Frequency conversion coal rock circulation dynamic and static combination loading device and method under gas-solid coupling environment

Abstract

The invention belongs to the technical field of rock mechanical tests, and provides a variable-frequency coal rock circulation dynamic and static combined loading device and method under a gas-solid coupling environment, and the device comprises a confining pressure cavity, a gas-solid coupling cavity is arranged in the confining pressure cavity, a coal rock sample is arranged in the gas-solid coupling cavity, and a pressure measuring assembly is arranged on the confining pressure cavity and is used for monitoring the load borne by the coal rock sample; the dynamic and static combined loading unit comprises a hydraulic oil supply assembly, a multi-channel reversing valve block and an integrated dynamic and static loading oil cylinder, the multi-channel reversing valve block is in a first circulation state, the integrated dynamic and static loading oil cylinder performs pure static loading on the coal rock sample, the multi-channel reversing valve block is in a second circulation state, and the integrated dynamic and static loading oil cylinder performs pure static loading on the coal rock sample. The integrated dynamic and static loading oil cylinder is used for carrying out pure dynamic or dynamic and static combined loading on the coal rock sample; and the gas introduction assembly is used for creating a vacuum environment in the gas-solid coupling cavity and introducing required gas. According to the invention, triaxial static load application, cyclic dynamic load superposition and high-pressure gas environment sealing can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of rock mechanics testing, and in particular relates to a variable frequency coal-rock cyclic dynamic-static combined loading device and method under a gas-solid coupling environment. Background Art

[0002] Demanding resources, energy and space from deep underground is an inevitable choice to ensure the economic and social development of mankind. In the process of deep mining, coal and gas outbursts, rock burst and other coal-rock dynamic disasters occur frequently, which will cause huge economic and social losses. Due to the suddenness of disasters and the complexity of the disaster-pregnancy process, its prevention and control has become a global problem. For the mining of deep resources, coal and rock masses are in a complex geological environment, in which high ground stress and high gas pressure will have a huge impact on the physical and mechanical properties of coal and rock masses and the damage, instability and destruction process; at the same time, the cyclic action of external dynamic loads such as artificial blasting and mechanical excavation will destroy the original balance and cause the internal multi-physical field coupling evolution. Therefore, in order to study such problems, it is necessary to simulate the multi-field coupling occurrence environment of deep coal and rock masses and the cyclic disturbance of external loads.

[0003] At present, the industry has carried out a lot of research work on the cyclic dynamic and static combined loading of coal and rock. For example, the patent with application number CN201821002136.6 discloses a multi-parameter test device for the fracture process of gas-containing coal and rock under dynamic-static coupling. This patent realizes the impact dynamic-static coupling loading of gas-containing coal, but its dynamic and static load superposition requires a separate dynamic load application system and static load application system, and can only apply impact loads, and cannot apply cyclic dynamic loads of a certain frequency. In addition, the patent with application number CN201711332507.7 discloses a test device and method for infrared observation of coal-rock gas-solid coupled dynamic and static loading and unloading, but the dynamic load application of the device is through a drop hammer structure, and it is impossible to achieve a certain frequency of cyclic dynamic load disturbance. The patent with application number CN202110191641.X discloses a high-frequency and high-load cyclic dynamic load test device and test method for rocks. However, the superposition of dynamic and static loads in this invention also requires a separate dynamic load application system and a static load application system, and the structure is complicated. In addition, due to the structure of this device, the sealing of the gas-solid coupling environment cannot be achieved, and thus the cyclic dynamic and static combined loading of gas-containing coal and rock cannot be achieved.

[0004] In summary, the existing coal-rock dynamic and static combined loading device can only realize the application of impact loads, the frequency is not adjustable, and the cyclic dynamic load test device cannot be applied to the gas-solid coupling environment. Summary of the invention

[0005] The purpose of the present invention is to provide a variable frequency coal-rock cyclic static and dynamic combined loading device and method under a gas-solid coupling environment to solve the above problems and achieve the purpose of triaxial static load application, cyclic dynamic load superposition and high-pressure gas environment sealing.

