A cyclic dynamic load instantaneous unloading confining pressure mechanical test device and its usage method

Abstract

The present invention relates to a cyclic dynamic load instantaneous confining pressure unloading mechanical test device and a using method thereof, belonging to the technical field of rock mechanics test devices. The device comprises a bearing frame system, a cyclic dynamic load system, a confining pressure loading system, a monitoring system, a control system and a data analysis system. Among them, the cyclic dynamic load system is arranged at the top of the bearing frame system, the cyclic dynamic load system is connected with the control system, the confining pressure loading system is arranged at the bottom of the bearing frame system, the monitoring system is arranged on the cyclic dynamic load system and the confining pressure loading system, and both the monitoring system and the control system are connected with the data analysis system. The present invention is simple to operate and has high test accuracy. When the specimen undergoes expansion failure, it can realize instantaneous confining pressure unloading of the specimen, has a high similarity with the actual conditions of the surrounding rock of the underground roadway, and the test results are reliable.

Description

Technical Field

[0001] The present invention relates to a cyclic dynamic load instantaneous unloading confining pressure mechanical test device and a using method thereof, belonging to the technical field of rock mechanics test devices. Background Technique

[0002] During the coal mining process, coal seams are often subjected to cyclic dynamic loads, such as geological tectonic movements, roadway excavation and support, periodic roof weighting, extrusion of the coal seam by blasting stress waves, and the action of support lifting on the top coal. The mechanical properties of the coal seam under the action of cyclic dynamic load disturbance are one of the important factors affecting the safe production of coal mines. In the actual production process, the continuous change of the excavation and extraction time-space relationship caused by coal mining leads to the redistribution of surrounding rock stress, resulting in the loading conditions of the coal body being cyclic, such as the reserved coal pillars and the surrounding rock of roadways affected by multiple mining activities. Coal mining underground often generates periodic disturbances to the surrounding coal and rock mass. Studying the deformation and failure characteristics of coal (rock) under cyclic loading conditions helps to deeply understand the damage, deterioration and instability failure mechanisms of coal (rock), and provides an effective analysis method for obtaining the precursors of coal (rock) instability. At the same time, in the actual production process, when the coal (rock) mass is unstable, the impact force generated by the unstable expansion and failure of the coal (rock) causes the roadway support means to fail instantly, and the surrounding rock is damaged by the impact. Therefore, to study the mechanical conditions of the underground roadway surrounding rock under actual conditions, it is necessary to consider the mechanical properties of the coal seam under the action of cyclic dynamic load disturbance and under the condition of instantaneous unloading of confining pressure at the same time.

[0003] At present, when studying the mechanical properties of coal (rock) under cyclic dynamic load in the laboratory, generally two test methods are adopted. One is to apply cyclic dynamic load through a hydraulic cylinder system. Chinese patent document CN112986026A provides a cyclic dynamic load test device and test method for high-frequency and high-load rocks. This device can provide high-frequency, high-load and steplessly adjustable cyclic dynamic load for rock tests. Its cyclic dynamic load is adjusted by means of a ball screw to push a piston pump to regulate the oil flow rate entering the dynamic load cylinder, thereby driving the piston rod of the cylinder to apply cyclic dynamic load to the coal (rock) specimen. However, the buffer performance of the ball screw is very low and there is wear, which will affect the positioning accuracy due to friction, thereby affecting the oil flow rate entering the cylinder, resulting in low accuracy of the applied cyclic dynamic load and great influence on the test results. At the same time, the hydraulic oil is easy to leak, causing safety hazards. Chinese patent document CN113075049A provides a variable-frequency and variable-intensity static and dynamic combined loading rock mechanics testing machine and a test method. This device can provide cyclic dynamic load for rock specimens. Its cyclic dynamic load is realized by the meshing movement of the impact screw and the thread of the asymmetric gear, thereby driving the loading chassis to perform axial harmonic motion to apply dynamic load to the rock specimen. However, this device does not consider the confining pressure on the rock specimen, and the test range is small.

