Rock characteristic research method and system based on acoustic emission

Abstract

The invention discloses a rock characteristic research method and system based on acoustic emission, and belongs to the technical field of acoustic wave detection. The device further comprises a detection module, the loading assembly comprises a box body, a rotation driving mechanism, a bottom plate, a top plate and a loading mechanism, the bottom plate is connected to the output end of the rotation driving mechanism, the rotation driving mechanism is used for driving the bottom plate to rotate, the loading mechanism is fixed to the top of the box body, and the top plate is connected with the output end of the loading mechanism through a thrust bearing; the detection module comprises an acoustic emission detection module and a tomography detection module; the acoustic emission detection module comprises a first probe assembly, a second probe assembly and a third probe assembly; the tomography detection module comprises a ray source assembly and an imaging assembly. The method is a method for carrying out rock characteristic research on the system.

Description

Technical Field

[0001] The invention relates to the technical field of acoustic wave detection, and in particular to a rock property research method and system based on acoustic emission. Background Art

[0002] Acoustic wave detection technology is widely used in the fields of geology and engineering. For example, when sound waves propagate in rocks, they will be affected by the internal structure and properties of the rocks, thus showing different propagation speeds. Specifically, it can be used to explore the stratification and geological structure of strata, to evaluate the mechanical characteristics and stability of rocks, and to provide a basis for engineering design and construction. When the internal structure of rocks changes under corresponding loads, they will show acoustic properties different from those before being loaded. By utilizing the differences in acoustic properties, the occurrence and development process of rock damage can be effectively evolved and constructed. Specifically, it can be used to evaluate the strength of rocks. When the internal structure of rocks changes under external loads, the sound waves emitted by the rocks due to cracks can be obtained by sound wave extraction devices. By studying the characteristics of sound waves, it can be effectively inferred that cracks have occurred in the rocks under load. In this case, acoustic wave detection technology can be used to fully understand the physical characteristics, structure and properties of rocks. The specific application areas cover geological exploration, engineering geological evaluation, rock classification and grading, rock engineering and other fields. In recent years, such as the technical solutions provided by patent documents with patent application numbers CN202210109749.4 and CN202111078715.5, with the development of instrument and equipment technology, the accuracy and reliability of acoustic wave detection technology have been further improved, providing rich data support for geological and engineering research. In the preparation and construction of hydropower station construction, acoustic wave detection technology is used by design and construction units to understand and master the physical characteristics, structure and properties of rocks in the dam area, as well as related evolutions, which provides a strong guarantee for the rationality of engineering design, construction safety and construction quality.

[0003] Regarding the application of acoustic emission technology under external loads, it is a non-destructive testing technology that evaluates rock damage and destruction processes by detecting and analyzing elastic waves generated during the stress release process inside the rock. Its principle is that when the rock is subjected to external loads, new cracks are generated inside it or existing cracks expand under the action of stress. The expansion and generation of these cracks will be accompanied by energy release and propagate outward in the form of transient elastic waves. These elastic wave signals can be captured by acoustic emission sensors arranged on the rock surface, and then the damage state and development process inside the rock can be obtained through analysis.

[0004] In view of the value of acoustic wave detection technology in exploration and engineering, it is necessary to further optimize relevant technical means. Summary of the invention

[0005] The present invention aims to optimize the acoustic wave detection technology proposed above. This scheme proposes a rock property research method and system based on acoustic emission. This scheme combines rock acoustic emission technology with rock tomography technology to obtain the research results of the destruction process of rock properties under external loads and the research results of the specific internal structure of the rock.

[0006] The specific technical scheme is: a rock property research system based on acoustic emission, including a loading component, the loading component is used to fix the rock sample and provide an external load to the rock sample; and also includes a detection module for detecting the internal damage characteristics of the rock sample under the external load. The loading component includes a box, a rotating drive mechanism installed at the bottom of the box, a bottom plate for providing bottom support for the rock sample, a top plate for supporting the top of the rock sample, and a loading mechanism for providing an external load for the rock sample, the bottom plate is connected to the output end of the rotating drive mechanism, the rotating drive mechanism is used to drive the bottom plate to rotate, the loading mechanism is fixed to the top of the box, the top plate is connected to the output end of the loading mechanism through a thrust bearing, the loading mechanism is used to provide downward pressure for the top plate, and the thrust bearing allows the top plate to rotate relative to the loading mechanism around the axis of the thrust bearing;

[0007] The detection module includes an acoustic emission detection module and a tomography detection module;

[0008] The acoustic emission detection module includes a first probe assembly for picking up the acoustic emission of the loading mechanism, a second probe assembly for picking up the acoustic emission of the rock sample, and a third probe assembly for picking up the acoustic emission of the rotating drive mechanism;

[0009] The tomography detection module includes a ray source assembly and an imaging assembly installed on a pair of opposite sides of a box.

