A test device and test method capable of simulating gypsum rock karst collapse

Abstract

The present invention relates to the technical field of gypsum rock karst collapse, and provides a test device and test method thereof that can simulate gypsum rock karst collapse, wherein the test device comprises a model box structure, a karst cave simulation box, a water level control system and a circulating water tank that are cyclically connected in sequence; the model box structure comprises an upper barrel and a lower barrel connected up and down, and both the upper barrel and the lower barrel are double-side wall structures, and the double-side wall structures form an inner cavity and an outer cavity, and the inner cavity and the outer cavity are connected through an inner side wall provided with water-permeable holes, and a partition is provided between the outer cavity of the upper barrel and the outer cavity of the lower barrel, and the water level control system comprises a water level box, a water flow isolation mechanism and an air pressure control mechanism. This scheme can be used not only to simulate the karst disaster process of covering type, but also to simulate the disaster process of gypsum rock without covering layer, and this structure makes the actual test operation more convenient, and the test conditions can be adjusted quickly, thereby shortening the test cycle and improving the research efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of gypsum rock karst collapse, and in particular to a test device and a test method thereof which can simulate gypsum rock karst collapse. Background Art

[0002] Karst collapse is a complex geological disaster. Its occurrence mechanism is closely related to the interaction between water, soil and rock. There are complex physical, mechanical and chemical interactions between groundwater and rock and soil, and stress transfer and material transmission between soil and shelter. Changes in groundwater accelerate the dissolution of rock mass, forming karst channels, providing migration channels for the collapse of the covering layer, and may even cause the collapse of weak rock layers (such as gypsum). The dynamic changes in groundwater levels affect not only the rock mass, but also the covering soil, thereby causing the collapse of the cover layer.

[0003] Studies have shown that human activities account for 75% of the total collapses, among which excessive groundwater exploitation is the main reason for accelerating or causing collapses, which can significantly accelerate or directly trigger collapses. At present, most of the experiments on covered karst collapse simulate the water level changes in the covering layer by changing the water level in the water tank, but this experimental method does not fully match the complex conditions of the actual disaster site and has certain limitations.

[0004] In addition, gypsum and carbonate rocks usually coexist. In a water environment, sulfates in gypsum react chemically with carbonates, further leading to rock collapse. However, current research mainly focuses on overburden karst collapse, while there are relatively few studies on the catastrophic mechanism of gypsum karst collapse under the condition of no overburden. There is an urgent need for an experimental device and method that can simulate gypsum karst collapse. Summary of the invention

[0005] In order to solve the problems existing in the background technology, the present invention proposes a test device and a test method that can simulate gypsum karst collapse, which can simultaneously meet the needs of studying the evolution mechanism of gypsum karst dissolution collapse under changes in groundwater dynamic conditions and karst collapse under the coupling of water-soil-rock.

[0006] To achieve the above object, the present invention adopts the following scheme:

[0007] A test device capable of simulating gypsum rock karst collapse comprises a model box structure, a karst cave simulation box, a water level control system and a circulating water tank which are cyclically connected in sequence;

[0008] The model box structure comprises an upper barrel and a lower barrel connected up and down, the upper barrel and the lower barrel are both double-side wall structures, the double-side wall structures form an inner cavity and an outer cavity, the inner cavity and the outer cavity are connected through an inner side wall provided with water-permeable holes, a partition is provided between the outer cavity of the upper barrel and the outer cavity of the lower barrel, the inner cavity of the upper barrel and the inner cavity of the lower barrel are connected up and down, and a cover plate for maintaining a consistent pressure in the model box structure is detachably provided in the outer cavities of the upper barrel and the lower barrel, soil is provided in the inner cavity of the upper barrel, gypsum rock is provided in the inner cavity of the lower barrel, the bottom of the inner cavity of the lower barrel is connected to the karst cave simulation box, and the bottom of the outer cavity of the lower barrel is connected to the circulating water tank;

[0009] The water level control system includes a water level box, a water flow isolation mechanism and an air pressure control mechanism, the air pressure control mechanism includes a control panel, the water flow isolation mechanism is arranged on either left or right side of the water level box, the control panel is slidably arranged on the other side of the water level box, the water flow isolation mechanism is used to adjust the water flow exchange between the water level control system and the cave simulation box, the air pressure control mechanism adjusts the air pressure in the water level box by moving the control panel, and an exhaust valve is arranged on the top of the water level box away from the water flow isolation mechanism.