[0004] In the prior art, there is also a test method that uses a split Hopkinson bar system (SHPB) to apply multiple cyclic loads to a specimen, and a compressive stress is generated on the specimen by means of the Hopkinson bar for testing. However, using this device to conduct cyclic dynamic load tests on specimens is intermittent and independent, and continuous cyclic tests cannot be carried out.

[0005] In the actual production process, when the coal (rock) mass becomes unstable, the impact force generated by the expansion and failure of the coal (rock) during instability causes the roadway support means to fail instantly, and the surrounding rock is damaged by the impact. At present, in the laboratory, unloading the confining pressure is generally carried out by controlling the oil pressure or air pressure, but neither can simulate instantaneous unloading of the confining pressure, which does not conform to the actual on-site engineering. However, at present, there is no test device and method for studying the mechanical properties of rocks under the conditions of cyclic loading and instantaneous unloading of the confining pressure. Therefore, the present invention is proposed. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the present invention provides a cyclic dynamic load instantaneous unloading confining pressure mechanical test device, which is simple to operate and has high test accuracy. When the specimen expands and fails, instantaneous unloading of the confining pressure of the specimen is achieved, which has a high similarity to the actual conditions of the surrounding rock of the underground roadway, and the test results are reliable.

[0007] The present invention also provides a use method of the above cyclic dynamic load instantaneous unloading confining pressure mechanical test device.

[0008] The technical solution of the present invention is as follows:

[0009] A cyclic dynamic load instantaneous unloading confining pressure mechanical test device includes a load-bearing frame system, a cyclic dynamic load system, a confining pressure loading system, a monitoring system, a control system, and a data analysis system. Among them,

[0010] A cyclic dynamic load system is arranged at the top of the load-bearing frame system. The cyclic dynamic load system is connected to a control system. A confining pressure loading system is arranged at the bottom of the load-bearing frame system. A monitoring system is arranged on the cyclic dynamic load system and the confining pressure loading system. Both the monitoring system and the control system are connected to a data analysis system.

[0011] The cyclic dynamic load system is used to apply an axial cyclic load from top to bottom to the specimen;

[0012] The confining pressure loading system is used to load the radial confining pressure on the specimen;

[0013] The monitoring system is used to monitor the force, deformation, and failure conditions of the specimen during the loading and unloading process;

[0014] The control system is used to control the cyclic loading system;

[0015] The data analysis system is connected to the monitoring system and the control system, and is used to receive the data of the monitoring system and process and analyze it.

[0016] Preferably, the load-bearing frame system includes a base, an operating platform, columns, and a top plate. An operating platform is provided on the upper surface of the base. A confining pressure loading system is provided on the operating platform. The top plate is fixed above the base by columns, and a cyclic dynamic load system is provided on the lower side of the top plate.

[0017] Preferably, the cyclic dynamic load system includes a servo motor, a rotating shaft, a rotating wheel, a cam, a first connecting rod, a second connecting rod, and a weight. The servo motor is horizontally fixed to the load-bearing frame system. The output shaft of the servo motor is connected to a rotating wheel through a rotating shaft. Arc-shaped grooves are uniformly arranged on the rotating wheel. A cam is arranged on the lower side of the rotating wheel. The cam is connected to a first connecting rod through a connecting shaft. The lower side of the first connecting rod is connected to a weight through a second connecting rod. The second connecting rod is elastically fixed to the top of the load-bearing frame system by 4 vertically clamping devices uniformly arranged in the circumferential direction.

[0018] The control system controls the servo motor to drive the rotating shaft to rotate. The rotating wheel rotates by means of the rotating shaft. The rotating wheel is an irregular circle. When its protruding part contacts the cam, it drives the cam to move vertically downward. Thus, the weight is driven to move vertically downward through the first connecting rod and the second connecting rod. When the cam rotates to below the arc-shaped groove of the rotating wheel, the vertical clamping device drives the cam to move vertically upward under the action of the spring elasticity. The cam contacts the rotating wheel, completing one application of dynamic load. The vertical clamping device enables the weight to move up and down while maintaining a vertical state, making the force acting on the specimen more uniform. Controlling the output speed of the rotating shaft can achieve the application of cyclic loads with different cyclic amplitudes and different load intensities; the rotating wheel that rotates at a constant speed or a non-uniform speed by means of the rotating shaft is independent for each rotation of one week, and rotations with different speeds and accelerations can be achieved.

