustic emission joint monitoring as claimed in claim 1 is characterized in that: A circular hole is drilled on the loading plate, and a detachable limiting ring concentric with the circular hole is installed outside the loading plate and fixed by a limiting bolt; the diameter of the circular hole of the steel loading plate is larger than the inner diameter of the limiting ring, and the inner diameter of the limiting ring is larger than the outer diameter of the regular prism waveguide rod.

4. The mining earthquake physical simulation test system based on microseismic and acoustic emission joint monitoring as claimed in claim 1 is characterized in that: The waveguide rod is a regular prism and the width of a single outer side surface is greater than the diameter of the acoustic emission sensor. The exposed end of the regular prism waveguide rod is processed into a thread matching the all-fiber microseismic sensor.

5. The mining earthquake physical simulation test system based on microseismic and acoustic emission joint monitoring according to claim 1 is characterized in that: An acrylic plate is arranged in front of the combined visual reaction force combined stand device, and the acrylic plate is in close contact with the surface of the model body.

6. The mining earthquake physical simulation test system based on microseismic and acoustic emission joint monitoring according to claim 1 is characterized in that: It includes a segmented lattice steel beam with a hollow middle and closed two ends connected by bolts, a visible acrylic plate on the front wall of a pull-out reaction stand, and a coal-blocking acrylic plate. The lattice steel beam is used for free combination to adapt to the mining model test of coal seams of different heights under different similar scales; a pull-out reaction stand front wall is arranged inside the steel beam, and the pull-out reaction stand front wall provides passive constraints for the model body and reserves operating space for coal seam mining; an acrylic plate is arranged in the groove of the steel beam to provide passive constraints for the model body and realize visual observation of overburden fracture.

7. The test method of the mining earthquake physical simulation test system based on microseismic and acoustic emission joint monitoring according to any one of claims 1 to 6 is characterized in that: Select the coordinate origin and establish a spatial rectangular coordinate system; Taking the spatial rectangular coordinate system as a reference system, designing a spatial layout plan of the all-fiber microseismic sensor and the acoustic emission sensor and determining the three-dimensional coordinates of the two sensors; Based on the spatial arrangement scheme of the all-fiber microseismic sensor and the acoustic emission sensor, a circular hole is drilled on the loading plate and a detachable limiting circular ring concentric with the circular hole is installed outside the plate; When the model body is made to the height of the circular hole by the layered compaction and air-drying method, the regular prism waveguide rod is sequentially inserted into the limit ring and the circular hole of the loading plate to the specified depth inside the model body, and the filling is compacted to continue making the model body; The acoustic emission sensor is pasted on a designated position in the outer wall plane of the regular prism waveguide rod, and the all-fiber microseismic sensor is connected to the regular prism waveguide rod through a threaded connection; Based on the knocking positioning test, determine whether the microseismic-acoustic emission positioning error meets the accuracy requirements; If the accuracy requirements are met, the mine earthquake model test will continue to be carried out, and microseismic and acoustic emission events will be monitored and collected in real time. Otherwise, the all-fiber microseismic monitoring system, acoustic emission system and corresponding sensors will need to be repaired and the knock positioning test will be carried out again until the positioning accuracy meets the requirements.

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