Visual test device and method for stability of mine cave under circulating hydrogen storage and release condition

Abstract

The invention discloses a visual testing device and method for mine stability under the condition of circulating hydrogen storage and release, and relates to the technical field of engineering tests.The testing device comprises two device bodies which are vertically connected, an axial pressure chamber and a piston type axial pressure head are arranged in the first device body, and the second device body is detachably connected with the first device body; a lofting chamber and an air pressure chamber are arranged; the axial pressure head enters the sample placing chamber to apply pressure to a sample, the air pressure chamber is sealed by the sample to form a sealed space, the air pressure chamber is connected with an air inlet pipeline and an air outlet pipeline, air is supplemented through a high-pressure air source, internal air is discharged into an air storage bottle through an air pump, and air flow is controlled by a valve, a pressure gauge and the like on the pipelines. And the gas storage bottle is connected with the gas chromatograph for analysis. The device is simple in structure and convenient to operate, the test precision can be improved, and various working conditions can be simulated. Meanwhile, the device can accurately control and monitor parameters such as pressure, flow and temperature, and ensures the safety of the test and the stability of the hydrogen storage process.

Description

Technical Field

[0001] The present invention relates to the field of engineering test technology, and in particular to a visualization test device and method for mine cave stability under cyclic hydrogen storage and release conditions. Background Art

[0002] With the transformation of the global energy structure and the rapid development of clean energy, gas storage technology has become the key to achieving efficient energy utilization and sustainable development. Hydrogen energy, as a low-carbon new energy source, is regarded as a key carrier of energy transformation. As a new energy storage method, hydrogen energy storage has the advantages of long discharge time, large capacity, high economy and environmental friendliness, which is of great significance to achieving the goals of "carbon peak and carbon neutrality". As an important energy storage facility, the safety and stability of the construction and operation of hydrogen storage depots have received widespread attention.

[0003] Abandoned mines, as a potential hydrogen storage resource, have attracted much attention due to their large storage capacity and good safety. However, the stability of the surrounding rock is a key factor in determining whether the mine can be safely used. At present, the existing test methods have great uncertainty in evaluating the stability of the surrounding rock, and the design rationality and performance of these methods directly affect the accuracy and practicality of the research results. In addition, the existing test devices generally have problems such as complex structure, cumbersome operation and insufficient test accuracy, which can hardly meet the growing scientific research and engineering needs. Summary of the invention

[0004] The purpose of the present invention is to provide a visualization test device and method for mine cave stability under cyclic hydrogen storage and release conditions with simple structure, convenient operation, high test accuracy and the ability to simulate various working conditions, so as to meet the growing scientific research and engineering needs.

[0005] To achieve the above objectives, on the one hand, the present invention provides a visualization test device for mine cave stability under cyclic hydrogen storage and release conditions, comprising:

[0006] A first device body, wherein the first device body is hollow inside to form an axial pressure chamber, an axial pressure head is provided in the axial pressure chamber to reciprocate in a piston-like manner, and a lower pressure port is provided at the bottom of the axial pressure chamber to accommodate the axial pressure head to slide out;

[0007] The second device body is detachably connected to the first device body, and a sample placement chamber is provided on the second device body and docked with the lower pressure port. The sample placement chamber is used to place the sample and allow the axial pressure head to be pressed in. An air pressure chamber is sunken at the bottom of the sample placement chamber, and an annular step is formed on the top of the air pressure chamber. After the sample is placed in, it forms a sealed contact with the annular step, and the air pressure chamber at the bottom is closed into a closed space;

[0008] The axial pressure head enters from the entrance of the sample chamber to apply downward pressure to the sample;

[0009] The air pressure chamber is connected to a high-pressure gas source and a gas flow pump through an air inlet pipeline, and is connected to an air extraction pump and a gas storage bottle through an air outlet pipeline. Valves, pressure gauges, temperature gauges and flow meters are provided on the air inlet pipeline and the air outlet pipeline, and the gas storage bottle is connected to a gas chromatograph.

