Experimental device for measuring three-way sound waves in loading process of gas-containing coal rock sample

Abstract

The utility model discloses an experimental device for measuring three-way sound waves in the loading process of a gas-containing coal rock sample, which comprises an axial loading module consisting of a portal frame structure pressure device and a computer and used for applying and monitoring pressure; the vacuumizing module consists of an extraction valve and a vacuum pump and is used for vacuumizing the detection environment of the coal sample to be detected; the gas adsorption module consists of a pressure tank comprising a top rod, an upper cover, a tank body and a base, and is used for providing an adsorption loading condition of the coal rock sample to be tested; the gas source module consists of a gas tank, a gas valve and a gas pressure meter and is used for filling CH4 into the vacuumized pressure tank; the waste gas collection module consists of a waste gas tank and a gas valve and is used for collecting harmful waste gas after the test is finished; and the sound wave test module consists of a sound wave sensor and a sound wave tester and is used for measuring the three-way wave velocity of the coal rock sample in the test process. According to the utility model, a mechanical loading experiment can be carried out on the gas-containing coal rock sample under the condition of gas-solid-force three-field coupling, and the real-time transverse and longitudinal wave velocities of the sample are monitored in real time by using the sonic sensor.

Description

Technical Field

[0001] The utility model relates to the technical field of rock mechanics acoustic parameter testing, and particularly relates to an experimental device for measuring three-directional acoustic waves during the loading process of a gas-containing coal-rock sample. Background Technique

[0002] Elastic waves propagating in rock masses can be generally divided into two categories. One is body waves propagating inside the rock mass, and the other is surface waves propagating only along the rock mass surface. Body waves can be further divided into two categories. One is the wave in which the particle vibration direction is consistent with the wave propagation direction, called longitudinal wave, which generates compression or tensile deformation. The other is the wave in which the particle vibration direction is perpendicular to the wave propagation direction, called transverse wave, which generates shear deformation. The propagation characteristics of acoustic waves in media such as coal and rock can reflect the physical and mechanical characteristics of coal-rock media and can be used to calculate relevant mechanical parameters. Studying the physical and mechanical behavior of gas-containing coal-rock masses under load has important theoretical significance for revealing the mechanism of surrounding rock instability and disaster and predicting and preventing instability accidents. It is precisely because acoustic waves carry acoustic information closely related to the physical and mechanical properties of coal bodies that the measured acoustic characteristic parameters can accurately perceive the development and expansion of pore fractures inside the coal bodies and the degree of damage and deterioration. Therefore, acoustic wave detection has become an important test method for measuring the physical and mechanical behavior of coal-rock masses.

[0003] Gas is a by-product during the formation of coal seams. All coal seams in China contain gas. After the coal-rock mass adsorbs gas, its physical and mechanical properties will change. Therefore, relevant physical and mechanical tests need to be carried out on gas-containing coal-rock masses. Under the condition of no gas, the acoustic wave propagation characteristics of coal-rock media can be directly measured by an acoustic wave tester. For gas-containing coal-rock masses, they need to be placed in a certain gas pressure environment. In laboratory experiments, the coal-rock sample needs to be placed in a sealed container and a press is used for loading tests. At present, the existing gas-solid coupling devices for gas-containing coal-rock masses cannot measure the acoustic waves of coal-rock samples or can only test in a single direction, and cannot completely measure the acoustic parameters during the loading process of coal-rock samples. Therefore, a new test device needs to be designed for the three-directional acoustic wave test of loaded gas-containing coal-rock samples. Content of the Utility Model

[0004] To solve the deficiencies of the existing technology, the purpose of the utility model is to provide an experimental device for measuring three-directional acoustic waves during the loading process of a gas-containing coal-rock sample, and can display the acoustic wave image in real time, providing convenience for the determination of acoustic parameters of gas-containing coal-rock.

[0005] To achieve the above purpose, an experimental device for measuring the strain field of a gas-containing coal-rock during the loading process provided by the utility model involves a coal-rock sample to be inspected, and includes:

[0006] An axial loading module for applying axial pressure to the coal-rock sample to be measured;

[0007] A vacuum pumping module for evacuating the gas environment of the coal and rock sample to be tested;

[0008] A gas source module for filling CH into the gas-solid coupling module after evacuation 4 to make the sample reach the gas pressure required for the test.

[0009] A gas adsorption module for providing the gas adsorption test conditions for the coal and rock sample to be tested.

