Method and system for studying rock properties based on acoustic emission

Abstract

The application discloses a rock characteristic research method and system based on acoustic emission and belongs to the technical field of acoustic wave detection. The system comprises a loading assembly and a detection module. The loading assembly comprises a box body, a rotary driving mechanism, a bottom plate, a top plate and a loading mechanism. The bottom plate is connected to the output end of the rotary driving mechanism. The rotary driving mechanism is used for driving the bottom plate to rotate. The loading mechanism is fixed to the top of the box body. The top plate is connected to the output end of the loading mechanism through a thrust bearing. The detection module comprises an acoustic emission detection module and a tomographic detection module. The acoustic emission detection module comprises a first probe assembly, a second probe assembly and a third probe assembly. The tomographic detection module comprises a radiation source assembly and an imaging assembly. The method is a method for researching rock characteristics of the system.

Description

TECHNICAL FIELD

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

[0002] Acoustic wave detection technology is widely used in geology and engineering, for example, when sound waves propagate in rock, they will be affected by the internal structure and properties of the rock, thus showing different propagation speeds, which can be used for stratigraphic exploration and geological structure, for evaluating the mechanical properties and stability of rock, and providing a basis for engineering design and construction. When the rock undergoes internal structural changes under corresponding load, it will exhibit different acoustic characteristics from before, and the difference in acoustic characteristics can effectively evolve the development process of rock damage, which can be used for rock strength evaluation. When the rock undergoes internal structural changes under external load, the sound waves emitted by the rock due to cracks can be captured by the acoustic wave extraction device. By studying the acoustic characteristics, the occurrence of cracks in the rock under load can be effectively inferred. Acoustic wave detection technology can be used to fully understand the physical properties, structure and properties of rock, and is widely used in geological exploration, engineering geological evaluation, rock classification and grading, and rock engineering. In recent years, with the development of instrument and equipment technology, the precision 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 process of a hydropower station, acoustic wave detection technology is used by design and construction units to understand and master the physical properties, structure and properties of the rock in the dam area, as well as related evolution, providing a strong guarantee for the rationality of engineering design, construction safety and construction quality.

[0003] Regarding the use of acoustic emission technology under external load, it is a non-destructive testing technology that evaluates the damage and failure process of rock by detecting and analyzing the elastic waves generated during the internal stress release process of rock. The principle is that when rock is subjected to external load, new cracks are generated or existing cracks are expanded under stress, which is accompanied by energy release and propagation in the form of transient elastic waves. By arranging acoustic emission sensors on the surface of the rock, these elastic wave signals can be captured, and the internal damage state and development process of the rock can be obtained by analysis.

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

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

[0006] The specific technical solution is as follows: a rock property research system based on acoustic emission, including a loading assembly, the loading assembly is used to fix the rock sample and provide an external load to the rock sample; it also includes a detection module for detecting the internal damage characteristics of the rock sample under the external load, the loading assembly includes a box, a rotary 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 to the rock sample, the bottom plate is connected to the output end of the rotary drive mechanism, the rotary 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 to the top plate, and the thrust bearing enables 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 acoustic emissions from a loading mechanism, a second probe assembly for picking up acoustic emissions from a rock sample, and a third probe assembly for picking up acoustic emissions from a rotary 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 assembly. When the rock sample 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 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] Further, the present scheme is to configure the bottom plate in the box by adopting the rotary driving mechanism, and to set the thrust bearing between the top plate and the loading mechanism. Thus, for the tomographic detection module arranged on the box, when the rotary driving mechanism drives the bottom plate to rotate, the loading mechanism has only a small resistance to the rotation of the top plate due to the thrust bearing between the top plate and the loading mechanism. Thus, the rock sample and the top plate can rotate synchronously under the friction between them and the rotary driving mechanism. The scanned area of the rock sample on the ray propagation path between the ray source assembly and the imaging assembly can be changed (for example, the ray beam is located on the side of the rock sample rotation axis or 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 effective area of the tomographic detection module on the rock sample remains unchanged), which can effectively improve the identification degree of the rock sample fracture characteristics and ensure the volume of the specific structure identification area inside the rock sample.