[0010] In some optional implementations, the axial pressure head includes a downward pressure section, a piston section and a shaft section, the piston section is in piston-like sliding cooperation with the inner wall of the axial pressure chamber, the downward pressure section is located at the bottom center of the piston section, its outer diameter is smaller than the piston section and is adapted to the inner diameter of the sample chamber, the shaft section is located above the piston section, and the shaft section passes through and is guided to slide on the top of the first device body.

[0011] In some optional implementations, the piston section divides the axial pressure chamber into an upper chamber and a lower chamber; the upper chamber is connected to an oil blowing pipeline and an oil inlet / outlet pipeline, the oil blowing pipeline is connected to an air pump, and the oil inlet / outlet pipeline is connected to an oil pump, an oil tank and a liquid flow pump; the lower chamber is connected to an exhaust pipeline, and an air compression conversion switch is provided on the exhaust pipeline.

[0012] In some optional implementations, the visualization test device for mine cave stability under cyclic hydrogen storage and release conditions also includes a control system, and the liquid flow pump, the gas flow pump and the gas chromatograph are all electrically connected to the control system.

[0013] In some optional implementations, the shaft section of the axial pressure head is provided with an axial displacement sensor.

[0014] In some optional implementations, an annular groove is provided on the annular step, and a sealing ring is provided in the annular groove.

[0015] In some optional implementations, at least one side of the sample placement chamber is made of transparent material to facilitate observation of changes in the sample during the test process.

[0016] In some optional implementations, an electric heating ring is provided on the inner wall of the air pressure chamber, and a temperature thermocouple is also provided in the air pressure chamber.

[0017] In some optional implementations, the first device body and the second device body are fastened together by bolts.

[0018] The above structure is intended to provide a visualization test device for the deformation mechanism of the multi-layer composite structure of an abandoned mine cave under cyclic hydrogen storage and release conditions. It is mainly used to study and test the stability of the surrounding rock when the abandoned mine cave is used as a hydrogen storage reservoir. Pressure-resistant oil is injected into the axial pressure chamber through the oil tank, and the hydraulic pump is controlled by the control system to apply axial pressure. At the same time, an air pressure chamber is provided under the specimen, and gas is injected into the air pressure chamber through a high-pressure gas source. The gas compressor is controlled by the control system to apply gas pressure.

[0019] On the other hand, the present invention provides a method for visualizing the stability of a mine cave under cyclic hydrogen storage and release conditions, using any of the above-mentioned visualizing the stability of a mine cave under cyclic hydrogen storage and release conditions test device, the method comprising the following steps:

[0020] Step S1, placing the sample in the sample placement chamber of the second device body, and ensuring that the bottom of the sample contacts the sealing ring to form a seal, so that the air pressure chamber is in a closed state;

[0021] Step S2, connecting the first device body and the second device body shell, and ensuring sealing;

[0022] Step S3, controlling the axial pressure head to apply an axial load to the sample through a control system;

[0023] Step S4, injecting gas into the air pressure chamber and applying gas pressure, while monitoring the gas flow, pressure, and temperature;

[0024] Step S5: After the test, the gas and axial pressure are removed, the gas is collected and the gas purity and components are analyzed, the hydraulic oil is returned to the oil tank, the air compression conversion switch is turned off, and the sample is taken out and stored;

[0025] Step S6: record the test data and obtain the test results based on the test data.

[0026] The present invention has the following technical effects:

[0027] The visualization test device for mine cave stability under cyclic hydrogen storage and release conditions of the present invention has a simple structure and is easy to operate, can improve the test accuracy, can simulate a variety of working conditions, and realize the visualization of the test process. The device can accurately control and monitor parameters such as pressure, flow, and temperature to ensure the safety of the test and the stability of the hydrogen storage process. The test device and method of the present invention are used to support the storage and utilization of hydrogen energy, help improve the utilization rate of abandoned mine cave resources, promote energy transformation and environmental protection, meet scientific research and engineering needs, and provide a scientific basis for the design and stability research of abandoned mine cave hydrogen storage depots. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] 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.