[0006] To achieve the above-mentioned purpose, the present invention provides the following scheme: a variable frequency coal-rock cyclic dynamic and static combined loading device under a gas-solid coupling environment, comprising:

[0007] A confining pressure chamber, wherein a gas-solid coupling chamber is provided in the confining pressure chamber, a coal-rock sample is provided in the gas-solid coupling chamber, the gas-solid coupling chamber and the confining pressure chamber are isolated by a flexible material, a pressure measuring assembly is provided on the confining pressure chamber, the pressure measuring assembly abuts against one end of the coal-rock sample and is used to monitor the load on the coal-rock sample, and an oil injection piece is also provided on the confining pressure chamber;

[0008] A dynamic-static combined loading unit, comprising a hydraulic oil supply assembly, a multi-channel reversing valve block and an integrated dynamic-static loading cylinder, wherein the integrated dynamic-static loading cylinder applies a load to an end of the coal-rock sample away from the pressure measuring assembly, the hydraulic oil supply assembly is connected to the integrated dynamic-static loading cylinder through the multi-channel reversing valve block, the multi-channel reversing valve block is in a first flow state, the integrated dynamic-static loading cylinder performs pure static loading on the coal-rock sample, and the multi-channel reversing valve block is in a second flow state, the integrated dynamic-static loading cylinder performs pure dynamic loading or dynamic-static combined loading on the coal-rock sample;

[0009] A gas introduction component is communicated with the interior of the gas-solid coupling cavity, and is used to create a vacuum environment in the gas-solid coupling cavity and introduce required gas.

[0010] Preferably, the integrated dynamic and static loading cylinder includes an outer wall of the cylinder, which is fixedly connected to one end of the confining pressure chamber away from the pressure measuring assembly, a piston is slidably connected to the inner side of the outer wall of the cylinder, a loading piston rod is fixedly passed through the piston, one end of the loading piston rod passes through the outer wall of the cylinder and abuts against one end of the coal and rock sample away from the pressure measuring assembly, an oil inlet channel and an oil return channel are opened on the outer wall of the cylinder, and the oil inlet channel and the oil return channel are respectively located on both sides of the piston.

[0011] Preferably, the multi-channel reversing valve block is provided with a first channel, a second channel, a third channel, a fourth channel and a solenoid valve, one end of the first channel, the second channel, the third channel and the fourth channel are respectively connected to the solenoid valve, the other end of the first channel and the second channel are connected to the hydraulic oil supply assembly, and the other end of the third channel and the fourth channel are respectively connected to the oil inlet channel and the oil return channel.

[0012] Preferably, the hydraulic oil supply assembly comprises a dynamic hydraulic oil source and a refrigeration device, and the dynamic hydraulic oil source is connected to the first channel and one end of the second channel away from the solenoid valve through the refrigeration device.

[0013] Preferably, a dynamic sealing piston sleeve is fixedly connected between the inner walls of the confining pressure chamber, a dynamic sealing piston is slidably connected inside the dynamic sealing piston sleeve, one end of the dynamic sealing piston abuts against an end of the coal rock sample away from the loading piston rod, and the other end of the dynamic sealing piston abuts against the pressure measuring assembly.

[0014] Preferably, the pressure measuring assembly comprises a hollow load sensor, which is fixedly connected to one end of the confining pressure chamber away from the outer wall of the oil cylinder, and the hollow load sensor abuts against one end of the dynamic sealing piston away from the coal and rock sample.

[0015] Preferably, the gas-solid coupling cavity includes a latex sleeve, both ends of which are respectively provided with openings, the coal rock sample is placed in the latex sleeve, and the outer wall of the coal rock sample is in contact with the inner wall of the latex sleeve, the loading piston rod and the dynamic sealing piston are respectively in contact with the coal rock sample through the openings at both ends of the latex sleeve, and sealing components are respectively provided between the openings at both ends of the latex sleeve and the dynamic sealing piston sleeve and the confining pressure chamber.

[0016] Preferably, the sealing assembly located between the confining pressure chamber and the latex sleeve includes a wedge-shaped sealing base fixedly connected to the confining pressure chamber, the wedge-shaped sealing base is arranged close to the outer wall of the cylinder, the inner wall of the latex sleeve is fitted with the outer wall of the wedge-shaped sealing base, a wedge-shaped sealing sleeve is arranged on the wedge-shaped sealing base, the wedge-shaped sealing base is adapted to the wedge-shaped sealing sleeve, and the latex sleeve is arranged between the sealing base and the wedge-shaped sealing sleeve.