[0010] This system is used to complete the characteristic research of rock samples under external loads. The method of use is to support the rock sample on the bottom plate, and provide a downward external load to the top surface of the rock sample through the top plate connected to the bottom of the loading component. When the rock sample is destroyed under the external structure to form cracks and generate sound waves, the sound waves are picked up by the acoustic emission detection module and used to obtain the research results of the destruction process of the rock sample under the external load from the perspective of acoustic emission characteristics. The research results of the destruction morphology of the rock sample under the external load are obtained from the image perspective through the tomography detection module. Therefore, this scheme combines rock acoustic emission technology with rock tomography technology to solve the problem that tomography technology cannot accurately reflect the destruction process of rock samples, and solves the problem that acoustic emission extraction and analysis technology cannot intuitively reflect the internal structure of rock samples. In a single test study, the research results of the destruction process of rock characteristics under external loads and the research results of the specific internal structure of the rock can be obtained at the same time, so as to achieve the purpose of intuitively obtaining the destruction evolution process and destruction results.

[0011] Furthermore, the present invention configures the bottom plate in the box body by adopting a rotary drive mechanism, and sets a thrust bearing between the top plate and the loading mechanism. Thus, for the tomography detection module set on the box body, when the rotary drive mechanism drives the bottom plate to rotate, since there is a thrust bearing between the top plate and the loading mechanism, the loading mechanism has only a small resistance to the rotation of the top plate. Thus, the rock sample can rotate synchronously with the rotary drive mechanism under the friction between the rock sample and the bottom plate, and the top plate can rotate synchronously with the rotary drive mechanism under the friction between the rock sample and the bottom plate. On the ray propagation path between the ray source assembly and the imaging assembly, the scanned area of ​​the rock sample can be changed (for example, the ray beam is located on the side of the rock sample rotation axis or the ray beam deviates to one side of the rock sample rotation axis, the effective imaging area of ​​the ray beam or the imaging plate only covers a part of the rock sample, the ray beam is inclined in the direction of the rock sample rotation axis, etc.) or the scanning angle of the same scanning area is changed (for example, after the rock sample rotates, the action area of ​​the tomography detection module on the rock sample remains unchanged), which can effectively improve the recognition of the fracture characteristics of the rock sample and ensure the volume of the specific structure recognition area inside the rock sample.

[0012] Further, by setting it to include a first probe assembly, a second probe assembly, and a third probe assembly, and these three probe assemblies are respectively used to pick up the acoustic emission of the loading mechanism, pick up the acoustic emission of the rock sample, and pick up the acoustic emission of the rotating drive mechanism. In the process of obtaining the acoustic emission characteristic research results through the acoustic emission pickup results, the pickup results of the first probe assembly and the third probe assembly are used as feature extraction signals, and the extracted features are used to reduce the noise of the pickup results of the second probe assembly. In this way, the research quality of the crushing process characteristics of the rock sample under the external load can be effectively guaranteed. It is easy to understand that the above first probe assembly, the second probe assembly, and the third probe assembly form a pickup array. For each probe assembly of the pickup array, the acoustic emissions of the loading mechanism, the rotating drive mechanism, and the rock sample are respectively from different positions. The signal extraction quality of the rock sample acoustic emission can be optimized through the directional noise reduction method. In addition, the acoustic emission from the loading mechanism and the rotating drive mechanism can also be identified by the acoustic wave signal with the same waveform but different wave amplitude.

[0013] In a specific embodiment, the loading mechanism includes a loading motor installed on the top of the box, a ball screw structure connected to the loading motor rotor and coaxial with the rotor, and a first pressure plate connected to the ball screw structure. The ball screw structure is used to convert the rotational motion output by the loading motor into a linear reciprocating motion of the first pressure plate, and the motion direction of the linear reciprocating motion is parallel to the axial direction of the ball screw structure; the thrust bearing is arranged between the bottom surface of the first pressure plate and the top surface of the top plate.

[0014] The above scheme provides a specific implementation form of the loading mechanism. Specifically, the loading motor serves as the driving motor of the loading mechanism. By driving the lead screw to rotate, the lead screw nut is forced to move linearly along the lead screw. The first pressure plate moves synchronously with the lead screw nut, thereby providing an external load for the rock sample. In this scheme, a ball screw structure is used as a motion form conversion component. The ball screw structure has the characteristics of high transmission accuracy, low resistance and stability, so as to achieve high-precision control of the size of the external load loaded on the rock sample.

[0015] In a specific embodiment, the ball screw structure includes a screw, a screw nut and a connecting tube, the screw is coaxial with the rotor, the upper end of the screw is fixedly connected to the lower end of the rotor, the screw nut is threadedly connected to the screw, the connecting tube is coaxial with the screw nut, the upper end of the connecting tube is fixedly connected to the screw nut, the first pressure plate is fixedly connected to the lower end of the connecting tube, and the thrust bearing is coaxial with the connecting tube;

[0016] It also includes a guide frame fixed on the top of the box body and a guide slider, which is arranged between the connecting tube and the guide frame or between the lead screw nut and the guide frame, and the guide slider prevents the lead screw nut from rotating through the guide frame.

[0017] The above scheme provides the specific structural form of the ball screw structure and the assembly method on this system, specifically: the guide frame prevents the screw nut from rotating through the guide slider. When the screw rotates, according to the rotation direction of the screw, the first pressure plate moves upward or downward synchronously with the screw nut under the action of the connecting tube.

[0018] In a specific embodiment, the top plate includes a second pressure plate, a first sound absorbing plate and a third pressure plate stacked in sequence from top to bottom. The top plate forms a matching relationship with the thrust bearing through the second pressure plate. The first probe assembly is installed on the second pressure plate, and the second probe assembly is installed on the third pressure plate.

