Rock high-intensity rockburst test simulation method

Abstract

The invention discloses a rock high-intensity rockburst test simulation method. The method comprises the following steps: 1) taking out upper, lower, front, rear, left and right cushion blocks in a true triaxial test loading system; 2) mounting a rock sample into the system; 3) closely attaching the upper, left and right cushion blocks in the system to the rock sample; (4) tightly attaching the upper loading head, the left loading head and the right loading head in the system to the corresponding cushion blocks; 5) fixing a right loading head and a lower loading head; (6) tightly attaching the front cushion block and the rear cushion block to the rock sample, and adjusting the positions of the cushion blocks and the rock sample; 7) sequentially controlling the upper, left, front and rear servo loading oil cylinders to apply tiny load; according to the rock burst testing device and method, the fixing mode of the loading head is optimized, synchronous monitoring of the acoustic emission sensor and the high-speed camera is integrated, instantaneous unloading is achieved in combination with the air pressure control supporting column, and the problems that in the prior art, operation is tedious, the unloading speed is low, and the rock burst dynamic process cannot be quantified are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to a test simulation method, in particular to a high-intensity rock burst test simulation method. BACKGROUND

[0002] Rock burst, as a geological disaster, often occurs in deep underground engineering, such as mines and tunnels. The occurrence of rock burst is closely related to the mechanical properties of rock, stress state, and energy storage and release. Therefore, through the true triaxial rock burst test system, the stress state and disturbance of deep underground engineering can be simulated, the deformation, strength and energy conversion characteristics of rock under complex stress conditions can be studied, and thus theoretical basis for predicting and preventing rock burst can be provided.

[0003] In CN107941615B, an invention patent entitled "Triaxial testing machine and testing system" is disclosed, which includes a loading frame, a test piece box, a base, six actuators, a lifting oil cylinder, and a locking oil cylinder. The axes of the six actuators intersect at a point O. The actuators are used to provide six loads perpendicular to the six surfaces of the test piece in the test piece box, so that the test piece has independent loading / unloading capability in three directions perpendicular to the test piece surface. The test piece box is used to install and position the test piece, so that the geometric center 0' of the test piece coincides with the geometric center 0' of the test piece box, and the geometric center O' of the test piece box coincides with the point O. At the same time, any one face of the test piece is perpendicular to the axis of any one actuator. The testing machine and testing system realize one-way unloading (such as free falling of the movable pressure block in the rock burst test piece box) through the actuator, need to coordinate multiple hydraulic systems (lifting oil cylinder, locking oil cylinder, etc.), and are difficult to achieve instantaneous high-intensity unloading due to complicated operation and limited response speed. At the same time, high-speed cameras and acoustic emission systems are not integrated, and it is difficult to analyze the energy release law by synchronously capturing the rock burst block collapse process and micro-fracture acoustic emission signals.

[0004] In CN114965080A, an invention patent application entitled "Rock burst inducing device and rock burst inducing method" is disclosed. The device includes a rock burst inducing box, a cubic rock sample, and an unloading rod. The rock sample has a sample hole, and the unloading rod can be advanced and withdrawn in the sample hole. The rock sample has external power in one vertical dimension and two horizontal dimensions perpendicular to each other, which can press the rock sample. The device relies on pre-drilled holes and pull rods for unloading, which needs to drill holes in the center of the sample (with a depth of 0.5 times the side length), which damages the integrity of the sample and is inconsistent with the actual tunnel excavation unloading mechanism (exposure of free surface). At the same time, high-speed cameras or acoustic emission systems are not mentioned, and only macroscopic damage phenomena can be recorded, which cannot quantify the dynamic process of rock burst.