[0017] Preferably, the gas introduction assembly includes an air inlet channel and an air outlet channel, one end of the air inlet channel passes through the dynamic sealing piston and is connected to the interior of the gas-solid coupling cavity, the other end of the air inlet channel is connected to a gas source through a pressure regulating valve, one end of the air outlet channel passes through the loading piston rod and is connected to the interior of the gas-solid coupling cavity, and the other end of the air outlet channel is connected to a vacuum pump.

[0018] The variable frequency coal-rock cyclic dynamic and static combined loading method under the gas-solid coupling environment includes the following steps:

[0019] Place the coal and rock samples into the gas-solid coupling chamber and check the air tightness of the device;

[0020] The gas-solid coupling cavity is evacuated through the gas introduction component, and high-pressure hydraulic oil is injected into the confining pressure cavity through the oil injection piece. After that, the required gas is introduced into the gas-solid coupling cavity through the gas introduction component;

[0021] By setting the flow state of the multi-channel reversing valve block and the working parameters of the hydraulic oil supply component, the integrated dynamic and static loading cylinder can perform pure static loading, pure dynamic loading or dynamic and static combined loading on the coal and rock samples;

[0022] After the coal and rock samples are destroyed, the test is stopped and the measurement data of the pressure measuring assembly is saved.

[0023] Compared with the prior art, the present invention has the following advantages and technical effects: the main function of the oil injection part is to inject hydraulic oil into the confining pressure cavity to form a confining pressure on the coal-rock sample outside the gas-solid coupling cavity; the main function of the gas-solid coupling cavity is to fill the coal-rock sample with gas to form a gas environment; the main function of the multi-channel reversing valve block is to adjust its own flow state to achieve the effect of pure static loading, pure dynamic loading and dynamic and static combined loading of the coal-rock sample by the integrated dynamic and static loading cylinder; the main function of the gas introduction component is to inject gas into the gas-solid coupling cavity, and at the same time, the gas-solid coupling cavity can be vacuumed before injecting gas. On the whole, the present invention can realize triaxial cyclic loading of coal-rock samples in a gas-solid coupling environment, and at the same time, the multi-channel reversing valve block can realize the loading mode of pure static, pure dynamic or dynamic and static load superposition of coal-rock samples, and the present invention realizes that the coal-rock sample is in a high-pressure environment during the load loading process by setting a flexible isolation material between the confining pressure cavity and the gas-solid coupling cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is a structural schematic diagram of the loading device of the present invention;

[0026] Figure 2 It is a structural schematic diagram of the multi-channel reversing valve block of the present invention;

[0027] Figure 3 A schematic diagram of the path of the cyclic dynamic and static combined loading method of the present invention;

[0028] Among them, 1. dynamic hydraulic oil source; 2. refrigeration equipment; 3. multi-channel reversing valve block; 4. dynamic and static loading cylinder; 5. outer wall of cylinder; 6. oil inlet channel; 7. oil return channel; 8. loading piston rod; 9. dynamic sealing ring; 10. gas source; 11. pressure regulating valve; 12. air inlet channel; 13. air outlet channel; 14. vacuum pump; 15. confining pressure chamber; 16. gas-solid coupling chamber; 17. confining pressure loading channel; 18. hollow load sensor; 19. fastening bolts; 20. upper flange; 21. acquisition equipment; 22. control equipment; 23. dynamic sealing piston; 24. dynamic sealing piston sleeve; 25. latex sleeve; 26. wedge-shaped sealing base; 27. wedge-shaped sealing sleeve; 28. piston; 29. ​​first channel; 30. second channel; 31. third channel; 32. fourth channel; 33. solenoid valve. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Reference Figure 1-Figure 3 The present invention provides a variable frequency coal-rock cycle dynamic and static combined loading device under a gas-solid coupling environment, comprising:

[0032] A confining pressure chamber 15, wherein a gas-solid coupling chamber 16 is provided in the confining pressure chamber 15, wherein a coal-rock sample is provided in the gas-solid coupling chamber 16, wherein the gas-solid coupling chamber 16 and the confining pressure chamber 15 are isolated by a flexible material, wherein a pressure measuring assembly is provided on the confining pressure chamber 15, wherein the pressure measuring assembly abuts against one end of the coal-rock sample and is used for monitoring the load on the coal-rock sample, and an oil injection piece is also provided on the confining pressure chamber 15;