[0019] Further preferably, the vertical clamping device is an L-shaped rod. The top of the vertical clamping device is fixed to the load-bearing frame system by a spring, and the L-shaped rod can better cooperate with the spring to do work.

[0020] Preferably, at least 2 arc-shaped grooves are arranged on the rotating wheel, and by changing the number of arc-shaped grooves, the application of loads with different numbers of times for one rotation can be achieved.

[0021] Preferably, the second connecting rod is threadedly connected to the weight. By replacing weights with different weights, the application of cyclic loads with different load intensities can be achieved.

[0022] Preferably, the confining pressure loading system includes a first arc-shaped confining plate, a second arc-shaped confining plate, a third arc-shaped confining plate, and a fourth arc-shaped confining plate. The first arc-shaped confining plate and the second arc-shaped confining plate are connected by bolts. The second arc-shaped confining plate is connected to the fourth arc-shaped confining plate through a first hinge. The fourth arc-shaped confining plate is connected to the third arc-shaped confining plate through a second hinge. The third arc-shaped confining plate is connected to the first arc-shaped confining plate through a third hinge.

[0023] Preferably, the monitoring system includes a first force sensor, a second force sensor, a displacement sensor, and an acoustic emission sensor. The first force sensor is arranged on the weight, and the second force sensor, the displacement sensor, and the acoustic emission sensor are arranged on the surface of the specimen in the confining pressure loading system. The first force sensor, the second force sensor, the displacement sensor, and the acoustic emission sensor are connected to a data analysis system through a signal collector.

[0024] The usage method of the above cyclic dynamic load instantaneous unloading confining pressure mechanical test device is as follows:

[0025] The first step: fabricate a cylindrical specimen;

[0026] The second step: fix the specimen at the middle position on the surface of the operating table, and then place the confining pressure loading system around the specimen along the radial direction of the specimen. The confining pressure loading system applies confining pressure to the specimen;

[0027] The third step: according to the load intensity required by the test, determine a weight that meets the test requirements, adjust the rotation speed of the servo motor, and apply a cyclic load with the target load intensity to the specimen;

[0028] The fourth step: the specimen expands and fails under the action of cyclic dynamic load. The confining pressure loading system is subjected to an outward acting force due to the expansion of the specimen, the hinge is tensioned and fails, the confining pressure loading system loses contact with the specimen, and the specimen instantaneously unloads the confining pressure;

[0029] The fifth step: after the data analysis system processes and analyzes the data from the monitoring system, stress, strain curves, and acoustic emission energy curves of the specimen are obtained, and the mechanical characteristics of the specimen before and after instantaneous unloading of the confining pressure are analyzed.

[0030] Further preferably, in the second step, when the confining pressure loading system applies confining pressure to the specimen, according to the test requirements, use a digital display torque wrench to tighten the bolts to apply confining pressure with the target intensity to the specimen.

[0031] Preferably, in the fourth step, when the specimen expands and fails in the horizontal direction where the second hinge of the bolt is located, the first hinge and the third hinge are tensioned and fail, the confining pressure loading system loses contact with the specimen, and the specimen instantaneously unloads the confining pressure; when the specimen expands and fails in the horizontal direction where the first hinge and the third hinge are located, the second hinge is tensioned and fails, the confining pressure loading system loses contact with the specimen, and the specimen instantaneously unloads the confining pressure.

[0032] The beneficial effects of the present invention are as follows:

[0033] 1. The operation of the present invention is simple and the test accuracy is high. When the test piece undergoes expansion failure, the confining pressure on the test piece can be instantaneously unloaded. The way of applying the confining pressure is passive application. The magnitude of the confining pressure is proportional to the expansion deformation amount of the test piece and the ratio can be adjusted. The maximum confining pressure can be set in advance. When it exceeds the set value, the confining pressure can instantaneously drop to zero. The similarity between the confining pressure loading and unloading conditions and the actual conditions of the surrounding rock of the underground roadway is high, and the test results are reliable.

