A test device and method for simulating the influence of karst cave mouth size on soil potential erosion

Abstract

The present application relates to geotechnical engineering test technical field, especially to a kind of simulation karst cave mouth size influence on soil subsurface erosion test device and method, by controlling current size, and then control electromagnet magnetic force, to reach the purpose of controlling cave mouth size, mechanism of soil subsurface erosion under the action of different karst cave mouth size is studied systematically;Further, the present application extracts the air at the bottom of subsurface erosion soil sample, so that the top and bottom of soil sample form a certain pressure head difference, finally increase total water head, can form larger water head in smaller test box;The present application can simulate constant, variable water head subsurface erosion test to soil, finally by controlling the water flow of in and out weighing box equal, so that the weight of weighing box increases is the weight of soil particle subsurface erosion, realize in indoor simulation different subsurface erosion cave mouth size on soil subsurface erosion, provide basis for the study of soil subsurface erosion mechanism.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geotechnical engineering test, in particular to a test device and method for simulating the influence of karst cave opening size on soil erosion. BACKGROUND

[0002] Karst refers to the long-term erosion of soluble rocks by surface water and groundwater and various karst phenomena formed by the long-term erosion of groundwater. Due to the long-term erosion of groundwater, karst areas often form caves of different sizes, and the soil above the karst is often covered by soil. Under the action of rainwater and groundwater, different water head conditions are often formed. Under the action of rainwater or groundwater, fine particles will be carried away by water and flow out of the karst cave, which will cause serious ground subsidence and seriously threaten urban construction, economic development and even life and property safety.

[0003] The influence of karst cave opening size on soil erosion hides the relationship and mechanism behind it. Therefore, in order to study the mechanism of soil erosion, it is necessary to jointly study the factors leading to soil erosion.

[0004] There is still a lack of equipment to show the influence of water accumulation on soil erosion, and there is also a lack of test method for the characteristics of soil erosion under the action of karst cave opening size. SUMMARY

[0005] The purpose of the present application is to provide a test device and method for simulating the influence of karst cave opening size on soil erosion, which reveals the influence of different erosion cave opening sizes on soil erosion by simulating karst environment, calculates the mass loss of soil particles, and further studies the mechanism of soil erosion.

[0006] To achieve the above purpose, the present application provides a test device for simulating the influence of karst cave opening size on soil erosion, which comprises a soil erosion test system, a water supply system and a weighing system, the input end of the soil erosion test system is connected with the output end of the water supply system, the output end of the soil erosion test system is connected with the input end of the weighing system, the soil erosion test system is used for placing soil samples and forming a test environment, the water for soil erosion test is provided, and the weighing system is used for measuring the mass of soil particles eroded;

[0007] The soil erosion test system comprises a soil erosion test box, an infrared sensing device, an infrared sensing water valve, a cave opening adjusting device, a square funnel and a hose, the soil erosion test box is provided in a hollow box body, the infrared sensing device is arranged on one side of the soil erosion test box, the infrared sensing water valve is arranged on the pipeline through which the water supply system supplies water to the soil erosion test box, the cave opening adjusting device is arranged directly below the soil erosion test box, one end of the square funnel is connected with the cave opening adjusting device, the other end is connected with the hose, and the infrared sensing device is electrically connected with the infrared sensing water valve;

[0008] The side plate of the latent corrosion test box is transparent and visualized, a bottom plate hole opening is formed in the center of the bottom plate of the latent corrosion test box, the bottom plate hole opening is located above the hole adjusting device, the infrared induction device includes four infrared sensors and four infrared induction circuit switches, the four infrared sensors are arranged in the vertical direction outside the side plate of the latent corrosion test box, the infrared sensor at the bottom is located at a vertical height difference of not less than 1m from the bottom plate of the latent corrosion test box, and each infrared sensor is arranged at a vertical distance of 0.25m, the four infrared induction circuit switches are respectively connected with one infrared sensor, are arranged in parallel, and are connected with the infrared induction water valve, the infrared induction water valve has an induction effect when the circuit between the infrared induction device and the infrared induction water valve is closed, and is an ordinary water valve when not connected.

