Karst bank slope rock mass corrosion simulation experiment device and method in water pumping and storage engineering environment

Abstract

The invention provides a karst bank slope rock mass corrosion simulation experiment device and method in a water pumping and storage engineering environment, and relates to geotechnical engineering.The karst bank slope rock mass corrosion simulation experiment device comprises a reaction box, a rock mass corrosion simulation experiment device and a rock mass corrosion simulation experiment device, the corrosion liquid circulating box is connected with the bottom of the reaction box through a backflow pipeline; the corrosion liquid pumping and storing adjusting system and the corrosion liquid circulating box are connected with the reaction box, the floating ball switch is arranged in the reaction box and connected with the suction pump, the floating ball switch controls the suction pump to be started and stopped according to the height of the water level in the reaction box, the second adjusting valve, the second flow meter and the control valve are arranged on the backflow pipeline, and the PLC controls the suction pump and the control valve to work; a temperature control system; a pressure control system; and the pH automatic control system is used for controlling the peristaltic pump to work according to the pH value in the corrosion liquid circulating box. The device has the beneficial effects that the actual engineering environment is accurately simulated, and the rock mass corrosion characteristics under the coupling action of multiple factors such as complex water level fluctuation and water pressure change in the water pumping and storage engineering are researched.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering technology, and in particular to an experimental device and method for simulating the dissolution of karst slope rock mass in a pumped water storage engineering environment. Background Technology

[0002] Pumped storage power stations, as a highly efficient and reliable energy storage method, operate by using reversible turbines as pumps during periods of low grid load (such as at night). This pumps water from the lower reservoir to the upper reservoir, where it is stored and the electrical energy is converted into the water's gravitational potential energy. During periods of high grid load (such as during the day), the upper reservoir gates are opened, and water is rapidly pumped down to the lower reservoir, driving the reversible turbines to rotate. The turbines then drive generators, converting the water's potential energy into electrical energy, which is then fed into the grid. During operation, the water levels in the upper and lower reservoirs experience periodic and significant fluctuations. These fluctuations cause karst slopes to be exposed to alternating wet and dry conditions and dynamic water pressure changes, potentially impacting their stability.

[0003] The stability of karst slopes is one of the key factors for the safe operation of pumped storage power stations. Once karst slopes become unstable, experience landslides or other geological disasters, they will not only directly damage the power station's buildings and facilities, leading to huge economic losses, but may also trigger secondary disasters, posing a serious threat to the lives and property of people in the surrounding areas. Therefore, in-depth research on the dissolution characteristics of karst slope rock masses in pumped storage engineering environments is of great significance.

[0004] Currently, scholars both domestically and internationally have conducted some research on rock dissolution, mainly focusing on the dissolution process under static water environments or single-factor effects. Some studies have explored the dissolution rate and characteristics of dissolution products under different water quality conditions through indoor immersion experiments. However, this neglects the rock dissolution characteristics under the complex coupling effects of multiple factors such as water level fluctuations and water pressure changes in pumped water storage projects, making it difficult to accurately simulate actual engineering environments. Regarding experimental equipment, existing rock dissolution experimental equipment is mostly single-function and cannot meet the needs of multi-factor coupled simulation in pumped water storage engineering environments. Some experimental devices can only achieve static water level control and cannot simulate large fluctuations in water level. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide an experimental apparatus and method for simulating the dissolution of karst slope rock mass in a pumped water storage engineering environment.

[0006] An embodiment of the present invention provides an experimental device for simulating the dissolution of karst slope rock mass under pumped water storage engineering conditions, comprising: The reaction chamber has a tray at the bottom for placing core samples. A solvent circulation tank, which is used to store solvent, is connected to the bottom of the reaction tank via a return pipe; A solvent extraction and storage regulation system includes an extraction pipe, an extraction pump, a first regulating valve, a first flow meter, a float switch, a second regulating valve, a second flow meter, a control valve, and a PLC controller. One end of the extraction pipe is connected to the bottom of the solvent circulation tank, and the other end is connected to the top of the reaction tank. The extraction pump, the first regulating valve, and the first flow meter are sequentially arranged on the extraction pipe. The float switch is located inside the reaction tank and connected to the extraction pump. The float switch is used to control the extraction pump to start and stop according to the water level in the reaction tank. The second regulating valve, the second flow meter, and the control valve are arranged on the return pipe. The PLC controller is connected to the extraction pump and the control valve to control the operation of the extraction pump and the control valve at timed intervals. A temperature control system, connected to the reaction chamber, is used to control the temperature inside the reaction chamber; A pressure control system, connected to the reaction chamber, is used to control the pressure inside the reaction chamber; The system includes an automatic pH control system comprising a replenishment tank, a pH electrode, a peristaltic pump, and a pH controller. The replenishment tank is connected to the solvent circulation tank via a replenishment pipe. The pH electrode is located inside the solvent circulation tank. The peristaltic pump is located on the replenishment pipe. The pH controller is connected to the pH electrode and the peristaltic pump to control the operation of the peristaltic pump according to the pH value in the solvent circulation tank.