[0033] The dynamic-static combined loading unit comprises a hydraulic oil supply assembly, a multi-channel reversing valve block 3 and an integrated dynamic-static loading cylinder 4. The integrated dynamic-static loading cylinder 4 applies a load to an end of the coal-rock sample away from the pressure measuring assembly. The hydraulic oil supply assembly is connected to the integrated dynamic-static loading cylinder 4 through the multi-channel reversing valve block 3. When the multi-channel reversing valve block 3 is in a first flow state, the integrated dynamic-static loading cylinder 4 performs pure static loading on the coal-rock sample. When the multi-channel reversing valve block 3 is in a second flow state, the integrated dynamic-static loading cylinder 4 performs pure dynamic loading or dynamic-static combined loading on the coal-rock sample.

[0034] The gas introduction component is communicated with the interior of the gas-solid coupling cavity 16 , and is used to create a vacuum environment in the gas-solid coupling cavity 16 and introduce required gas.

[0035] The main function of the oil filling part is to inject hydraulic oil into the confining pressure chamber 15, and form a confining pressure on the coal-rock sample outside the gas-solid coupling chamber 16; the main function of the gas-solid coupling chamber 16 is to fill the coal-rock sample with gas to form a gas environment; the main function of the multi-channel reversing valve block 3 is to adjust its own flow state to achieve the effects of pure static loading, pure dynamic loading and dynamic and static combined loading of the coal-rock sample by the integrated dynamic and static loading cylinder 4; the main function of the gas introduction component is to inject gas into the gas-solid coupling chamber 16, and at the same time, the gas-solid coupling chamber 16 can be vacuumed before injecting gas. On the whole, the present invention can realize triaxial cyclic loading of coal-rock samples in a gas-solid coupling environment, and at the same time, a loading mode of pure static, pure dynamic or dynamic and static load superposition can be realized for the coal-rock samples through the multi-channel reversing valve block, and the present invention realizes that the coal-rock samples are in a high-pressure environment during the load loading process by setting a flexible isolation material between the confining pressure chamber and the gas-solid coupling chamber.

[0036] To further optimize the solution, a control device 22 is also provided, and the control device 22 is electrically connected to the pressure measuring component, the multi-channel reversing valve block 3, the hydraulic oil supply component and the gas introduction component.

[0037] According to a further optimized solution, the oil injection member includes a plurality of confining pressure loading channels 17 opened on the side wall of the confining pressure chamber 15 , and hydraulic oil can be injected into the confining pressure chamber 15 through the confining pressure loading channels 17 .

[0038] To further optimize the solution, the integrated dynamic and static loading cylinder 4 includes an outer cylinder wall 5, which is fixedly connected to the end of the confining pressure chamber 15 away from the pressure measuring assembly. A piston 28 is slidably connected inside the outer cylinder wall 5, and a loading piston rod 8 is fixedly penetrated through the piston 28. One end of the loading piston rod 8 penetrates the outer cylinder wall 5 and abuts against the end of the coal and rock sample away from the pressure measuring assembly. An oil inlet channel 6 and an oil return channel 7 are opened on the outer cylinder wall 5, and the oil inlet channel 6 and the oil return channel 7 are respectively located on both sides of the piston 28.

[0039] As a further optimization scheme, a dynamic sealing ring 9 is fixedly sleeved on the side wall of the piston 28 , and a sealing connection between the piston 28 and the inner side of the outer wall 5 of the oil cylinder is achieved through the dynamic sealing ring 9 .

[0040] To further optimize the solution, the multi-channel reversing valve block 3 is provided with a first channel 29, a second channel 30, a third channel 31, a fourth channel 32 and a solenoid valve 33. One ends of the first channel 29, the second channel 30, the third channel 31 and the fourth channel 32 are respectively connected to the solenoid valve 33, the other ends of the first channel 29 and the second channel 30 are connected to the hydraulic oil supply assembly, and the other ends of the third channel 31 and the fourth channel 32 are respectively connected to the oil inlet channel 6 and the oil return channel 7.

[0041] like Figure 1 and Figure 2 As shown, when the control device 22 controls the solenoid valve 33 to put the multi-channel reversing valve block 3 in the first flow state, the first channel 29 is connected to the third channel 31, and the second channel 30 is connected to the fourth channel 32. At this time, pure static loading can be performed; when the control device 22 controls the solenoid valve 33 to put the multi-channel reversing valve block 3 in the second flow state, the first channel 29 is connected to the fourth channel 32, and the second channel 30 is connected to the third channel 31. At this time, pure dynamic loading or dynamic and static combined loading can be performed.