[0010] A first through hole is provided at the lower part of any front and rear side wall of the water level box body near one end of the water flow isolation mechanism. The first through hole is connected to the water level box body and the circulating water tank through a first pipe. A first valve is provided on the first pipe.

[0011] Furthermore, the top of the upper barrel is open, the bottom of the lower barrel is provided with a base plate, the gypsum rock or soil is provided with a sensor for monitoring the state of the gypsum rock or soil, the sensor is electrically connected to a controller, and a PH monitoring device is provided in the outer cavity of the lower barrel, and the PH monitoring device is electrically connected to the controller.

[0012] Furthermore, a sliding cavity is provided in one side wall of the water level box body connected to the cave simulation box, and second through holes for connecting the water level box body and the cave simulation box are relatively provided on the side walls of the water level box body located on both sides of the sliding cavity. The water flow isolation mechanism includes a sliding plate slidably connected to the water level box body, one end of the sliding plate is located outside the water level box body, and the other end is located inside the sliding cavity and is provided with a plug for opening or closing the second through hole.

[0013] Furthermore, the air pressure control mechanism also includes an electric telescopic rod, the control panel is arranged in the water level box and divides the cavity of the water level box into two non-connected cavities, one end of the electric telescopic rod is fixedly arranged outside the water level box, and the output end of the electric telescopic rod penetrates into the water level box and is fixed to the control panel.

[0014] Furthermore, the inner cavity of the lower barrel is connected to the cave simulation box through a second pipe, the outer cavity of the lower barrel is connected to the circulating water tank through a third pipe, the cave simulation box and the water level box are connected through a fourth pipe, a second valve is provided on the second pipe, and a third valve is provided on the third pipe.

[0015] Furthermore, both side walls of the outer cavity of the upper barrel and the lower barrel are provided with slots for placing the cover plate.

[0016] A test method for a test device capable of simulating gypsum rock karst collapse comprises the following:

[0017] Study the catastrophic mechanism of water level drop on covered karst collapse:

[0018] Step A1: Calibrate sensors and pH monitoring device;

[0019] Step A2: Close all valves and water flow isolation mechanisms, place gypsum rock in the inner cavity of the lower barrel to the top of the lower barrel, cover the soil on the gypsum rock, bury the soil pressure gauge sensor and displacement gauge sensor in the soil, place the pH monitoring device in the outer cavity of the lower barrel, place the cover plate in the outer cavity of the upper barrel at the same level as the top of the soil, and move the control panel to the side wall of the water level box (inside the opposite side of the water flow isolation mechanism);

[0020] Step A3: Open the exhaust valve and the first valve, fill the water level box with water through the circulating water tank, and then close the first valve;

[0021] Step A4: Open the water flow isolation mechanism and the second valve, drive the control panel to move in the direction close to the water flow isolation mechanism, and inject water into the model box structure through the cave simulation box. If the water in the water level box is not enough to make the water level in the model box structure reach the set height, repeat steps A3 and A4 until the water level in the model box structure reaches the set height;

[0022] Step A5: Close the water flow isolation mechanism, open the first valve, drain the water in the water level box into the circulating water tank, and ensure that the control panel is pushed to the side wall of the water level box close to the water flow isolation mechanism, close the first valve, and let the test device stand for 1 hour;

[0023] Step A6: Open the earth pressure gauge sensor, displacement gauge sensor, PH monitoring device, first valve and water flow isolation mechanism, move the control panel to absorb the water in the cave simulation box into the water level box, close the water flow isolation mechanism after the water level in the model box structure drops to the set height, and let the test device stand for 10 minutes. The sensor and PH monitoring device transmit the information of the model box structure to the controller in real time;

[0024] Step A7: close the second valve, open the third valve, drain the water in the model box structure into the circulating water tank, and drain the water through the circulating water tank to end the test;

[0025] Mechanism of gypsum rock karst collapse disaster under changing hydrodynamic conditions:

[0026] Step B1: Calibrate sensors and pH monitoring device;

[0027] Step B2: Close all valves and water flow isolation mechanisms, remove the upper barrel, place gypsum rock in the inner cavity of the lower barrel, attach the strain gauge pressure sensor to the gypsum rock during the placement process, place the pH monitoring device in the outer cavity of the lower barrel, place the cover plate in the outer cavity at the same level as the top of the soil body, make the pressure in the model box structure consistent, and move the control panel to the side wall of the water level box opposite to the water flow isolation mechanism;

[0028] Step B3: Open the exhaust valve and the first valve, fill the water level box with water through the circulating water tank, and then close the first valve;

