Variable-pressure rock-soil deformation and damage simulation experiment device

Abstract

The invention provides a variable-pressure rock-soil deformation and damage simulation experiment device, which relates to the field of hydrogeology and comprises a pressed main body part, an air pressure liquid tank part, a liquid supply part, an air supply part and a load change control center part. The pressed main body part is used for carrying out solid-liquid-gas three-phase reaction and collecting reaction products; the air pressure liquid tank part is used for carrying out air-liquid mixing, air compression and heating; the liquid supply part is used for supplying liquid to the air pressure liquid tank part; the gas supply part is used for supplying gas to the gas pressure liquid tank part; the load change control center part is used for coordinating the air supply part, the liquid supply part and the air pressure liquid tank part and simulating the actual load change condition. The experimental device can be used for reactions in solid-liquid-gas three-phase media under series of high-pressure conditions such as seepage deformation, acid fracturing and rock rheology, rock deformation and damage conditions with dynamic pressure changes in actual conditions are simulated, and the device is convenient to adjust, safe and reliable.

Description

Technical Field

[0001] The invention relates to the field of hydrogeology, and in particular to a variable pressure rock and soil deformation and destruction simulation experimental device. Background Art

[0002] The advancement of national infrastructure projects has put forward higher requirements for hydrogeological operations. When solving practical problems, hydrogeological research on topics such as tunnel water inrush prediction and prevention, geothermal water exploitation, utilization and operation often requires the use of geotechnical experiments to obtain relevant hydrogeological parameters. However, the existing experimental devices often only conduct experiments on the deformation and damage of geotechnical rocks in a certain state, and lack experimental devices and methods for geotechnical, liquid and gas three-phase media, simulating the pressure changes over time due to water level fluctuations in real situations, which can meet the requirements of hydrogeologists in conducting relevant experiments. Summary of the invention

[0003] Based on the actual engineering needs encountered in the fields of tunnel sudden water inrush prediction and prevention, geothermal water exploitation, utilization and operation, and in order to simulate the pressure changes over time due to water level fluctuations in real situations for the three-phase medium of rock, liquid and gas, the present invention provides a multi-purpose, easy-to-adjust, safe and reliable experimental device and experimental method for the rock and soil deformation and failure experiment under high pressure conditions.

[0004] A variable pressure rock and soil deformation and destruction simulation experimental device, the device comprises a pressure body part A, a gas pressure liquid tank part B, a liquid supply part C, a gas supply part D and a load change control center part E; the pressure body part A comprises an upper outlet collection tank, a first valve, a pressure rock and soil tank, a second valve, a lower outlet collection tank, a three-way pipe and a connecting pipeline; the gas pressure liquid tank part B comprises a safety valve, an exhaust device, a gas pressure liquid tank, a pressure monitoring device, a liquid level monitoring device, a first one-way valve, a second one-way valve and a connecting pipeline; the liquid supply part C comprises a third one-way valve, a pump, and a liquid tank; The gas supply part D includes a pressure gauge, a gas compressor, a third valve, a fourth valve and a gas tank; the load change control center part E has a built-in single-chip processor, which is connected to the second one-way valve and the liquid level monitoring device, the gas compressor and the pump, and the third one-way valve through the line and the pressure monitoring device for coordinated control; the three-way pipe is connected to the lower liquid outlet of the pressure liquid tank through a connecting pipe; the upper outlet of the pressure liquid tank is connected to the pressure gauge through a connecting pipe, and the exhaust is controlled by the exhaust device; the left outlet of the pressure liquid tank is connected to the gas compressor through a connecting pipe, and is controlled by the first one-way valve.

[0005] When the rock and soil deformation and failure simulation experimental device with variable pressure is used to perform the rock and soil deformation and failure experiment, the specific steps are as follows:

[0006] ① Setting of the pressure main body A, opening the second valve and the fifth valve, closing the sixth valve and the first valve; wherein the arrangement of the permeable stones in the second permeable stone container and the first permeable stone container is selected as α, and the rock and soil container is filled with experimental rock and soil;

[0007] ② The setting of the pressure tank part B, opening the second one-way valve, and closing the second one-way valve;