[0012] Further, by setting the first probe assembly, the second probe assembly and the third probe assembly, and the three probe assemblies are respectively used to pick up the acoustic emission of the loading mechanism, the acoustic emission of the rock sample and the acoustic emission of the rotary driving mechanism, in the process of obtaining the acoustic emission characteristic research result through the acoustic emission pickup result, the pickup results of the first probe assembly and the third probe assembly are taken as the feature extraction signals, and the extracted features are used to denoise the pickup result of the second probe assembly. Thus, the research quality of the rock sample breaking process characteristics under external load can be effectively ensured. It is easy to understand that the above first probe assembly, second probe assembly and third probe assembly form a sound pickup array. The acoustic emission of the loading mechanism, the rotary driving mechanism and the rock sample from different positions is respectively from the acoustic source of each probe assembly of the sound pickup array. Through the directional denoising method, the signal extraction quality of the rock sample acoustic emission can be optimized. In addition, the acoustic emission from the loading mechanism and the rotary driving mechanism can also be identified through acoustic wave signals with the same waveform but different wave amplitudes.

[0013] In one specific embodiment, the loading mechanism includes a loading motor mounted on the top of the box, a ball screw structure connected to the rotor of the loading motor and coaxial with the rotor, and a first pressing plate connected to the ball screw structure. The ball screw structure is used to convert the rotary motion output by the loading motor into the linear reciprocating motion of the first pressing plate. The motion direction of the linear reciprocating motion is parallel to the axis direction of the ball screw structure. The thrust bearing is arranged between the bottom surface of the first pressing 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 is used as the driving motor of the loading mechanism, rotates the lead screw, forces the lead screw nut to move linearly along the lead screw, and the first pressing plate moves synchronously with the lead screw nut, thereby providing external load for the rock sample.

[0015] In one specific embodiment, the ball screw structure includes a lead screw, a lead screw nut, and a connecting cylinder, the lead screw is coaxial with the rotor, the upper end of the lead screw is fixedly connected with the lower end of the rotor, the lead screw nut is threadedly connected with the lead screw, the connecting cylinder is coaxial with the lead screw nut, the upper end of the connecting cylinder is fixedly connected with the lead screw nut, the first pressing plate is fixedly connected with the lower end of the connecting cylinder, and the thrust bearing is coaxial with the connecting cylinder.

[0016] It also includes a guide frame fixed on the top of the box body, and a guide slider, the guide slider is arranged between the connecting cylinder 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 a specific structure of the ball screw structure and an assembly method on the system, specifically, the guide frame prevents the lead screw nut from rotating through the guide slider, and when the lead screw rotates, the first pressing plate moves upward or downward synchronously with the lead screw nut under the action of the connecting cylinder according to the rotating direction of the lead screw.

[0018] In one specific embodiment, the top plate includes a second pressing plate, a first sound absorption plate, and a third pressing plate stacked from top to bottom, the top plate forms a fitting relationship with the thrust bearing through the second pressing plate, the first probe assembly is installed on the second pressing plate, and the second probe assembly is installed on the third pressing plate.

[0019] The above scheme provides an implementation form of the top plate, specifically, the second pressing plate and the third pressing plate are respectively used as rigid plates on both sides of the first sound absorption plate, and are both metal plates, the first sound absorption plate is used as a flexible plate for energy absorption, and can be a rubber plate considering the need of load transmission, the above rigid plates are used for maintaining the basic shape of the top plate and maintaining stable top and bottom stress surfaces, the above flexible plate is used for sound absorption, maintaining the load on the rock sample through elastic deformation, and facilitating the control of the size of the load, in specific application, the flexible plate is reasonably selected according to the acoustic frequency characteristics of the loading assembly, so as to better isolate the acoustic waves generated by the loading assembly from the rock sample, at the same time, the second pressing plate is used as the installation base of the first probe assembly, and the first sound absorption plate can isolate the acoustic emission generated by the thrust bearing, the ball screw mechanism, the guide frame, and the loading motor.