[0029] Step B4: Open the water flow isolation mechanism and the second valve, drive the control panel to move in the direction close to the water flow isolation mechanism, and inject water into the model box structure through the cave simulation box. If the water in the water level box is not enough to make the water level in the model box structure reach the set height, repeat steps B3 and B4 until the water level in the model box structure reaches the set height;

[0030] Step B5: Close the water flow isolation mechanism, open the first valve, drain the water in the water level box into the circulating water tank, and ensure that the control panel is pushed to the side wall of the water level box close to the water flow isolation mechanism, close the first valve, and let the test device stand for 1 hour;

[0031] Step B6: Open the strain gauge pressure sensor, the pH monitoring device, the first valve and the water flow isolation mechanism, move the control panel to suck the water in the cave simulation box into the water level box, and close the water flow isolation mechanism after the water level in the model box structure drops to the set height;

[0032] Step B7: Repeat steps B3-B6 until the water level changes and causes the gypsum rock to collapse, and the sensor and the pH monitoring device transmit the information of the model box structure to the controller in real time;

[0033] Step B8: Close the second valve, open the third valve, drain the water in the model box structure into the circulating water tank, and drain the water through the circulating water tank to end the test.

[0034] The beneficial effects of the present invention are as follows: the present scheme includes a plurality of separate and interconnected structures, namely a model box structure in which an upper barrel and a lower barrel are buckled, a karst cave simulation box, a water level control system and a circulating water tank. The entire structure is compact and can be used not only to simulate the catastrophe process of covered karst, but also to simulate the catastrophe process of gypsum rock without a covering layer. The present structure makes the test operation more convenient and the test conditions can be quickly adjusted, thereby shortening the test cycle and improving research efficiency.

[0035] In addition, the model box structure can adjust the combination of the upper barrel and the lower barrel as needed. When studying the gypsum karst dissolution and collapse under the change of groundwater dynamic conditions, it is only necessary to place the gypsum rock sample in the lower barrel. When simulating the karst collapse evolution mechanism under the coupling of water, soil and rock, it is necessary to place soil and gypsum rock, which greatly improves the application range of the test device and is easy to operate. Moreover, the water level control system realizes the water level change in the model box structure through the water flow isolation mechanism and the air pressure control mechanism. When the water level needs to be lowered, it is only necessary to open the sliding plate and use the electric telescopic rod to pull the control plate to reduce the air pressure in the water level box, so as to produce a suction effect on the water in the cave simulation box, which not only simplifies the structure of the test device, but also reduces the test cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the present invention;

[0037] Figure 2 This is a schematic cross-sectional view of a model box structure according to an embodiment of the present invention;

[0038] Figure 3 This is a schematic cross-sectional view of a water level control system according to a first embodiment of the present invention;

[0039] Figure 4 This is a schematic diagram of the structure of a water flow isolation mechanism according to an embodiment of the present invention.

[0040] Numbers in the figure: In the figure: 1. Model box structure; 101. Upper barrel; 102. Lower barrel; 103. Inner cavity; 104. Outer cavity; 105. Cover plate; 106. Partition; 2. Cave simulation box; 3. Water level control system; 301. Water level box; 302. Control board; 303. Exhaust valve; 304. Sliding cavity; 305. Sliding plate; 306. Plug; 307. First through hole; 308. Second through hole; 309. Electric telescopic rod; 4. Circulating water tank; 5. Second pipeline; 6. Third pipeline; 7. Fourth pipeline. DETAILED DESCRIPTION

[0041] In order to make the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the given embodiment is only one implementation method and does not represent all embodiments.

[0042] Embodiment 1

[0043] Combination Figure 1-Figure 4 This embodiment provides a test device for simulating gypsum rock karst collapse, including a model box structure 1, a cave simulation box 2, a water level control system 3 and a circulating water tank 4 which are cyclically connected in sequence.