[0007] Furthermore, the sample carrier disk is provided with multiple embedding holes, each of which can be used to embed the lower end of a core sample.

[0008] Furthermore, the float switch is vertically fixed to the inner wall of the reaction tank. The suction pump is connected to the float switch via an electromagnetic relay. When the float switch detects that the water level in the reaction tank is lower than the minimum preset height, it triggers the electromagnetic relay to close, energizing the suction pump. When the float switch detects that the water level in the reaction tank is higher than the maximum preset height, it triggers the electromagnetic relay to open, de-energizing the suction pump.

[0009] Furthermore, the minimum preset height is the height of the bottom of the core sample placed on the tray; the maximum preset height is the height of the top of the core sample or half the height of the core sample.

[0010] Furthermore, the solvent circulation tank is provided with an inlet on the upper left and an outlet on the lower right.

[0011] Furthermore, the top of the reaction chamber is provided with an openable lid.

[0012] Furthermore, the temperature control system includes a temperature controller and a thermometer. The temperature controller is connected to the reaction chamber to control the temperature of the reaction chamber; the thermometer is installed on the top of the reaction chamber to measure the temperature inside the reaction chamber.

[0013] Furthermore, the pressure control system includes a pressure regulator, a pressure gauge, and a differential pressure sensor; the pressure regulator is connected to the reaction chamber to adjust the pressure inside the reaction chamber; the pressure gauge is located at the top of the reaction chamber to measure the pressure inside the reaction chamber; the differential pressure sensor is located between the reaction chamber and the solvent circulation tank to measure the pressure difference between the reaction chamber and the solvent circulation tank.

[0014] Furthermore, the pressure control system also includes a first gas valve, a first suction pump, a second gas valve, and a second suction pump. The first gas valve is located at the upper part of the solvent circulation tank, and the first suction pump is connected to the first gas valve. The second gas valve is located at the upper part of the reaction tank, and the second suction pump is connected to the second gas valve.

[0015] Furthermore, embodiments of the present invention also provide a method for simulating the dissolution of karst slope rock mass under pumped water storage engineering conditions, using the aforementioned karst slope rock mass dissolution simulation experimental device under pumped water storage engineering conditions, and including the following steps: S1. Prepare artificial core samples of carbonate rock; S2. Measure and record the pore structure characteristics of the core sample before the experiment; S3. Prepare the etching solution; S4. Install the core sample on the loading plate for a water level test. Inject clean water into the solvent circulation tank, open the first regulating valve, and start the suction pump to pump the clean water in the solvent circulation tank into the reaction tank. When the float switch detects that the water level in the reaction tank has risen to the bottom of the core sample, open the second regulating valve to control the inflow rate of the reaction tank to be greater than the outflow rate. Some of the water in the reaction tank flows back to the solvent circulation tank, ensuring that the water level in the reaction tank continues to rise. When the clean water completely submerges the core sample, the float switch controls the suction pump to stop, and the water level in the reaction tank drops. When the float switch detects that the water level has dropped to the bottom of the core sample, it controls the suction pump to start again. This process is repeated until the test is completed. Obtain the total volume of solvent required for the solvent simulation experiment and how to adjust the opening of the first and second regulating valves to control the rate of rise and fall of the water level in the reaction tank. S5. Rock Mass Dissolution Experiment: The core sample is mounted on the loading tray. The prepared dissolution solution is added to the dissolution solution circulation tank and the replenishment tank respectively. The first gas valve, the first suction pump, the second gas valve, and the second suction pump are opened. The temperature and pressure in the reaction chamber are adjusted according to the preset experimental conditions through the temperature control system and the pressure control system. The PLC controller controls the suction pump and the control valve to intermittently enter and stop working states. When the working state is started, the PLC controller controls the suction pump to start and the control valve to open, according to the second regulating valve in step S4. The first adjustment controls the inlet and outlet water rates of the reaction tank; in the stopped state, the PLC controller controls the suction pump to shut down and the control valve to close; when the pH electrode detects that the pH value of the solvent in the solvent circulation tank has dropped to the preset pH value, the pH controller will start the peristaltic pump to draw the solvent from the replenishment tank to the solvent circulation tank until the pH value of the solvent in the solvent circulation tank reaches the target pH value; the core sample in the reaction tank is subjected to erosion under the periodic rise and fall of water level, and the experiment ends after the simulated experimental time is reached; S6. Take out the dissolved rock core sample, measure the pore structure characteristics of the dissolved rock core sample, and compare and analyze it with the pre-experiment analysis.