[0005] An invention patent application entitled "A true triaxial rock burst physical simulation test system for deep buried tunnel" is disclosed in CN103398861A, which is composed of a true triaxial loading system composed of a counterforce frame, a vertical loading system, a horizontal front and rear loading system and a horizontal left and right loading system, the counterforce frame is composed of a steel beam frame, a front door and a rear door connected by a pull rod, the vertical loading system is fixed at the top of the counterforce frame, the horizontal front and rear loading system is fixed on the inner wall of the rear door, and the horizontal left and right loading system is fixed on the right side wall in the counterforce frame. The test system needs to manually take out the excavation hole and fill the cylinder, and then mechanically excavate, the unloading speed is slow (second level), and the instantaneous energy release of high intensity rock burst cannot be simulated; although a vibration jack is provided to simulate the disturbance of blasting, only simple frequency / amplitude vibration can be applied, and the disturbance direction and stress path coupling cannot be accurately controlled (such as only vertical or horizontal single disturbance); at the same time, the counterforce frame, guide table and pressure plate need to be combined, and the sample installation takes time (needs to be hoisted, pushed in and pre-pressed). SUMMARY

[0006] The purpose of the present application is to provide a rock high-intensity rock burst test simulation method which is easy to operate, can realize instantaneous high-intensity unloading, synchronously capture the dynamic process and energy release law of rock burst, and can.

[0007] The purpose of the present application is achieved by the technical scheme, a rock high-intensity rock burst test simulation method, the method comprising the following steps: 1) Take out the upper, lower, front, rear, left and right pads in the true triaxial test loading system, install the acoustic emission sensor on the true triaxial test loading system and connect it to the acoustic emission console; 2) Install the rock sample into the true triaxial test loading system; 3) Make the upper, left and right pads in the true triaxial test loading system adhere to the rock sample, and adjust the position of the pads and the rock sample; 4) Make the upper, left and right loading heads in the true triaxial test loading system adhere to the corresponding pads; 5) Fix the right and lower loading heads to provide counterforce for the load applied to the left and upper loading heads; 6) Make the front and rear pads adhere to the rock sample, and adjust the position of the pads and the rock sample; 7) Control the upper, left, front and rear servo loading cylinders to apply a small load in sequence, observe the value of the force sensor, and control the small load range to be 0.5kN-1kN; 8) Set the stress path; 9) Start loading, at the same time, start the acoustic emission sensor to collect signals and start the high-speed camera set outside the true triaxial test loading system to take pictures, until the rock sample bursts; 10) After the end of the test, the acoustic emission sensor and high-speed camera are closed, the load is removed, the rock sample is taken out, the rock debris is cleaned, the loading table is kept clean, and the next test is waited.

[0008] Wherein, in order to guarantee the instantaneous unloading when the rock burst state is simulated, the front loading head is integrally arranged with the front pad, and the rear loading head is integrally arranged with the rear pad.

[0009] Wherein, the front loading head support is arranged at the lower end of the front servo loading oil cylinder, and the front loading head support is controlled to stretch and retract through air pressure.

[0010] Further, in the step 7), when the micro load is applied, the load force should be perpendicular to the pad.

[0011] Wherein, the stress path is arranged as follows: the loading is used to load the stress in three directions to the high-intensity rock burst stress level, the upper and lower directions are the directions of the major principal stress, the left and right directions are the directions of the intermediate principal stress, and the front and rear directions are the directions of the minor principal stress; when the stress is loaded to the predetermined level, the stress level is maintained for 60s; the front and rear servo loading oil cylinders become displacement maintaining mode; the front loading head support is retracted, the front servo loading oil cylinder is retracted by 5cm, the front loading head is dropped, and the high-intensity rock burst occurs.

[0012] Wherein, the magnetic force chuck capable of driving the displacement of the front loading head is arranged in the end portion of the front servo loading oil cylinder.

[0013] Further description, the pad is provided with the acoustic emission mounting hole for the acoustic emission sensor installation.

[0014] Due to the adoption of the above technical scheme, the present application realizes instantaneous unloading by optimizing the loading head fixing mode, integrating the acoustic emission sensor and the high-speed camera for synchronous monitoring, and combining the air pressure control support, solves the problems of complicated operation, slow unloading speed and inability to quantify the rock burst dynamic process in the prior art, and has the advantages of simplifying the test process, accurately capturing the energy release law and improving the simulation reality. BRIEF DESCRIPTION OF DRAWINGS

[0015] The drawings of the present application are as follows: Figure 1 is a structural schematic view of the present application; Figure 2 is a schematic view of the loading system of the present application; Figure 3 is a layout position diagram of the high-speed camera of the present application; Figure 4 is a schematic view of the acoustic emission system of the present application. DETAILED DESCRIPTION

[0016] The application will be further described in detail below with reference to the accompanying drawings, but the application is not limited to these embodiments, and any improvement or substitution within the basic spirit of the embodiments still falls within the scope of the claims of the application.