[0044] The model box structure 1 is the core part of the whole experimental device, which is used to place other reactants such as simulated gypsum rock samples. When studying the gypsum karst dissolution and collapse under the change of groundwater dynamic conditions, it is only necessary to place the gypsum rock samples. When simulating the karst collapse evolution mechanism under the coupling of water, soil and rock, it is necessary not only to place the gypsum rock, but also to cover the soil on the gypsum rock. The cave simulation box 2 is a rectangular parallelepiped with a length of 30cm, a width of 15cm and a width of 30cm. The cave simulation box 2 is used to simulate the karst cave. The cave simulation box 2 is detachable, which is convenient for removing the collapsed soil inside after the test. The water level control system 3 is responsible for controlling the water level of the whole experimental device to simulate the process of gypsum karst collapse under different hydrodynamic conditions. The length, width and height of the circulating water tank 4 are all 30cm. The role of the circulating water tank 4 is to provide a circulating water source for the whole experimental system to ensure the stability of water quality and the consistency of experimental conditions during the experiment. The circulating water tank 4 can be used to effectively recycle and utilize experimental water, thereby reducing the waste of water resources. Preferably, a water inlet is provided at the top of the circulating water tank 4, and a drainage outlet is provided at the lower part of one side wall of the circulating water tank 4.

[0045] The model box structure 1 includes an upper barrel 101 and a lower barrel 102 connected up and down, and the upper barrel 101 and the lower barrel 102 are both double-side wall structures, and the double-side wall structure forms an inner cavity 103 and an outer cavity 104, and the inner cavity 103 and the outer cavity 104 are connected through the inner side wall provided with water-permeable holes, and a partition 106 is provided between the outer cavity 104 of the upper barrel 101 and the outer cavity 104 of the lower barrel 102, and the inner cavity 103 of the upper barrel 101 and the lower barrel 102 are connected. The inner cavity 103 of the upper barrel 101 and the outer cavity 104 of the lower barrel 102 are detachably provided with a cover plate 105 for maintaining a consistent pressure in the model box structure 1. The inner cavity 103 of the upper barrel 101 is provided with soil, and the inner cavity 103 of the lower barrel 102 is provided with gypsum rock. The bottom of the inner cavity 103 of the lower barrel 102 is connected to the cave simulation box 2, and the bottom of the outer cavity 104 of the lower barrel 102 is connected to the circulating water tank 4. The gypsum rock or soil is provided with a sensor for monitoring the state of the gypsum rock or soil, and the sensor is electrically connected to a controller. The outer cavity 104 of the lower barrel 102 is provided with a PH monitoring device, and the PH monitoring device is electrically connected to the controller. In this embodiment, when studying the erosion and collapse of gypsum rock under the change of groundwater dynamic conditions, it is only necessary to set a strain gauge pressure sensor on the gypsum rock sample. When simulating the evolution mechanism of karst collapse under the coupling of water, soil and rock, it is necessary to set a soil pressure gauge sensor and a displacement gauge sensor in the soil. Two upper and lower barrel bodies are set, and the upper and lower barrel body outer cavities 104 are separated by a partition 106 to prevent the exchange of the upper and lower outer cavities 104 from affecting the pH monitoring in the outer cavity 104 of the lower barrel 102.

[0046] The upper barrel 101 and the lower barrel 102 in this embodiment are both cylindrical with an inner cavity 103 radius of 50 cm and an outer cavity 104 radius of 60 cm. The upper barrel 101 is 35 cm high and the lower barrel 102 is 20 cm high. The top of the upper barrel 101 is open, and the bottom of the lower barrel 102 is provided with a bottom plate. Holes are respectively provided on the bottom plates corresponding to the inner cavity 103 and the outer cavity 104 of the upper barrel 101, so as to facilitate communication with the cave simulation box 2 and the circulating water tank 4 respectively.

[0047] Specifically, both side walls of the outer cavity 104 of the upper barrel 101 and the lower barrel 102 are provided with slots for placing the cover plate 105. During the experiment, the cover plate 105 is moved to make the pressure in the model box structure 1 consistent. In this embodiment, a slot is set every 5 cm in the vertical direction on the two side walls. The inner cavity 103 of the lower barrel 102 is connected to the cave simulation box 2 through the second pipe 5, the outer cavity 104 of the lower barrel 102 is connected to the circulating water tank 4 through the third pipe 6, and the cave simulation box 2 is connected to the water level box 301 through the fourth pipe 7. The second pipe 5 is provided with a second valve, and the third pipe 6 is provided with a third valve. During the experiment, the third valve is closed. When the entire experiment is completed, the third valve is opened to discharge the water in the model box structure 1 directly into the circulating water tank 4 without passing through the cave simulation box 2 and the water level control system 3.