[0016] The beneficial effects of the technical solution provided by the embodiments of the present invention are as follows: The present invention provides a simulation experimental device and method for karst slope rock mass erosion in a pumped water storage engineering environment. It controls the start and stop of the pumping pump by detecting the immersion depth of the core sample using a float switch, and controls the immersion rate of the core sample using a second and first regulating valve. This not only simulates the pumping conditions from complete exposure to complete immersion of the rock sample, but also allows for the simulation of pumping experiments with different immersion depths based on different rock sample sizes by adjusting the height of the float switch. Furthermore, the rate of water level rise and fall can be controlled by adjusting the second and first regulating valves. This system meets the needs of different water level fluctuation rates and controls the suction pumps and control valves at regular intervals to simulate the dissolution mode of actual pumping projects, where operations are stopped for a period of time after several pumping cycles are completed, and then operations continue. In this way, it is possible to conduct carbonate karst erosion experiments on reservoir karst slopes under different temperatures, pressures, pH values ​​of dissolving solutions, rock samples of different sizes, and different pumping conditions (different immersion heights, different water level rise and fall rates, and timed stops of pumping operations) according to the proposed experimental plan. This accurately simulates the actual engineering environment and studies the rock mass dissolution characteristics under the complex coupling effects of multiple factors such as water level fluctuations and water pressure changes in pumping projects. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an experimental device for simulating the dissolution of karst slope rock mass under pumped water storage engineering conditions, according to the present invention.

[0018] In the diagram: 1. Reaction chamber; 2. Loading tray; 3. Embedding hole; 4. Box cover; 5. Support; 6. Core sample; 7. Dissolving solution circulation tank; 8. Inlet; 9. Outlet; 10. Suction pump; 11. Float switch; 12. First regulating valve; 13. First flow meter; 14. Second regulating valve; 15. Second flow meter; 16. Control valve; 17. Temperature controller; 18. Thermometer; 19. Pressure regulator; 20. Pressure gauge; 21. Differential pressure sensor; 22. First gas valve; 23. First suction pump; 24. pH electrode; 25. pH controller; 26. Peristaltic pump; 27. Replenishment tank; 28. Second gas valve; 29. ​​Second suction pump; 30. Return pipe; 31. Suction pipe; 32. Replenishment pipe. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described below with reference to the accompanying drawings. The following description presents a preferred embodiment of the various possible embodiments of the present invention, intended to provide a basic understanding of the invention, but not intended to identify key or decisive elements of the invention or to limit the scope of protection sought.

[0020] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0021] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures. Also, it should be understood that, for ease of description, the dimensions of the various parts shown in the figures are not drawn to actual scale.

[0023] It should be noted that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0024] Please refer to Figure 1The present invention provides an experimental device for simulating the dissolution of karst slope rock mass under pumped water storage engineering conditions. It is used to simulate the dissolution process of karst slope rock mass in reservoirs under different pumped water storage conditions. It mainly includes a reaction tank 1, a dissolution liquid circulation tank 7, a dissolution liquid pumping and storage regulation system, a temperature control system, a pressure control system, and a pH automatic control system.

[0025] The bottom of the reaction chamber 1 is provided with a tray 2 for placing core sample 6. The interior of the reaction chamber 1 is the dissolution space for the core sample 6, and the tray 2 is fixedly installed at the bottom of the reaction chamber 1. The tray 2 has multiple embedding holes 3, each of which allows the lower end of a core sample 6 to be embedded. The shape of the embedding hole 3 is designed according to the cross-sectional shape of the core sample 6. For example, if the core sample 6 is a cylinder, the embedding hole 3 is a circular hole, and the diameter of the embedding hole 3 is slightly larger than the bottom diameter of the core sample 6.