[0009] The hole adjusting device includes two slides, two hole baffle plates, two springs and two electromagnets, the slide is a cuboid with a thickness, the two slides are symmetrically arranged along the central axis of the long side of the latent corrosion test box, a cuboid groove is formed in the long side edge of each slide along the short side direction, two cuboid grooves are combined to form a large groove, the two hole baffle plates are embedded in the large groove, the long side of the hole baffle plate is transversely arranged, each hole baffle plate can slide along the long side of the slide, the two springs are embedded in the hole baffle plate and symmetrically arranged, the two ends of each spring are fixedly connected with the hole baffle plates on both sides, and the two groups of electromagnets are separately arranged on the two sides of the latent corrosion test box, and the long side direction of the electromagnet is parallel to the long side of the hole baffle plate.

[0010] The bottom plate hole opening is a circular opening, the overall size of the two hole baffle plates when closed is greater than the size of the bottom plate hole opening, and the sliding distance of the hole baffle plate along the slide is not less than the radius of the bottom plate hole opening.

[0011] The hole baffle plate, the slide and the square funnel are all made of non-magnetic material, each hole baffle plate is provided with an iron strip on the outside of the long side, and the spring is in the initial state when the two hole baffle plates are closed.

[0012] The water supply system includes an external water source and a water inlet tank, the external water source is connected to the water inlet tank from the top, and the bottom of the water inlet tank is provided with a water supply pipeline connected with the latent corrosion test box.

[0013] The weighing system includes a weighing tank, a filter screen, a vacuum pump, a weighing sensor and a water storage tank, the filter screen is arranged in the weighing tank, the weighing sensor is arranged at the bottom of the weighing tank, the vacuum pump is connected with the upper part of the weighing tank through an air pipe, and the water storage tank is arranged below the weighing tank and connected with the weighing tank through a drainage pipe.

[0014] The end of the hose is connected with the top of the weighing box, an inlet flow meter is arranged on the hose, an outlet flow meter and a drainage adjusting valve are arranged on the drainage pipeline connecting the weighing box with the water storage tank, and an air exhaust valve is arranged on the air pipeline between the vacuum pump and the weighing box.

[0015] The application further provides a test method for simulating the influence of karst cave opening size on soil body hidden erosion.

[0016] Close all valves and set all infrared induction switches to open circuit;

[0017] According to the test requirements, add undisturbed soil or remolded soil into the hidden erosion test box;

[0018] According to the test requirements, add water into the hidden erosion test box and adjust the water level;

[0019] Fix the size of the hidden erosion cave opening at the designed value by adjusting the current of the electromagnet;

[0020] Measure the mass of the lost soil particles in the test environment by using a weighing system;

[0021] After the test is completed, reduce the current of the electromagnet, so that the area of the hidden erosion cave opening is reduced to 0.

[0022] The application provides a test device and method for simulating the influence of karst cave opening size on soil body hidden erosion. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description.

[0024] Figure 1It is a structural schematic view of a test device for simulating the influence of karst cave opening size on soil body hidden erosion according to the present application.

[0025] Figure 2 It is a schematic view of the internal structure of a hidden erosion test box according to the present application.

[0026] Figure 3 It is a structural schematic view of the bottom view of a hidden erosion test box according to the present application.

[0027] Figure 4 It is a structural schematic view of the relationship between the chute-cave baffle according to the present application.

[0028] Figure 5 It is a structural schematic view of the relationship between the square funnel and the hose according to the present application.

[0029] Figure 6 It is a flow schematic view of a test method for simulating the influence of karst cave opening size on soil body hidden erosion according to the present application.

[0030] 1-hidden erosion test system, 11-hidden erosion test box, 111-bottom plate cave opening, 12-infrared induction device, 121-infrared inductor, 122-infrared induction circuit switch, 13-infrared induction water valve, 14-cave adjusting device, 141-chute, 142-cave baffle, 143-spring, 144-electromagnet, 15-square funnel, 16-hose, 2-water supply system, 21-external water source, 22-water inlet tank, 3-weighing system, 31-weighing tank, 32-anti-filtration net, 33-vacuum pump, 34-weighing sensor, 35-water storage tank, 40-inlet flow meter, 41-outlet flow meter, 42-drainage regulating valve, 43-air extraction valve. DETAILED DESCRIPTION

[0031] The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by reference to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0032] Please refer to Figures 1 to 5 The present application provides a test device for simulating the influence of karst cave opening size on soil body hidden erosion, which comprises a hidden erosion test system 1, a water supply system 2 and a weighing system 3. The input end of the hidden erosion test system 1 is connected with the output end of the water supply system 2, and the output end of the hidden erosion test system 1 is connected with the input end of the weighing system 3. The hidden erosion test system 1 is used for placing soil samples and forming a test environment. The water supply system 2 is used for providing water for hidden erosion test. The weighing system 3 is used for measuring the mass of hidden erosion soil particles.