[0029] Figure 1 It is a structural schematic diagram of a visualization test device for mine cave stability under cyclic hydrogen storage and release conditions of the present invention.

[0030] In the figure: 1. axial pressure chamber; 2. axial pressure head; 3. flange; 4. air compression conversion switch; 5. axial displacement sensor; 6. oil blowing pipeline; 7. air pump; 8. oil inlet / outlet pipeline; 9. oil tank; 10. liquid flow pump; 11. control system; 12. annular groove; 13. sealing ring; 14. bolt; 15. test sample; 16. high-strength transparent glass plate; 17. annular step; 18. removable wire mesh; 19. air pressure chamber; 20. air inlet pipeline; 21. high-pressure gas source; 22. gas flow pump; 23. temperature thermocouple; 24. electric heating ring; 25. air outlet pipeline; 26. vacuum pump; 27. gas storage bottle; 28. gas chromatograph; 29. ​​needle valve; 30. ball valve; 31. pressure gauge; 32. temperature gauge; 33. flow meter. DETAILED DESCRIPTION

[0031] 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.

[0032] At present, there are technologies that involve converting abandoned mines into hydrogen storage depots to improve the utilization rate of abandoned mine resources and ensure the safety and stability of hydrogen storage. This structure includes an initial support layer, a drainage structure, an impermeable concrete layer, a steel lining layer and a sealing device, in which the steel lining layer is a double-layer sandwich structure, including an outer steel lining, an inner steel lining and a UHPC concrete filling layer filled between the two steel linings. This design aims to utilize the stable environmental factors of the mine to achieve safe storage and improve the safety of the hydrogen storage depot structure.

[0033] Current research progress includes the optimization of underground hydrogen storage, the determination of the interfacial tension between rocks and fluids, and the comprehensive characterization of the wettability and interfacial tension of the hydrogen-brine-quartz system. These studies provide a scientific basis for the design of multi-layer composite structures and the understanding of deformation mechanisms of abandoned mine hydrogen storage. Some studies have used a combination of numerical simulation, indoor experiments and theoretical analysis to study the damage evolution characteristics of rocks under cyclic loading and unloading, the seepage-damage-stress coupling mechanical model, and the stability mechanism of gas storage surrounding rocks under injection and production cycle conditions.

[0034] In summary, the visualization test device for the deformation mechanism of the multi-layer composite structure of abandoned mine caves under cyclic hydrogen storage and release conditions is in the active research and development stage. The present invention aims to provide a visualization test device and method for the stability of mine caves under cyclic hydrogen storage and release conditions, so as to help study and understand the deformation mechanism of abandoned mine caves under hydrogen storage and release conditions and ensure the safety and stability of the hydrogen storage process.

[0035] 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.

[0036] Reference Figure 1As shown, an embodiment of the present invention provides a visualization test device for mine cave stability under cyclic hydrogen storage and release conditions, comprising a first device body and a second device body sealed and connected to each other at the upper and lower parts, the first device body and the second device body shell are detachably connected, wherein the interior of the first device body is hollow to form an axial pressure chamber 1, an axial pressure head 2 is piston-mounted in the axial pressure chamber 1, a downward pressure port is opened at the bottom of the first device body, the size of the downward pressure port is consistent with the size of the upper end opening of the second device body shell, and is adapted to the outer diameter of the downward pressure section of the axial pressure head 2, the axial pressure head 2 enters into the second device body shell through the downward pressure port of the first device body, so as to apply downward pressure to the sample 15 placed in the second device body shell. The axial pressure head 2 includes a downward pressure section close to and facing the sample 15, a piston section located above the downward pressure section, and a shaft section located above the piston section, wherein the shaft section passes through and slides in the top center of the first device body, and the piston section has an outer diameter that matches the inner diameter of the axial pressure chamber 1, and the two form a piston-like sliding fit. The inner diameter of the downward pressure section is smaller than that of the piston section, and is close to the size of the inner cavity (sample chamber) of the second device body shell at the bottom, and can slide back and forth between the axial pressure chamber 1 and the sample chamber in a piston-like manner. The second device body is a shell structure with an open top and a T-shaped chamber inside. At least one side of the second device body shell is made of transparent material to facilitate observation of the internal situation. The T-shaped chamber includes a sample placement chamber located at the upper part and an air pressure chamber 19 located at the lower part. The sample placement chamber is used to hold the sample 15. The sample 15 can be supported on the annular step 17 above the air pressure chamber 19. After placing the sample 15, the air pressure chamber 19 at the bottom forms a closed space. The pressure of the air pressure chamber 19 can be adjusted by injecting or extracting gas into or out of the air pressure chamber 19 to achieve the corresponding test purpose.