[0026] Considering the installation and removal of the core sample 6 inside the reaction chamber 1, the top of the reaction chamber 1 is provided with an openable cover 4. The cover 4 closes to the upper port of the reaction chamber 1, thus sealing the reaction chamber 1.

[0027] The solvent circulation tank 7 is used to store solvent, and it is connected to the bottom of the reaction tank 1 via a return pipe 30. For example, the bottom of the reaction tank 1 is supported on a bracket 5, and the height of the bottom of the reaction tank 1 is higher than the height of the top of the solvent circulation tank 7.

[0028] The solvent extraction and storage regulation system includes a suction pipe 31, a suction pump 10, a first regulating valve 12, a first flow meter 13, a float switch 11, a second regulating valve 14, a second flow meter 15, a control valve 16, and a PLC controller (not shown in the figure). One end of the suction pipe 31 is connected to the bottom of the solvent circulation tank 7, and the other end is connected to the top of the reaction tank 1. The suction pump 10, the first regulating valve 12, and the first flow meter 13 are sequentially arranged on the suction pipe 31. The float switch 11 is arranged inside the reaction tank 1 and connected to the suction pump 10. The float switch 11 is used to control the suction pump 10 to start and stop according to the water level in the reaction tank 1. The second regulating valve 14, the second flow meter 15, and the control valve 16 are arranged on the return pipe 30. The PLC controller is connected to the suction pump 10 and the control valve 16 to control the operation of the suction pump 10 and the control valve 16 at regular intervals.

[0029] The float switch 11 is vertically fixed to the inner wall of the reaction tank 1. The suction pump 10 is connected to the float switch 11 via an electromagnetic relay (not shown in the figure). When the float switch 11 detects that the water level in the reaction tank 1 is lower than a minimum preset height, it triggers the electromagnetic relay to close, energizing the suction pump 10. When the float switch 11 detects that the water level in the reaction tank 1 is higher than a maximum preset height, it triggers the electromagnetic relay to open, de-energizing the suction pump 10. The float switch 11 has inductive switches at both its upper and lower ends. When the water level reaches the inductive switch at the lower end of the float switch 11, the float switch 11 controls the suction pump 10 to start; when the water level reaches the inductive switch at the upper end of the float switch 11, the float switch 11 controls the suction pump 10 to shut down.

[0030] The upper and lower inductive switches of the float switch 11 are set according to the experimental requirements. The minimum preset height is generally the height of the bottom of the core sample 6 placed on the loading tray 2. The maximum preset height can be set to the height of the top of the core sample 6 placed on the loading plate 2, or it can be set to half the height of the core sample 6 placed on the loading plate 2.

[0031] The PLC controller connects the suction pump 10 and the control valve 16 to control their operation at regular intervals. The control valve 16 is typically an electric valve, such as a solenoid valve. The PLC controller can control the suction pump 10 and the control valve 16 to intermittently enter and stop working states, that is, intermittently control the start and stop of the suction pump 10 and the opening and closing of the control valve 16. In the working state, the suction pump 10 is started and the control valve 16 is open; conversely, in the stopped working state, the suction pump 10 is turned off and the control valve 16 is closed.

[0032] In some embodiments, considering the injection and discharge of the etchant in the etchant circulation tank 7, the etchant circulation tank 7 is provided with an inlet 8 at the top and an outlet 9 at the bottom.

[0033] The temperature control system is connected to the reaction chamber 1 and is used to control the temperature inside the reaction chamber 1. Specifically, the temperature control system includes a temperature controller 17 and a thermometer 18. The temperature controller 17 is connected to the reaction chamber 1 to control the temperature of the reaction chamber 1; the thermometer 18 is installed on the top of the reaction chamber 1 and is used to measure the temperature inside the reaction chamber 1.

[0034] The pressure control system is connected to the reaction chamber 1 and is used to control the pressure inside the reaction chamber 1. Specifically, the pressure control system includes a pressure regulator 19, a pressure gauge 20, and a differential pressure sensor 21; the pressure regulator 19 is connected to the reaction chamber 1 to adjust the pressure inside the reaction chamber 1; the pressure gauge 20 is located at the top of the reaction chamber 1 to measure the pressure inside the reaction chamber 1; the differential pressure sensor 21 is located between the reaction chamber 1 and the solvent circulation tank 7, and the differential pressure sensor 21 is used to measure the pressure difference between the reaction chamber 1 and the solvent circulation tank 7.