[0020] In one specific embodiment, the bottom plate comprises a fourth pressing plate, a second sound absorption plate and a fifth pressing plate stacked in sequence from top to bottom, the bottom plate forms a cooperation relationship with the rotary driving mechanism through the fifth pressing plate, the fourth pressing plate is provided with the second probe assembly, and the third probe assembly is arranged on the fifth pressing plate or the rotary driving mechanism.

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

[0022] In one specific embodiment, the structure of any one of the first probe assembly, the second probe assembly and the third probe assembly comprises an acoustic pickup sensor, a compression spring, a compression column and a shell. The assembly mode on the mounting base is as follows: a groove is arranged on the mounting base, the shell is fixed on the mounting base, the internal space of the shell and the space of the groove form a mounting space, the acoustic pickup sensor and the compression spring are arranged in the groove, the acoustic pickup end of the acoustic pickup sensor is attached to the bottom surface of the groove, the compression column is threadedly connected to the end of the shell away from the mounting base, one end of the compression column extends into the mounting space, and the compression spring is clamped in an elastic compression state between the compression column and the acoustic pickup sensor.

[0023] The above scheme provides an installation form of the corresponding probe assembly, that is, the acoustic pickup sensor of each probe assembly is fixed in the groove of the corresponding mounting base through the compression spring. The compression spring maintains the attachment quality of the acoustic pickup sensor and the bottom surface of the groove through elastic recovery, and the force of the elastic recovery is realized by rotating the compression column. It is easy to understand that the second pressing plate is used as the mounting base of the first probe assembly, the third pressing plate and the fourth pressing plate are used as the mounting base of the second probe assembly, and the rotary driving mechanism or the fifth pressing plate is used as the mounting base of the third probe assembly.

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

[0025] In the above scheme, the temperature control device is used to control the experimental environment parameters, the heat preservation layer is used to improve the controllability of the experimental environment temperature and reduce the 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, further, the humidity control device for controlling the humidity inside the box is arranged in the box, which is used to maintain the humidity of the rock sample during the pre-test standing process.

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

[0027] In the above scheme, the arrangement mode of the top surface of the box and the box facilitates the placement of the rock sample into the box in a hoisting manner after the top surface is removed, and then the top surface is closed to obtain a closed test environment on the box, and the positioning column is used to determine the position of the first pressing 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 bolted to the side surface of the box, and the positioning column is arranged on any one of the lower side of the top surface and the upper end of the side surface of the box, and a positioning hole matched with the positioning column is arranged on the other one.

[0028] In one specific embodiment, the thrust bearing includes a bearing retainer and a plurality of balls mounted on the bearing retainer, and the bottom surface of the first pressing plate and the top surface of the top plate are both provided with an annular ball groove, 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 pressing plate supports the top of the ball, and 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 thrust bearing implementation form, which has simple structure and convenient assembly, and specifically, the ball is used as the rolling body between the first pressing plate and the top plate, the retainer is used to maintain the relative position between the balls, the ball is rotatably arranged in the ball hole of the retainer, when the ball cooperates with the ball groove on the first pressing plate and the ball groove on the top plate respectively, the position of the thrust bearing relative to the first pressing plate and the top plate is constrained by the ball groove, when the rotary driving mechanism rotates, the rotation of the first pressing plate on the rock sample is avoided by the rolling of the ball, and no matter whether the rock sample rotates or not, the thrust bearing does not affect the external load continuously applied on the rock sample.

[0030] The present scheme also relates to a rock property research method based on acoustic emission, which is based on the rock property research system according to any one of the above schemes, and realizes the rock property research under the external load of the rock sample.

[0031] The loading assembly is used to fix the rock sample and provide the external load to the rock sample.

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

[0033] The tomography detection module is used to acquire the internal structure destruction of the rock sample under external load from different angles under the action of the rotary driving mechanism.