[0037] Specifically, in the above embodiment, a hole is opened at the top center of the first device body, and a flange 3 is installed. The shaft section of the axial pressure head 2 cooperates with the flange 3 to form a sealed sliding connection. Under the action of the driving mechanism, the shaft section drives the piston section and the lower pressure section to reciprocate up and down. The piston section is in sliding contact with the inner wall of the axial pressure chamber 1, and a sealing ring 13 embedded in the inner wall of the axial pressure chamber 1 is provided on the inner wall of the axial pressure chamber 1 to achieve a sealed sliding connection. The piston section divides the axial pressure chamber 1 into an upper chamber and a lower chamber, and the upper chamber is connected to the oil blowing pipeline 6 and the inlet / outlet oil pipeline 8, wherein the oil blowing pipeline 6 is connected to the air pump 7, and a pressure gauge 31 and a valve are provided on the pipeline; the inlet / outlet oil pipeline 8 is connected to the oil pump, the oil tank 9 and the liquid flow pump 10, and a pressure gauge 31 and a valve are provided on the pipeline. The oil pump, as the driving mechanism of the axial pressure head 2, transports the hydraulic oil in the oil tank 9 to the axial pressure chamber 1 through the inlet / outlet oil pipeline 8, thereby generating a downward hydraulic force on the axial pressure head 2 to drive the axial pressure head 2 downward. The air pump 7 can blow air into the axial pressure chamber 1 through the oil blowing pipeline 6, thereby returning the hydraulic oil in the axial pressure chamber 1 to the oil tank 9 through the inlet / outlet oil pipeline 8. The lower chamber is connected to an exhaust pipeline, and an air compression conversion switch 4 is arranged on the exhaust pipeline. In the axial pressure loading stage, the air compression conversion switch 4 needs to be opened so as to timely discharge the gas in the lower section of the axial pressure chamber 1 during the downward process of the axial pressure head 2, so that the axial pressure head 2 can smoothly descend.

[0038] In some embodiments, the first device body and the second device body shell are fastened together by bolts 14, and a sealing ring 13 is provided at the connection position between the two. Specifically, an annular groove 12 is provided on the cross-section where the first device body and the second device body shell are connected, and a sealing ring 13 is placed in the annular groove 12, so that the first device body and the second device body shell can be detachably sealed and connected, which is convenient for placing the sample 15 and ensures the sealing of the connection between the two.

[0039] It should be understood that in actual applications, the first device body and the second device body shell can also adopt other detachable fastening connection methods, such as snap connection, fastener clamping, etc., but the firmness and tightness of the connection between the two must be ensured.

[0040] In some embodiments, a groove for placing the sealing ring 13 is also opened on the middle inner wall of the axial pressure chamber 1, and a groove for placing the sealing ring 13 is also opened on the inner circumferential surface of the bottom outlet of the axial pressure chamber 1, so that after the sealing ring 13 is placed in, the inner walls can be basically in the same vertical plane, thereby achieving a good sealing effect without affecting the piston-like movement of the axial pressure head 2.