[0035] The pressure control system further includes a first gas valve 22, a first suction pump 23, a second gas valve 28, and a second suction pump 29. The first gas valve 22 is located at the upper part of the solvent circulation tank 7, and the first suction pump 23 is connected to the first gas valve 22. The second gas valve 28 is located at the upper part of the reaction tank 1, and the second suction pump 29 is connected to the second gas valve 28. The first gas valve 22 and the first suction pump 23 are used to depressurize and vent air in the solvent circulation tank 7, and the second gas valve 28 and the second suction pump 29 are used to depressurize and vent air in the reaction tank 1, in order to cope with the sudden increase in gas pressure in the solvent circulation tank 7 and the reaction tank 1 caused by the generation of volatile gases when the acidic solvent is first added to the solvent circulation tank 7, and to replenish the gas required for the reaction.

[0036] The automatic pH control system includes a replenishment tank 27, a pH electrode 24, a peristaltic pump 26, and a pH controller 25. The replenishment tank 27 is connected to the solvent circulation tank 7 via a replenishment pipe 32. The pH electrode 24 is located inside the solvent circulation tank 7, and the peristaltic pump 26 is located on the replenishment pipe 32. The pH controller 25 connects the pH electrode 24 and the peristaltic pump 26 to control the operation of the peristaltic pump 26 according to the pH value in the solvent circulation tank 7. As the etching reaction proceeds in the reaction tank 1, the pH value of the solvent gradually decreases. When the pH electrode 24 detects that the pH value of the solvent in the solvent circulation tank 7 has dropped to a preset pH value, the pH controller 25 will activate the peristaltic pump 26 to draw the solvent from the replenishment tank 27 into the solvent circulation tank 7 until the pH value of the solvent in the solvent circulation tank 7 reaches the target pH value.

[0037] Furthermore, embodiments of the present invention also provide a method for simulating the dissolution of karst slope rock mass under pumped water storage engineering conditions, simulating pumped water storage conditions from complete exposure to complete submersion of rock samples, using the aforementioned karst slope rock mass dissolution simulation experimental device under pumped water storage engineering conditions, and including the following steps: S1. Preparation of artificial carbonate rock core sample 6. For example, in this simulation experiment, rock-like materials (cement, quartz sand, silica fume, etc.) are used to prepare rock core sample 6. The sample is made into a cylindrical standard specimen with a bottom diameter of 50 mm and a height of 100 mm.

[0038] S2. Measure and record the pore structure characteristics of core sample 6 before the experiment. Pore structure characteristics include mass, permeability, porosity, and two-dimensional pore structure.

[0039] S3. Prepare the etching solution. The etching solution is an acidic solution selected according to the simulation requirements. For example, in this simulation experiment, a 0.1 mol / L (pH=1) hydrochloric acid solution is prepared as the etching solution.

[0040] S4. Install the core sample 6 on the loading plate 2 for a water level test. Only one core sample 6 can be installed. Adjust the float switch 11 so that the lower end of the float switch 11 is flush with the bottom of the core sample 6, and the upper end of the float switch 11 is flush with the top of the core sample 6. Inject clean water into the solvent circulation tank 7. The clean water can be tap water or purified water. Open the first regulating valve 12, and the control valve 16 is in the open state. Start the suction pump 11 to pump the clean water in the solvent circulation tank 7 into the reaction tank 1. When the float switch 11 detects that the water level in the reaction tank 1 has risen to the bottom of the core sample 6, it opens the second regulating valve 14 to control the inflow rate of the reaction tank 1 to be greater than the outflow rate. By observing the readings of the first flow meter 13 and the second flow meter 15, determine that the reading of the first flow meter 13 is greater than the reading of the second flow meter 15, that is, the inflow rate of the reaction tank 1 is greater than the outflow rate. Part of the water in reaction chamber 1 flows back to the solvent circulation tank 7, ensuring that the water level in reaction chamber 1 continues to rise. When the clean water completely submerges the core sample 6, the float switch 11 controls the suction pump 10 to shut down, and the water level in reaction chamber 1 drops. When the float switch 11 detects that the water level has dropped to the lower end of the core sample 6, it controls the suction pump 10 to start again. This process is repeated until the test experiment ends, obtaining the total volume of solvent required for the solvent simulation experiment, and how to adjust the opening of the second regulating valve 14 and the first regulating valve 12 to control the rate of rise and fall of the water level in reaction chamber 1.