[0048] The water level control system 3 includes a water level box 301, a water flow isolation mechanism and an air pressure control mechanism, the air pressure control mechanism includes a control panel 302, the water flow isolation mechanism is arranged on either side of the water level box 301, the control panel 302 is slidably arranged on the other side of the water level box 301, the water flow isolation mechanism is used to adjust the water flow exchange between the water level control system 3 and the cave simulation box 2, the air pressure control mechanism adjusts the air pressure in the water level box 301 by moving the control panel 302, and an exhaust valve 303 is arranged on the top of the water level box 301 away from the end of the water flow isolation mechanism. Preferably, the water level box 301 is a cuboid with a length of 40 cm, a height of 30 cm and a width of 30 cm, and the exhaust valve 303 is arranged at the top of the water level box 301 at a position 4 cm away from the right wall.

[0049] Specifically, a sliding cavity 304 is provided in one side wall of the water level box 301 communicating with the cave simulation box 2, and second through holes 308 for communicating the water level box 301 with the cave simulation box 2 are provided on the side walls of the water level box 301 located on both sides of the sliding cavity 304. The water flow isolation mechanism includes a sliding plate 305 slidably connected to the water level box 301, one end of the sliding plate 305 is located outside the water level box 301, and the other end is located in the sliding cavity 304 and is provided with a plug 306 for opening or blocking the second through hole 308. The water flow isolation mechanism in this embodiment is arranged on the left side of the water level box 301. The thickness of the left side wall of the water level box 301 is 8 cm, which is thicker than other side walls, so as to facilitate the internal arrangement of the sliding cavity 304 and the sliding plate 305. The water flow isolation mechanism is arranged close to the cave simulation box 2, and the connection of the two second through holes 308 is changed by sliding the plug 306, thereby changing the flow of the water body.

[0050] Specifically, the air pressure control mechanism further includes an electric telescopic rod 309, the control panel 302 is arranged in the water level box 301 and divides the cavity of the water level box 301 into two unconnected cavities, one end of the electric telescopic rod 309 is fixedly arranged outside the water level box 301, and the output end of the electric telescopic rod 309 penetrates into the water level box 301 and is fixed to the control panel 302. The control panel 302 moves in the water level box 301 through the extension and retraction of the electric telescopic rod 309 to adjust the air pressure in the water level box 301.

[0051] Specifically, a first through hole 307 is provided at the lower part of any front and rear side wall of the water level box 301 near one end of the water flow isolation mechanism, and the first through hole 307 connects the water level box 301 and the circulating water tank 4 through a first pipe, and a first valve is provided on the first pipe. The position of the first through hole 307 is convenient for pushing the water in the water level box 301 by pushing the control board 302.

[0052] Embodiment 2

[0053] The present invention also provides a test method for a test device capable of simulating gypsum rock karst collapse, comprising the following steps:

[0054] Study the catastrophic mechanism of water level drop on covered karst collapse:

[0055] Step A1: Calibrate sensors and pH monitoring devices. In this embodiment, the sensors involved in studying the catastrophic mechanism of water level drop on covered karst collapse are mainly earth pressure gauge sensors and displacement gauge sensors.

[0056] Step A2: Close all valves and water flow isolation mechanisms, place gypsum rock in the inner cavity 103 of the lower barrel 102 to the top of the lower barrel 102, the gypsum rock is gypsum rock containing karst channels, cover the soil on the gypsum rock, bury the soil pressure gauge sensor and displacement gauge sensor in the soil, place the pH monitoring device in the outer cavity 104 of the lower barrel 102, place the cover plate 105 in the outer cavity 104 of the upper barrel 101 at the same level as the top of the soil, so that the pressure in the model box structure 1 is consistent, and at the same time move the control board 302 to the side wall of the water level box 301 opposite to the water flow isolation mechanism, so that the volume in the water box reaches the maximum. It should be noted that the gypsum rock containing karst channels in this embodiment is specifically the gypsum rock used to contain holes, and these holes are connected to each other.

[0057] Step A3: Open the exhaust valve 303 and the first valve, fill the water level box 301 with water through the circulating water tank 4, and then close the first valve.

[0058] Step A4: Open the water flow isolation mechanism and the second valve, drive the control board 302 to move in the direction close to the water flow isolation mechanism, and inject water into the model box structure 1 through the cave simulation box 2. The water in the model box structure 1 passes through the inner cavity 103 of the lower barrel 102, the outer cavity 104 of the lower barrel 102, and the inner cavity 103 of the upper barrel 101 to the outer cavity 104 of the upper barrel 101. If the water in the water level box 301 is not enough to make the water level in the model box structure 1 reach the set height, repeat steps A3 and A4 until the water level in the model box structure 1 reaches the set height. The set height depends on the test needs. The water level within the soil range can verify the influence of water-soil-rock coupling on the cover karst collapse, and the water level within the gypsum rock layer range is used to verify the influence of gas pressure drive on the cover layer collapse.