[0033] The corrosion test system 1 comprises a corrosion test box 11, an infrared induction device 12, an infrared induction water valve 13, an opening adjusting device 14, a square funnel 15 and a hose 16, the corrosion test box 11 is provided in a hollow box body, the infrared induction device 12 is arranged on one side of the corrosion test box 11, the infrared induction water valve 13 is arranged on a pipeline through which the water supply system 2 supplies water to the corrosion test box 11, the opening adjusting device 14 is arranged directly below the corrosion test box 11, one end of the square funnel 15 is connected with the opening adjusting device 14, the other end is connected with the hose 16, and the infrared induction device 12 is electrically connected with the infrared induction water valve 13;

[0034] The side plate of the corrosion test box 11 is provided in a transparent visual manner, a bottom plate opening 111 is formed in the center of the bottom plate of the corrosion test box 11, the bottom plate opening 111 is located above the opening adjusting device 14, the infrared induction device 12 comprises four infrared sensors 121 and four infrared induction circuit switches 122, the four infrared sensors 121 are arranged in a vertical direction outside the side plate of the corrosion test box 11, the infrared sensor 121 located at the bottom is spaced apart from the bottom plate of the corrosion test box 11 by a vertical height difference of not less than 1 m, and each infrared sensor 121 is arranged at a vertical distance of 0.25 m, the four infrared induction circuit switches 122 are respectively connected with one infrared sensor 121 in parallel and then connected with the infrared induction water valve 13, the infrared induction water valve 13 has an induction effect when the circuit between the infrared induction water valve 13 and the infrared induction device 12 is closed, and is an ordinary water valve when not connected.

[0035] The opening adjusting device 14 comprises two slides 141, two opening baffles 142, two springs 143 and two groups of electromagnets 144, the slide 141 is a cuboid with a thickness, the two slides 141 are symmetrically arranged along the central axis of the long side of the corrosion test box 11, a cuboid groove is dug in the long side edge of each slide 141 along the short side direction, two cuboid grooves are combined to form a large groove, the two opening baffles 142 are embedded in the large groove, the long side of the opening baffle 142 is arranged transversely, each opening baffle 142 can slide along the long side of the slide 141, the two springs 143 are embedded in the opening baffle 142 and symmetrically arranged, the two ends of each spring 143 are fixedly connected with the opening baffles 142 on both sides, and the two groups of electromagnets 144 are separately arranged on the two sides of the corrosion test box 11, and the long side direction of the electromagnet 144 is parallel to the long side of the opening baffle 142.

[0036] The bottom plate hole opening 111 is a circular opening, and the overall size of the two hole flaps 142 when closed is greater than the size of the bottom plate hole opening 111, and the sliding distance of the hole flaps 142 along the slide 141 is not less than the radius of the bottom plate hole opening 111.

[0037] The hole flaps 142, the slide 141 and the square funnel 15 are all made of non-magnetic materials, and each hole flap 142 is provided with an iron strip outside the long side, and the spring 143 is in the initial state when the two hole flaps 142 are closed.

[0038] The water supply system 2 comprises an external water source 21 and a water inlet tank 22, the external water source 21 is connected to the water inlet tank 22 from above, and the bottom of the water inlet tank 22 is provided with a water supply pipeline connected with the hidden corrosion test box 11.

[0039] The weighing system 3 comprises a weighing tank 31, a back filter screen 32, a vacuum pump 33, a weighing sensor 34 and a water storage tank 35, the back filter screen 32 is arranged in the weighing tank 31, the weighing sensor 34 is arranged at the bottom of the weighing tank 31, the vacuum pump 33 is connected with the upper part of the weighing tank 31 through an air duct, and the water storage tank 35 is arranged below the weighing tank 31 and connected with the weighing tank 31 through a drainage pipeline.