[0041] In other words, step S4 above involves using clean water instead of the dissolving fluid in a test experiment before the formal rock dissolution experiment. The purpose is to determine the appropriate total volume of the dissolving fluid and the appropriate flow rate control based on experimental requirements, so that the formal rock dissolution experiment can begin immediately after adding the dissolving fluid. Using hydrochloric acid solution directly, frequently replenishing the dissolving fluid, and adjusting the valve to control the flow rate for extended periods could lead to hydrochloric acid evaporation and laboratory safety hazards. For example, the total volume of the dissolving fluid required for this simulation experiment is 30L. The flow rate control of the first flow meter 13 is 200ml / s, and the flow rate control of the second flow meter 15 is 100ml / s. A complete pumping and storage process takes approximately 10 minutes. S5. Rock dissolution test: Install the core sample 6 on the carrier plate 2, and install the lower end of all the core samples 6 in the mounting holes 3 on the carrier plate 2. Adjust the float switch 11 so that the lower end of the float switch 11 is flush with the bottom end of the core sample 6 and the upper end of the float switch 11 is flush with the top end of the core sample 6.

[0042] The prepared etching solution is added to the etching solution circulation tank 7 and the replenishment tank 27. The etching solution added to the etching solution circulation tank 7 is 30L of hydrochloric acid solution. Since the hydrochloric acid solution will react violently when it first enters the reaction tank 1, releasing a large amount of gas, the first gas valve 22 and the second gas valve 28 are opened before injecting the hydrochloric acid solution. The first gas valve 22 and the second gas valve 28 are kept open for the first few pumping cycles. After the released gas is discharged, the first gas valve 22 and the second gas valve 28 are closed. The gas discharge can be accelerated by starting the first suction pump 23 and the second suction pump 29.

[0043] The temperature and pressure inside the reaction chamber are adjusted according to preset experimental conditions by a temperature control system and a pressure control system to maintain a constant temperature and pressure inside reaction chamber 1. For example, this experiment simulates the karst slope erosion phenomenon of a pumped-storage power station in central China during winter, with the temperature set at 0-5℃ and the pressure at atmospheric pressure.

[0044] The PLC controller uses a timing function to control the suction pump 10 and the control valve 16 to intermittently enter and stop working states. When starting working, the PLC controller starts the suction pump 10 and opens the control valve 16. The suction pump 10 draws the solvent from the solvent circulation tank and pumps it into the reaction tank. The inlet and outlet water rates of the reaction tank 1 are controlled according to the opening degrees of the second regulating valve 12 and the first regulating valve 14 in step S4. The float switch controls the start and stop of the suction pump 10 until the working state ends. By adjusting the first regulating valve 12 and the second regulating valve 14, and in conjunction with the readings of the first flow meter 13 and the second flow meter 15, different inlet and outlet water rates of the reaction tank can be controlled to meet the needs of actual pumped storage projects for different water level rise and fall rates.

[0045] Then, it enters a stop-work state, with the suction pump 10 shut down and the control valve 16 closed. Taking this simulation experiment as an example, the PLC controller controls the suction pump 10 and control valve 16 to operate for one hour each time, and to stop for half an hour. That is, after completing several pumping cycles within one hour, the pumping operation is temporarily stopped for half an hour, and then resumed for another hour. This cycle repeats, and the core sample 6 in the reaction tank 1 is subjected to dissolution under the periodic rise and fall of water level. The experiment ends after the simulated experimental duration is reached.

[0046] During the rock dissolution experiment, as the dissolution reaction proceeds in the reaction tank, the pH value of the dissolving solution gradually decreases. When the pH electrode 24 detects that the pH value of the dissolving solution in the dissolving solution circulation tank 7 has dropped to a preset pH value, the pH controller 25 will activate the peristaltic pump 26 to draw the dissolving solution from the replenishment tank 27 into the dissolving solution circulation tank 7 until the pH value of the dissolving solution in the dissolving solution circulation tank 7 reaches the target pH value. This process monitors, replenishes, and maintains the pH value of the dissolving solution in the dissolving solution circulation tank 7. For example, the preset pH value is 0.5, and the target pH value is 1.