[0059] Step A5: Close the water flow isolation mechanism, open the first valve, drain the water in the water level box 301 into the circulating water tank 4 and ensure that the control panel 302 is pushed to the side wall of the water level box 301 close to the water flow isolation mechanism, close the first valve, and let the test device stand for 1 hour to fully saturate the water in the soil and rock layers and restore the simulation scene.

[0060] Step A6: Open the soil pressure gauge sensor, displacement gauge sensor, PH monitoring device, first valve and water flow isolation mechanism, move the control board 302 to absorb the water in the cave simulation box 2 into the water level box 301, and close the water flow isolation mechanism after the water level in the model box structure 1 drops to the set height. Let the test device stand for 10 minutes to ensure that the test is completed and the soil layer will not collapse subsequently after the water level stops changing. The sensor and PH monitoring device transmit the information of the model box structure 1 to the controller in real time.

[0061] Step A7: Close the second valve, open the third valve, drain the water in the model box structure 1 into the circulating water tank 4, and drain the water through the circulating water tank 4 to end the test. Drain the water in the model box structure 1 directly into the circulating water tank 4 without passing through the karst cave simulation box 2 and the water level control system 3, disassemble the karst cave simulation box 2, and clean the collapsed soil inside.

[0062] Mechanism of gypsum rock karst collapse disaster under changing hydrodynamic conditions:

[0063] Step B1: calibrate sensors and pH monitoring devices. In this embodiment, the sensors involved in studying the mechanism of gypsum rock erosion and collapse disaster under changing hydrodynamic conditions are mainly strain gauge pressure sensors.

[0064] Step B2: Close all valves and water flow isolation mechanisms, remove the upper barrel 101, and place gypsum rock in the inner cavity 103 of the lower barrel 102. The gypsum rock contains 20% carbonate rock and karst channels. During the placement process, a strain gauge pressure sensor is attached to the gypsum rock, and a pH monitoring device is placed in the outer cavity 104 of the lower barrel 102. The cover plate 105 is placed in the outer cavity 104 at the same level as the top of the soil body to make the pressure in the model box structure 1 consistent. At the same time, the control panel 302 is moved to the side wall of the water level box 301 opposite to the water flow isolation mechanism to maximize the volume in the water tank.

[0065] Step B3: Open the exhaust valve 303 and the first valve, fill the water level box 301 with water through the circulating water tank 4, and then close the first valve.

[0066] Step B4: Open the water flow isolation mechanism and the second valve, drive the control board 302 to move in the direction close to the water flow isolation mechanism, and inject water into the model box structure 1 through the cave simulation box 2. If the water in the water level box 301 is not enough to make the water level in the model box structure 1 reach the set height, repeat steps B3 and B4 until the water level in the model box structure 1 reaches the set height.

[0067] Step B5: Close the water flow isolation mechanism, open the first valve, drain the water in the water level box 301 into the circulating water tank 4 and ensure that the control panel 302 is pushed to the side wall of the water level box 301 close to the water flow isolation mechanism, close the first valve, and let the test device stand for 1 hour.

[0068] Step B6: Open the strain gauge pressure sensor, pH monitoring device, first valve and water flow isolation mechanism, move the control board 302 to absorb the water in the cave simulation box 2 into the water level box 301, and close the water flow isolation mechanism after the water level in the model box structure 1 drops to the set height.

[0069] Step B7: Repeat steps B3-B6 until the water level changes and causes the gypsum rock to collapse. It should be noted that each time step B5 is repeated, because the rock layer is not easy to collapse, the repeated changes in water level will not cause too much change in the rock layer, so there is no need to leave the test device still for another hour. At the same time, because the test is always ongoing, there is no need to repeatedly open the sensor and PH monitoring device. The sensor and PH monitoring device transmit the information of the model box structure 1 to the controller in real time;

[0070] Step B8: close the second valve, open the third valve, drain the water in the model box structure 1 into the circulating water tank 4, and drain the water through the circulating water tank 4 to end the test.

[0071] The present invention includes a plurality of separate and interconnected structures, namely, a model box structure 1 in which an upper barrel 101 and a lower barrel 102 are buckled, a karst cave simulation box 2, a water level control system 3 and a circulating water tank 4. The entire structure is compact and can be used not only to simulate the karst disaster process of covering type, but also to simulate the disaster process of gypsum rock without covering layer. This structure makes the actual test operation more convenient and can quickly adjust the test conditions, thereby shortening the test cycle and improving the research efficiency.