[0019] The above scheme provides an implementation form of the top plate. Specifically, the second pressure plate and the third pressure plate are respectively used as rigid plates on both sides of the first sound absorbing plate. If both are metal plates, the first sound absorbing plate is used as a flexible plate for energy absorption. Considering the need for load transfer, a rubber plate can be used. The above rigid plates are used to maintain the basic shape of the top plate and to maintain stable top and bottom stress surfaces. The above flexible plates are used to play a sound absorption role, maintain the load on the rock sample through elastic deformation, and facilitate the precise control of the load size. In specific applications, the flexible plates are reasonably selected according to the sound wave frequency characteristics of the loading assembly to better isolate the sound waves generated by the loading assembly from the rock sample. At the same time, the second pressure plate serves as the installation base of the first probe assembly. For the second probe assembly, the first sound absorbing plate can isolate the acoustic emission generated by the thrust bearing, roller screw mechanism, guide frame, and loading motor.

[0020] In a specific embodiment, the base plate includes a fourth pressure plate, a second sound absorbing plate and a fifth pressure plate stacked in sequence from top to bottom. The base plate forms a matching relationship with the rotating drive mechanism through the fifth pressure plate. The second probe assembly is installed on the fourth pressure plate, and the third probe assembly is installed on the fifth pressure plate or the rotating drive mechanism.

[0021] The above scheme provides an implementation form of the bottom plate. Specifically, the fourth pressure plate and the fifth pressure plate are respectively used as rigid plates on both sides of the second sound absorbing plate. For example, metal plates are used. The second sound absorbing plate is used as a flexible plate for energy absorption. Considering the need for load transfer, a rubber plate can be used. The above rigid plates are used to maintain the basic shape of the bottom plate and to maintain stable top and bottom stress surfaces. The above flexible plates are used to play a sound absorption role, maintain the load on the rock sample through elastic deformation, and facilitate the precise control of the load size. In specific applications, the flexible plate is reasonably selected according to the sound wave frequency characteristics of the rotating drive mechanism to better isolate the sound waves generated by the rotating drive mechanism from the rock sample. At the same time, the fourth pressure plate serves as the installation base of the second probe assembly, and forms a multi-point detection model for the acoustic emission of the rock sample with the second probe assembly on the third pressure plate. For the second probe assembly, the second sound absorbing plate can isolate the acoustic emission generated by the rotating drive mechanism.

[0022] In a specific embodiment, for any one of the first probe assembly, the second probe assembly, and the third probe assembly, its structure includes an acoustic wave pickup sensor, a compression spring, a compression column, and a cover shell, and its assembly method on the mounting base is: the mounting base is provided with a groove, the cover shell is fixed on the mounting base, the internal space of the cover shell and the space of the groove form an installation space, the acoustic wave pickup sensor and the compression spring are both arranged in the groove, the acoustic wave pickup end of the acoustic wave pickup sensor is in contact with the bottom surface of the groove, the compression column is threadedly connected to one end of the cover shell away from the mounting base, one end of the compression column extends into the installation space, and the compression spring is clamped between the compression column and the acoustic wave pickup sensor in an elastic compression posture.

[0023] The above scheme provides the installation form of the corresponding probe assembly, that is, each acoustic wave pickup sensor is fixed in the groove of the corresponding installation base by a compression spring, and the compression spring maintains the fit quality between the acoustic wave pickup sensor and the bottom surface of the groove by elastic recovery, and the magnitude of the elastic recovery force is achieved by rotating the pressure column. It is easy to understand that the second pressure plate serves as the installation base of the first probe assembly, the third pressure plate and the fourth pressure plate serve as the installation base of the second probe assembly, and the rotating drive mechanism or the fifth pressure plate serves as the installation base of the third probe assembly.

[0024] In a specific embodiment, the box body is provided with a temperature control device for controlling the temperature inside the box body, and also includes a heat preservation layer provided on the wall surface of the box body.

[0025] In the above scheme, the temperature control device is used to control the experimental environment parameters, and the insulation layer is used to improve the controllability of the experimental environment temperature and reduce energy consumption. In specific application, the temperature inside the box is controlled by the temperature control device, and the rock sample is placed in the box before the test so that the rock sample has the required test temperature during the test. Furthermore, the box is provided with a humidity control device for controlling the humidity inside the box, which is used to maintain the humidity of the rock sample during the standing process before the test.

[0026] In a specific embodiment, the top surface of the box body is detachable relative to the box body, and a positioning column is arranged between the top surface of the box body and the side wall of the box body.

[0027] In the above scheme, the configuration of the top surface of the box and the box is convenient for placing the rock sample into the box by hoisting after removing the top surface, and then closing the top surface to obtain a closed test environment on the box. The above positioning column is used to determine the position of the first pressure plate connected to the top surface by the loading assembly in the box space after the top surface is installed. More specifically, the top plate is connected to the side of the box by bolts, and the positioning column is configured on either the lower side of the top surface or the upper end of the side of the box, and a positioning hole adapted to the positioning column is configured on the other.

[0028] In a specific embodiment, the thrust bearing includes a bearing retainer and a plurality of balls mounted on the bearing retainer. The bottom surface of the first pressure plate and the top surface of the top plate are both provided with annular ball grooves. The bottom of the ball is supported in the ball groove on the top surface of the top plate, and the ball groove on the bottom surface of the first pressure plate is supported on the top of the ball. The cross-section of the ball groove is a spherical surface with a radius consistent with the radius of the ball.