[0047] Due to the control of the inflow and outflow rates in step S4 above, the rock mass inside reaction tank 1 is subjected to dissolution under the periodic rise and fall of water level. This, combined with the timed control device of the PLC controller, stops and starts operation, mirroring the actual dissolution of karst slope rock masses in a pumped-storage power station. The simulation experiment duration is flexibly determined based on the actual karst slope rock mass dissolution conditions. For example, the simulation experiment duration is set to four groups: 8h, 16h, 24h, and 32h.

[0048] S6. Take out the dissolved rock core sample 6, measure the pore structure characteristics of the dissolved rock core sample 6, and compare it with the pre-experiment analysis to obtain the dissolution status of the rock core sample 6. Study the rock mass dissolution characteristics under the complex coupling effects of multiple factors such as water level fluctuations and water pressure changes in pumped water storage projects. In this way, the mechanism of carbonate rock karst corrosion on reservoir karst slopes can be studied according to the proposed experimental plan under different temperature and pressure, different pH values ​​of dissolving solutions, different rock sample sizes, and different pumping conditions (different immersion heights, different water level rise and fall rates, and timed cessation of pumping operations).

[0049] In this document, the directional terms such as front, back, top, and bottom are defined based on the position of the components in the accompanying drawings and their relative positions to each other, solely for the purpose of clarity and convenience in expressing the technical solution. It should be understood that these are relative concepts and can vary depending on different methods of use and placement; the use of these directional terms should not limit the scope of protection claimed in this application.

[0050] Where there is no conflict, the embodiments and features described above can be combined with each other. The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An experimental device for simulating the dissolution of karst slope rock mass under pumped water storage engineering conditions, characterized in that, include: The reaction chamber has a tray at the bottom for placing core samples. A solvent circulation tank, which is used to store solvent, is connected to the bottom of the reaction tank via a return pipe; A solvent extraction and storage regulation system includes an extraction pipe, an extraction pump, a first regulating valve, a first flow meter, a float switch, a second regulating valve, a second flow meter, a control valve, and a PLC controller. One end of the extraction pipe is connected to the bottom of the solvent circulation tank, and the other end is connected to the top of the reaction tank. The extraction pump, the first regulating valve, and the first flow meter are sequentially arranged on the extraction pipe. The float switch is located inside the reaction tank and connected to the extraction pump. The float switch is used to control the extraction pump to start and stop according to the water level in the reaction tank. The second regulating valve, the second flow meter, and the control valve are arranged on the return pipe. The PLC controller is connected to the extraction pump and the control valve to control the operation of the extraction pump and the control valve at timed intervals. A temperature control system, connected to the reaction chamber, is used to control the temperature inside the reaction chamber; A pressure control system, connected to the reaction chamber, is used to control the pressure inside the reaction chamber; The system includes an automatic pH control system comprising a replenishment tank, a pH electrode, a peristaltic pump, and a pH controller. The replenishment tank is connected to the solvent circulation tank via a replenishment pipe. The pH electrode is located inside the solvent circulation tank. The peristaltic pump is located on the replenishment pipe. The pH controller is connected to the pH electrode and the peristaltic pump to control the operation of the peristaltic pump according to the pH value in the solvent circulation tank.

2. The experimental device for simulating the dissolution of karst slope rock mass under pumped water storage engineering environment as described in claim 1, characterized in that: The sample carrier disk is provided with multiple embedding holes, each of which can be used to embed the lower end of a core sample.

3. The experimental device for simulating the dissolution of karst slope rock mass under pumped water storage engineering environment as described in claim 1, characterized in that: The float switch is vertically fixed to the inner wall of the reaction tank. The suction pump is connected to the float switch via an electromagnetic relay. When the float switch detects that the water level in the reaction tank is lower than the minimum preset height, it triggers the electromagnetic relay to close, energizing the suction pump. When the float switch detects that the water level in the reaction tank is higher than the maximum preset height, it triggers the electromagnetic relay to open, de-energizing the suction pump.

4. The experimental device for simulating the dissolution of karst slope rock mass under pumped water storage engineering environment as described in claim 3, characterized in that: The minimum preset height is the height of the bottom of the core sample placed on the tray; the maximum preset height is the height of the top of the core sample or half the height of the core sample.

