Dual-medium water flow and solute interactive simulation device and test method

Abstract

The invention provides a dual-medium water flow and solute interactive simulation device, and relates to the technical field of hydrogeology. A water tank; a drainage pipe and a rock simulant are arranged in the sand box, the rock simulant is filled between the drainage pipe and the sand box, a water passing opening is formed in the pipe wall of the drainage pipe, one end of the drainage pipe is connected with the water inlet box through a water conveying pipe, a plurality of drainage holes are formed in one side of the sand box, and a rainfall simulator is arranged at the top of the sand box; the tracer injector is arranged on the water conveying pipe; the flow control valve is arranged on the water conveying pipe; and the pressure monitoring system is detachably connected with part of the drainage holes respectively. The device has the beneficial effects that the device can be used for simulating the solute interaction process of the sinkhole-karst pipeline under the condition of concentrated supply, and can control the flow rate, the tracer dosage and the number of closed drain holes; the water flow and solute transport process of the sinkhole-karst pipeline system under the influence of various supplement, diameter and drainage conditions, especially rainfall supplement and open fracture outward drainage is simulated.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogeology, and particularly relates to a dual-medium water flow and solute interaction simulation device and test method. Background Art

[0002] During the recharge process of karst water, various water sources from the surface often carry pollutants in karst depressions and enter the underground river system through sinkholes in a concentrated injection manner. The migration law of pollutants in karst conduits and fracture media directly controls the pollution process of the underground river system and affects the change of water quality. Therefore, studying the migration law of solutes in karst conduits is very important for studying and evaluating water quality and hydrogeological work. The development of karst starts from the dissolution and expansion of fractures. Erosive water flows into the fractures and continuously expands the water flow channels by dissolving the fracture walls to form karst conduits. In terms of the formation mechanism, there will be a large number of fractures on the wall of the karst conduit, and when the water flows in the karst conduit, it will disperse to the surrounding fractures. Especially in the southern karst area of China, the karst aquifer media have a high degree of heterogeneity, and often multiple aquifer media such as caves, conduits, fractures, and pores coexist, and the groundwater movement in different-sized voids is not synchronous. Therefore, when studying the solute loss in karst conduits, the influence of fractures on solute loss cannot be ignored. In current indoor physical model tests, the research on how different water flow velocities affect the solute transport in the sinkhole-karst conduit system is not sufficient. In addition, when designing a device for simulating the water flow and solute exchange in karst conduits, it is generally regarded as a closed system, ignoring the dynamic interaction of the external environment on the karst conduit system in terms of flow rate and solute. This is obviously inconsistent with the actual field process, and the hydrogeological factors considered in the simulation device are not comprehensive. Summary of the Invention

[0003] In view of this, in order to solve the above research problems regarding different water flow velocities and simulating open fractures on the solute loss in karst conduits, the embodiments of the present invention provide a dual-medium water flow and solute interaction simulation device and test method.

[0004] The embodiments of the present invention provide a dual-medium water flow and solute interaction simulation device, including:

[0005] A water inlet tank;

[0006] A water tank;

[0007] A sand box, which is arranged in the water tank and below the water inlet tank. A drain pipe and a rock simulator are arranged inside the sand box. The rock simulator is filled between the drain pipe and the sand box. Water passing holes are arranged on the pipe wall of the drain pipe. One end of the drain pipe is connected to the water inlet tank through a water delivery pipe. A plurality of drain holes are arranged on one side of the sand box, and a rainfall simulator is arranged on the top of the sand box;

[0008] A tracer injector, which is arranged on the water delivery pipe;

[0009] A flow control valve, which is arranged on the water delivery pipe and is located between the tracer injector and the drain pipe;

[0010] And a pressure monitoring system, which is respectively detachably connected to some of the drain holes to monitor the hydraulic pressure in some of the drain holes.

[0011] Furthermore, it further includes a first water collecting tank and a second water collecting tank. The first water collecting tank is connected to the other end of the drain pipe through a first water outlet pipe, and a flow meter is arranged on the first water outlet pipe. The second water collecting tank is connected to the water tank through a second water outlet pipe.

[0012] Furthermore, the sand box is a cuboid-shaped box body, and the drain holes are arranged in multiple rows and columns.