[0017] Embodiment 1: as Figure 1 、 2 , 3, 4, a rock high-intensity rock burst test simulation method, the method comprises the following steps: 1) remove the upper, lower, front, rear, left and right pads 9, 10, 13, 14, 11, 12 in the true triaxial test loading system, install the acoustic emission sensor 18 to the true triaxial test loading system and connect it to the acoustic emission console 17; 2) install the rock sample to the true triaxial test loading system; 3) tightly attach the upper, left and right pads 9, 11, 12 in the true triaxial test loading system to the rock sample 15, and adjust the position of the pads and the rock sample 15; 4) tightly attach the upper, left and right loading heads 1, 3, 4 in the true triaxial test loading system to the corresponding pads; 5) fix the right and lower loading heads 4, 2 to provide counterforce for the load applied to the left and upper loading heads 3, 1; 6) tightly attach the front and rear pads 13, 14 to the rock sample 15, and adjust the position of the pads and the rock sample 15; 7) sequentially control the upper, left, front and rear servo loading oil cylinders to apply a small load, observe the force sensor value, and control the small load range to be 0.5kN-1kN; 8) set the stress path; 9) start loading, at the same time, start the acoustic emission sensor 18 for signal acquisition and start the high-speed camera 16 set outside the true triaxial test loading system for shooting, until the rock sample 15 occurs rock burst; 10) after the test is completed, close the acoustic emission sensor 18 and the high-speed camera 16, unload the load, remove the rock sample 15, clean the rock debris, keep the loading table clean, and wait for the next test.

[0018] The acoustic emission sensor installation refers to arranging a detection element on the surface of the loading system frame. The cushion block position adjustment refers to completely matching the contact surface of the cushion block and the sample through a precise guide mechanism, and specifically can adopt a laser alignment system to assist the operation, and ensure uniform transmission of loading force in each direction. The loading head fixation refers to using a hydraulic locking device to keep the positions of the right and lower loading heads constant, and specifically can adopt a two-way hydraulic lock to provide rigid reaction force support for the active loading direction. The small load application refers to preloading with a force lower than the initial value of the conventional test, and specifically can be realized through the micro-feeding function of the servo oil cylinder, which eliminates the assembly gap without affecting the initial stress state of the sample. The stress path setting refers to adjusting the three-dimensional stress components in a predetermined order and rate, and specifically can be realized through computer control system programming to simulate the stress redistribution process in the deep rock mass excavation process. Specifically, the sensor installation is provided with space by removing all the cushion blocks at the beginning of the test, eliminating the damage to the sample structure caused by the traditional embedded method. The cushion blocks are installed in stages and the position adjustment ensures uniform contact of each loading surface, avoiding stress concentration. The right and lower loading heads are fixed to form a stable reaction force system, making the active loading in the left and upper directions more accurate. The servo system precisely controls the oil cylinder stroke in the small load application stage, eliminating assembly errors while establishing the initial contact stress. The stress path control module loads in the direction of the large, medium and small principal stress in stages to the critical state of high intensity rock burst, and the holding stage allows the internal energy of the sample to accumulate fully. When triggering unloading, the front loading head support is quickly retracted by air pressure driving, and the magnetic suction disc is released to form a millisecond free surface. The acoustic emission system collects micro-fracture signals throughout the process, and the high-speed camera records the trajectory of the rock fragments at a rate of ten thousand frames per second. The data of the two are precisely synchronized through a time code generator. Compared with the prior art, the traditional method needs to coordinate multiple hydraulic systems to complete loading and unloading, and the present application simplifies the operation process through split cushion block installation and independent servo control; the prior art adopts mechanical pull rod or manual excavation method to unload, which takes seconds, and the present application realizes millisecond instantaneous unloading through air pressure control; the traditional embedded sensor destroys the integrity of the sample, and the present application maintains the original structure of the sample by using external acoustic emission detection; the existing system mainly uses a single monitoring method, and the present application realizes the spatiotemporal synchronous acquisition of acoustic emission signals and high-speed images. Through the above technical solutions, the present application solves the problem of low test efficiency caused by multi-system coordination, simplifies the operation process, realizes millisecond unloading simulation of high-intensity rock burst characteristics, improves the test authenticity, maintains the sample structure integrity, ensures the reliability of the test data, and synchronously acquires the data of micro-fracture evolution and macroscopic failure process, providing multi-dimensional information support for rock burst mechanism research.