[0034] 2. The present invention uses the cooperation of a runner and a cam, and uses a vertical clamping device to clamp a weight, so that the weight moves up and down while maintaining a vertical state. The force acting on the test piece is more uniform, making the structure tend to be stable while also ensuring the stability of the load.

[0035] 3. The present invention can select a weight that meets the test requirements according to the load intensity required by the test, and realize the cyclic dynamic load of applying the target load intensity to the test piece by adjusting the rotation speed of the servo motor required for the test.

[0036] 4. According to the design of the test scheme, the present invention can select different runners, weights, and confining pressure loading systems, with high replaceability, simple device structure, and convenient operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic structural diagram of the present invention;

[0038] Figure 2 is a schematic structural diagram of the cyclic dynamic load system of the present invention;

[0039] Figure 3 is a schematic structural diagram of the confining pressure loading system of the present invention;

[0040] Figure 4 is a schematic diagram of the installation position of the vertical clamping device of the present invention;

[0041] Figure 5 is a relative position diagram of the test piece of the present invention;

[0042] In the figure: 1. Bearing frame system, 11. Base, 12. Operating platform, 13. Column, 14. Roof;

[0043] 2. Cyclic dynamic load system, 21. Servo motor, 22. Rotating shaft, 23. Keyway, 24. Runner, 25. Cam, 26. Connecting shaft, 27. First connecting rod, 28. Second connecting rod, 29. Weight, 210. Vertical clamping device;

[0044] 3. Confining pressure loading system, 31. First arc-shaped confining pressure plate, 32. Second arc-shaped confining pressure plate, 33. Third arc-shaped confining pressure plate, 34. Fourth arc-shaped confining pressure plate, 35. Screw hole, 36. Bolt, 37. First hinge, 38. Second hinge, 39. Third hinge;

[0045] 4. Monitoring system, 41. First force sensor, 42. Second force sensor, 43. Displacement sensor, 44. Acoustic emission sensor, 45. Signal collector;

[0046] 5. Control system;

[0047] 6. Data analysis system;

[0048] 7. Specimen. Specific implementation mode

[0049] The present invention will be further described below through embodiments in conjunction with the drawings, but is not limited thereto.

[0050] Embodiment 1:

[0051] As Figures 1-5 shown, this embodiment provides a cyclic dynamic load instantaneous unloading confining pressure mechanical test device, including a bearing frame system 1, a cyclic dynamic load system 2, a confining pressure loading system 3, a monitoring system 4, a control system 5 and a data analysis system 6, wherein,

[0052] A cyclic dynamic load system 2 is arranged on the top of the bearing frame system 1, the cyclic dynamic load system 2 is connected with a control system 5, a confining pressure loading system 3 is arranged at the bottom of the bearing frame system 1, a monitoring system 4 is arranged on the cyclic dynamic load system 2 and the confining pressure loading system 3, and both the monitoring system 4 and the control system 5 are connected with a data analysis system 6.

[0053] The cyclic dynamic load system 2 is used to apply an axial cyclic load from top to bottom to the specimen;

[0054] The confining pressure loading system 3 is used to apply a radial confining pressure to the specimen;

[0055] The monitoring system 4 is used to monitor the stress, deformation and failure conditions of the specimen during the loading and unloading process;

[0056] The control system 5 is used to control the cyclic loading system;

[0057] The data analysis system 6 is connected with the monitoring system and the control system, and is used to receive and process and analyze the data of the monitoring system.

[0058] The bearing frame system 1 includes a base 11, an operating table 12, columns 13 and a top plate 14. An operating table 12 is arranged on the upper surface of the base 11, a confining pressure loading system 3 is arranged on the operating table 12, a top plate 14 is fixed above the base 11 through columns 13, and a cyclic dynamic load system 2 is arranged on the lower side of the top plate 14.