[0029] The above scheme provides a specific implementation form of the thrust bearing, which has a simple structure and is easy to assemble. Specifically, the ball serves as a rolling body between the first pressure plate and the top plate, and the retaining frame is used to maintain the relative position between the balls. The ball can be rotatably arranged in the ball hole of the retaining frame. When the ball is respectively matched with the ball groove on the first pressure plate and the ball groove on the top plate, the position of the thrust bearing relative to the first pressure plate and the top plate is constrained by the roller groove. When the rotary drive mechanism rotates, the first pressure plate is prevented from affecting the rotation of the rock sample by rolling. At the same time, regardless of whether the rock sample rotates or not, the thrust bearing does not affect the continuous external load loaded on the rock sample.

[0030] The present solution also relates to a rock property research method based on acoustic emission, which is based on the rock property research system as described in any one of the above items to realize the rock property research under the external load of the rock sample;

[0031] Wherein, the loading assembly is used to fix the rock sample and provide external load to the rock sample;

[0032] The acoustic emission detection module is used to obtain the acoustic emission characteristics of the rock sample during the destruction process under external load;

[0033] The tomography detection module is used to obtain the internal structural damage of the rock sample under the external load from different angles under the action of the rotation drive mechanism;

[0034] The picking results of the first probe assembly and the third probe assembly are used to reduce noise on the picking results of the second probe assembly.

[0035] The above method is the method of using the rock property research system when conducting rock property research.

[0036] The present invention has the following beneficial effects:

[0037] This scheme combines rock acoustic emission technology with rock tomography technology to solve the problem that tomography technology cannot accurately reflect the destruction process of rock samples, and solves the problem that acoustic emission extraction and analysis technology cannot intuitively reflect the internal structure of rock samples. In a single test study, the results of the destruction process of rock characteristics under external loads and the results of the specific internal structure of the rock can be obtained simultaneously, so as to achieve the purpose of intuitively obtaining the destruction evolution process and destruction results.

[0038] Furthermore, the present invention configures the bottom plate in the box body by adopting a rotary drive mechanism, and sets a thrust bearing between the top plate and the loading mechanism. Thus, for the tomography detection module set on the box body, when the rotary drive mechanism drives the bottom plate to rotate, since there is a thrust bearing between the top plate and the loading mechanism, the loading mechanism has only a small resistance to the rotation of the top plate. Thus, the rock sample can rotate synchronously with the rotary drive mechanism due to the friction between the rock sample and the bottom plate, and the top plate can rotate synchronously with the rotary drive mechanism due to the friction between the rock sample and the bottom plate. On the ray propagation path between the ray source assembly and the imaging assembly, the scanned area of ​​the rock sample can be changed or the scanning angle of the same scanning area can be changed, which can effectively improve the recognition of the fracture characteristics of the rock sample and ensure the volume of the specific structure recognition area inside the rock sample.

[0039] Furthermore, by configuring the system to include a first probe assembly, a second probe assembly, and a third probe assembly, and these three probe assemblies are respectively used to pick up the acoustic emission of the loading mechanism, pick up the acoustic emission of the rock sample, and pick up the acoustic emission of the rotating drive mechanism. In the process of obtaining the acoustic emission characteristic research results through the acoustic emission picking results, the picking results of the first probe assembly and the third probe assembly are used as feature extraction signals, and the extracted features are used to reduce the noise of the picking results of the second probe assembly. In this way, the research quality of the crushing process characteristics of the rock sample under external load can be effectively guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a structural schematic diagram of a specific embodiment of the rock property research system based on acoustic emission described in this scheme, and the schematic diagram is a partial cross-sectional view;

[0041] Figure 2 for Figure 1 A partial enlarged view of part A.

[0042] The reference numerals in the accompanying drawings are respectively: 1. loading motor, 2. ball screw structure, 3. first pressure plate, 4. thrust bearing, 5. first probe assembly, 6. second pressure plate, 7. first sound absorbing plate, 8. third pressure plate, 9. second probe assembly, 10. ray source assembly, 11. rock sample, 12. imaging assembly, 13. fourth pressure plate, 14. second sound absorbing plate, 15. fifth pressure plate, 16. rotation drive mechanism, 17. third probe assembly, 18. box, 19. connecting tube, 20. guide frame, 21. acoustic wave pickup sensor, 22. compression spring, 23. pressure column, 24. cover, 25. installation space. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with embodiments, but the present invention is not limited to the following embodiments:

[0044] Embodiment 1:

[0045] like Figure 1-2 The rock property research system provided based on acoustic emission includes a loading component, the loading component is used to fix the rock sample 11 and provide an external load to the rock sample 11; and also includes a detection module for detecting the internal damage characteristics of the rock sample 11 under the external load. The loading component includes a box 18, a rotating drive mechanism 16 installed at the bottom of the box 18, a bottom plate for providing bottom support for the rock sample 11, a top plate for supporting the top of the rock sample 11, and a loading mechanism for providing an external load to the rock sample 11, the bottom plate is connected to the output end of the rotating drive mechanism 16, the rotating drive mechanism 16 is used to drive the bottom plate to rotate, the loading mechanism is fixed to the top of the box 18, the top plate is connected to the output end of the loading mechanism through a thrust bearing 4, the loading mechanism is used to provide downward pressure to the top plate, and the thrust bearing 4 allows the top plate to rotate relative to the loading mechanism around the axis of the thrust bearing 4;

[0046] The detection module includes an acoustic emission detection module and a tomography detection module;

[0047] The acoustic emission detection module includes a first probe assembly 5 for picking up the acoustic emission of the loading mechanism, a second probe assembly 9 for picking up the acoustic emission of the rock sample 11, and a third probe assembly 17 for picking up the acoustic emission of the rotating drive mechanism 16;

[0048] The tomography detection module includes a ray source assembly 10 and an imaging assembly 12 installed on a pair of opposite sides of a housing 18 .