[0013] Furthermore, the upper end of the sand box is open. The rainfall simulator includes a rainwater pipe, a regulating valve and a plurality of rain distribution pipes. The rainwater pipe is arranged along the edge of the upper port of the sand box. The regulating valve is arranged at the input end of the rainwater pipe. Each rain distribution pipe is arranged in the rainwater pipe at intervals, and the rain distribution pipe is provided with rain holes.

[0014] Furthermore, the rock simulant is a glass brick or quartz sand grains.

[0015] Furthermore, the tracer injector includes a syringe and a first valve, and the first valve is located downstream of the syringe.

[0016] Furthermore, an overflow plate is arranged in the water inlet tank. The overflow plate is vertically arranged, and the lower end is fixedly connected to the bottom surface of the water inlet tank. One end of the water delivery pipe is connected to the bottom surface of the water inlet tank on one side of the overflow plate, and the bottom surface of the water inlet tank on the other side of the overflow plate is connected to a third water outlet pipe.

[0017] Furthermore, the pressure monitoring system includes a scale plate and a plurality of piezometers. Each piezometer is vertically arranged on the scale plate, and each piezometer can be detachably connected to a drain hole through a connecting hose.

[0018] Furthermore, each drain hole is provided with a plug.

[0019] In addition, an embodiment of the present invention also provides a dual-medium water flow and solute interaction test method, which uses the above-mentioned dual-medium water flow and solute interaction simulation device, and includes the following steps:

[0020] S1. Connect some of the drain holes to the pressure monitoring system;

[0021] S2. After the water level in the water inlet tank reaches a predetermined height, water is conveyed into the sand box through the water conveyance pipe. The water flow rate into the sand box is adjusted by the flow control valve, and water is sprayed onto the top of the sand box through the rainfall simulator.

[0022] S3. After the water flow rate flowing out of the drain pipe becomes stable, the water pressure in the sand box is obtained by the pressure monitoring system, and then the drain holes connected to the pressure monitoring system are blocked.

[0023] S4. A tracer solution is injected into the water conveyance pipe, and the changes in the tracer concentrations at the outlet of the drain pipe and in the water tank are obtained.

[0024] S5. Multiple sets of test data are obtained by changing variables. The variables are at least one of the rainfall intensity controlled by the rainfall simulator, the concentration of the injected tracer solution, the water flow velocity controlled by the flow control valve, and the number of closed drain holes, so as to study the solute interaction law of the sinkhole-karst pipeline under different conditions.

[0025] The beneficial effects brought by the technical solution provided by the embodiment of the present invention are as follows:

[0026] 1. For the dual-medium water flow and solute interaction simulation device and test method of the present invention, rock analogs are filled in the sand box to simulate the fractured medium, water passing holes are opened on the pipe wall of the drain pipe to simulate the karst pipeline, and the drain holes enable water flow and solutes to be discharged from the fractured medium, simulating the function of open fractures. It can be used to simulate the solute interaction process of the sinkhole-karst pipeline under the condition of concentrated recharge, and simulation tests can be carried out by controlling the flow velocity, the amount of tracer, and the number of closed drain holes, simulating the water flow and solute transport processes of the sinkhole-karst pipeline system under various recharge, runoff, and drainage conditions, especially the influence of rainfall recharge and open fractures on external drainage.

[0027] 2. The dual-medium water flow and solute interaction simulation device of the present invention is similar to the dynamic interaction characteristics of the water flow and solutes of the sinkhole-karst pipeline under the condition of concentrated recharge. The simulation device is conducive to observation, has strong operability, and the influencing factors are controllable. It is beneficial to realize the quantitative research of hydraulic transmission and solute transport, and is of great significance for the theoretical research on groundwater solute transport. Description of the Drawings

[0028] Figure 1 is a schematic diagram of a dual-medium water flow and solute interaction simulation device of the present invention;

[0029] Figure 2 is a schematic diagram of the internal structure of the sand box.