[0059] The cyclic dynamic loading system 2 includes a servo motor 21, a rotating shaft 22, a runner 24, a cam 25, a first connecting rod 27, a second connecting rod 28 and a weight 29. The servo motor 21 is horizontally fixed to the load-bearing frame system 1. The output shaft of the servo motor 21 is connected to the keyway 23 on the runner 24 through the rotating shaft 22. Arc-shaped grooves are evenly arranged on the runner 24. A cam 25 is arranged below the runner 24. The cam 25 is connected with a first connecting rod 27 through a connecting shaft 26. The lower side of the first connecting rod 27 is connected with a weight 29 through a second connecting rod 28. The second connecting rod 28 is elastically fixed to the top of the load-bearing frame system 1 through 4 vertical clamping devices 210 evenly arranged in the circumferential direction. The first connecting rod 27, the second connecting rod 28, the weight 29 and the test piece 7 are concentrically arranged.

[0060] The control system 5 controls the servo motor 21 to drive the rotating shaft 22 to rotate. The runner 24 rotates by means of the rotating shaft 22. The runner 24 is an irregular circle. After its protruding part contacts the cam, it drives the cam 25 to move vertically downward. Thus, the weight 29 is driven to move vertically downward through the first connecting rod 27 and the second connecting rod 28. When the cam 25 rotates to below the arc-shaped groove of the runner 24, the vertical clamping device 210 drives the cam 25 to move vertically upward under the action of the spring elastic force. The cam 25 contacts the runner 24, completing one application of dynamic load. The vertical clamping device 210 enables the weight 29 to move up and down while maintaining a vertical state, making the force acting on the test piece 7 more uniform. Controlling the output speed of the rotating shaft 22 can achieve the application of cyclic loads with different cyclic amplitudes and different load intensities; by means of a runner that rotates at a constant or non-constant speed around the rotating shaft, each rotation of one week is independent, and rotations with different speeds and accelerations can be achieved.

[0061] The vertical clamping device 210 is an L-shaped rod. The top of the vertical clamping device 210 is fixed to the load-bearing frame system 1 through a spring. The L-shaped rod can better cooperate with the spring to do work.

[0062] Six arc-shaped grooves are arranged on the runner 24. By changing the number of arc-shaped grooves, the application of loads with different numbers of times during one rotation can be achieved.

[0063] The confining pressure loading system 3 includes a first arc-shaped confining pressure plate 31, a second arc-shaped confining pressure plate 32, a third arc-shaped confining pressure plate 33 and a fourth arc-shaped confining pressure plate 34. Screw holes 35 are arranged on the first arc-shaped confining pressure plate 31 and the second arc-shaped confining pressure plate 32. The first arc-shaped confining pressure plate 31 and the second arc-shaped confining pressure plate 32 are connected by bolts 36. The second arc-shaped confining pressure plate 32 is connected with the fourth arc-shaped confining pressure plate 34 through a first hinge 37. The fourth arc-shaped confining pressure plate 34 is connected with the third arc-shaped confining pressure plate 33 through a second hinge 38. The third arc-shaped confining pressure plate 33 is connected with the first arc-shaped confining pressure plate 31 through a third hinge 39.

[0064] The monitoring system 4 includes a first force sensor 41, a second force sensor 42, a displacement sensor 43, and an acoustic emission sensor 44. The first force sensor 41 is provided on the weight 29, and the second force sensor 42, the displacement sensor 43, and the acoustic emission sensor 44 are provided on the surface of the test piece 7 within the confining pressure loading system 3. The first force sensor 41, the second force sensor 42, the displacement sensor 43, and the acoustic emission sensor 44 are connected to a data analysis system 6 through a signal collector 45.