[0010] An acoustic wave testing module for measuring the longitudinal and transverse wave velocities of the coal and rock sample during the test.

[0011] An exhaust gas collection module for collecting the harmful exhaust gas generated during the test.

[0012] Further, the gas adsorption module includes a pressure tank, an inlet valve and an exhaust valve. There are two gas ports and one data transmission port on the pressure tank. The two gas ports are respectively connected to the gas source module and the exhaust gas collection module through gas pipes, and are respectively named the inlet port and the exhaust port. Inlet valves and exhaust valves are respectively provided at the gas port connection points.

[0013] Further, a pressure tank upper cover is provided on the pressure tank. A top rod extending into the pressure tank is inserted on the pressure tank upper cover. A bolt locking device with a thread penetrating the pressure tank upper cover is provided on one side of the top rod. A rubber sealing ring is provided at the contact end of the top rod with the tank mouth of the pressure tank. Specifically, two groups of four adjustable acoustic wave probes are horizontally embedded on the inner wall of the pressure tank, and one acoustic wave sensor is embedded at the lower end; further, sealing rings are provided at all connection points of the pressure tank.

[0014] Further, the acoustic wave testing module includes an acoustic wave tester, four horizontally adjustable acoustic wave sensors, one longitudinally fixed acoustic wave sensor, and a movable pressing block embedded in the acoustic wave sensor. All acoustic wave sensors are connected to the acoustic wave tester through signal transmission lines. Specifically, the data lines of the four horizontally adjustable acoustic wave sensors are arranged in a spiral shape; specifically, the four horizontally adjustable acoustic wave sensors are used to measure the transverse wave velocity of the loaded coal and rock sample, and the longitudinally fixed acoustic wave sensor and a movable pressing block embedded in the acoustic wave sensor are used to measure the longitudinal wave velocity of the loaded coal and rock sample.

[0015] Further, the exhaust gas collection module includes an exhaust gas tank and an exhaust gas tank valve. The exhaust gas tank valve is connected to the exhaust valve of the gas adsorption module through a gas pipe.

[0016] Further, the pressure loading module includes a frame structure pressure device and a computer control part. The frame structure pressure device includes a control cabinet, an actuator, a force rod that can move up and down, and a test platform. The force rod is controlled to move through the control cabinet and the actuator.

[0017] Further, the vacuum pumping module includes a vacuum pump and an air extraction valve. The air extraction valve is connected to the exhaust valve of the gas adsorption module through an air pipe, and the air extraction rate of the vacuum pump is 50 L / min.

[0018] Further, the maximum pressure applied by the gantry frame structure pressure device is 4600 kN, and the test accuracy is ≤ ±0.5%.

[0019] The usage method of this device is as follows:

[0020] Step 1: Apply vaseline to the six surfaces of the coal rock sample to be tested so that it can be coupled with the acoustic wave sensor. Place the sample directly above the acoustic wave sensor at the bottom of the pressure tank. Adjust the four acoustic wave sensors on the tank wall of the pressure tank through the movable nut to closely adhere to the side end face of the sample, and press the side of the movable pressing block with the acoustic wave sensor against the upper end face of the sample;

[0021] Step 2: Hold the upper cover of the pressure tank and place it on the cylinder body of the pressure tank. The lower end of the top rod contacts the upper end of the pressing block, and tighten the sealing screw to complete the sealing of the tank body;

[0022] Step 3: Connect the data signal line of the acoustic wave sensor outside the pressure tank to the acoustic wave tester, and send a collection command through the control computer to store the acoustic wave data and display the acoustic wave waveform. After connection, test the acoustic wave condition of the sample in the initial state, check the operation status of the equipment, and store and record the data;

[0023] Step 4: Connect the air pipe to the exhaust port, open the exhaust valve, close the intake valve, open the air extraction valve, and perform a vacuum pumping operation on the tank body;

[0024] Step 5: After the vacuum pumping is completed, close the exhaust valve, open the intake valve, open the gas valve of the gas tank, and inject CH 4 from the gas tank into the pressure tank. Observe the pressure gauge. When the pressure gauge value is stable, close the gas valve, and the sample undergoes the adsorption process.