[0040] The end of the hose 16 is connected with the top of the weighing tank 31, an inlet flow meter 40 is arranged on the hose 16, an outlet flow meter 41 and a drainage adjusting valve 42 are arranged on the drainage pipeline connecting the weighing tank 31 with the water storage tank 35, and an air exhaust valve 43 is arranged on the air duct between the vacuum pump 33 and the weighing tank 31.

[0041] Specifically, the influence of different karst hole sizes on soil hidden corrosion is simulated, the magnetic force generated by the electromagnet 144 is increased by increasing the current size, so that the opening area of the hole flap 142 is increased, so that the area of the bottom plate hole opening 111 blocked by the flap is increased, and finally the expansion of the hole is realized; the spring 143 located in the middle of the groove of the hole flap 142 is in the original length state when the two hole flaps 142 are closed, and the spring 143 is deformed due to the magnetic force, so that the elastic force is increased; when the magnetic force and the elastic force are equal, the size of the bottom plate hole opening 111 is fixed at the design value; by reducing the current, the magnetic force is reduced, and the spring 143 located in the groove of the hole flap 142 will cause the opening area of the hole flap 142 to decrease due to the elastic force, so that the exposed hole area decreases, and finally the reduction of the bottom plate hole opening 111 is realized.

[0042] Further, please refer to Figure 6The application further provides a test method for simulating the influence of karst cave opening size on soil potential erosion, and the test method comprises the following steps by using the test device for simulating the influence of karst cave opening size on soil potential erosion:

[0043] S1: close all valves, and set all infrared induction switches to open circuit;

[0044] S2: add undisturbed soil or remolded soil in the potential erosion test box according to test requirements;

[0045] S3: add water in the potential erosion test box and adjust the water level according to test requirements;

[0046] S4: fix the size of the potential erosion cave opening at the test design value by adjusting the current of the electromagnet;

[0047] S5: measure the mass of soil particles lost in the test environment by using the weighing system;

[0048] S6: reduce the area of the potential erosion cave opening to 0 by reducing the current of the electromagnet after the test is completed.

[0049] Specifically, the test method for simulating several environments is further described as follows:

[0050] 1. When a variable water head test is performed:

[0051] Step one, close all water valves and gas valves, and set all infrared induction switch lines 122 to open circuit;

[0052] Step two, fill undisturbed soil or remolded soil with the same bottom area as the bottom area of the potential erosion test box 11 into the potential erosion test box 11; the height of the undisturbed soil or remolded soil sample is self-determined according to the test;

[0053] Step three, according to the required water head of the test, fill the water in the water inlet tank 22 with a water source, manually open the infrared induction water valve 13, add water to the potential erosion test box 11, and manually close the infrared induction water valve 13 when the water level reaches the design water level;

[0054] Step four, fill a certain amount of water into the weighing tank 31, and record the reading of the weighing sensor 34 at this time;

[0055] Step five, increase the current passing through the electromagnet 144, so that the potential erosion cave opening is opened to the set value, so that the size of the cave opening is fixed at the test design value;

[0056] Step six, according to the reading of the inlet flow meter 40, manually control the drainage adjusting valve 42 so that the reading of the outlet flow meter 41 is the same as that of the inlet flow meter 40, and record the reading of the weighing sensor 34 at this time, and the increased weight is the mass of soil particles lost from the potential erosion test box 11;

[0057] Step seven, when the water level of the underground erosion test box 11 is reduced to zero, the water in the underground erosion test box 11 flows into the water storage box 35 in the weighing system 3 along with the occurrence of the underground erosion; the infrared induction water valve 13 is manually opened, and the underground erosion test box 11 is replenished with water to the set water level line;

[0058] Step eight, the reading of the weighing sensor 34 is recorded after each cycle; the above operation is repeated until the reading of the weighing sensor 34 no longer changes after a cycle of water, the test is stopped, and all devices of the equipment are turned off.