[0065] The usage method of the above cyclic dynamic load instantaneous unloading confining pressure mechanical test device is as follows:

[0066] The first step: fabricate a cylindrical test piece;

[0067] The second step: fix the test piece 7 at the middle position on the surface of the operation table 12, and then place the confining pressure loading system 3 around the test piece 7 along the radial direction of the test piece. The confining pressure loading system 3 applies confining pressure to the test piece 7;

[0068] The third step: according to the load intensity required by the test, determine the weight 29 that meets the test requirements, adjust the rotation speed of the servo motor 21, and apply a cyclic load with the target load intensity to the test piece 7;

[0069] The fourth step: the test piece 7 undergoes expansion failure under the action of cyclic dynamic load. The confining pressure loading system 3 is subjected to an outward acting force due to the expansion of the test piece, the hinge is damaged under tension, the confining pressure loading system 3 loses contact with the test piece 7, and the test piece 7 instantaneously unloads the confining pressure;

[0070] The fifth step: after the data analysis system 6 processes and analyzes the data from the monitoring system 4, the stress, strain curve, and acoustic emission energy curve of the test piece are obtained, and the mechanical characteristics of the test piece 7 before and after instantaneous unloading of the confining pressure are analyzed.

[0071] Embodiment 2:

[0072] A cyclic dynamic load instantaneous unloading confining pressure mechanical test device has a structure as described in Embodiment 1. The difference is that there are 2 arc-shaped grooves provided on the runner 24, and the second connecting rod 28 is threadedly connected to the weight 29. By replacing weights of different weights, cyclic loads with different load intensities can be applied.

[0073] Embodiment 3:

[0074] The usage method of a cyclic dynamic load instantaneous unloading confining pressure mechanical test device is as described in Embodiment 1. The difference is that in the second step, when the confining pressure loading system 3 applies confining pressure to the test piece 7, according to the test requirements, a digital display torque wrench is used to tighten the bolts to apply confining pressure with the target intensity to the test piece.

[0075] Embodiment 4:

[0076] A method for using a cyclic dynamic load instantaneous unloading confining pressure test device, the steps are as described in Example 1, except that, in the fourth step, when the specimen 7 undergoes expansion failure in the horizontal direction where the second hinge of the bolt is located, the first hinge 37 and the third hinge 39 are tensilely damaged, the confining pressure loading system 3 loses contact with the specimen 7, and the specimen 7 instantaneously unloads the confining pressure; when the specimen 7 undergoes expansion failure in the horizontal direction where the first hinge and the third hinge are located, the second hinge 38 is tensilely damaged, the confining pressure loading system 3 loses contact with the specimen 7, and the specimen 7 instantaneously unloads the confining pressure.

[0077] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that are not conceived through creative work should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined in the claims.

Claims

1. A cyclic dynamic load - instantaneous unloading confining pressure mechanical test device, characterized in that, it includes a bearing frame system, a cyclic dynamic load system, a confining pressure loading system, a monitoring system, a control system and a data analysis system. Among them, the cyclic dynamic load system is arranged at the top of the bearing frame system. The cyclic dynamic load system is connected to the control system. The confining pressure loading system is arranged at the bottom of the bearing frame system. The monitoring system is arranged on the cyclic dynamic load system and the confining pressure loading system. Both the monitoring system and the control system are connected to the data analysis system; the confining pressure loading system includes a first arc-shaped confining pressure plate, a second arc-shaped confining pressure plate, a third arc-shaped confining pressure plate and a fourth arc-shaped confining pressure plate. The first arc-shaped confining pressure plate and the second arc-shaped confining pressure plate are connected by bolts. The second arc-shaped confining pressure plate is connected to the fourth arc-shaped confining pressure plate through a first hinge. The fourth arc-shaped confining pressure plate is connected to the third arc-shaped confining pressure plate through a second hinge. The third arc-shaped confining pressure plate is connected to the first arc-shaped confining pressure plate through a third hinge; the cyclic dynamic load system includes a servo motor, a rotating shaft, a rotating wheel, a cam, a first connecting rod, a second connecting rod and a weight. The servo motor is horizontally fixed on the bearing frame system. The output shaft of the servo motor is connected to the rotating wheel through the rotating shaft. Arc-shaped grooves are evenly arranged on the rotating wheel. A cam is arranged below the rotating wheel. The cam is connected to the first connecting rod through a connecting shaft. The lower side of the first connecting rod is connected to the weight through the second connecting rod. The second connecting rod is elastically fixed to the top of the bearing frame system through 4 vertically clamping devices evenly arranged in the circumferential direction.