[0034] The pickup results of the first probe assembly and the third probe assembly are used to denoise the pickup results of the second probe assembly.

[0035] The above method is a use method of the rock property research system when the rock property research system is used to research rock properties.

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

[0037] The present application combines the rock acoustic emission technology with the rock tomography technology, solves the problem that the tomography technology cannot accurately reflect the destruction process of the rock sample, solves the problem that the acoustic emission extraction and analysis technology cannot intuitively reflect the internal structure of the rock sample, in a single test research, the destruction process research result and the internal specific structure research result of the rock under external load can be obtained at the same time, and the purpose of intuitively obtaining the destruction evolution process and the destruction result is achieved.

[0038] Further, the bottom plate is arranged in the box by adopting the rotary driving mechanism, and the thrust bearing is arranged between the top plate and the loading mechanism, so that when the tomography detection module arranged on the box is driven to rotate by the rotary driving mechanism, the loading mechanism only has small resistance to the rotation of the top plate due to the thrust bearing between the top plate and the loading mechanism, so that the rock sample can rotate synchronously under the friction between the rock sample and the bottom plate, and the top plate can rotate under the friction between the rock sample and the top plate, the scanned area of the rock sample on the ray propagation path between the ray source assembly and the imaging assembly can be changed or the scanning angle of the same scanned area can be changed, and the rock sample breaking property recognition degree and the volume of the rock sample internal specific structure recognition area can be effectively improved.

[0039] Further, by arranging the first probe assembly, the second probe assembly and the third probe assembly, and arranging the three kinds of probe assemblies to pick up the acoustic emission of the loading mechanism, the acoustic emission of the rock sample and the acoustic emission of the rotary driving mechanism, in the process of obtaining the acoustic emission characteristic research result through the acoustic emission pickup result, 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 denoise the pickup results of the second probe assembly, so that the research quality of the rock sample breaking process characteristics under external load can be effectively guaranteed. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 This is a schematic structural diagram of a specific embodiment of the rock property research system based on acoustic emission described in this solution, which 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: 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 will be further described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments:

[0044] Example 1:

[0045] like Figures 1-2 The provided rock property research system based on acoustic emission includes a loading assembly for fixing a rock sample 11 and providing an external load to the rock sample 11; and a detection module for detecting internal damage characteristics of the rock sample 11 under the external load. The loading assembly includes a housing 18, a rotary drive mechanism 16 mounted at the bottom of the housing 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 rotary drive mechanism 16, which is used to drive the bottom plate to rotate. The loading mechanism is fixed to the top of the housing 18, and 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 on 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.

[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 acoustic emissions from the loading mechanism, a second probe assembly 9 for picking up acoustic emissions from the rock sample 11, and a third probe assembly 17 for picking up acoustic emissions from the rotary drive mechanism 16;

[0048] The tomography detection module comprises a radiation source assembly 10 and an imaging assembly 12 mounted on a pair of opposite sides of the box 18.

[0049] The system is used to complete the characteristic research of the rock sample 11 under external load, and the use method is to support the rock sample 11 on the bottom plate, and provide downward external load for the top surface of the rock sample 11 through the top plate connected at the bottom of the loading assembly, when the rock sample 11 is damaged to form cracks and generate acoustic waves under the external structure, the acoustic emission detection module picks up the acoustic waves, and the research results of the damage process of the rock sample 11 under the external load are obtained from the perspective of acoustic emission characteristics, and the research results of the damage form of the rock sample 11 under the external load are obtained from the perspective of the tomography detection module, so that the rock acoustic emission technology and the rock tomography technology are combined, the problem that the tomography technology cannot accurately reflect the damage process of the rock sample 11 is solved, and the problem that the acoustic emission extraction and analysis technology cannot directly reflect the internal structure of the rock sample 11 is solved. In a single test research, the damage process research results and the internal specific structure research results of the rock under external load can be obtained at the same time, and the purpose of directly obtaining the damage evolution process and the damage results is achieved.