[0008] ③ The setting of the liquid supply part C, after the liquid tank is filled with water, the third one-way valve is opened, the pump is turned on, and the pump drives the water in the liquid tank to flow to the air pressure liquid tank. After the water in the air pressure liquid tank is filled to the first preset depth, the pump is turned off;

[0009] ④ Setting of the gas supply part D, closing the fourth valve and opening the third valve, so that the gas source after the gas compressor is turned on is air, and at this time, there is no need to open the load change control center part E;

[0010] ⑤ Turn on the gas compressor. After the air is pressurized, it passes through the first one-way valve and enters the gas pressure liquid tank, where it comes into contact with the water. During this process, the pressure of the pressurized air is obtained through the pressure gauge, and the pressure in the gas pressure liquid tank is obtained through the pressure monitoring device;

[0011] ⑥Depending on the different lithology in the geotechnical container, the exhaust and infiltration time is also different. After the exhaust and infiltration are completed, close the second valve and the fifth valve, open the first valve and the sixth valve, change the direction of the liquid entering after being pressurized to flow from top to bottom, and finally enter the lower outlet collection tank;

[0012] ⑦ The arrangement of the permeable stones in the second permeable stone container and the first permeable stone container can be changed to simulate different deformation and failure mechanisms of the rock and soil. The specific steps are as follows:

[0013] The pressure-bearing main body A is set up, the second valve and the fifth valve are opened, and the sixth valve and the first valve are closed; the experimental rock and soil are filled in the rock and soil container. When the rock and soil body seepage deformation failure is simulated, the arrangement of the permeable stones in the second permeable stone container and the first permeable stone container is selected as α, and when the rock and soil body shear deformation failure is simulated, the arrangement of the permeable stones in the second permeable stone container and the first permeable stone container is selected as β;

[0014] The pressure tank part B is set to open the second one-way valve and close the second one-way valve;

[0015] The setting of the liquid supply part C, after the liquid tank is filled with water, the third one-way valve is opened, the pump is turned on, and the pump drives the water in the liquid tank to flow to the air pressure liquid tank. After the water in the air pressure liquid tank is filled to a certain extent, the pump is turned off;

[0016] The setting of the gas supply part D closes the fourth valve and opens the third valve, so that the gas source after the gas compressor is turned on is air, and at this time, the load change control center part E does not need to be turned on;

[0017] The gas compressor is turned on, and the pressurized air enters the gas pressure liquid tank through the first one-way valve and contacts the water therein. During this process, the pressure of the pressurized air is obtained through the pressure gauge, and the pressure in the gas pressure liquid tank is obtained through the pressure monitoring device;

[0018] According to the different lithology in the geotechnical container, the exhaust and infiltration time is also different. After the exhaust and infiltration are completed, the second valve and the fifth valve are closed, and the first valve and the sixth valve are opened to change the direction of the liquid entering after being pressurized to flow from top to bottom, and finally enter the lower outlet collection tank;

[0019] When simulating the seepage deformation and damage of rock and soil, according to the seepage deformation and damage mechanism, liquid will be collected in the lower outlet collection tank. At this time, the data of the flow rate and pressure monitoring device after stabilization in the outlet collection tank are recorded; after stabilization for a period of time, the pressure in the gas pressure liquid tank is increased by the gas compressor. The increase in pressure will increase the entrainment of the particles by the seepage, further causing the destruction of the rock and soil structure. The data of the flow rate and pressure monitoring device after stabilization in the collection tank are collected, and the above operation is repeated;

[0020] According to the Darcy experimental principle: Q = KA (ΔH / L), the stable flow rate Q is obtained, where K is the permeability coefficient, A is the water-passing cross-sectional area, L is the permeability path, that is, the length of the geotechnical container along the water flow direction, and ΔH is the pressure in the gas pressure liquid tank;

[0021] The water passes through the geotechnical container under pressure, flows from top to bottom, and flows out from the water outlet at the bottom. The pressure in the gas pressure tank is increased, so that the geotechnical sample in the geotechnical container is subjected to a certain osmotic pressure difference. When the critical hydraulic / pressure state is reached, the geotechnical sample will be osmotic and deformed, and the water will carry the geotechnical sample out from the water outlet at the bottom of the geotechnical container.