[0025] Step 6: After the adsorption is completed, use the computer to adjust the indenter of the loading device through the control cabinet so that it descends at a certain rate. When the indenter is about to contact the top rod, adjust the rate again so that it presses the top rod downward at a slower rate. When the top rod coincides with the upper surface of the pressing block and there is a force feedback, start the experiment;

[0026] Step 7: Determine whether the sample is damaged through the stress-strain curve shown by the computer. When the coal rock sample to be inspected ruptures, stop the test, open the exhaust valve and the waste gas tank valve, and store the waste gas in the waste gas tank;

[0027] Step 8: After exhausting the waste gas in the pressure tank, close all valves, open the upper cover of the pressure tank, loosen the acoustic wave sensor, and take out the sample;

[0028] Step 9: If out of control occurs during the loading process, the stop button can be pressed immediately, and the instrument will stop to ensure the safety of the experiment.

[0029] The beneficial effects of the present utility model are as follows:

[0030] 1. It can conduct mechanical loading experiments on gas-containing coal and rock masses under the coupling conditions of gas-solid-force, and has good sealing performance;

[0031] 2. It can use acoustic wave sensors to monitor the wave velocity of the specimen, conduct real-time sampling and recording of the wave velocity of coal and rock specimens under loading conditions, and after processing the measured information through software, obtain the changes in the acoustic parameters of the specimen during the loading process, so as to determine the physical and mechanical state of the specimen;

[0032] 3. It can use the acoustic wave test module to simultaneously collect the three-direction wave velocity data of the loaded specimen. Description of the Drawings

[0033] Figure 1 It is the acoustic wave test for the adsorption and loading of gas-containing coal and rock masses;

[0034] Figure 2 It is a schematic diagram of the loading module;

[0035] Figure 3 It is the overall sectional view of the adsorption pressure tank;

[0036] Figure 4 It is the internal top view of the adsorption pressure tank;

[0037] Figure 5 It is a schematic diagram of the acoustic wave test module on the inner wall of the pressure tank;

[0038] Figure 6 It is the coal sample.

[0039] Description of the reference numerals: 1. Computer; 2. Acoustic wave tester; 3. Control cabinet; 4. Pressure gauge; 5. Gas tank for gas; 6. Gas valve of the gas tank for gas; 7. Data transmission line; 8. Intake valve; 9. Actuator; 10. Pressure head; 11. Pressure tank; 12. Exhaust valve; 13. Exhaust gas tank valve; 14. Exhaust gas extraction valve; 15. Exhaust gas tank; 16. Vacuum pump; 17. Test platform; 18. Top rod; 19. Sealing screw; 20. Upper cover of the pressure tank; 21. Sealing ring; 22. Pressure block; 23. Pressure tank cylinder body; 24. Specimen; 25-1 to 6. Acoustic wave sensors; 26. Exhaust port; 27. Intake port; 28. Data transmission line port; 29. Movable nut; 30. Threaded bolt; 31. Air pipe Specific embodiments

[0040] The following will clearly and completely describe the technical solutions in the present utility model in conjunction with the accompanying drawings in the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present utility model.

[0041] Step 1: Coat the six surfaces of the coal rock sample 24 to be measured with vaseline so that it can be coupled with the acoustic wave sensors 25-1 to 6. Place the sample 24 directly above the acoustic wave sensor 25-2 at the bottom end of the pressure tank 11. Adjust the four acoustic wave sensors 25-3 to 6 on the tank wall of the pressure tank tightly against the side end face of the sample through the movable nut 29, and press the side of the movable pressing block 22 containing the acoustic wave sensor 25-1 tightly against the upper end face of the sample;

[0042] Step 2: Hold the upper cover 20 of the pressure tank and place it on the cylinder body 23 of the pressure tank. The lower end of the top rod 18 contacts the upper end of the pressing block 22, and tighten the sealing screw 19 to complete the sealing of the tank body;

[0043] Step 3: Connect the acoustic wave sensor data signal line 17 outside the pressure tank to the acoustic wave tester 2, and issue a collection command through the control computer 1 to store the acoustic wave data and display the acoustic wave waveform. After connection, test the acoustic wave condition of the sample in the initial state, check the operation status of the equipment, and store and record the data;

[0044] Step 4: Connect the air pipe 31 to the exhaust port, open the exhaust valve 12, close the intake valve 8, open the air extraction valve 14, and perform a vacuum pumping operation on the tank body;

[0045] Step 5: After the vacuum pumping is completed, close the exhaust valve 12, close the air extraction valve 14, open the intake valve 8, open the gas valve 6 of the gas tank, and inject the CH 4 in the gas tank 5 into the pressure tank 11. Observe the pressure gauge 4. When the pressure gauge value is stable, close the gas valve 6, and the sample undergoes the adsorption process;