[0030] In the figure: 1, water supply pipe; 2, water inlet tank; 3, overflow plate; 4, second valve; 5, syringe; 6, first valve; 7, flow control valve; 8, sand box; 9, drain hole; 10, water tank; 11, flow meter; 12, third valve; 13, rainwater pipe; 14, first water collection tank; 15, frame; 16, roller; 17, piezometric tube; 18, connecting hose; 19, column; 20, water delivery pipe; 21, first water outlet pipe; 22, third water outlet pipe; 23, rain distribution pipe; 24, rainwater injection pipe; 25, second water outlet pipe; 26, second water collection tank; 27, drain pipe; 28, rock simulant; 29, scale board; 30, water passing opening. Detailed implementation manners

[0031] To make the objectives, technical solutions and advantages of the present invention clearer, the following will further describe the implementation manners of the present invention with reference to the accompanying drawings. The following introduces a relatively superior one among multiple possible embodiments of the present invention, aiming to provide a basic understanding of the present invention, but not aiming to identify the key or decisive elements of the present invention or limit the scope to be protected.

[0032] In all the examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0033] For technologies, methods and devices known to those of ordinary skill in the relevant fields, they may not be discussed in detail, but where appropriate, the said technologies, methods and devices should be regarded as part of the specification.

[0034] It should be noted that: Similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0035] In the description of the present invention, it should be noted that the circuits, electronic components and modules involved in the present invention are all prior arts, and those skilled in the art can fully implement them without further elaboration. The content protected by the present invention does not involve improvements to the internal structure and methods either.

[0036] Furthermore, it should be noted that unless otherwise clearly specified and defined, the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0037] Please refer to Figure 1 , an embodiment of the present invention provides a dual-medium water flow and solute interaction simulation device, including a water inlet tank 2, a water tank 10, a sand box 8, a tracer injector, a flow control valve 7 and a pressure monitoring system.

[0038] The water inlet tank 2 is used to input water flow with a predetermined pressure into the sand box 8. A plurality of columns 19 are provided at the bottom of the water inlet tank 2, and the water inlet tank 2 is supported on the columns 19, so that the height of the water inlet tank 2 is higher than that of the sand box 8, and the accumulated water in the water inlet tank 2 can automatically enter the sand box 8 by gravity.

[0039] Combined with Figure 2 As shown, the sand box 8 is arranged in the water tank 10 and is located below the water inlet tank 2. A drain pipe 27 and a rock simulator 28 are arranged inside the sand box 8. The rock simulator 28 is filled between the drain pipe 27 and the sand box 8. Water passing holes 30 are provided on the pipe wall of the drain pipe 27. One end of the drain pipe 27 is connected to the water inlet tank 2 through a water delivery pipe 20. A plurality of drain holes 9 are provided on one side of the sand box 8, and a rainfall simulator is provided on the top of the sand box 8.

[0040] Specifically, an overflow plate 3 is arranged in the water inlet tank 2. The overflow plate 3 is vertically arranged, and the lower end is fixedly connected to the bottom surface of the water inlet tank 2. The overflow plate 3 divides the inside of the water inlet tank 2 into two parts at intervals. One end of the water delivery pipe 20 is connected to the bottom surface of the water inlet tank 2 on one side of the overflow plate 3, and the bottom surface of the water inlet tank 2 on the other side of the overflow plate 3 is connected to a third water outlet pipe 22. One side of the water inlet tank 2 is connected to a water supply pipe 1, and the bottom surface of this side of the water inlet tank 2 is connected to the water delivery pipe 20. Water is input into the water inlet tank 2 through the water supply pipe 1. When the accumulated water on one side of the overflow plate 3 in the water inlet tank 2 reaches the height of the overflow plate 3, it will overflow to the other side of the overflow plate 3 and then be discharged by the third water outlet pipe 22, so that the accumulated water in the water inlet tank 2 always remains at the height of the overflow plate 3. A second valve 4 is provided on the water delivery pipe 20, and the opening and closing of the water delivery pipe 20 are controlled through the second valve 4.

[0041] It should be noted that the height and position of the overflow plate 3 can be flexibly designed according to the required water inlet conditions for the test. For example, in this embodiment, the overflow plate 3 is located at the 1 / 5 position in the length direction of the water inlet tank 2, dividing the space inside the water inlet tank 2 into two parts with a ratio of 1:4. Generally, the overflow plate 3 is more than 5 cm lower than the top surface height of the water inlet tank 2.