[0022] According to the above principle, when the change of the stable flow Q in the lower outlet collection tank and the change of the pressure H in the pressure monitoring device change, it means that the permeability coefficient K changes. At this time, the reading in the pressure monitoring device minus the permeability path L is the critical hydraulic gradient ΔH / L of the rock and soil sample;

[0023] When simulating the shear deformation failure of rock and soil, according to the shear deformation failure mechanism, no liquid will be collected in the lower outlet collection tank at the beginning. The pressure in the gas pressure liquid tank will continue to be increased through the gas compressor. The rock and soil in the pressurized rock and soil tank will produce structural damage under the action of pressure. When the pressure exceeds the compressive capacity of the rock and soil, the rock and soil will produce shear deformation failure, and high-pressure liquid will be collected in the lower outlet collection tank. The pressure indication in the pressure monitoring device is the critical pressure at which the rock and soil sample undergoes structural collapse.

[0024] When the device is used to perform rock rheology-related or multiple rounds of acid fracturing tests with pressure and time correlation, the specific steps are as follows:

[0025] ① Setting of the pressure-bearing main body A, closing the second valve and the fifth valve, and opening the sixth valve and the first valve; wherein, when conducting multiple rounds of acid fracturing tests, the arrangement of the permeable stones in the second permeable stone container and the first permeable stone container is selected as α; when conducting a rock rheology experiment related to pressure and time, the arrangement of the permeable stones in the second permeable stone container and the first permeable stone container is selected as β; the rock and soil container is filled with experimental rock and soil;

[0026] ② Setting of the pressure tank part B, closing the second one-way valve and opening the first one-way valve;

[0027] ③ The setting of the liquid supply part C, after the liquid tank is filled with liquid, open the third one-way valve, turn on the pump, and the pump drives the liquid in the liquid tank to flow to the air pressure liquid tank. After the liquid in the air pressure liquid tank is filled to the second preset depth, turn off the pump and close the one-way valve;

[0028] ④ The setting of the gas supply part D, close the fourth valve and open the third valve, so that the gas source after the gas compressor is turned on is air; when conducting a fracturing experiment of special gas, open the fourth valve and close the third valve, so that the gas source after the gas compressor is turned on is the gas in the gas tank;

[0029] ⑤ The setting of the load change control center part E, the required pressure and time relationship is input into the built-in single chip microcomputer of the load change control center E, the load change control center part E controls to open the gas compressor, and the air enters the pressure liquid tank through the first one-way valve after being pressurized, and contacts with the liquid therein. In this process, the pressure of the pressurized air is obtained through the pressure gauge, and the pressure in the pressure liquid tank is obtained through the pressure monitoring device. When the target pressure is reached, the load change control center part E controls to close the gas compressor; the liquid in the pressure liquid tank is pressurized and enters the pressurized rock and soil tank through the first valve; in this process, the load change control center part E monitors the pressure change in the pressure liquid tank in real time through the pressure monitoring device. When the monitoring pressure is detected When the internal pressure of the liquid tank does not match the preset pressure, if the pressure is too low, the pressure in the gas pressure tank is increased by controlling the opening of the gas compressor, and the gas compressor is controlled to be closed after the pressure reaches the preset pressure; if the pressure is too high, the pressure in the gas pressure tank is reduced by controlling the opening of the second one-way valve, and the second one-way valve is controlled to be closed after the pressure is reduced to the preset pressure; the load change control center part E monitors the amount of liquid in the gas pressure tank through the liquid level monitoring device, and when it is monitored that the amount of liquid in the gas pressure tank is less than the first preset amount, the pump is controlled to be turned on, and when the pump pressure is increased to a value greater than the indication of the pressure monitoring device, the liquid is pumped into the gas pressure tank through the third one-way valve, and when the liquid level monitoring device monitors that the liquid level is greater than the second preset amount, the pump is controlled to be closed;

[0030] ⑥ In this process, the data of the flow and pressure monitoring device after stabilization in the upper outlet collection tank are recorded. The permeability k of the rock and soil at different times can be calculated according to the Darcy experimental principle formula and the permeability coefficient and permeability conversion formula, thereby obtaining the rock rheology or the changes in rock and soil properties during multiple rounds of acid fracturing.