[0042] According to a further optimized solution, the hydraulic oil supply assembly includes a dynamic hydraulic oil source 1 and a refrigeration device 2 , and the dynamic hydraulic oil source 1 is connected to the first channel 29 and the second channel 30 at one end away from the solenoid valve 33 through the refrigeration device 2 .

[0043] like Figure 1 As shown, the control device 22 can control the dynamic hydraulic oil source 1 to introduce hydraulic oil into the multi-channel reversing valve block 3 at a certain frequency.

[0044] To further optimize the solution, a dynamic sealing piston sleeve 24 is fixedly connected between the inner walls of the confining pressure chamber 15, a dynamic sealing piston 23 is slidably connected inside the dynamic sealing piston sleeve 24, one end of the dynamic sealing piston 23 abuts against the end of the coal rock sample away from the loading piston rod 8, and the other end of the dynamic sealing piston 23 abuts against the pressure measuring assembly.

[0045] In a further optimized solution, the end of the confining pressure chamber 15 away from the outer wall 5 of the oil cylinder is fixedly connected to the upper flange 20, and the end of the dynamic sealing piston sleeve 24 away from the coal and rock sample is in contact with the upper flange 20. The pressure measuring assembly is fixedly connected to the upper flange 20, a through hole is provided in the center of the upper flange 20, and the end of the dynamic sealing piston 23 away from the coal and rock sample passes through the upper flange 20 and is arranged corresponding to the pressure measuring assembly.

[0046] like Figure 1 As shown, a plurality of dynamic sealing rings are arranged between the dynamic sealing piston sleeve 24 and the confining pressure chamber, and between the dynamic sealing piston 23 and the dynamic sealing piston sleeve 24, so as to ensure the sealing performance of the equipment during the experiment.

[0047] According to a further optimization scheme, the pressure measuring assembly includes a hollow load sensor 18, which is fixedly connected to one end of the confining pressure chamber 15 away from the outer wall 5 of the oil cylinder, and the hollow load sensor 18 abuts against one end of the dynamic sealing piston 23 away from the coal and rock sample.

[0048] According to a further optimized solution, the hollow load sensor 18 is connected to the control device 22 via the acquisition device 21 .

[0049] like Figure 1 As shown, the hollow load sensor 18 is fixedly connected to the end of the upper flange 20 away from the confining pressure chamber 15 by means of a fastening bolt 19. When the loading piston rod 8 applies a load to the coal rock sample, the coal rock sample will push the dynamic sealing piston 23 upward, and apply pressure to the hollow load sensor 18 through the dynamic sealing piston 23, thereby measuring the load magnitude applied to the coal rock sample.

[0050] A further optimized solution is that the gas-solid coupling chamber 16 includes a latex sleeve 25, both ends of which are respectively provided with openings, the coal rock sample is placed in the latex sleeve 25, and the outer wall of the coal rock sample is in contact with the inner wall of the latex sleeve 25, the loading piston rod 8 and the dynamic sealing piston 23 are respectively in contact with the coal rock sample through the openings at both ends of the latex sleeve 25, and sealing components are respectively provided between the openings at both ends of the latex sleeve 25 and the dynamic sealing piston sleeve 24 and the confining pressure chamber 15.

[0051] like Figure 1 As shown, by using the latex sleeve 25, the hydraulic oil in the confining pressure chamber 15 can generate confining pressure on the coal-rock sample and prevent the outer hydraulic oil from contacting the coal-rock sample.

[0052] A further optimized solution is that the sealing assembly located between the confining pressure chamber 15 and the latex sleeve 25 includes a wedge-shaped sealing base 26 fixedly connected to the confining pressure chamber 15, the wedge-shaped sealing base 26 is arranged close to the outer wall 5 of the cylinder, the inner wall of the latex sleeve 25 is fitted with the outer wall of the wedge-shaped sealing base 26, a wedge-shaped sealing sleeve 27 is arranged on the wedge-shaped sealing base 26, the wedge-shaped sealing base 26 is adapted to the wedge-shaped sealing sleeve 27, and the latex sleeve 25 is arranged between the wedge-shaped sealing base 26 and the wedge-shaped sealing sleeve 27.