[0049] This system is used to complete the characteristic research of rock sample 11 under external load. The method of use is to support the rock sample 11 on the bottom plate, and provide a downward external load to the top surface of the rock sample 11 through the top plate connected to the bottom of the loading assembly. When the rock sample 11 is damaged under the external structure to form cracks and generate sound waves, the sound waves are picked up by the acoustic emission detection module and used to obtain the research results of the destruction process of the rock sample 11 under the external load from the perspective of acoustic emission characteristics, and the research results of the destruction morphology of the rock sample 11 under the external load are obtained from the image perspective through the tomography detection module. Therefore, this scheme combines rock acoustic emission technology with rock tomography technology to solve the problem that tomography technology cannot accurately reflect the destruction process of rock sample 11, and solves the problem that acoustic emission extraction and analysis technology cannot intuitively reflect the internal structure of rock sample 11. In a single test study, the research results of the destruction process of rock characteristics under external loads and the research results of the specific internal structure of the rock can be obtained at the same time, so as to achieve the purpose of intuitively obtaining the destruction evolution process and destruction results.

[0050] Furthermore, the present invention configures the bottom plate in the box 18 by using a rotary drive mechanism 16, and sets a thrust bearing 4 between the top plate and the loading mechanism. Thus, for the tomography detection module set on the box 18, when the rotary drive mechanism 16 drives the bottom plate to rotate, since there is a thrust bearing 4 between the top plate and the loading mechanism, the loading mechanism has only a small resistance to the rotation of the top plate. Thus, the rock sample 11 can rotate synchronously with the rotary drive mechanism 16 under the friction between the rock sample 11 and the bottom plate, and the top plate can rotate synchronously with the rotary drive mechanism 16 under the friction between the rock sample 11 and the top plate. On the ray propagation path between the ray source assembly 10 and the imaging assembly 12, the rock sample 11 can rotate synchronously with the rotary drive mechanism 16. The scanned area 11 can be changed (for example, the beam of rays is located on the side of the rotation axis of the rock sample 11 or the beam of rays deviates to one side of the rotation axis of the rock sample 11, the effective imaging area of ​​the beam of rays or the imaging plate only covers a part of the rock sample 11, the beam of rays is inclined in the direction of the rotation axis of the rock sample 11, etc.) or the scanning angle of the same scanning area can be changed (for example, after the rock sample 11 rotates, the effective area of ​​the tomography detection module on the rock sample 11 remains unchanged), which can effectively improve the recognition of the fracture characteristics of the rock sample 11 and ensure the volume of the specific structure recognition area inside the rock sample 11.

[0051] Further, by setting it to include a first probe assembly 5, a second probe assembly 9, and a third probe assembly 17, and these three probe assemblies are respectively used to pick up the acoustic emission of the loading mechanism, pick up the acoustic emission of the rock sample 11, and pick up the acoustic emission of the rotating drive mechanism 16. In the process of obtaining the acoustic emission characteristic research results through the acoustic emission pickup results, the pickup results of the first probe assembly 5 and the third probe assembly 17 are used as feature extraction signals, and the extracted features are used to reduce the noise of the pickup results of the second probe assembly 9. In this way, the research quality of the crushing process characteristics of the rock sample 11 under external load can be effectively guaranteed. It is easy to understand that the above first probe assembly 5, the second probe assembly 9, and the third probe assembly 17 form a pickup array. For each probe assembly of the pickup array, the acoustic emissions of the loading mechanism, the rotating drive mechanism 16, and the rock sample 11 are respectively from different positions. The signal extraction quality of the acoustic emission of the rock sample 11 can be optimized through the directional noise reduction method. In addition, the acoustic emission from the loading mechanism and the rotating drive mechanism 16 can also be identified by the acoustic wave signal with the same waveform but different wave amplitude.

[0052] A more detailed solution is: the loading mechanism includes a loading motor 1 installed on the top of the box body 18, a ball screw structure 2 connected to the rotor of the loading motor 1 and coaxial with the rotor, and a first pressure plate 3 connected to the ball screw structure 2, wherein the ball screw structure 2 is used to convert the rotational motion output by the loading motor 1 into a linear reciprocating motion of the first pressure plate 3, and the motion direction of the linear reciprocating motion is parallel to the axial direction of the ball screw structure 2; the thrust bearing 4 is arranged between the bottom surface of the first pressure plate 3 and the top surface of the top plate.