[0041] In this embodiment, the air pressure chamber 19 at the bottom of the second device body shell is connected to the high-pressure gas source 21 through the air inlet pipeline 20, and a valve, a pressure gauge 31, a temperature gauge 32 and a flow meter 33 are provided on the air inlet pipeline 20. The air pressure chamber 19 is connected to the air pump 26 and the gas storage bottle 27 through the air outlet pipeline 25, and a ball valve 30, a pressure gauge 31, a temperature gauge 32 and a flow meter 33 are provided on the air outlet pipeline 25, and the gas storage bottle 27 is connected to the gas chromatograph 28. During the test, the changes in gas pressure, temperature and flow can be intuitively perceived by observing the pressure gauge 31, the temperature gauge 32 and the flow meter 33.

[0042] In some embodiments, a control system 11 is further included, and the gas chromatograph 28 is electrically connected to the control system 11. The control system 11 is also electrically connected to the liquid flow pump 10 and the gas flow pump 22.

[0043] In some embodiments, an axial displacement sensor 5 is provided on the shaft section of the axial pressure head 2 .

[0044] In some embodiments, the valves on the air inlet pipeline 20 and the air outlet pipeline 25 are ball valves 30 , and the valve close to the gas storage bottle 27 is a needle valve 29 .

[0045] In some embodiments, an annular groove 12 is provided on the annular step 17 for placing the sealing ring 13. When the sample 15 is placed on the annular step 17, it is pressed against the sealing ring 13 to form a seal, thereby ensuring that the air pressure chamber 19 at the bottom forms a closed space.

[0046] In some embodiments, according to the requirements of the test, a detachable wire mesh 18 may be placed on the annular step 17. The detachable wire mesh 18 is mainly used to prevent the sample 15 from peeling off and falling into the bottom of the air pressure chamber 19 due to damage.

[0047] In some embodiments, an electric heating ring 24 is installed on the inner wall of the air pressure chamber 19, and the gas can be heated by the electric heating ring 24.

[0048] In some embodiments, a temperature thermocouple 23 is further provided in the air pressure chamber 19 , and the temperature change of the air pressure can be intuitively sensed through the temperature meter 32 , and the temperature change of the gas in the air pressure chamber 19 can be further accurately sensed through the temperature thermocouple 23 .

[0049] In some embodiments, the second device body shell can be made of high-strength transparent glass, which can be an integrally formed high-strength transparent glass shell, or high-strength transparent glass can be installed on one side of the second device body shell (the observation side directly in front of the sample 15) to achieve visualization of the test process.

[0050] The present invention also provides a method for visualizing the stability of a mine cave under cyclic hydrogen storage and release conditions, using the visualizing the stability of a mine cave under cyclic hydrogen storage and release conditions described in the above embodiment. The method comprises the following steps:

[0051] Step S1, preparation stage: open the first device body and the second device body, place the sealing ring 13 on the annular step 17 at the bottom of the sample chamber, place the sample 15 in the sample chamber of the second device body, the bottom of the sample 15 is in full contact with the sealing ring 13 to form a seal, and the air pressure chamber 19 at the bottom of the sample 15 is in a closed state;

[0052] Step S2, connection stage; sealingly connecting the first device body and the second device body shell, specifically placing a sealing ring 13 in the annular groove 12 on the lower end surface of the first device body, and then fastening the first device body and the second device body shell along the circumferential side by bolts 14;

[0053] Step S3, axial pressure loading: first, turn on the air compression conversion switch 4, then inject hydraulic oil into the sealed space above the axial pressure chamber 1 through the oil tank 9 and the inlet / outlet oil pipeline 8, drive the axial pressure head 2 to move downward, and finally control the liquid flow pump 10 through the control system 11 to apply an axial load to the sample 15;

[0054] Step S4, air pressure loading: first, the air pressure chamber 19 is evacuated to a vacuum state through the air pump 26 and the air outlet pipeline 25, and then gas is injected into the air pressure chamber 19 through the high-pressure gas source 21 and the air inlet pipeline 20, and finally the control system 11 controls the gas flow pump 22 to apply gas pressure to the bottom of the sample 15; at the same time, the pressure gauge 31 and the flow meter 33 are observed to intuitively perceive the changes in gas pressure and flow, and the test process is completed;