[0050] Further, the bottom plate is arranged in the box 18 by the rotary driving mechanism 16, and the thrust bearing 4 is arranged between the top plate and the loading mechanism, so that when the rotary driving mechanism 16 drives the bottom plate to rotate, the loading mechanism has only small resistance to the rotation of the top plate due to the thrust bearing 4 between the top plate and the loading mechanism, so that the rock sample 11 can rotate synchronously with the rotary driving mechanism 16 under the friction between the rock sample 11 and the bottom plate, and the top plate can rotate synchronously with the rotary driving mechanism 16 under the friction between the rock sample 11 and the top plate. The scanned area of the rock sample 11 on the radiation propagation path between the radiation source assembly 10 and the imaging assembly 12 can be changed (for example, the radiation beam is located on the side of the rotation axis of the rock sample 11 or the radiation beam deviates to one side of the rotation axis of the rock sample 11, the effective imaging area of the radiation beam or the imaging plate only covers part of the rock sample 11, the radiation beam is inclined in the direction of the rotation axis of the rock sample 11, etc.) or the scanning angle of the same scanning area is changed (for example, after the rock sample 11 rotates, the acting area of the tomography detection module on the rock sample 11 remains unchanged), which can effectively improve the rock sample 11 fracture characteristic identification and ensure the volume of the rock sample 11 internal specific structure identification area.

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

[0052] More detailed scheme is: the loading mechanism includes a loading motor 1 mounted 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, a first pressing plate 3 connected to the ball screw structure 2, the ball screw structure 2 is used to convert the rotary motion output by the loading motor 1 into the linear reciprocating motion of the first pressing 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 pressing 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 is used 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, and the first pressing plate 3 moves synchronously with the screw nut, thereby providing external load for the rock sample 11. In this scheme, the ball screw structure 2 is used as a motion form conversion component. By using the characteristics of high transmission precision, small resistance and stability of the ball screw structure 2, the size of the external load applied to the rock sample 11 can be controlled with high precision.

[0054] More detailed scheme is: the ball screw structure 2 includes a screw, a screw nut and a connecting cylinder 19, the screw is coaxial with the rotor, the upper end of the screw is fixedly connected with the lower end of the rotor, the screw nut is threadedly connected with the screw, the connecting cylinder 19 is coaxial with the screw nut, the upper end of the connecting cylinder 19 is fixedly connected with the screw nut, the first pressing plate 3 is fixedly connected with the lower end of the connecting cylinder 19, and the thrust bearing 4 is coaxial with the connecting cylinder 19;

[0055] The guiding frame 20 is fixed on the top of the box 18, and a guiding slider is arranged between the connecting cylinder 19 and the guiding frame 20 or between the screw nut and the guiding frame 20, and the guiding slider prevents the screw nut from rotating through the guiding frame 20.

[0056] The above scheme provides a specific structure of the ball screw structure 2 and an assembly mode on the system, specifically, the guiding frame 20 prevents the screw nut from rotating through the guiding slider, and when the screw rotates, the first pressing plate 3 moves upward or downward synchronously with the screw nut under the action of the connecting cylinder 19 according to the rotating direction of the screw.

[0057] A more detailed scheme is that the top plate includes a second pressing plate 6, a first sound absorption plate 7 and a third pressing plate 8 stacked from top to bottom, the top plate forms a cooperation relationship with the thrust bearing 4 through the second pressing plate 6, the first probe assembly 5 is installed on the second pressing plate 6, and the third pressing plate 8 is provided with the second probe assembly 9.

[0058] The above scheme provides an implementation form of the top plate, specifically, the second pressing plate 6 and the third pressing plate 8 are respectively rigid plates on both sides of the first sound absorption plate 7, which are metal plates, the first sound absorption plate 7 is a flexible plate for energy absorption, which is a rubber plate considering the need of load transmission, the above rigid plates are used for maintaining the basic shape of the top plate and maintaining stable top and bottom stress surfaces, the above flexible plate is used for playing a sound absorption role, maintaining the load on the rock sample 11 through elastic deformation and facilitating the control of the size and precision of the load, in specific application, the flexible plate is reasonably selected according to the acoustic frequency characteristics of the loading assembly, so as to better isolate the acoustic waves generated by the loading assembly from the rock sample 11, at the same time, the second pressing plate 6 is the installation basis of the first probe assembly 5, and the first sound absorption plate 7 can isolate the acoustic emission generated by the thrust bearing 4, the roller screw mechanism, the guiding frame 20 and the loading motor 1 for the second probe assembly 9.