[0053] The above scheme provides a specific implementation form of the loading mechanism. Specifically, the loading motor 1 serves as the driving motor of the loading mechanism. By driving the screw to rotate, the screw nut is forced to move linearly along the screw. The first pressure plate 3 moves synchronously with the screw nut, thereby providing an external load for the rock sample 11. In this scheme, a ball screw structure 2 is used as a motion form conversion component. The ball screw structure 2 has the characteristics of high transmission accuracy, low resistance and stability, so as to achieve high-precision control of the size of the external load loaded on the rock sample 11.

[0054] A more detailed scheme is as follows: the ball screw structure 2 includes a screw, a screw nut and a connecting tube 19, the screw is coaxial with the rotor, the upper end of the screw is fixedly connected to the lower end of the rotor, the screw nut is threadedly connected to the screw, the connecting tube 19 is coaxial with the screw nut, the upper end of the connecting tube 19 is fixedly connected to the screw nut, the first pressure plate 3 is fixedly connected to the lower end of the connecting tube 19, and the thrust bearing 4 is coaxial with the connecting tube 19;

[0055] It also includes a guide frame 20 fixed on the top of the box body 18 and a guide slider, which is arranged between the connecting tube 19 and the guide frame 20 or between the screw nut and the guide frame 20, and the guide slider prevents the screw nut from rotating through the guide frame 20.

[0056] The above scheme provides the specific structural form of the ball screw structure 2 and the assembly method on this system, specifically: the guide frame 20 prevents the screw nut from rotating through the guide slider. When the screw rotates, according to the rotation direction of the screw, the first pressure plate 3 moves upward or downward synchronously with the screw nut under the action of the connecting tube 19.

[0057] A more detailed solution is: the top plate includes a second pressure plate 6, a first sound absorbing plate 7 and a third pressure plate 8 stacked in sequence from top to bottom, the top plate forms a matching relationship with the thrust bearing 4 through the second pressure plate 6, the first probe assembly 5 is installed on the second pressure plate 6, and the second probe assembly 9 is installed on the third pressure plate 8.

[0058] The above scheme provides an implementation form of the top plate. Specifically, the second pressure plate 6 and the third pressure plate 8 are respectively used as rigid plates on both sides of the first sound absorbing plate 7. If both are metal plates, the first sound absorbing plate 7 is used as a flexible plate for absorbing energy. Considering the need for load transfer, a rubber plate can be used. The above rigid plates are used to maintain the basic shape of the top plate and to maintain stable top and bottom stress surfaces. The above flexible plates are used to play a sound absorption role, maintain the load on the rock sample 11 through elastic deformation, and facilitate the precise control of the load size. In specific applications, the flexible plates are reasonably selected according to the sound wave frequency characteristics of the loading assembly to better isolate the sound waves generated by the loading assembly from the rock sample 11. At the same time, the second pressure plate 6 serves as the installation base of the first probe assembly 5. For the second probe assembly 9, the first sound absorbing plate 7 can isolate the acoustic emission generated by the thrust bearing 4, the roller screw mechanism, the guide frame 20, and the loading motor 1.

[0059] A more detailed solution is: the base plate includes a fourth pressure plate 13, a second sound absorbing plate 14 and a fifth pressure plate 15 stacked in sequence from top to bottom, the base plate forms a matching relationship with the rotating drive mechanism 16 through the fifth pressure plate 15, the second probe assembly 9 is installed on the fourth pressure plate 13, and the third probe assembly 17 is installed on the fifth pressure plate 15 or the rotating drive mechanism 16.

[0060] The above scheme provides an implementation form of the bottom plate. Specifically, the fourth pressing plate 13 and the fifth pressing plate 15 are respectively used as rigid plates on both sides of the second sound absorbing plate 14. If both are metal plates, the second sound absorbing plate 14 is used as a flexible plate for absorbing energy. Considering the need for load transfer, a rubber plate can be used. The above rigid plates are used to maintain the basic shape of the bottom plate and to maintain stable top and bottom stress surfaces. The above flexible plates are used to play a sound absorption role, maintain the load on the rock sample 11 through elastic deformation, and facilitate the precise control of the load size. In specific applications, the flexible plate is reasonably selected according to the sound wave frequency characteristics of the rotating drive mechanism 16 to better isolate the sound waves generated by the rotating drive mechanism 16 from the rock sample 11. At the same time, the fourth pressing plate 13 serves as the installation base of the second probe assembly 9, and forms a multi-point detection model for the acoustic emission of the rock sample 11 with the second probe assembly 9 on the third pressing plate 8. For the second probe assembly 9, the second sound absorbing plate 14 can isolate the acoustic emission generated by the rotating drive mechanism 16.

[0061] A more detailed scheme is: for any one of the first probe assembly 5, the second probe assembly 9, and the third probe assembly 17, its structure includes an acoustic wave pickup sensor 21, a compression spring 22, a compression column 23 and a cover shell 24, and its assembly method on the mounting base is: the mounting base is provided with a groove, the cover shell 24 is fixed on the mounting base, the internal space of the cover shell 24 and the space of the groove form an installation space 25, the acoustic wave pickup sensor 21 and the compression spring 22 are both arranged in the groove, the acoustic wave pickup end of the acoustic wave pickup sensor 21 is in contact with the bottom surface of the groove, the compression column 23 is threadedly connected to one end of the cover shell 24 away from the mounting base, one end of the compression column 23 extends into the installation space 25, and the compression spring 22 is clamped between the compression column 23 and the acoustic wave pickup sensor 21 in an elastically compressed posture.