[0059] Step nine, the current passing through the electromagnet 144 is reduced, so that the hole area is reduced to 0;

[0060] 2. When performing the constant water head test:

[0061] Step one, all water valves, air valves are closed, and all line infrared induction line switches 122 are set to open circuit;

[0062] Step two, the undisturbed soil with the same bottom area as the underground erosion test box 11 is filled into the underground erosion test box 11; the underground erosion test box 11 provides four infrared sensing devices 12, each of which represents a design water head, the selected constant water head position is matched with the infrared sensing device 12, and the line between the corresponding infrared sensing device 12 and the infrared sensing water valve 13 is closed; the height of the undisturbed soil or remolded soil sample maintains a vertical distance of 1 m from the selected infrared sensing device 12, or it can be self-determined according to the test requirements, but the height of the soil sample should not be the same as the height of the selected infrared sensing device 12 from the bottom plate of the underground erosion test box 111.

[0063] Step three, according to the required water head of the test, the water in the water inlet box 22 is filled through the water source, the infrared sensing water valve 13 is opened, and water is added to the underground erosion test box 11;

[0064] Step four, the infrared sensing water valve 13 is opened, the water inlet box 22 is filled with water to the underground erosion test box 11 through the water supply pipeline, when the water level reaches the height of the selected infrared sensing device 12, the infrared sensing water valve 13 is automatically closed; when the water level is lower than the height of the selected infrared sensing device 12, the infrared sensing water valve 13 is automatically opened, and the water inlet box 22 automatically replenishes water to the underground erosion test box 11;

[0065] Step five, a certain amount of water is filled into the weighing box 31, and the reading of the weighing sensor 34 at this time is recorded;

[0066] Step six, increase the current passing through the electromagnet 144, so that the underground erosion hole opens to a set value, so that the size of the hole is fixed at the design value of the test;

[0067] Step seven, according to the reading of the inlet flow meter 40, manually control the drainage regulating valve 42, so that the reading of the outlet flow meter 41 is the same as that of the inlet flow meter 40, at this time the increased weight of the weighing sensor 34 is the mass of soil particles lost from the underground erosion test box 11;

[0068] Step eight, according to the set weighing interval time, record the value of the weighing sensor 34 once every time interval until there is no change in the reading in a certain time interval, stop the test, and turn off all equipment switches.

[0069] Step nine, reduce the current passing through the electromagnet 144 so that the hole opening area is reduced to 0;

[0070] 3. When performing a variable head test on soil that requires a certain critical hydraulic gradient to occur underground erosion, etc.:

[0071] Step one, close all water valves and air valves, and set all infrared induction circuit switches 122 to open circuit;

[0072] Step two, fill the undisturbed soil with the same bottom area as the underground erosion test box 11 into the underground erosion test box 11; the height of the undisturbed soil sample is determined according to the test;

[0073] Step three, according to the required water head of the test, fill the water in the water inlet tank 22 through the water source, open the infrared induction water valve 13, and add water to the underground erosion test box 11, when the water level reaches the designed water level, close the infrared induction water valve 13;

[0074] Step four, fill the weighing tank 31 with a certain amount of water, and record the reading of the weighing sensor 34 at this time;

[0075] Step five, open the air valve 43, and according to the test requirements, use the vacuum pump 33 to pump out the air in the space between the bottom of the underground erosion test box 11 and the weighing tank 31;

[0076] Step six, increase the current passing through the electromagnet 144 so that the underground erosion hole opens to a set value, so that the hole size is fixed at the designed value of the test;

[0077] Step seven, according to the reading of the inlet flow meter 40, manually control the drainage regulating valve 42, so that the reading of the outlet flow meter 41 is the same as that of the inlet flow meter 40, record the reading of the weighing sensor 34 at this time, and the increased weight is the mass of soil particles lost from the underground erosion test box 11;

[0078] Step eight, when the water level in the underground erosion test box 11 drops to zero, the water in the underground erosion test box 11 flows into the water storage tank 35 in the weighing system 3 with the occurrence of underground erosion; manually open the infrared induction water valve 13 to replenish the underground erosion test box 111 to the set water level line;

[0079] Step nine, record the reading of the load cell 34 after each cycle; repeat the above operation until the reading of the load cell 34 does not change after a cycle of water, stop the test, and turn off all the devices of the equipment.