[0019] In order to ensure instantaneous unloading in the simulated rock burst state, the front loading head and the front cushion block are integrally arranged, and the rear loading head and the rear cushion block are integrally arranged.

[0020] The integrated structure of the front loading head and the front pad block means that the front loading head and the front pad block are formed into a single structure by integral machining or casting, and can specifically be implemented by using an integrated metal component. The structure eliminates the assembly gap between the split components and ensures that the loading force is directly transmitted to the rock sample. The integrated structure of the rear loading head and the rear pad block means that the rear loading head and the rear pad block are formed into a whole structure by the same way, and can specifically be implemented by welding or integral forming process. The design avoids the stress transmission delay caused by split connection and enhances the stability of the rearward load transmission. Specifically, the integrated structure of the front loading head and the front pad block directly integrates the loading and pressure bearing functions, reducing the connecting components required in the traditional split design. During the loading process, the load directly acts on the front pad block through the front loading head support, without the need for additional adjustment or fixation of the relative position of the split components, thereby simplifying the operation steps. The integrated design of the rear loading head and the rear pad block also eliminates the assembly error of the rearward loading, ensuring the continuity of the load transmission path. This whole structure reduces the complexity of the coordinated action of multiple components, enabling the loading system to quickly respond to stress changes and providing a stable mechanical basis for instantaneous unloading.

[0021] Compared with the prior art, the loading head and the pad block in the prior art adopt a split design, for example, are connected by bolts or hydraulic locking devices, and the actions of multiple independent components need to be coordinated, resulting in complicated operation and limited response speed. The integrated structure of the present application directly shortens the load transmission path by eliminating assembly gaps and connection links, avoids energy loss and delay between split components, and significantly improves the response speed and instantaneousness of unloading of the loading system. Through the above technical solutions, the present application solves the problems of response delay and operation complexity caused by the split loading head and the pad block, realizes the rapid transmission and instantaneous unloading of the load, and provides stable mechanical conditions for synchronous capture of the dynamic failure process in high-intensity rock burst tests.

[0022] Further, a front loading head support 8 is arranged at the lower end of the front servo loading oil cylinder, and the front loading head support 8 is controlled to extend and retract by air pressure.

[0023] The front loading head support refers to a supporting structure connecting the front servo loading oil cylinder and the loading head, and can specifically be implemented by using a columnar component with a pneumatic piston. The front loading head support provides independent support for the loading head and realizes axial displacement control. The extension and retraction controlled by air pressure means that the piston is driven to move by compressed gas, and can specifically be implemented by using a gas pump and a solenoid valve to work together. The gas can be compressed to achieve rapid response, maintain stable support during the stress loading stage, and realize millisecond-level displacement retraction during the unloading stage.

[0024] Specifically, when the current servo loading oil cylinder applies a load to a predetermined level, the gas pressure control device maintains the front loading head support in an elongated state to fix the loading head. When it is necessary to trigger rockburst, the electromagnetic valve opens to release compressed gas, and the pneumatic piston quickly retracts under the action of sudden gas pressure drop, causing the front loading head support to instantaneously shorten, so that the loading head loses support and freely falls. This process realizes displacement mutation through the rapid flow characteristics of gas medium, compared with the hydraulic system, the oil way switching and valve coordination link are omitted, and the instantaneous unloading action can be completed directly through single gas path control.