[0062] The above scheme provides the installation form of the corresponding probe assembly, that is, each acoustic wave pickup sensor 21 is fixed in the groove of the corresponding installation base by the compression spring 22, and the compression spring 22 maintains the fitting quality of the acoustic wave pickup sensor 21 and the bottom surface of the groove by elastic recovery, and the magnitude of the elastic recovery force is achieved by rotating the pressure column 23. It is easy to understand that the second pressure plate 6 serves as the installation base of the first probe assembly 5, the third pressure plate 8 and the fourth pressure plate 13 serve as the installation base of the second probe assembly 9, and the rotation drive mechanism 16 or the fifth pressure plate 15 serves as the installation base of the third probe assembly 17.

[0063] A more detailed solution is: the box body 18 is provided with a temperature control device for controlling the internal temperature of the box body 18 , and also includes a heat preservation layer provided on the wall surface of the box body 18 .

[0064] In the above scheme, the temperature control device is used to control the experimental environment parameters, and the insulation layer is used to improve the controllability of the experimental environment temperature and reduce energy consumption. In specific application, the temperature inside the box 18 is controlled by the temperature control device, and the rock sample is placed in the box 18 before the test so that the rock sample has the required test temperature during the test. Furthermore, the box 18 is provided with a humidity control device for controlling the humidity inside the box 18, which is used to maintain the humidity of the rock sample during the standing process before the test.

[0065] A more detailed solution is that the top surface of the box body 18 is detachable relative to the box body 18 , and a positioning column is arranged between the top surface of the box body 18 and the side wall of the box body 18 .

[0066] In the above scheme, the configuration of the top surface of the box 18 and the box 18 is convenient for placing the rock sample 11 into the box 18 in a hoisting manner after removing the top surface, and then closing the top surface to obtain a closed test environment on the box 18. The above positioning columns are used to determine the position of the first pressing plate 3 connected to the top surface through the loading assembly in the space of the box 18 after the top surface is installed. More specifically, the top plate is connected to the side of the box 18 by bolts, and the positioning column is configured on either the lower side of the top surface or the upper end of the side of the box 18, and the positioning hole adapted to the positioning column is configured on the other.

[0067] A more detailed solution is: the thrust bearing 4 includes a bearing retainer and a plurality of balls mounted on the bearing retainer, and annular ball grooves are arranged on the bottom surface of the first pressure plate 3 and the top surface of the top plate. The bottom of the ball is supported in the ball groove on the top surface of the top plate, and the ball groove on the bottom surface of the first pressure plate 3 is supported on the top of the ball. The cross-section of the ball groove is a spherical surface with a radius consistent with the radius of the ball.

[0068] The above scheme provides a specific implementation form of the thrust bearing 4, which has a simple structure and is easy to assemble. Specifically, the ball serves as a rolling body between the first pressure plate 3 and the top plate, and the retaining frame is used to maintain the relative position between the balls. The ball can be rotatably arranged in the ball hole of the retaining frame. When the ball is respectively matched with the ball groove on the first pressure plate 3 and the ball groove on the top plate, the position of the thrust bearing 4 relative to the first pressure plate 3 and the top plate is constrained by the roller groove. When the rotary drive mechanism 16 rotates, the first pressure plate 3 is prevented from affecting the rotation of the rock sample 11 through the rolling of the balls. At the same time, regardless of whether the rock sample 11 rotates, the thrust bearing 4 does not affect the continuous external load loaded on the rock sample 11.

[0069] The present solution also relates to a rock property research method based on acoustic emission, which is based on the rock property research system as described in any one of the above items to realize the rock property research under external load of the rock sample 11;

[0070] Wherein, the loading assembly is used to fix the rock sample 11 and provide an external load to the rock sample 11;

[0071] The acoustic emission detection module is used to obtain the acoustic emission characteristics of the rock sample 11 during the destruction process under external load;

[0072] The tomography detection module is used to obtain the internal structural damage of the rock sample 11 under the external load from different angles under the action of the rotation drive mechanism 16;

[0073] The picking results of the first probe assembly 5 and the third probe assembly 17 are used to reduce noise on the picking results of the second probe assembly 9 .

[0074] The above method is the method of using the rock property research system when conducting rock property research.

[0075] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific embodiments of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, other embodiments obtained without departing from the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A rock property research system based on acoustic emission, comprising a loading assembly, the loading assembly being used to fix a rock sample (11) and provide an external load to the rock sample (11); and also comprising a detection module for detecting internal damage characteristics of the rock sample (11) under the action of the external load, characterized in that: The loading assembly comprises a box (18), a rotary drive mechanism (16) installed at the bottom of the box (18), a bottom plate for providing bottom support for the rock sample (11), a top plate for supporting the top of the rock sample (11), and a loading mechanism for providing an external load for the rock sample (11), wherein the bottom plate is connected to the output end of the rotary drive mechanism (16), the rotary drive mechanism (16) is used to drive the bottom plate to rotate, the loading mechanism is fixed to the top of the box (18), the top plate is connected to the output end of the loading mechanism via a thrust bearing (4), the loading mechanism is used to provide downward pressure for the top plate, and the thrust bearing (4) enables the top plate to rotate relative to the loading mechanism around the axis of the thrust bearing (4); The detection module includes an acoustic emission detection module and a tomography detection module; The acoustic emission detection module comprises a first probe assembly (5) for picking up the acoustic emission of a loading mechanism, a second probe assembly (9) for picking up the acoustic emission of a rock sample (11), and a third probe assembly (17) for picking up the acoustic emission of a rotating drive mechanism (16); The tomography detection module comprises a ray source assembly (10) and an imaging assembly (12) mounted on a pair of opposite sides of a housing (18).