[0042] The shape of the sand box 8 can be flexibly set according to actual test requirements. In this embodiment, for example, the sand box 8 is a cuboid box made of transparent acrylic plates. A frame 15 is provided at the bottom of the sand box 8. Here, the water tank 10 is supported on the frame 15, the sand box 8 is fixed in the water tank 10, and a plurality of rollers 16 are provided at the bottom of the frame 15. The frame 15 can be moved through the rollers 16 to freely move the sand box 8.

[0043] The drain pipe 27 is generally horizontally arranged in the middle of the sand box 8, and both ends of the drain pipe 27 extend to both ends of the sand box 8. The rock analog 28 can be selected from glass bricks or quartz sand grains. The rock analog 28 is filled between the outer wall of the drain pipe 27 and the inner wall of the sand box 8 to simulate a fractured medium. The water passing holes 30 on the drain pipe 27 cover the pipe wall. The water passing holes 30 can be selected as long strip-shaped notches to simulate karst pipelines, and the specifications of the water passing holes 30 are changed according to the different pipe diameters of the drain pipe 27.

[0044] The flowing water flowing out from the drain holes 9 on the sand box 8 flows into the water tank 10, so that the water flow and solutes in the sand box 8 can be discharged from the fractured medium, achieving the function of simulating open fractures. The drain holes 9 are generally arranged in multiple rows and columns, so that water flows and solutes at different heights can be discharged. Preferably, each drain hole 9 is provided with a plug, and the drain hole 9 can be blocked by the plug, so that some of the drain holes 9 can be selected to simulate open fractures according to experimental needs.

[0045] The upper end of the sand box 8 is open. The rainfall simulator includes a rainwater pipe 13, a regulating valve, and a plurality of rain distribution pipes 23. The rainwater pipe 13 is arranged along the edge of the upper port of the sand box 8. The regulating valve is arranged at the input end of the rainwater pipe 13. The rain distribution pipes 23 are arranged at intervals in the rainwater pipe 13, and the rain distribution pipes 23 are provided with rainwater holes. The rainwater pipe 13 is connected to a rainwater injection pipe 24. The injected rainwater is input into each rain distribution pipe 23 through the rainwater pipe 13, and then sprayed onto the rock analog 28 in the sand box 8 through the rainwater holes. By adjusting the regulating valve, the spraying speed of the rainwater from the rainwater holes can be adjusted, so as to simulate rainfall of different intensities.

[0046] The tracer injector is arranged on the water delivery pipe 20. Specifically, the tracer injector includes a syringe 5 and a first valve 6. The first valve 6 is located downstream of the syringe 5. The syringe 5 is manually controlled, and the injection amount and injection rate of the tracer can be artificially controlled. The first valve 6 can control the opening and closing of the water delivery pipe 20 and the injection rate.

[0047] The flow control valve 7 is arranged on the water delivery pipe 20 and is located between the tracer injector and the drain pipe 27. The flow control valve 7 can control the water flow velocity input from the water delivery pipe 20 into the drain pipe 27.

[0048] The pressure monitoring system is detachably connected to some of the drain holes 9 respectively to monitor the hydraulic pressure in some of the drain holes 9. The pressure monitoring system includes a scale plate 29 and a plurality of piezometric tubes 17. Each piezometric tube 17 is vertically arranged on the scale plate 29, and each piezometric tube 17 can be detachably connected to a drain hole 9 through a connecting hose 18. Specifically, the scale plate 29 is fixed to a support plate, and the bottom of the support plate is provided with a bracket and is fixed through the bracket. The piezometric tube 17 is a hollow tubular transparent structure, the top of the piezometric tube 17 has an open end, the scale plate 29 is provided with scale lines, and the piezometric tube 17 is arranged along the scale lines. The water flow in the drain hole 9 can flow into the piezometric tube 17, and the liquid level height in the piezometric tube 17 is observed through the scale lines, so as to measure the water pressure at different heights of the drain holes 9 in the sand box 8.

[0049] In some embodiments, a dual-medium water flow and solute interaction simulation device of the present invention further includes a first water collecting tank 14 and a second water collecting tank 26. The first water collecting tank 14 is connected to the other end of the drain pipe 27 through a first water outlet pipe 21, and a flow meter 11 is arranged on the first water outlet pipe 21. The second water collecting tank 26 is connected to the water tank 10 through a second water outlet pipe 25. The water flow containing the tracer output from the drain pipe 27 is collected through the first water collecting tank 14, and the water flow containing the tracer output from the drain hole 9 is collected through the second water collecting tank 26. A third valve 12 can also be arranged on the first water outlet pipe 21 to control the opening and closing of the first water outlet pipe 21.