[0080] Step ten, reduce the current through the electromagnet 144 so that the hole area is reduced to 0;

[0081] 4. When performing a constant water head test on soil that requires a certain critical hydraulic gradient to occur, such as hidden corrosion:

[0082] Step one, close all water valves, air valves, and set all infrared induction circuit switches 122 to open circuit;

[0083] Step two, fill the undisturbed soil with the same bottom area as the hidden corrosion test box 11 into the hidden corrosion test box 11; the hidden corrosion test box 11 provides four infrared sensing devices 12, each of which represents a designed water head, and the selected constant water head position is matched with the infrared sensing device 12, and the line between the corresponding infrared sensing device 12 and the infrared sensing water valve 13 is closed; the height of the undisturbed soil sample is kept 1m vertically away from the selected infrared sensing device 12, or it can be self-determined according to the test requirements, but the height of the soil sample should not be the same as the height of the selected infrared sensing device 12 from the bottom plate of the hidden corrosion test box 11.

[0084] Step three, according to the required water head of the test, fill the water in the water inlet tank 22 through the water source, open the infrared sensing water valve 13, and add water to the hidden corrosion test box 11;

[0085] Step four, open the infrared sensing water valve 13, fill the water in the water inlet tank 22 through the water supply pipeline to the hidden corrosion test box 11, when the water level reaches the height of the selected infrared sensing device 12, the infrared sensing water valve 13 automatically closes; when the water level is lower than the height of the selected infrared sensing device 12, the infrared sensing water valve 13 automatically opens, and the water inlet tank 22 automatically supplements water to the hidden corrosion test box 11;

[0086] Step five, fill a certain amount of water into the weighing tank 31, and record the reading of the load cell 34 at this time;

[0087] Step six, open the air valve 43, and use the vacuum pump 33 to extract the air in the space between the bottom of the hidden corrosion test box 11 and the weighing tank 31;

[0088] Step seven, increase the current through the electromagnet 144 so that the hidden corrosion hole opens to a set value, so that the hole size is fixed at the design value of the test;

[0089] Step eight, according to the reading of the inlet flow meter 40, manually control the drainage regulating valve 42, so that the reading of the outlet flow meter 41 is the same as that of the inlet flow meter 40, at this time the increased weight of the weighing sensor 34 is the mass of the soil particles lost from the underground erosion test box 11;

[0090] Step nine, according to the set weighing interval time, record the value of the weighing sensor 34 once every time interval until the reading does not change in a certain time interval, stop the test, and turn off all the equipment switches.

[0091] Step ten, reduce the current through the electromagnet 144, so that the hole area is reduced to 0.

[0092] In summary, the application has the beneficial effects that:

[0093] (1) The application controls the size of the hole by controlling the size of the current and the magnetic force of the electromagnet, thereby controlling the change of the size of the hole

[0094] (2) The application designs a new device that can independently control the size of the underground erosion hole, and systematically studies the mechanism of underground erosion of soil under the action of different sizes of karst holes;

[0095] (3) The application extracts the air at the bottom of the underground erosion soil sample, so that a certain pressure head difference is formed between the top and bottom of the soil sample, and finally the total water head is increased, so that a larger water head can be formed in a smaller test box;

[0096] (4) The application can simulate a new device for conducting underground erosion tests on soil under the action of constant and variable water heads;

[0097] (5) The application controls the water flow into and out of the weighing tank to be equal through the water valve, so that the increased weight of the weighing tank is the weight of the soil particles eroded from the underground erosion test box, and the mass of the soil particles lost can be weighed in real time;

[0098] (6) The application automatically supplies water to the underground erosion test box or stops supplying water through the infrared sensing device and the infrared sensing water valve, realizes the automation of maintaining the stability of the water head, and simplifies the operation.

[0099] The above disclosure is only one preferred embodiment of the application, and of course cannot limit the scope of the rights of the application, and those skilled in the art can understand that all or part of the above-mentioned embodiments can be implemented, and equivalent changes made according to the claims of the application still belong to the scope covered by the application.