5. The experimental device for simulating the dissolution of karst slope rock mass under pumped water storage engineering environment as described in claim 1, characterized in that: The solvent circulation tank has an inlet on the upper left and an outlet on the lower right.

6. The experimental device for simulating the dissolution of karst slope rock mass under pumped water storage engineering environment as described in claim 1, characterized in that: The reaction chamber has an openable lid on top.

7. The experimental device for simulating the dissolution of karst slope rock mass under pumped water storage engineering environment as described in claim 1, characterized in that: The temperature control system includes a temperature controller and a thermometer. The temperature controller is connected to the reaction chamber to control the temperature of the reaction chamber. The thermometer is installed on the top of the reaction chamber to measure the temperature inside the reaction chamber.

8. The experimental device for simulating the dissolution of karst slope rock mass under pumped water storage engineering environment as described in claim 1, characterized in that: The pressure control system includes a pressure regulator, a pressure gauge, and a differential pressure sensor; the pressure regulator is connected to the reaction chamber to adjust the pressure inside the reaction chamber; the pressure gauge is located on the top of the reaction chamber and is used to measure the pressure inside the reaction chamber; the differential pressure sensor is located between the reaction chamber and the solvent circulation tank and is used to measure the pressure difference between the reaction chamber and the solvent circulation tank.

9. The experimental device for simulating the dissolution of karst slope rock mass under pumped water storage engineering environment as described in claim 1, characterized in that: The pressure control system further includes a first gas valve, a first suction pump, a second gas valve, and a second suction pump. The first gas valve is located at the top of the solvent circulation tank, and the first suction pump is connected to the first gas valve. The second gas valve is located at the top of the reaction tank, and the second suction pump is connected to the second gas valve.

10. A method for simulating the dissolution of karst slope rock mass under pumped water storage engineering conditions, characterized in that: The experimental apparatus for simulating the karst slope rock mass erosion under a pumped water storage engineering environment, as described in any one of claims 1-9, includes the following steps: S1. Prepare artificial core samples of carbonate rock; S2. Measure and record the pore structure characteristics of the core sample before the experiment; S3. Prepare the etching solution; S4. Install the core sample on the loading plate for a water level test. Inject clean water into the solvent circulation tank, open the first regulating valve, and start the suction pump to pump the clean water in the solvent circulation tank into the reaction tank. When the float switch detects that the water level in the reaction tank has risen to the lower end of the core sample, open the second regulating valve to control the inflow rate of the reaction tank to be greater than the outflow rate. Some of the water in the reaction tank flows back to the solvent circulation tank, ensuring that the water level in the reaction tank continues to rise. When the clean water completely submerges the core sample, the float switch controls the suction pump to stop, and the water level in the reaction tank drops. When the float switch detects that the water level has dropped to the lower end of the core sample, it controls the suction pump to start again. This process is repeated until the test is completed. Obtain the total volume of solvent required for the solvent simulation experiment and how to adjust the opening of the first and second regulating valves to control the rate of rise and fall of the water level in the reaction tank. S5. Rock Mass Dissolution Experiment: The core sample is mounted on the support plate. The prepared dissolution solution is added to the dissolution solution circulation tank and the replenishment tank respectively. The first gas valve, the first suction pump, the second gas valve, and the second suction pump are opened. The temperature and pressure in the reaction tank are adjusted according to the preset experimental conditions through the temperature control system and the pressure control system. The PLC controller controls the suction pump and the control valve to intermittently enter and stop working states. When the working state is started, the PLC controller controls the suction pump to start and the control valve to open, according to the second regulating valve and the first regulating valve in step S4. The opening degree controls the inlet and outlet water rates of the reaction tank until the working state ends; in the stopped working state, the PLC controller controls the suction pump to shut down and the control valve to close; when the pH electrode detects that the pH value of the solvent in the solvent circulation tank has dropped to the preset pH value, the pH controller will start the peristaltic pump to draw the solvent in the replenishment tank to the solvent circulation tank until the pH value of the solvent in the solvent circulation tank reaches the target pH value; the core column sample in the reaction tank is subjected to dissolution under the periodic rise and fall of water level, and the experiment ends after the simulated experimental time is reached; S6. Take out the dissolved rock core sample, measure the pore structure characteristics of the dissolved rock core sample, and compare and analyze it with the pre-experiment analysis.

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