[0053] like Figure 1 As shown, the wedge-shaped sealing sleeve 27 is connected to the confining pressure chamber 15 by fastening bolts 19, and the wedge-shaped sealing sleeve 27 tightly presses the bottom opening of the latex sleeve 25 between the wedge-shaped sealing sleeve 27 and the wedge-shaped sealing base 26 by fastening bolts 19, and by increasing the contact area, the surface seal ensures that the hydraulic oil in the confining pressure chamber 15 will not enter the gas-solid coupling chamber 16. The loading piston rod 8 passes through the wedge-shaped sealing base 26 and abuts against the bottom of the coal and rock sample.

[0054] Similarly, the wedge-shaped sealing base 26 is fixedly connected to the bottom of the dynamic sealing piston sleeve 24, and the wedge-shaped sealing sleeve 27 is fixedly connected to the dynamic sealing piston sleeve 24 by tightening bolts, and the opening at the top of the latex sleeve 25 is tightly pressed between the wedge-shaped sealing sleeve 27 and the wedge-shaped sealing base 26 to form a good seal. The dynamic sealing piston 23 penetrates the wedge-shaped sealing base 26 and abuts against the top of the coal and rock sample.

[0055] To further optimize the solution, the gas introduction component includes an air inlet channel 12 and an air outlet channel 13. One end of the air inlet channel 12 passes through the dynamic sealing piston 23 and is connected to the interior of the gas-solid coupling cavity 16. The other end of the air inlet channel 12 is connected to the gas source 10 through the pressure regulating valve 11. One end of the air outlet channel 13 passes through the loading piston rod 8 and is connected to the interior of the gas-solid coupling cavity 16. The other end of the air outlet channel 13 is connected to the vacuum pump 14.

[0056] The variable frequency coal-rock cyclic dynamic and static combined loading method under the gas-solid coupling environment includes the following steps:

[0057] Place the coal and rock samples into the gas-solid coupling chamber 16 and check the air tightness of the device;

[0058] A standard cylindrical coal sample with a size of Φ50╳100mm is selected and loaded into a latex sleeve 25. After that, the latex sleeve 25 is connected between the upper and lower wedge-shaped sealing bases 26 to form a gas-solid coupling cavity 16. The wedge-shaped sealing sleeve 27 is connected, and the dynamic sealing piston sleeve 24, the upper flange 20, the dynamic sealing piston 23, and the hollow load sensor 18 are connected to the confining pressure cavity 15 in sequence. Ensure that the dynamic sealing ring 9 is not missed during the entire installation process, and the fastening bolts 19 between the components are connected intact.

[0059] The gas-solid coupling cavity 16 is evacuated through the gas introduction component, and high-pressure hydraulic oil is injected into the confining pressure cavity 15 through the oil injection piece. After that, the required gas is introduced into the gas-solid coupling cavity 16 through the gas introduction component;

[0060] The vacuum pump 14 is started by the control device 22 to evacuate the gas-solid coupling chamber 16. After that, the required confining pressure value is set and hydraulic oil is injected into the confining pressure chamber 15. It should be noted that the residual air inside the confining pressure chamber 15 needs to be discharged during the oil filling process to prevent it from causing confining pressure fluctuations.

[0061] According to the set value, the gas source 10 is opened, and the outlet pressure of the pressure regulating valve 11 is adjusted to the set value. In this process, it is necessary to always ensure that the gas pressure in the gas-solid coupling cavity 16 is less than the surrounding pressure outside the gas-solid coupling cavity 16 to prevent the gas from bypassing the coal sample directly.

[0062] By setting the flow state of the multi-channel reversing valve block 3 and the working parameters of the hydraulic oil supply component, the integrated dynamic and static loading cylinder 4 can perform pure static loading, pure dynamic loading or dynamic and static combined loading on the coal and rock samples;

[0063] Taking dynamic and static combined loading as an example, start the dynamic hydraulic oil source 1, according to Figure 3 The test loading path shown applies a predetermined initial axial load to the coal rock specimen.