[0072] The specific embodiments of the present invention are described in detail above with reference to the drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions and variations of these embodiments are made without departing from the principles and spirit of the present invention, and still fall within the scope of protection of the present invention.

Claims

1. A test device capable of simulating gypsum rock karst collapse, characterized in that: It comprises a model box structure (1), a cave simulation box (2), a water level control system (3) and a circulating water tank (4) which are cyclically connected in sequence; The model box structure (1) comprises an upper barrel (101) and a lower barrel (102) connected up and down, the upper barrel (101) and the lower barrel (102) both being double-side wall structures, the double-side wall structures forming an inner cavity (103) and an outer cavity (104), the inner cavity (103) and the outer cavity (104) being connected via an inner wall provided with water-permeable holes, a partition (106) being provided between the outer cavity (104) of the upper barrel (101) and the outer cavity (104) of the lower barrel (102), and the inner cavity (103) of the upper barrel (101) and the outer cavity (104) of the lower barrel (102) being connected to each other. The inner cavity (103) of the upper barrel (101) and the outer cavity (104) of the lower barrel (102) are arranged to be connected from top to bottom, and a cover plate (105) for maintaining a consistent pressure in the model box structure (1) is detachably provided in the outer cavity (104) of the upper barrel (101) and the lower barrel (102); soil is provided in the inner cavity (103) of the upper barrel (101), and gypsum rock is provided in the inner cavity (103) of the lower barrel (102); the bottom of the inner cavity (103) of the lower barrel (102) is connected to the karst cave simulation box (2), and the bottom of the outer cavity (104) of the lower barrel (102) is connected to the circulating water tank (4); The water level control system (3) comprises a water level box (301), a water flow isolation mechanism and an air pressure control mechanism, the air pressure control mechanism comprising a control panel (302), the water flow isolation mechanism being arranged on either the left or right side of the water level box (301), the control panel (302) being slidably arranged on the other side of the water level box (301), the water flow isolation mechanism being used to adjust the water flow exchange between the water level control system (3) and the karst cave simulation box (2), the air pressure control mechanism adjusting the air pressure in the water level box (301) by moving the control panel (302), and an exhaust valve (303) being arranged on the top of the water level box (301) at one end away from the water flow isolation mechanism; A first through hole (307) is provided at the lower part of any front and rear side wall of the water level box (301) near one end of the water flow isolation mechanism. The first through hole (307) is connected to the water level box (301) and the circulating water tank (4) through a first pipe. A first valve is provided on the first pipe.

2. A test device capable of simulating gypsum rock karst collapse according to claim 1, characterized in that: The top of the upper barrel (101) is open, and the bottom of the lower barrel (102) is provided with a bottom plate. The gypsum rock or soil is provided with a sensor for monitoring the state of the gypsum rock or soil, and the sensor is electrically connected to a controller. A pH monitoring device is provided in the outer cavity (104) of the lower barrel (102), and the pH monitoring device is electrically connected to the controller.

3. The test device for simulating gypsum rock karst collapse according to claim 1, characterized in that: A sliding cavity (304) is provided in a side wall of the water level box (301) communicating with the karst cave simulation box (2); second through holes (308) for communicating the water level box (301) with the karst cave simulation box (2) are provided on the side walls of the water level box (301) located on both sides of the sliding cavity (304); the water flow isolation mechanism comprises a sliding plate (305) slidably connected to the water level box (301); one end of the sliding plate (305) is located outside the water level box (301), and the other end is located in the sliding cavity (304) and is provided with a plug (306) for opening or blocking the second through hole (308).

4. A test device capable of simulating gypsum rock karst collapse according to claim 3, characterized in that: The air pressure control mechanism further comprises an electric telescopic rod (309); the control panel (302) is arranged in the water level box (301) and divides the cavity of the water level box (301) into two non-connected cavities; one end of the electric telescopic rod (309) is fixedly arranged outside the water level box (301); and the output end of the electric telescopic rod (309) penetrates into the water level box (301) and is fixed to the control panel (302).

5. The test device capable of simulating gypsum rock karst collapse according to claim 1, characterized in that: The inner cavity (103) of the lower barrel (102) is connected to the karst cave simulation box (2) via a second pipe (5), the outer cavity (104) of the lower barrel (102) is connected to the circulating water tank (4) via a third pipe (6), the karst cave simulation box (2) is connected to the water level box (301) via a fourth pipe (7), the second pipe (5) is provided with a second valve, and the third pipe (6) is provided with a third valve.