2. The rock property research system based on acoustic emission according to claim 1 is characterized in that: The loading mechanism comprises a loading motor (1) mounted on the top of a housing (18), a ball screw structure (2) connected to a rotor of the loading motor (1) and coaxial with the rotor, and a first pressure plate (3) connected to the ball screw structure (2), wherein the ball screw structure (2) is used to convert the rotational motion output by the loading motor (1) into a linear reciprocating motion of the first pressure plate (3), wherein the direction of the linear reciprocating motion is parallel to the axial direction of the ball screw structure (2); and the thrust bearing (4) is arranged between the bottom surface of the first pressure plate (3) and the top surface of the top plate.

3. The rock property research system based on acoustic emission according to claim 2 is characterized in that: The ball screw structure (2) comprises a screw, a screw nut and a connecting tube, the screw is coaxial with the rotor, the upper end of the screw is fixedly connected to the lower end of the rotor, the screw nut is threadedly connected to the screw, the connecting tube is coaxial with the screw nut, the upper end of the connecting tube (19) is fixedly connected to the screw nut, the first pressure plate (3) is fixedly connected to the lower end of the connecting tube (19), and the thrust bearing (4) is coaxial with the connecting tube (19); It also includes a guide frame (20) fixed on the top of the box body (18) and a guide slider, wherein the guide slider is arranged between the connecting tube (19) and the guide frame (20) or between the lead screw nut and the guide frame (20), and the guide slider prevents the lead screw nut from rotating through the guide frame (20).

4. The rock property research system based on acoustic emission according to claim 1 is characterized in that: The top plate comprises a second pressing plate (6), a first sound absorbing plate (7) and a third pressing plate (8) which are stacked in sequence from top to bottom. The top plate forms a matching relationship with the thrust bearing (4) through the second pressing plate (6). The first probe assembly (5) is mounted on the second pressing plate (6), and the second probe assembly (9) is mounted on the third pressing plate (8).

5. The rock property research system based on acoustic emission according to claim 1, characterized in that: The bottom plate comprises a fourth pressing plate (13), a second sound absorbing plate (14) and a fifth pressing plate (15) which are stacked in sequence from top to bottom. The bottom plate forms a matching relationship with a rotating drive mechanism (16) through the fifth pressing plate (15). The second probe assembly (9) is installed on the fourth pressing plate (13), and the third probe assembly (17) is installed on the fifth pressing plate (15) or the rotating drive mechanism (16).

6. The rock property research system based on acoustic emission according to claim 1, characterized in that: For any one of the first probe assembly (5), the second probe assembly (9) and the third probe assembly (17), the structure includes a sound wave pickup sensor (21), a compression spring (22), a compression column (23) and a cover shell (24), and the assembly method thereof on the installation base is as follows: the installation base is provided with a groove, the cover shell (24) is fixed on the installation base, the internal space of the cover shell (24) and the space of the groove form an installation space (25), the sound wave pickup sensor (21) and the compression spring (22) are both arranged in the groove, the sound wave pickup end of the sound wave pickup sensor (21) is in contact with the bottom surface of the groove, the compression column (23) is threadedly connected to the end of the cover shell (24) away from the installation base, one end of the compression column (23) extends into the installation space (25), and the compression spring (22) is clamped between the compression column (23) and the sound wave pickup sensor (21) in an elastically compressed posture.

7. The rock property research system based on acoustic emission according to claim 1, characterized in that: The box (18) is provided with a temperature control device for controlling the temperature inside the box, and also includes a heat-insulating layer provided on the wall surface of the box (18).

8. The rock property research system based on acoustic emission according to claim 1, characterized in that: The top surface of the box body (18) is detachable relative to the box body (18), and a positioning column is arranged between the top surface of the box body (18) and the side wall of the box body (18).

9. The rock property research system based on acoustic emission according to claim 1, characterized in that: The thrust bearing (4) comprises a bearing retainer and a plurality of balls mounted on the bearing retainer. The bottom surface of the first pressure plate (3) and the top surface of the top plate are both provided with annular ball grooves. The bottom of the ball is supported in the ball groove on the top surface of the top plate. The ball groove on the bottom surface of the first pressure plate (3) is supported on the top of the ball. The cross section of the ball groove is a spherical surface with a radius consistent with the radius of the ball.

10. A method for studying rock properties based on acoustic emission, characterized in that: The method is based on the rock property research system described in any one of claims 1 to 9, and realizes the rock property research under external load of the rock sample (11); Wherein, the loading assembly is used to fix the rock sample (11) and provide an external load to the rock sample (11); The acoustic emission detection module is used to obtain the acoustic emission characteristics of the rock sample (11) during the destruction process under external load; The tomography detection module is used to obtain internal structural damage of the rock sample (11) under external load from different angles under the action of the rotation drive mechanism (16); The picking results of the first probe assembly (5) and the third probe assembly (17) are used to reduce the noise of the picking results of the second probe assembly (9).

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