[0025] Compared with the prior art, the traditional hydraulic drive needs to coordinate multiple actuators and locking devices, and the oil way switching has mechanical delay, while the gas pressure control can realize millisecond response speed through the characteristics of gas compression energy storage and rapid release. The present application only needs to control a single gas path electromagnetic valve to complete the instantaneous displacement release, simplifying the operation steps and improving the response efficiency.

[0026] Through the above technical scheme, the present application effectively solves the unloading delay problem caused by the complex operation of the hydraulic system, realizes the rapid retraction action of the loading head support by using gas pressure control, matches the rockburst triggering process with the energy release characteristics in the real geological conditions, and provides an accurate and controllable instantaneous unloading means for high-intensity rockburst simulation test.

[0027] Further, when a small load is applied, the load force should be perpendicular to the pad.

[0028] The vertical pad means that the direction of the applied load is perpendicular to the surface of the pad, which can be realized by using a force sensor to monitor the load direction in real time and combining the feedback adjustment system of the servo loading oil cylinder, and by adjusting the angle of the loading head in real time to ensure that the force direction is consistent with the normal direction of the pad surface. The range of the small load is controlled between 0.5kN and 1kN, which can be realized by the precise pressure control system of the servo oil cylinder, for example, a closed-loop control algorithm is used to dynamically adjust the output force of the oil cylinder to ensure stable application of the initial load. Specifically, after the servo loading oil cylinder is started, the load direction is fed back to the control system through the force sensor, and if it is detected that the load direction deviates from the vertical state, the system automatically adjusts the spatial posture of the loading head, for example, the angle of the loading head is corrected through a multi-axis linkage mechanism, so that the load force line is perpendicular to the surface of the pad. In this process, the contact surface between the pad and the rock sample is uniformly pressed, avoiding local stress concentration or sample position deviation caused by load inclination. Through this way, the matching degree of the stress distribution of the rock sample in the initial loading stage and the preset stress path is improved, providing accurate initial conditions for subsequent high-intensity rockburst simulation. Compared with the prior art, some test methods do not clearly control the load direction mechanism, for example, only rely on artificial visual inspection or simple mechanical limiting adjustment of the loading direction, which is easy to cause deviation of the force direction. The scheme realizes dynamic calibration of the load direction by integrating force sensors and a servo control system, solves the problem of uneven stress of the sample caused by deviation of the force direction in the traditional method, and significantly improves the reliability of the test data. Through the above technical scheme, the present application effectively avoids the stress state distortion caused by direction deviation in the micro load application stage, ensures the accuracy of the subsequent stress path control, reduces the additional error of the test system caused by asymmetric stress, and makes the rock burst dynamic process recorded by the acoustic emission signal and the high-speed camera more truly reflect the actual mechanical behavior.

[0029] In the present application, the stress path is set as: loading makes the stress in three directions to the high-intensity rock burst stress level, the upper and lower directions are the major principal stress directions, the left and right directions are the intermediate principal stress directions, and the front and back directions are the minor principal stress directions; when the stress is loaded to the predetermined level, the stress level is maintained for 60s; the front and back servo loading oil cylinders change to displacement maintaining mode; the front loading head support retracts, the front servo loading oil cylinder retracts 5cm, the front loading head falls, and the high-intensity rock burst occurs.