[0031] The beneficial effect of the present invention is that different experiments related to rock and soil deformation and failure can be carried out by coordinating and controlling the change of gas sources, pressure tank contents, pressurized liquid sources or changing the controlled changes in pressure, so that it can be applied to parameter-seeking work or teaching experiments in solid-liquid-gas three-phase media under high-pressure conditions such as permeability deformation, pressure-time related rock rheology experiments or multiple rounds of acid fracturing tests, to obtain the critical pressure gradient of rock and soil deformation and failure, and simulate the changes of related parameters such as permeability coefficient K and permeability k in production practice, so as to provide a practical, multi-purpose, easy-to-adjust, safe and reliable experimental device and experimental method for rock and soil deformation and failure related work and teaching in hydrogeology and environmental geology. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a structural diagram of a variable pressure rock and soil deformation and failure simulation experimental device proposed by the present invention.

[0033] Figure 2It is a structural diagram of the pressure rock and soil tank in the present invention. DETAILED DESCRIPTION

[0034] like Figure 1 As shown, a variable pressure rock and soil deformation and destruction simulation experimental device includes a pressure body part A, a gas pressure liquid tank part B, a liquid supply part C, a gas supply part D and a load change control center part E. The pressure body part A includes an upper outlet collection tank 1, a first valve 2, a pressure rock and soil tank 3, a second valve 4, a lower outlet collection tank 5, a three-way pipe 6 and a connecting pipeline; the gas pressure liquid tank part B includes a safety valve 7, an exhaust device 8, a gas pressure liquid tank 9, a pressure monitoring device 10, a liquid level monitoring device 11, a first one-way valve 12, a second one-way valve 13 and a connecting pipeline; the liquid supply part C includes a third one-way valve 14, a pump 15, and a liquid tank 16; the gas supply part D includes a pressure gauge 17, a gas compressor 18, a third valve 19, a fourth valve 20 and a gas tank 21. The load change control center part E has a built-in single-chip processor, which is connected to the pressure monitoring device 10 in the gas pressure tank B, the second one-way valve 13 and the liquid level monitoring device 11, the gas compressor 18 in the gas supply part D, the pump 15 of the liquid supply part, and the third one-way valve 14 through the line for coordinated control. Among them, the three-way pipe 6 in the pressurized main body part A is connected to the lower liquid outlet of the gas pressure tank 9 in the gas pressure tank part B through a connecting pipeline; the pressure gauge 17 in the gas supply part C is connected in series between the upper outlet of the gas pressure tank 9 in the gas pressure tank part B and the gas compressor 18 through a connecting pipeline, and the gas pressure tank 9 is exhausted to the outside by the exhaust device 8. The left outlet of the gas pressure tank 9 in the gas pressure tank part B is connected to the gas compressor 18 in the liquid supply part D through a connecting pipeline, and is controlled by the first one-way valve 12. Through such a connection, the load control center part E can coordinate and control the other parts B, C, and D to achieve the control of the A part. This control function is achieved by obtaining relevant information of the pressure gauge 17 and the liquid level monitoring device 11, coordinating and operating the first one-way valve 12, the second one-way valve 13 and the third one-way valve 14 to control parts B, C and D, and transmitting the liquid of the target pressure to the pressurized main part A. The pressure gauge 17 can transmit the pressure information to the control center E and also transmit the pressure information to the operator.

[0035] Most of the existing seepage deformation test devices have a low degree of automation and mostly rely on manual operation, and the output of the device is coordinated and controlled by two input factors (water level and pressure). Therefore, the present invention adds a load control center E to realize the control input of the main body A under pressure. Moreover, the device described in the present invention can not only simulate seepage deformation, but also simulate acid fracturing experiments. Acid fracturing experiments are an important step in the development of geothermal resources. High-pressure acidic solutions are used to increase rock cracks to achieve efficient mining and re-injection of geothermal water. When conducting deformation experiments on rock and soil, according to the formation and evolution of seepage, it can be divided into two categories. The first category is seepage deformation that first generates seepage, and the seepage entrains the loss of particles, causing the destruction of the rock and soil structure, and further leading to an increase in seepage volume. The second category is seepage deformation that does not generate seepage, but the seepage pressure acts on the rock and soil, causing the rock and soil structure to be destroyed and shear deformation damage caused by high-pressure water flow. The device described in the present invention can be applied to different geotechnical problems, realize simulation experiments on rock and soil deformation and failure, obtain the critical pressure gradient of rock and soil deformation and failure, simulate the changes of relevant parameters such as permeability coefficient K and permeability k in production practice, and provide a practical, multi-purpose, easy-to-adjust, safe and reliable experimental device and experimental method for the work and teaching related to rock and soil deformation and failure in hydrogeology and environmental geology.