[0064] After that, when the coal-rock sample reaches adsorption equilibrium (adsorption time 24h), the solenoid valve 33 is first controlled by the control device 22 to connect the first channel 29 with the fourth channel 32, and the second channel 30 with the third channel 31. After that, the dynamic hydraulic oil source 1 is started, and constant displacement loading is performed at a rate of 0.1mm / min. After the test force reaches a predetermined value, a cyclic dynamic load of a certain frequency and magnitude is performed. After the dynamic load is completed, the loading continues in the constant displacement mode until the coal-rock sample is destroyed.

[0065] The sample needs to be subjected to pure static loading, and the dynamic hydraulic oil source 1 is started to perform constant speed displacement loading at a rate of 0.1 mm / min until the coal-rock sample is destroyed;

[0066] If the sample needs to be subjected to pure dynamic loading, the solenoid valve 33 is controlled by the control device 22 to set the frequency and amplitude of the dynamic load, and the dynamic hydraulic oil source 1 is started to achieve pure dynamic loading.

[0067] After the coal and rock samples are destroyed, the test is stopped and the measurement data of the pressure measuring assembly is saved.

[0068] After the coal-rock sample is destroyed, the test is stopped, the data is saved, the gas source 10 is turned off, the gas inside the instrument is released, and the coal-rock sample is replaced after the axial and annular loads are removed. The confining pressure and injection gas pressure values ​​are adjusted and the test is conducted again until all tests are completed.

[0069] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0070] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A variable frequency coal-rock cycle dynamic and static combined loading device under gas-solid coupling environment, characterized in that: include: A confining pressure chamber (15), wherein a gas-solid coupling chamber (16) is arranged in the confining pressure chamber (15), a coal rock sample is arranged in the gas-solid coupling chamber (16), the gas-solid coupling chamber (16) and the confining pressure chamber (15) are isolated by a flexible material, a pressure measuring assembly is arranged on the confining pressure chamber (15), the pressure measuring assembly is in contact with one end of the coal rock sample and is used to monitor the load on the coal rock sample, and an oil injection piece is also arranged on the confining pressure chamber (15); A dynamic-static combined loading unit comprises a hydraulic oil supply assembly, a multi-channel reversing valve block (3) and an integrated dynamic-static loading cylinder (4), wherein the integrated dynamic-static loading cylinder (4) applies a load to an end of a coal-rock sample away from the pressure measuring assembly, the hydraulic oil supply assembly is connected to the integrated dynamic-static loading cylinder (4) through the multi-channel reversing valve block (3), when the multi-channel reversing valve block (3) is in a first flow state, the integrated dynamic-static loading cylinder (4) performs pure static loading on the coal-rock sample, and when the multi-channel reversing valve block (3) is in a second flow state, the integrated dynamic-static loading cylinder (4) performs pure dynamic loading or dynamic-static combined loading on the coal-rock sample; A gas introduction component is communicated with the interior of the gas-solid coupling cavity (16), and is used to create a vacuum environment in the gas-solid coupling cavity (16) and introduce required gas.

2. The variable frequency coal-rock cycle dynamic and static combined loading device under gas-solid coupling environment according to claim 1 is characterized in that: The integrated dynamic and static loading cylinder (4) comprises an outer cylinder wall (5), the outer cylinder wall (5) being fixedly connected to one end of the confining pressure chamber (15) away from the pressure measuring assembly, a piston (28) being slidably connected inside the outer cylinder wall (5), a loading piston rod (8) being fixedly passed through the piston (28), one end of the loading piston rod (8) passing through the outer cylinder wall (5) and abutting against one end of the coal and rock sample away from the pressure measuring assembly, an oil inlet channel (6) and an oil return channel (7) being opened on the outer cylinder wall (5), the oil inlet channel (6) and the oil return channel (7) being respectively located on two sides of the piston (28).

3. The variable frequency coal-rock cycle dynamic and static combined loading device under gas-solid coupling environment according to claim 2 is characterized by: The multi-channel reversing valve block (3) is provided with a first channel (29), a second channel (30), a third channel (31), a fourth channel (32) and a solenoid valve (33); one end of the first channel (29), the second channel (30), the third channel (31) and the fourth channel (32) are respectively connected to the solenoid valve (33); the other ends of the first channel (29) and the second channel (30) are respectively connected to the hydraulic oil supply assembly; the other ends of the third channel (31) and the fourth channel (32) are respectively connected to the oil inlet channel (6) and the oil return channel (7).