2. The cyclic dynamic load - instantaneous unloading confining pressure mechanical test device according to claim 1, characterized in that, the bearing frame system includes a base, an operating platform, columns and a top plate. The upper surface of the base is provided with an operating platform. The confining pressure loading system is arranged on the operating platform. The top plate is fixed above the base through columns. The cyclic dynamic load system is arranged below the top plate.

3. The cyclic dynamic load - instantaneous unloading confining pressure mechanical test device according to claim 2, characterized in that, the vertical clamping device is an L-shaped rod. The top of the vertical clamping device is fixed to the bearing frame system through a spring.

4. The cyclic dynamic load - instantaneous unloading confining pressure mechanical test device according to claim 3, characterized in that, at least 2 arc-shaped grooves are arranged on the rotating wheel. The second connecting rod is threadedly connected to the weight.

5. The cyclic dynamic load - instantaneous unloading confining pressure mechanical test device according to claim 4, characterized in that, the monitoring system includes a first force sensor, a second force sensor, a displacement sensor and an acoustic emission sensor. The first force sensor is arranged on the weight. The second force sensor, the displacement sensor and the acoustic emission sensor are arranged on the surface of the specimen in the confining pressure loading system. The first force sensor, the second force sensor, the displacement sensor and the acoustic emission sensor are connected to the data analysis system through a signal collector.

6. The using method of the cyclic dynamic load - instantaneous unloading confining pressure mechanical test device according to claim 5, characterized in that, the steps are as follows: The first step: fabricate a cylindrical specimen; The second step: fix the specimen at the middle position on the surface of the operating platform. Then place the confining pressure loading system around the specimen along the radial direction of the specimen. The confining pressure loading system applies confining pressure to the specimen; Step 3: Determine a drop hammer that meets the test requirements according to the load intensity required by the test, adjust the rotational speed of the servo motor, and apply cyclic loads with the target load intensity to the test piece. Step 4: The test piece undergoes expansion failure under the action of cyclic dynamic loads. The confining pressure loading system is subjected to an outward acting force generated by the expansion of the test piece, and the hinge is damaged under tension. The confining pressure loading system loses contact with the test piece, and the test piece instantaneously releases the confining pressure. Step 5: After the data analysis system processes and analyzes the data from the monitoring system, stress, strain curves, and acoustic emission energy curves of the test piece are obtained, and the mechanical characteristics of the test piece before and after the instantaneous release of the confining pressure are analyzed.

7. The method for using a cyclic dynamic load - instantaneous release of confining pressure mechanical test device as described in claim 6, characterized in that, in Step 2, when the confining pressure loading system applies confining pressure to the test piece, according to the test requirements, use a digital display torque wrench to tighten the bolts to apply confining pressure with the target intensity to the test piece.

8. The method for using a cyclic dynamic load - instantaneous release of confining pressure mechanical test device as described in claim 6, characterized in that, in Step 3, the process of applying cyclic loads is as follows: The control system controls the servo motor to drive the rotating shaft to rotate. The runner rotates by means of the rotating shaft. The runner is an irregular circle, and its protruding part drives the cam to move vertically downward after contacting the cam, thereby driving the drop hammer to move vertically downward through the first connecting rod and the second connecting rod. When the cam rotates to below the arc-shaped groove of the runner, the vertical clamping device drives the cam to move vertically upward under the action of the spring force. The cam contacts the runner, completing one application of dynamic load, and cyclic loads are applied under the rotation of the runner.

9. The method for using a cyclic dynamic load - instantaneous release of confining pressure mechanical test device as described in claim 6, characterized in that, in Step 4, when the test piece undergoes expansion failure in the horizontal direction where the second hinge of the bolt is located, the first hinge and the third hinge are damaged under tension, the confining pressure loading system loses contact with the test piece, and the test piece instantaneously releases the confining pressure; when the test piece undergoes expansion failure in the horizontal direction where the first hinge and the third hinge are located, the second hinge is damaged under tension, the confining pressure loading system loses contact with the test piece, and the test piece instantaneously releases the confining pressure.

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