[0036] A one-way valve is a valve that can only flow in one direction after it is opened. If it is not opened, neither direction can flow through; an ordinary valve is a valve that can flow in both directions after it is opened. If it is not opened, neither direction can flow through; a safety valve is set with a predetermined maximum pressure. When the pressure in the air pressure liquid tank device 9 equipped with the safety valve 7 is greater than the predetermined maximum pressure, the pressure will be gradually discharged to achieve the purpose of protecting the safety of the device. The one-way valve of the present invention is to control the one-way outflow of liquid / gas, and the use of the one-way valve can simplify the control object of the load change control center part E. For example, the use of the first one-way valve 12 is to avoid damage to the gas compressor 18 and the pressure gauge 17 during operation by the counter-flow. The use of the second one-way valve 13 is consistent with the ordinary valve in general, but when the gas contained in the gas tank 21 is not air, the internal gas consistency can be guaranteed to a greater extent; the third one-way valve 14 is to avoid liquid backflow and pressure tank 16 at the initial stage of liquid supply.

[0037] like Figure 2 As shown, the pressure rock and soil tank 3 is composed of a fifth valve 22, a first permeable stone container 23, a rock and soil container 24, a second permeable stone container 25 and a sixth valve 26. According to different experimental purposes, the first permeable stone container 23 and the second permeable stone container 25 can select the permeable stone filling method of α or β. Different experimental purposes can be achieved by changing the filling method of the permeable stone.

[0038] The first one-way valve 12 only allows fluid to flow from the gas compressor 18 to the pressure tank 9 through the pressure gauge 17, the one-way valve 13 only allows fluid to flow from the pressure tank 9 to the outside, and the second one-way valve 14 only allows fluid to flow from the pump 15 to the pressure tank 9.

[0039] The first valve 2 and the second valve 4 are responsible for controlling the flow of the liquid in the pressurized geotechnical tank 3. When the first valve 2 is closed and the second valve 4 is opened, the liquid only flows into the pressurized geotechnical tank 3 from the bottom; when the second valve 4 is closed and the first valve 2 is opened, the liquid only flows into the pressurized geotechnical tank 3 from the top; when the first valve 2 and the second valve 4 are opened at the same time, the liquid enters the pressurized geotechnical tank 3 from both the top and the bottom.

[0040] The third one-way valve 14 controls the liquid supply part C to pump liquid into the air pressure liquid tank part B.

[0041] The third valve 19 and the fourth valve 20 are responsible for controlling the gas source of the gas compressor 18. When the third valve 19 is opened and the fourth valve 20 is closed, the gas source of the gas compressor 18 is air; when the third valve 19 is closed and the fourth valve 20 is opened, the gas source of the gas compressor 18 is the gas in the gas tank 21. The gas in the gas tank 21 can be flexibly selected according to the working purpose.

[0042] The fifth valve 22 and the sixth valve 26 respectively control the liquid to flow into the upper outlet collection tank 1 and the lower outlet collection tank 5. When the liquid needs to enter the pressure rock and soil tank 3 from bottom to top, the sixth valve 26 is closed and the fifth valve 22 is opened; when the liquid needs to enter the pressure rock and soil tank 3 from top to bottom, the fifth valve 22 is closed and the sixth valve 26 is opened; when the liquid needs to enter the pressure rock and soil tank 3 from both sides, the fifth valve 22 and the sixth valve 26 are closed.

[0043] The load change control center part E is connected to the pressure monitoring device 10 and the second one-way valve 13 in the gas pressure liquid tank B, the gas compressor 18 in the gas supply part D, the pump 15 of the liquid supply part, and the third one-way valve 14 through the line. The built-in single chip microcomputer obtains the pressure in the gas pressure liquid tank 9 through the pressure monitoring device 10, and releases the pressure of the gas pressure liquid tank 9 by controlling the opening of the second one-way valve 13, controls the opening of the third one-way valve 14 and the pump 15, supplies liquid to the gas pressure liquid tank 9 through the liquid tank 16, and pressurizes the gas pressure liquid tank 9 by controlling the opening of the gas compressor 18. The upper part of the gas pressure liquid tank 9 is gas, and the lower part is liquid. Its function is to press the liquid in it to the pressurized rock and soil tank 3 under the action of gas pressure. There is only liquid in the liquid tank 16, which plays a role in liquid supply.