[0059] A more detailed scheme is that the bottom plate includes a fourth pressing plate 13, a second sound absorption plate 14 and a fifth pressing plate 15 stacked from top to bottom, the bottom plate forms a cooperation relationship with the rotary driving mechanism 16 through the fifth pressing plate 15, the fourth pressing plate 13 is provided with the second probe assembly 9, and the third probe assembly 17 is installed on the fifth pressing plate 15 or the rotary driving 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 rigid plates on both sides of the second sound absorption plate 14, for example, metal plates, the second sound absorption plate 14 is a flexible plate for absorbing energy, and rubber plate can be used considering the need of load transmission, the above rigid plates are used for maintaining the basic shape of the bottom plate and maintaining the stable top force surface and the bottom force surface, the above flexible plate is used for playing a sound absorption role, maintaining the load on the rock sample 11 through elastic deformation, and facilitating the precision control of the load size, in specific application, the flexible plate is reasonably selected according to the sound wave frequency characteristics of the rotary driving mechanism 16, so as to better isolate the sound wave generated by the rotary driving mechanism 16 from the rock sample 11, at the same time, the fourth pressing plate 13 is used as the mounting base of the second probe assembly 9, and the second probe assembly 9 on the third pressing plate 8 forms a multi-point detection model for the sound emission of the rock sample 11, and the second sound absorption plate 14 can isolate the sound emission generated by the rotary driving mechanism 16 for the second probe assembly 9.

[0061] More detailed schemes are as follows: for any one of the first probe assembly 5, the second probe assembly 9 and the third probe assembly 17, the structure thereof includes a sound wave pickup sensor 21, a compression spring 22, a compression column 23 and a cover 24, and the assembly manner thereof on the mounting base is as follows: a groove is arranged on the mounting base, the cover 24 is fixed on the mounting base, the internal space of the cover 24 and the space of the groove form an installation space 25, the sound wave pickup sensor 21 and the compression spring 22 are arranged in the groove, the sound wave pickup end of the sound wave pickup sensor 21 is attached to the bottom surface of the groove, the compression column 23 is threadedly connected to the end of the cover 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 in an elastic compression state between the compression column 23 and the sound wave pickup sensor 21.

[0062] The above scheme provides an installation form of the corresponding probe assembly, that is, the sound wave pickup sensor 21 of each is fixed in the groove of the corresponding mounting base through the compression spring 22, the compression spring 22 maintains the attachment quality of the sound wave pickup sensor 21 and the bottom surface of the groove through elastic recovery, and the force of the elastic recovery is realized by rotating the compression column 23. It is easy to understand that the second pressing plate 6 is used as the mounting base of the first probe assembly 5, the third pressing plate 8 and the fourth pressing plate 13 are used as the mounting bases of the second probe assembly 9, and the rotary driving mechanism 16 or the fifth pressing plate 15 is used as the mounting base of the third probe assembly 17.

[0063] More detailed schemes are as follows: the box body 18 is provided with a temperature control device for controlling the temperature in the box body 18, and further includes a heat preservation layer arranged 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, the heat preservation layer is used to improve the controllability of the experimental environment temperature and reduce the 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, further, the humidity control device for controlling the humidity inside the box 18 is arranged in the box 18, which is used to maintain the humidity of the rock sample during the standing process before the test.

[0065] More detailed scheme is: the top surface of the box 18 is detachable relative to the box 18, and the positioning column is arranged between the top surface of the box 18 and the side wall of the box 18.