Claims

1. An experimental apparatus for simulating the effect of karst cave entrance size on soil erosion, characterized in that, The system includes a erosion testing system, a water supply system, and a weighing system. The input end of the erosion testing system is connected to the output end of the water supply system, and the output end of the erosion testing system is connected to the input end of the weighing system. The erosion testing system is used to place soil samples and form a testing environment. The water supply system is used to provide water for the erosion test, and the weighing system is used to measure the mass of eroded soil particles. The erosion testing system includes an erosion test chamber, an infrared sensor, an infrared sensor water valve, an opening adjustment device, a square funnel, and a hose. The erosion test chamber is a hollow box. The infrared sensor is located on one side of the erosion test chamber. The infrared sensor water valve is located on the pipe that supplies water to the erosion test chamber from the water supply system. The opening adjustment device is located directly below the erosion test chamber. One end of the square funnel is connected to the opening adjustment device, and the other end is connected to the hose. The infrared sensor and the infrared sensor water valve are electrically connected. The side panels of the erosion test chamber are transparent and visible. The bottom plate of the erosion test chamber has a bottom plate opening in the center, which is located above the opening adjustment device. The infrared sensing device includes four infrared sensors and four infrared sensing circuit switches. The four infrared sensors are arranged vertically on the outside of the side panels of the erosion test chamber. The vertical height difference between the bottom infrared sensor and the bottom plate of the erosion test chamber is not less than 1m, and each infrared sensor is arranged 0.25m apart vertically. The four infrared sensing circuit switches are each connected to one infrared sensor and are arranged in parallel to the infrared sensing water valve. The infrared sensing water valve has a sensing function when the circuit between the infrared sensing device and the infrared sensing device is closed, and is a normal water valve when not connected. The opening adjustment device includes two slides, two opening baffles, two springs, and two sets of electromagnets. The slides are cuboids with thickness. The two slides are symmetrically arranged along the central axis of the long side of the erosion test chamber. Each slide has a cuboid groove dug along the short side at the edge of the long side. The two cuboid grooves are combined to form a large groove. The two opening baffles are fitted into the large groove. The long sides of the opening baffles are arranged laterally. Each opening baffle can slide along the long side of the slide. The two springs are embedded in the opening baffles and are symmetrically arranged. The two ends of each spring are fixedly connected to the opening baffles on both sides. The two sets of electromagnets are respectively located on both sides of the erosion test chamber. The long side of the electromagnets is parallel to the long side of the opening baffle. The opening baffle, the slide, and the square funnel are all made of non-magnetic materials.

2. The experimental apparatus for simulating the influence of karst cave entrance size on soil erosion as described in claim 1, characterized in that, Each of the opening baffles has an iron strip on its outer long side, and the spring is in its initial state when the two opening baffles are closed.

3. The experimental apparatus for simulating the influence of karst cave entrance size on soil erosion as described in claim 2, characterized in that, The water supply system includes an external water source and an inlet tank. The external water source is connected to the inlet tank from above, and a water supply pipe is provided at the bottom of the inlet tank to connect to the submerged corrosion test chamber.

4. The experimental apparatus for simulating the influence of karst cave entrance size on soil erosion as described in claim 3, characterized in that, The weighing system includes a weighing box, a reverse filter, a vacuum pump, a weighing sensor, and a water tank. The reverse filter is installed inside the weighing box, the weighing sensor is placed at the bottom of the weighing box, the vacuum pump is connected to the upper part of the weighing box through a ventilation pipe, and the water tank is located below the weighing box and connected to the weighing box through a drainage pipe.

5. The experimental apparatus for simulating the influence of karst cave entrance size on soil erosion as described in claim 4, characterized in that, The end of the hose is connected to the top of the weighing box. An inlet flow meter is installed on the hose. An outlet flow meter and a drainage regulating valve are installed on the drainage pipe connecting the weighing box and the water storage tank. An air extraction valve is installed on the ventilation pipe between the vacuum pump and the weighing box.

6. A test method for simulating the effect of karst cave entrance size on soil erosion, employing the test apparatus for simulating the effect of karst cave entrance size on soil erosion as described in claim 5, characterized in that, Includes the following steps: Close all valves and set all infrared sensor switches to open circuit; Add undisturbed soil or remolded soil to the erosion test chamber according to the test requirements; Add water to the erosion test chamber and adjust the water level according to the test requirements; The size of the erosion opening was fixed at the experimental design value by adjusting the current of the electromagnet; The mass of soil particles lost under test conditions was measured using a weighing system. The experiment was completed by reducing the current passing through the electromagnet, thereby reducing the area of ​​the erosion opening to 0.

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