[0055] In some embodiments, step S4 further includes: while performing gas pressure loading, heating the gas through the electric heating ring 24, and visually sensing the gas temperature through the temperature meter 32;

[0056] In some embodiments, a temperature thermocouple 23 is provided in the air pressure chamber 19 to further accurately obtain the temperature change of the gas in the air pressure chamber 19;

[0057] Step S5, end stage: first, the control system 11 controls the gas flow pump 22 to release the gas pressure, and then collects the gas through the gas outlet pipeline 25 and the gas storage bottle 27. The gas storage bottle 27 is connected to a gas chromatograph 28 to detect the gas purity and analyze the gas components. Then, the control system 11 controls the liquid flow pump 10 to release the axial pressure, and finally, the hydraulic oil in the axial pressure chamber 1 is returned to the oil tank 9 through the oil inlet / outlet pipeline 8 through the air pump 7 and the oil blowing pipeline 6, the air compression conversion switch 4 is turned off, and then the bolt 14 is opened, and the sample 15 is taken out and numbered and stored;

[0058] Step S6: Data processing: record the test data and obtain the test results based on the test data.

[0059] The visual test device and method for mine cave stability under cyclic hydrogen storage and release conditions disclosed in the embodiments of the present invention have at least the following beneficial effects compared with the prior art:

[0060] 1. The test device of the present invention has a simple structure, convenient operation, and is easy to assemble and operate, making the test process more efficient.

[0061] 2. The present invention has higher test accuracy. Through precise control systems and sensors, such as axial displacement sensors, it can accurately control and monitor parameters such as pressure, flow, temperature, etc. during the test, thereby improving the accuracy of the test results.

[0062] 3. The device of the present invention can simulate a variety of working conditions and realize the simulation of the stability of the mine cave under different hydrogen storage and release conditions, including the application of axial pressure and gas pressure, as well as the control of temperature and gas composition, providing a diverse experimental environment for research.

[0063] 4. The device of the present invention has a visualized test process, and at least one side of the sample chamber is made of transparent material, which is convenient for observing the changes of the sample during the test and enhances the intuitiveness of the test.

[0064] 5. The device of the present invention has higher safety and stability. By accurately controlling the pressure of gas and liquid, and monitoring the temperature and gas composition, the safety of the test process and the stability of the hydrogen storage process are ensured.

[0065] 6. The device of the present invention can meet the growing needs of scientific research and engineering, especially in the research on the safety and stability of abandoned mine caves as hydrogen storage reservoirs. By studying and testing the stability of the surrounding rock when abandoned mine caves are used as hydrogen storage reservoirs, it helps to improve the utilization rate of abandoned mine resources and ensure the safety and stability of hydrogen storage, providing a scientific basis for the multi-layer composite structure design of abandoned mine cave hydrogen storage reservoirs and the understanding of the deformation mechanism.

[0066] The details not described in detail in the present invention are all conventional technical means well known to those skilled in the art.

[0067] 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.

[0068] 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 visual test device for mine cave stability under cyclic hydrogen storage and release conditions, characterized in that: include: A first device body, wherein the first device body is hollow inside to form an axial pressure chamber (1), an axial pressure head (2) is piston-type reciprocatingly sliding in the axial pressure chamber (1), and a lower pressure port is opened at the bottom of the axial pressure chamber (1) to accommodate the axial pressure head (2) sliding out; A second device body is detachably connected to the first device body, and a sample placement chamber is provided on the second device body and is connected to the lower pressure port. The sample placement chamber is used to place the sample (15) and allow the axial pressure head (2) to be pressed in. A pressure chamber (19) is sunken at the bottom of the sample placement chamber, and an annular step (17) is formed at the top of the pressure chamber (19). After the sample (15) is placed in, it forms a sealed contact with the annular step (17), thereby sealing the bottom pressure chamber (19) into a closed space; The axial pressure head (2) enters from the entrance of the sample placement chamber to apply downward pressure to the sample (15); The air pressure chamber (19) is connected to a high-pressure gas source (21) and a gas flow pump (22) via an air inlet pipeline (20), and the air pressure chamber (19) is connected to an air pump (26) and a gas storage bottle (27) via an air outlet pipeline (25). The air inlet pipeline (20) and the air outlet pipeline (25) are both provided with valves, pressure gauges (31), temperature gauges (32) and flow meters (33), and the gas storage bottle (27) is connected to a gas chromatograph (28).