[0030] Among them, the stress path setting that the stress in three directions is loaded to the high-intensity rock burst stress level means that different levels of stress are applied by independently controlling the loading system in different directions, which can be realized by using a hierarchical loading program, and is used for simulating the actual stress state of deep rock mass. The stress level is maintained for 60s, which means that the predetermined stress value is maintained for a specific time, which can be realized by the time setting function of the servo control system, and is used to ensure the uniform distribution of stress in the sample. The front loading head support retracts, which means that the supporting structure is quickly retracted by the air pressure driving device, which can be realized by using a pneumatic telescopic rod, and is used to release the mechanical constraint on the front loading head. The front servo loading oil cylinder retracts 5cm, which means that the hydraulic actuator is controlled to move a specific distance, which can be realized by cooperating the displacement sensor with the closed-loop control system, and is used to form the physical condition of exposing the free surface. Specifically, the triaxial loading of the three principal stress directions can accurately reproduce the stress environment of the surrounding rock of underground engineering. The maximum principal stress is applied in the up-down direction to simulate the vertical stress, the intermediate principal stress is applied in the left-right direction to simulate the horizontal tectonic stress, and the minimum principal stress is applied in the front-back direction to simulate the stress state of the excavation free face. The stable stage of 60 seconds enables the internal stress of the sample to be fully transmitted and reach a critical equilibrium state. Subsequently, the front and back servo loading oil cylinders are switched to the displacement maintaining mode, the active loading control is released, the front loading head support is quickly retracted through air pressure control at this time, and the front servo oil cylinder synchronously performs a precise retraction action of 5 centimeters, both of which cooperate to make the front loading head lose support and instantaneously fall off, forming a mechanical condition similar to the sudden exposure of the rock mass free face in actual engineering, thereby triggering the rapid release of stored elastic energy. Through the above technical solutions, the application can realize the instantaneous energy release simulation of high-intensity rock burst, accurately control the mechanical coupling of the loading path and unloading direction of the three principal stress directions, avoid the distortion of test data caused by sample pre-damage in traditional methods, and significantly improve the unloading response speed and operation reliability by replacing the complex hydraulic coordination system with a mechanical linkage mechanism.

[0031] The magnetic chuck is arranged in the end of the front servo loading oil cylinder to drive the displacement of the front loading head.

[0032] The magnetic chuck is a device that directly drives the displacement of the front loading head through electromagnetic force, which can be realized by a combination structure of electromagnet and armature. The adsorption or release action is realized by controlling the on-off of the current. The device does not need to rely on hydraulic circuit or mechanical transmission, which can reduce energy loss and improve response speed. The end of the servo loading oil cylinder is provided with a magnetic chuck, which is integrated in the internal end of the oil cylinder, which can be realized by embedded installation, so that the magnetic chuck and the loading head are in direct contact, avoiding external structure interference, thereby simplifying the overall device layout. Specifically, during the stress maintaining stage, the magnetic chuck adsorbs the front loading head through electromagnetic field action, so that it maintains stable contact with the rock sample; when unloading is needed, the magnetic chuck releases the front loading head instantaneously by cutting off the current, and the front loading head is separated from the rock sample under the action of gravity or elastic potential energy, forming a free face. Since the driving process of the magnetic chuck only depends on the change of electromagnetic field, its response time can be shortened to milliseconds, which can accurately simulate the stress mutation phenomenon of deep rock mass caused by excavation, and meet the instantaneous energy release conditions required by high-intensity rock burst. Compared with the prior art, the traditional hydraulic system needs to coordinate multiple actuators and locking devices, and the unloading process relies on the pressure change of the hydraulic circuit, and the response speed is limited by the oil flow and valve switching time; while the magnetic chuck directly drives the loading head through electromagnetic control, without complex hydraulic linkage, and the triggering time of the unloading action is significantly shortened. In addition, the mechanical locking device in the prior art needs to transmit the restraining force through physical contact, and the friction resistance will cause energy loss, while the non-contact driving mode of the magnetic chuck eliminates mechanical friction, further improving the energy release efficiency. Through the above technical solutions, the application solves the problem that the traditional hydraulic system is complex and slow in response speed, which cannot realize instantaneous high-intensity unloading, and through the precise control of the magnetic chuck, the front loading head can quickly separate from the rock sample, accurately simulate the stress mutation condition after the excavation of deep rock mass, and effectively trigger the instantaneous energy release required by high-intensity rock burst.

[0033] Among them, the pad is provided with an acoustic emission mounting hole 19 for mounting the acoustic emission sensor 18.