[0066] In the above scheme, the configuration mode 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 the form of hoisting after the top surface is removed, and then closing the top surface to obtain a closed test environment on the box 18, and the positioning column is used to determine the position of the first pressing plate 3 connected to the top surface by the loading assembly in the space of the box 18 after the top surface is installed. More specifically, the top plate is bolted to the side of the box 18, and the positioning column is arranged on any one of the lower side of the top surface and the upper end of the side of the box 18, and a positioning hole matched with the positioning column is arranged on the other one.

[0067] More detailed scheme is: the thrust bearing 4 includes a bearing retainer and a plurality of balls mounted on the bearing retainer, the bottom surface of the first pressing plate 3 and the top surface of the top plate are both arranged 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 has a spherical cross section 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 simple structure and convenient assembly, and specifically, the ball is used as the rolling body between the first pressing plate 3 and the top plate, the retainer is used to maintain the relative position between the balls, and the ball is rotatably arranged in the ball hole of the retainer, when the ball cooperates with the ball groove on the first pressing plate 3 and the ball groove on the top plate respectively, the position of the thrust bearing 4 relative to the first pressing plate 3 and the top plate is constrained by the ball groove, when the rotary driving mechanism 16 rotates, the rotation of the first pressing plate 3 to the rock sample 11 is avoided by the rolling of the ball, and at the same time, whether the rock sample 11 rotates or not, the thrust bearing 4 does not affect the external load continuously loaded on the rock sample 11.

[0069] The present scheme also relates to a rock property research method based on acoustic emission, which is based on the rock property research system according to any one of the above schemes, and realizes the rock property research under the external load of the rock sample 11.

[0070] The loading assembly is used for fixing the rock sample 11 and providing external load to the rock sample 11;

[0071] The acoustic emission detection module is used for acquiring acoustic emission characteristics of the rock sample 11 in a failure process under the external load;

[0072] The tomography detection module is used for acquiring internal structure failure of the rock sample 11 under the external load from different angles under the action of the rotary driving mechanism 16.

[0073] The pickup results of the first probe assembly 5 and the third probe assembly 17 are used for noise reduction on the pickup results of the second probe assembly 9.

[0074] The above method is a use method of the rock property research system in the rock property research.

[0075] The above is a further detailed description of the present application in combination with specific preferred embodiments, and the specific embodiments of the present application cannot be limited to these descriptions. Other embodiments obtained by those skilled in the art without departing from the technical solutions of the present application should be included in the protection scope of the present application.

Claims

1. A rock property research system based on acoustic emission, comprising a loading assembly for fixing a rock sample (11) and providing an external load to the rock sample (11); further comprising a detection module for detecting internal damage properties of the rock sample (11) under the external load, characterized in that, The loading assembly comprises a box (18), a rotary driving 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 on the top of the rock sample (11), and a loading mechanism for providing external load for the rock sample (11), the bottom plate is connected to the output end of the rotary driving mechanism (16), the rotary driving mechanism (16) is used for driving the bottom plate to rotate, the loading mechanism is fixed on 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 for providing downward pressure to the top plate, and the thrust bearing (4) enables the top plate to rotate around the axis of the thrust bearing (4) relative to the loading mechanism; The detection module comprises an acoustic emission detection module and a tomography detection module; The acoustic emission detection module comprises a first probe assembly (5) for picking up acoustic emission of the loading mechanism, a second probe assembly (9) for picking up acoustic emission of the rock sample (11), and a third probe assembly (17) for picking up acoustic emission of the rotary driving mechanism (16); The tomography detection module comprises a radiation source assembly (10) and an imaging assembly (12) installed on a pair of opposite sides of the box (18); The top plate comprises a second pressing plate (6), a first sound-absorbing plate (7), and a third pressing plate (8) stacked in sequence from top to bottom, the top plate is in a matching relationship with the thrust bearing (4) through the second pressing plate (6), the first probe assembly (5) is installed on the second pressing plate (6), and the second probe assembly (9) is installed on the third pressing plate (8); The bottom plate comprises a fourth pressing plate (13), a second sound-absorbing plate (14), and a fifth pressing plate (15) stacked in sequence from top to bottom, the bottom plate is in a matching relationship with the rotary driving 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 rotary driving mechanism (16).