2. The visualization test device for mine cave stability under cyclic hydrogen storage and release conditions according to claim 1 is characterized in that: The axial pressure head (2) comprises a downward pressure section, a piston section and an axial section. The piston section is in piston-like sliding cooperation with the inner wall of the axial pressure chamber (1). The downward pressure section is located at the center of the bottom of the piston section. Its outer diameter is smaller than that of the piston section and is compatible with the inner diameter of the sample chamber. The axial section is located above the piston section. The axial section passes through and is guided to slide on the top of the first device body.

3. The visualization test device for mine cave stability under cyclic hydrogen storage and release conditions according to claim 2 is characterized in that: The piston section divides the axial pressure chamber (1) into an upper chamber and a lower chamber; the upper chamber is connected to an oil blowing pipeline (6) and an oil inlet / outlet pipeline (8), the oil blowing pipeline (6) is connected to an air pump (7), and the oil inlet / outlet pipeline (8) is connected to an oil pump, an oil tank (9) and a liquid flow pump (10); the lower chamber is connected to an exhaust pipeline, and an air compression conversion switch (4) is provided on the exhaust pipeline.

4. The visual test device for mine cave stability under cyclic hydrogen storage and release conditions according to claim 3, characterized in that: It also includes a control system (11), and the liquid flow pump (10), the gas flow pump (22) and the gas chromatograph (28) are all electrically connected to the control system (11).

5. The visualization test device for mine cave stability under cyclic hydrogen storage and release conditions according to claim 2, characterized in that: The shaft section of the axial pressure head (2) is provided with an axial displacement sensor (5).

6. The visualization test device for mine cave stability under cyclic hydrogen storage and release conditions according to claim 1, characterized in that: An annular groove (12) is provided on the annular step (17), and a sealing ring (13) is provided in the annular groove (12).

7. The visualization test device for mine cave stability under cyclic hydrogen storage and release conditions according to claim 1 is characterized in that: At least one side of the sample placement chamber is made of transparent material, which facilitates observation of changes in the sample (15) during the test process.

8. The visualization test device for mine cave stability under cyclic hydrogen storage and release conditions according to claim 1, characterized in that: An electric heating ring (24) is provided on the inner wall of the air pressure chamber (19), and a temperature thermocouple (23) is also provided in the air pressure chamber (19).

9. The visual test device for mine cave stability under cyclic hydrogen storage and release conditions according to claim 1, characterized in that: The first device body and the second device body are fastened and connected by bolts (14).

10. A method for visualizing the stability of a mine cave under cyclic storage and release of hydrogen conditions, using a visualizing the stability of a mine cave under cyclic storage and release of hydrogen conditions as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: Step S1, placing the sample (15) in the sample placement chamber of the second device body, and ensuring that the bottom of the sample (15) contacts the sealing ring (13) to form a seal, so that the air pressure chamber (19) is in a closed state; Step S2, connecting the first device body and the second device body shell, and ensuring sealing; Step S3, controlling the axial pressure head (2) to apply an axial load to the sample (15) through the control system (11); Step S4, injecting gas into the air pressure chamber (19) and applying gas pressure, while monitoring the gas flow, pressure, and temperature; Step S5: After the test is completed, the gas and axial pressure are released, the gas is collected and the gas purity and components are analyzed, the hydraulic oil is returned to the oil tank (9), the air compression conversion switch (4) is turned off, and the sample is taken out and stored (15); Step S6: record the test data and obtain the test results based on the test data.

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