[0050] In addition, an embodiment of the present invention further provides a dual-medium water flow and solute interaction test method, which uses the above dual-medium water flow and solute interaction simulation device and includes the following steps:

[0051] S1. Connect some of the drain holes 9 to the pressure monitoring system.

[0052] Before the test, the above dual-medium water flow and solute interaction simulation device should also be subjected to an airtightness test. For example, through a water tightness test, it is judged whether the airtightness is qualified. After the airtightness is qualified, some of the drain holes 9 are selected as piezometric holes and are connected to the piezometric tubes 17 through the connecting hoses 18.

[0053] S2. After the water level in the water inlet tank 2 reaches a predetermined height, water is conveyed into the sand box 8 through the water conveyance pipe 20. The flow rate of the water flowing into the sand box 8 is adjusted by the flow control valve 7, and the top of the sand box 8 is sprayed with water by the rainfall simulator. The predetermined height is set according to the test requirements. In this embodiment, for example, the predetermined height is controlled by the height of the overflow plate 3.

[0054] S3. After the water flow rate flowing out of the drain pipe 27 becomes stable, the water pressure in the sand box 8 is obtained by the pressure monitoring system, and then the drain hole 9 connected to the pressure monitoring system is blocked. The stability of the water flow rate flowing out of the drain pipe 27 is judged by the flow meter 11. After the drain hole 9 connected to the pressure monitoring system is blocked, the flow rates of the drain hole 9 and the flow control valve 7 are kept unchanged.

[0055] S4. A tracer solution is injected into the water conveyance pipe 20, and the changes in the tracer concentration at the outlet of the drain pipe 27 and in the water tank 10 are obtained. The tracer solution is pre-prepared and can be flexibly selected according to the actual test requirements. In this embodiment, for example, an NaCl solution is selected. Tracer concentration monitoring devices are arranged in the first water collection tank 14 and the second water collection tank 26, so that the tracer concentrations of the water flowing out of the drain pipe 27 and the drain hole 9 can be obtained. When the tracer concentrations in the first water collection tank 14 and the second water collection tank 26 drop to the same as the tracer concentration of the water flowing out of the water inlet tank 2, the test can be stopped.

[0056] S5. Multiple groups of test data are obtained by changing variables. The variables are at least one of the rainfall intensity controlled by the rainfall simulator, the concentration of the injected tracer solution, the water flow rate controlled by the flow control valve 7, and the scale of the open fissures controlled by the number of closed drain holes, so as to study the solute interaction law of the sinkhole-karst pipeline under different conditions.

[0057] In this embodiment, when the variable is the rainfall intensity controlled by the rainfall simulator, the water pressure of the water flowing into the rainwater pipe 13 is controlled, and the rainfall intensity is controlled at 0 mm / min (no water inflow), 1 mm / min, and 3 mm / min, so as to study the solute interaction and migration law under different rainfall intensities.

[0058] When the variable is the concentration of the injected tracer solution, 1 L of a specific concentration of NaCl solution is prepared before the test starts. After the water inlet tank 2 starts to supply water stably after the test starts, 50 mL, 100 mL, and 200 mL of the tracer are respectively injected into the water conveyance pipe 20 at the same injection rate, so as to study the solute interaction and migration law under different solute concentrations.

[0059] The variable is the water flow velocity. After the water flow to be injected is stabilized, the control flow rate of the flow control valve 7 is adjusted to 10 m / h, 100 m / h, and 500 m / h to study the solute interaction migration law under different flow velocities.

[0060] The variable is the scale of the open fissure. Before the experiment starts after the device is inspected, a certain number of drainage holes 9 are blocked with plugs, and the number of drainable drainage holes is controlled to be 80, 40, and 20 respectively to study the solute interaction migration law under different scales of open fissures.

[0061] In this article, the front, back, up, down and other orientation words are defined by the positions of the components in the drawings and the positions of the components relative to each other, just for the clarity and convenience of expressing the technical solution. It should be understood that they are relative concepts and can change accordingly according to different usage and placement methods. The use of the orientation words should not limit the scope of protection claimed in this application.