[0034] Among them, the acoustic emission mounting hole refers to a through hole or blind hole structure formed in the pad body in advance, which can be realized by mechanical drilling or milling, and the hole diameter size is matched with the outer diameter of the acoustic emission sensor, for example, the hole diameter can be set to 8mm to 12mm. The hole layout covers the pad in six directions, forming a three-dimensional monitoring network, and realizing the consistency of sensor positioning through standardized hole positions. Specifically, the six-direction pad completes the preposition of the acoustic emission mounting hole in the processing stage, and the mounting hole axis is perpendicular to the contact surface of the pad and the rock sample. During the test, the acoustic emission sensor is fixed in the mounting hole through threaded connection or interference fit, and the sensor receiving surface is in direct contact with the inner wall of the pad. Since the mounting hole is integrated in the pad body, the sensor and the pad form a rigid connection, avoiding the signal transmission loss caused by the gap between the contact surfaces in the traditional external installation mode. The six-direction mounting hole synchronously collects acoustic emission signals in different dimensions, such as the upper and lower pads monitoring the main stress direction fracture signal, and the left and right pads capturing the energy release characteristics in the intermediate principal stress direction. Through the above technical solutions, the application solves the problems of poor installation stability of the acoustic emission sensor and single signal collection dimension. The sensor realizes rapid and accurate positioning through standardized hole positions, avoiding installation errors caused by manual adjustment; the six-direction mounting hole of the pad synchronously collects acoustic emission signals in different stress directions, and records the spatial distribution characteristics of energy release in the rock burst process; the rigid connection of the sensor and the pad reduces the energy attenuation in the signal transmission path, and improves the signal-to-noise ratio of the acoustic emission signal.

Claims

1. A method for simulating high-intensity rockburst tests, characterized in that, The method includes the following steps: 1) Remove the upper, lower, front, rear, left, and right pads from the true triaxial test loading system, install the acoustic emission sensor onto the true triaxial test loading system, and connect it to the acoustic emission control console; 2) Mount the rock sample into the true triaxial test loading system; 3) Make sure the upper, left and right pads of the true triaxial test loading system are in close contact with the rock sample, and adjust the position of the pads and the rock sample; 4) Ensure that the upper, left, and right loading heads in the true triaxial test loading system are in close contact with the corresponding pads; 5) Fix the right and lower loading heads to provide reaction forces for the loads applied to the left and upper loading heads; 6) Place the front and rear pads in close contact with the rock sample and adjust the position of the pads relative to the rock sample; 7) Sequentially control the upper, left, front, and rear servo loading cylinders to apply a small load, observe the force sensor values, and control the small load range to be 0.5kN~1kN; 8) Set the stress path; 9) Start loading, and at the same time turn on the acoustic emission sensor to collect signals and turn on the high-speed camera set outside the true triaxial test loading system to take pictures until the rock sample explodes. 10) After the test, turn off the acoustic emission sensor and high-speed camera, unload the load, remove the rock sample, clean up the rock debris, keep the loading platform clean, and wait for the next test.

2. The method for simulating high-intensity rockburst tests as described in claim 1, characterized in that: The front loading head and the front pad are integrated into one piece, and the rear loading head and the rear pad are integrated into one piece.

3. The method for simulating high-intensity rockburst tests as described in claim 2, characterized in that: A front loading head support is provided at the lower end of the front servo loading cylinder, and the front loading head support extends and retracts by air pressure.

4. The method for simulating high-intensity rockburst tests as described in claim 3, characterized in that: In step 7), when a small load is applied, the load force should be perpendicular to the pad.

5. The method for simulating high-intensity rockburst tests as described in claim 4, characterized in that: in In step 8), the stress path is set as follows: the stress in three directions is applied to the high-intensity rockburst stress level, with the upper and lower directions being the major principal stress directions, the left and right directions being the intermediate principal stress directions, and the front and back directions being the minor principal stress directions; after the stress is applied to the predetermined level, the stress level is maintained for 60 seconds; the front and rear servo loading cylinders switch to displacement holding mode; the front loading head support retracts, the front servo loading cylinder retracts by 5 cm, the front loading head falls, and the high-intensity rockburst occurs.

6. The method for simulating high-intensity rockburst tests as described in claim 5, characterized in that: A magnetic chuck is provided inside the end of the front servo loading cylinder to drive the displacement of the front loading head.

7. The method for simulating high-intensity rockburst tests as described in claim 6, characterized in that: Each of the pads is provided with acoustic emission mounting holes for mounting the acoustic generator sensor.

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