[0046] Step 6: After the adsorption is completed, use the computer 1 to adjust the indenter 10 of the loading device through the control cabinet 3 so that it descends at a certain rate. When the indenter 10 is about to contact the top rod 18, adjust the rate again so that it presses the top rod downward at a slower rate. When the top rod 18 coincides with the upper surface of the pressing block 22 and there is a force feedback, start the experiment;

[0047] Step 7: Determine whether the sample is damaged through the stress-strain curve shown by the computer 1. When the coal rock sample to be inspected breaks, stop the test, open the exhaust valve 12 and the waste gas tank valve 13, and store the waste gas in the waste gas tank 15;

[0048] Step Eight: After exhausting the waste gas in the pressure tank 11, close all valves, open the upper cover 20 of the pressure tank, loosen the acoustic wave sensors 25-1 to 25-6, and take out the specimen 24;

[0049] Step Nine: If out of control occurs during the loading process, the stop button can be pressed immediately, and the instrument stops to ensure the safety of the experiment.

[0050] The above is only the preferred operation mode of the present utility model, and is not intended to limit the present utility model. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model shall be included in the protection scope of the present utility model.

Claims

1. An experimental device for measuring three-dimensional acoustic waves during the loading process of gas-containing coal and rock samples, involving coal and rock samples to be tested, characterized in that ,include: An axial loading module is used to apply axial pressure to the coal and rock samples to be tested; A vacuum module is used to vacuumize the gas environment of the coal and rock samples to be tested; The gas source module is used to inject CH4 into the vacuumized gas-solid coupling module to make the sample reach the gas pressure required for the test; Gas adsorption module, used to provide gas adsorption test conditions for coal and rock samples to be tested; Exhaust gas collection module, used to collect harmful exhaust gas after the test; The acoustic wave test module is used to measure the longitudinal and transverse wave velocities of coal and rock samples during the test.

2. An experimental device for measuring three-dimensional acoustic waves during the loading process of gas-containing coal and rock samples as claimed in claim 1, characterized in that: The gas adsorption module includes a pressure tank, an air inlet valve and an exhaust valve. The pressure tank is provided with two air ports and a data transmission port. The two air ports are respectively connected to the air source module and the exhaust gas collection module through air pipes, and are named as the air inlet and the exhaust port respectively. The air port connection points are respectively provided with an air inlet valve and an exhaust valve.

3. An experimental device for measuring three-dimensional acoustic waves during the loading process of gas-containing coal and rock samples as claimed in claim 2, characterized in that: The inner wall of the pressure tank is transversely embedded with two groups of four adjustable acoustic wave sensors, the lower end is embedded with an acoustic wave sensor, and a movable pressing block is embedded with an acoustic wave sensor.

4. The experimental device for measuring three-dimensional acoustic waves during the loading process of gas-containing coal and rock samples as claimed in claim 1, characterized in that: The axial loading module comprises a portal frame structure pressure device and a computer. The portal frame structure pressure device comprises a pressure head which can move up and down. The pressure head moves up and down under the control of the computer.

5. The experimental device for measuring three-dimensional acoustic waves during the loading process of gas-containing coal and rock samples as claimed in claim 1, characterized in that: The vacuum pumping module comprises a vacuum pump and an air extraction valve, and the vacuum pumping module is connected with the gas adsorption module through an air pipe.

6. The experimental device for measuring three-dimensional acoustic waves during the loading process of gas-containing coal and rock samples as claimed in claim 1, characterized in that: The acoustic wave testing module includes an acoustic wave tester, four laterally adjustable acoustic wave sensors, a longitudinally fixed acoustic wave sensor, and a movable pressing block embedded with the acoustic wave sensor. All the acoustic wave sensors are connected to the acoustic wave tester via signal transmission lines.

7. An experimental device for measuring three-dimensional acoustic waves during the loading process of gas-containing coal and rock samples as claimed in claim 4, characterized in that: The maximum applied pressure of the portal frame structure pressure device is 4600 kN, and the accuracy is greater than ±0.5%.

8. The experimental device for measuring three-dimensional acoustic waves during the loading process of gas-containing coal and rock samples as claimed in claim 1, characterized in that: The waste gas collection module comprises a waste gas collecting bottle and a waste gas tank valve, and the waste gas collection module is connected to the gas adsorption module through an air pipe.

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