[0062] Without conflict, the above embodiments and the features in the embodiments in this article can be combined with each other. The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A dual-medium water flow and solute interaction simulation device, characterized in that: include: Water inlet tank; sink; A sand box is arranged in the water tank and below the water inlet box. A drainage pipe and a rock simulant are arranged inside the sand box. The rock simulant is filled between the drainage pipe and the sand box. A water outlet is arranged on the wall of the drainage pipe. One end of the drainage pipe is connected to the water inlet box through a water pipe. A plurality of drainage holes are arranged on one side of the sand box. A rainfall simulator is arranged on the top of the sand box. a tracer injector, which is arranged on the water pipe; a flow control valve, which is disposed on the water delivery pipe and is located between the tracer injector and the drain pipe; And a pressure monitoring system, which is detachably connected to some of the drainage holes to monitor the hydraulic pressure in some of the drainage holes.

2. A dual-medium water flow and solute interaction simulation device as claimed in claim 1, characterized in that: It also includes a first water collecting tank and a second water collecting tank. The first water collecting tank is connected to the other end of the drainage pipe through a first water outlet pipe. A flow meter is provided on the first water outlet pipe. The second water collecting tank is connected to the water tank through a second water outlet pipe.

3. A dual-medium water flow and solute interaction simulation device as claimed in claim 1, characterized in that: The sand box is a rectangular parallelepiped box, and the drainage holes are arranged in multiple rows and columns.

4. A dual-medium water flow and solute interaction simulation device as claimed in claim 3, characterized in that: The upper end of the sand box is open, and the rainfall simulator includes a rainwater pipe, a regulating valve and a plurality of rain distribution pipes. The rainwater pipe is arranged along the edge of the upper port of the sand box, the regulating valve is arranged at the input end of the rainwater pipe, and each of the rain distribution pipes is arranged at intervals in the rainwater pipe, and the rain distribution pipe is provided with rainwater holes.

5. A dual-medium water flow and solute interaction simulation device as claimed in claim 1, characterized in that: The rock simulant is glass bricks or quartz sand.

6. A dual-medium water flow and solute interaction simulation device as claimed in claim 1, characterized in that: The tracer injector includes a syringe and a first valve, the first valve being located downstream of the syringe.

7. A dual-medium water flow and solute interaction simulation device as claimed in claim 1, characterized in that: An overflow plate is provided in the water inlet box, which is vertically arranged and fixedly connected to the bottom of the water inlet box at its lower end. One end of the water supply pipe is connected to the bottom of the water inlet box on one side of the overflow plate, and the bottom of the water inlet box on the other side of the overflow plate is connected to the third water outlet pipe.

8. A dual-medium water flow and solute interaction simulation device as claimed in claim 1, characterized in that: The pressure monitoring system includes a scale plate and a plurality of pressure measuring tubes, each of which is vertically arranged on the scale plate, and each of which can be detachably connected to a drain hole via a connecting hose.

9. A dual-medium water flow and solute interaction simulation device as claimed in claim 1, characterized in that: Each of the drainage holes is provided with a plug.

10. A dual medium water flow and solute interaction test method, characterized in that: A dual-medium water flow and solute interaction simulation device as described in any one of claims 1 to 9 is used, and includes the following steps: S1. Connect some drainage holes to the pressure monitoring system; S2, after the water flow in the water inlet box reaches a predetermined height, water is delivered to the sand box through the water delivery pipe, the water flow rate delivered to the sand box is adjusted through the flow control valve, and water is sprayed on the top of the sand box through the rainfall simulator; S3, after the water flow out of the drain pipe is stabilized, the water pressure in the sand box is obtained by the pressure monitoring system, and then the drain hole connected to the pressure monitoring system is blocked; S4, injecting a tracer solution into the water pipe, and obtaining changes in tracer concentrations at the outlet of the drain pipe and in the water tank; S5. Multiple sets of test data are obtained by changing variables, where the variables are at least one of the rainfall intensity controlled by the rainfall simulator, the concentration of the injected tracer solution, the water flow rate controlled by the flow control valve, and the number of drainage hole closures, to study the solute interaction law of the sinkhole-karst pipeline under different conditions.

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