2. The acoustic emission based rock property investigation system as claimed in claim 1, wherein, The loading mechanism comprises a loading motor (1) installed on the top of the box (18), a ball screw structure (2) connected to the rotor of the loading motor (1) and coaxial with the rotor, and a first pressing plate (3) connected to the ball screw structure (2), the ball screw structure (2) is used for converting the rotary motion output by the loading motor (1) into the linear reciprocating motion of the first pressing plate (3), and the motion direction of the linear reciprocating motion is parallel to the axis direction of the ball screw structure (2); the thrust bearing (4) is arranged between the bottom surface of the first pressing plate (3) and the top surface of the top plate.

3. The acoustic emission based rock property investigation system as claimed in claim 2, wherein, The ball screw structure (2) comprises a lead screw, a lead screw nut, and a connecting cylinder, the lead screw is coaxial with the rotor, the upper end of the lead screw is fixedly connected to the lower end of the rotor, the lead screw nut is threadedly connected to the lead screw, the connecting cylinder is coaxial with the lead screw nut, the upper end of the connecting cylinder (19) is fixedly connected to the lead screw nut, the first pressing plate (3) is fixedly connected to the lower end of the connecting cylinder (19), and the thrust bearing (4) is coaxial with the connecting cylinder (19). Further comprising a guide frame (20) fixed on the top of the box (18), further comprising a guide slider configured between the connecting cylinder (19) and the guide frame (20) or between the lead screw nut and the guide frame (20), the guide slider is prevented from rotating by the guide frame (20).

4. The acoustic emission based rock property investigation system as claimed in claim 1, wherein, For any one of the first probe assembly (5), the second probe assembly (9) and the third probe assembly (17), the structure comprises an acoustic pickup sensor (21), a compression spring (22), a compression column (23) and a cover (24), and the assembly mode on the mounting base is that: the mounting base is provided with a groove, the cover (24) is fixed on the mounting base, the internal space of the cover (24) and the space of the groove form an installation space (25), the acoustic pickup sensor (21) and the compression spring (22) are arranged in the groove, the acoustic pickup end of the acoustic pickup sensor (21) is attached to the bottom surface of the groove, the compression column (23) is threadedly connected to the end of the cover (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 in an elastically compressed state between the compression column (23) and the acoustic pickup sensor (21).

5. The acoustic emission based rock property investigation system as claimed in claim 1, wherein, The box (18) is provided with a temperature control device for controlling the temperature inside the box, and further comprises a heat preservation layer arranged on the wall surface of the box (18).

6. The acoustic emission based rock property investigation system as claimed in claim 1, wherein, The top surface of the box (18) is detachable relative to the box (18), and a positioning column is arranged between the top surface of the box (18) and the side wall of the box (18).

7. The acoustic emission based rock property investigation system as claimed in claim 1, wherein, The thrust bearing (4) comprises a bearing retainer and a plurality of balls mounted on the bearing retainer, the bottom surface of the first pressing plate (3) and the top surface of the top plate are both provided with an annular ball groove, 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 pressing plate (3) supports the top of the ball, and the cross section of the ball groove is a spherical surface with a radius consistent with the radius of the ball.

8. A method for studying rock properties based on acoustic emission, characterized by, The method is based on the rock property research system of any one of claims 1-7, and realizes the rock property research of the rock sample (11) under external load; The loading assembly is used for fixing the rock sample (11) and providing external load to the rock sample (11); The acoustic emission detection module is used for acquiring the acoustic emission characteristics of the rock sample (11) in the damage process under external load; The tomographic detection module is used for acquiring the internal structure damage of the rock sample (11) under external load from different angles under the action of the rotary driving mechanism (16); The pickup results of the first probe assembly (5) and the third probe assembly (17) are used for noise reduction of the pickup results of the second probe assembly (9).

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