6. The test device capable of simulating gypsum rock karst collapse according to claim 1, characterized in that: Both side walls of the outer cavity (104) of the upper barrel (101) and the lower barrel (102) are provided with slots for placing the cover plate (105).

7. A test method for a test device capable of simulating gypsum rock karst collapse according to any one of claims 1 to 6, characterized in that: Including the following, Study the catastrophic mechanism of water level drop on covered karst collapse: Step A1: Calibrate sensors and pH monitoring device; Step A2: Close all valves and water flow isolation mechanisms, place gypsum rock in the inner cavity (103) of the lower barrel (102) to the top of the lower barrel (102), cover the soil on the gypsum rock, bury the sensor in the soil, place the pH monitoring device in the outer cavity (104) of the lower barrel (102), place the cover plate (105) in the outer cavity (104) of the upper barrel (101) at the same level as the top of the soil, and move the control panel (302) to the side wall of the water level box (301) opposite to the water flow isolation mechanism; Step A3: Open the exhaust valve (303) and the first valve, fill the water level box (301) with water through the circulating water tank (4), and then close the first valve; Step A4: opening the water flow isolation mechanism and the second valve, driving the control panel (302) to move in a direction close to the water flow isolation mechanism, and injecting water into the model box structure (1) through the cave simulation box (2); if the water in the water level box (301) is insufficient to make the water level in the model box structure (1) reach the set height, repeating steps A3 and A4 until the water level in the model box structure (1) reaches the set height; Step A5: close the water flow isolation mechanism, open the first valve, drain the water in the water level box (301) into the circulating water tank (4), and ensure that the control panel (302) is pushed to the side wall of the water level box (301) close to the water flow isolation mechanism, close the first valve, and leave the test device to stand for 1 hour; Step A6: Open the sensor, the pH monitoring device, the first valve and the water flow isolation mechanism, move the control panel (302) to absorb the water in the cave simulation box (2) into the water level box (301), close the water flow isolation mechanism after the water level in the model box structure (1) drops to a set height, and leave the test device to stand for 10 minutes. The sensor and the pH monitoring device transmit the information of the model box structure (1) to the controller in real time; Step A7: close the second valve, open the third valve, drain the water in the model box structure (1) into the circulating water tank (4), and drain the water through the circulating water tank (4), thus ending the test; Mechanism of gypsum rock karst collapse disaster under changing hydrodynamic conditions: Step B1: Calibrate sensors and pH monitoring device; Step B2: Close all valves and water flow isolation mechanisms, remove the upper barrel (101), place gypsum rock in the inner cavity (103) of the lower barrel (102), attach the sensor to the gypsum rock during the placement process, place the pH monitoring device in the outer cavity (104) of the lower barrel (102), place the cover plate (105) in the outer cavity (104) at the same level as the top of the soil body, and move the control panel (302) to the side wall of the water level box (301) opposite to the water flow isolation mechanism; Step B3: Open the exhaust valve (303) and the first valve, fill the water level box (301) with water through the circulating water tank (4), and then close the first valve; Step B4: opening the water flow isolation mechanism and the second valve, driving the control panel (302) to move in a direction close to the water flow isolation mechanism, and injecting water into the model box structure (1) through the cave simulation box (2); if the water in the water level box (301) is insufficient to make the water level in the model box structure (1) reach the set height, repeating steps B3 and B4 until the water level in the model box structure (1) reaches the set height; Step B5: close the water flow isolation mechanism, open the first valve, drain the water in the water level box (301) into the circulating water tank (4), and ensure that the control panel (302) is pushed to the side wall of the water level box (301) close to the water flow isolation mechanism, close the first valve, and leave the test device to stand for 1 hour; Step B6: Open the sensor, the pH monitoring device, the first valve and the water flow isolation mechanism, move the control panel (302) to absorb the water in the cave simulation box (2) into the water level box (301), close the water flow isolation mechanism after the water level in the model box structure (1) drops to a set height, and leave the test device to stand for 10 minutes; Step B7: Repeat steps B3-B6 until the water level changes and causes the gypsum rock to collapse, and the sensor and the pH monitoring device transmit the information of the model box structure (1) to the controller in real time; Step B8: Close the second valve, open the third valve, drain the water in the model box structure (1) into the circulating water tank (4), and drain the water through the circulating water tank (4), thus ending the test.

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