4. The variable frequency coal-rock cycle dynamic and static combined loading device under gas-solid coupling environment according to claim 3 is characterized by: The hydraulic oil supply assembly comprises a dynamic hydraulic oil source (1) and a refrigeration device (2); the dynamic hydraulic oil source (1) is connected to the first channel (29) and one end of the second channel (30) away from the solenoid valve (33) through the refrigeration device (2).

5. The variable frequency coal-rock cycle dynamic and static combined loading device under gas-solid coupling environment according to claim 2 is characterized by: A dynamic sealing piston sleeve (24) is fixedly connected between the inner walls of the confining pressure chamber (15), and a dynamic sealing piston (23) is slidably connected inside the dynamic sealing piston sleeve (24). One end of the dynamic sealing piston (23) abuts against an end of the coal and rock sample away from the loading piston rod (8), and the other end of the dynamic sealing piston (23) abuts against the pressure measuring assembly.

6. The variable frequency coal-rock cycle dynamic and static combined loading device under gas-solid coupling environment according to claim 5 is characterized by: The pressure measuring assembly comprises a hollow load sensor (18), wherein the hollow load sensor (18) is fixedly connected to one end of the confining pressure chamber (15) away from the outer wall (5) of the oil cylinder, and the hollow load sensor (18) abuts against one end of the dynamic sealing piston (23) away from the coal and rock sample.

7. The variable frequency coal-rock cycle dynamic and static combined loading device under gas-solid coupling environment according to claim 5 is characterized by: The gas-solid coupling cavity (16) includes a latex sleeve (25), and openings are respectively provided at both ends of the latex sleeve (25). The coal rock sample is placed in the latex sleeve (25), and the outer wall of the coal rock sample is in contact with the inner wall of the latex sleeve (25). The loading piston rod (8) and the dynamic sealing piston (23) are respectively in contact with the coal rock sample through the openings at both ends of the latex sleeve (25). Sealing components are respectively provided between the openings at both ends of the latex sleeve (25) and the dynamic sealing piston sleeve (24) and the confining pressure cavity (15).

8. The variable frequency coal-rock cycle dynamic and static combined loading device under gas-solid coupling environment according to claim 7 is characterized by: The sealing assembly located between the confining pressure chamber (15) and the latex sleeve (25) includes a wedge-shaped sealing base (26) fixedly connected to the confining pressure chamber (15); the wedge-shaped sealing base (26) is arranged close to the outer wall of the oil cylinder (5); the inner wall of the latex sleeve (25) is in contact with the outer wall of the wedge-shaped sealing base (26); a wedge-shaped sealing sleeve (27) is arranged on the wedge-shaped sealing base (26); the wedge-shaped sealing base (26) is adapted to the wedge-shaped sealing sleeve (27); and the latex sleeve (25) is arranged between the sealing base (26) and the wedge-shaped sealing sleeve (27).

9. The variable frequency coal-rock cycle dynamic and static combined loading device under gas-solid coupling environment according to claim 5 is characterized by: The gas introduction component comprises an inlet channel (12) and an outlet channel (13); one end of the inlet channel (12) passes through the dynamic sealing piston (23) and is connected to the interior of the gas-solid coupling cavity (16); the other end of the inlet channel (12) is connected to a gas source (10) via a pressure regulating valve (11); one end of the outlet channel (13) passes through the loading piston rod (8) and is connected to the interior of the gas-solid coupling cavity (16); and the other end of the outlet channel (13) is connected to a vacuum pump (14).

10. A variable frequency coal-rock cyclic dynamic and static combined loading method under a gas-solid coupling environment, based on the variable frequency coal-rock cyclic dynamic and static combined loading device under a gas-solid coupling environment as claimed in claim 1, characterized in that: The steps include: Placing the coal and rock samples in the gas-solid coupling chamber (16) and checking the air tightness of the device; The gas-solid coupling cavity (16) is evacuated through the gas introduction component, and high-pressure hydraulic oil is injected into the confining pressure cavity (15) through the oil injection piece, and then the required gas is introduced into the gas-solid coupling cavity (16) through the gas introduction component; By setting the flow state of the multi-channel reversing valve block (3) and the working parameters of the hydraulic oil supply component, the integrated dynamic and static loading cylinder (4) performs pure static loading, pure dynamic loading or dynamic and static combined loading on the coal and rock samples; After the coal and rock samples are destroyed, the test is stopped and the measurement data of the pressure measuring assembly is saved.

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