[0044] Before using the device for experiments, the experimental device is set up according to different experimental objectives. The following uses the deformation and damage, pressure and time-related rock rheology correlation and multiple rounds of acid fracturing test experiments as examples to explain how to use the experimental device and the steps for conducting the experiment.

[0045] When the experiment is a rock and soil deformation and failure experiment, after the device is assembled, use the device according to the following steps:

[0046] ① Setting of the pressure body A, opening the second valve 4 and the fifth valve 22, closing the sixth valve 26 and the first valve 2; filling the experimental rock and soil in the rock and soil container 24. When the rock and soil body seepage deformation failure is simulated, the arrangement of the permeable stones in the second permeable stone container 25 and the first permeable stone container 23 is selected as α, and when the rock and soil body shear deformation failure is simulated, the arrangement of the permeable stones in the second permeable stone container 25 and the first permeable stone container 23 is selected as β;

[0047] ② The setting of the pressure tank part B, opening the second one-way valve 12, and closing the second one-way valve 13;

[0048] ③ The setting of the liquid supply part C, after the liquid tank 16 is filled with water, the third one-way valve 14 is opened, and the pump 15 is turned on. The pump 15 drives the water in the liquid tank 16 to flow to the air pressure liquid tank 9. After the water in the air pressure liquid tank 9 is filled to the first preset depth, the pump 15 is turned off;

[0049] ④ Setting of the gas supply part D, closing the fourth valve 20 and opening the third valve 19, so that the gas source after the gas compressor 18 is turned on is air, and at this time, there is no need to open the load change control center part E;

[0050] ⑤ Turn on the gas compressor 18, and the pressurized air enters the gas pressure liquid tank 9 through the first one-way valve 12 and contacts with the water therein. During this process, the pressure of the pressurized air is obtained through the pressure gauge 17, and the pressure in the gas pressure liquid tank 9 is obtained through the pressure monitoring device 10;

[0051] ⑥ According to the different lithology in the geotechnical container 24, the exhaust and infiltration time are different. After the exhaust and infiltration are completed, the second valve 4 and the fifth valve 22 are closed, and the first valve 2 and the sixth valve 26 are opened to change the direction of the liquid entering after being pressurized to flow from top to bottom, and finally enter the lower outlet collection tank 5;

[0052] ⑦ When simulating the seepage deformation and damage of the rock and soil mass, according to the seepage deformation and damage mechanism, liquid will be collected in the lower outlet collection tank 5. At this time, the data of the stabilized flow rate and the pressure monitoring device 10 in the outlet collection tank 5 are recorded; after stabilization for a period of time, the pressure in the gas pressure liquid tank 9 is increased by the gas compressor 18. The increase in pressure will increase the entrainment of the particles by the seepage flow, further causing the destruction of the rock and soil mass structure. The data of the stabilized flow rate and the pressure monitoring device 10 in the collection tank 5 are collected, and the above operation is repeated;

[0053] According to the Darcy experimental principle: Q = KA (ΔH / L), the stable flow rate Q is obtained, where K is the permeability coefficient, A is the water flow cross-sectional area, L is the permeation path, that is, the length of the geotechnical container 24 along the water flow direction, and ΔH is the pressure in the gas pressure liquid tank 9;

[0054] The water passes through the geotechnical container 24 under pressure, flows from top to bottom, and flows out from the water outlet at the bottom thereof; the pressure in the gas pressure tank 9 is increased, so that the geotechnical sample in the geotechnical container 24 is subjected to a certain osmotic pressure difference. When the critical hydraulic / pressure state is reached, the geotechnical sample will be osmotically deformed and damaged, and the water will carry the geotechnical sample out from the water outlet below the geotechnical container 24;

[0055] According to the above principle, when the change of the stable flow Q in the lower outlet collection tank 5 and the change of the pressure H in the pressure monitoring device 10 change, it means that the permeability coefficient K changes. At this time, the reading in the pressure monitoring device 10 minus the permeability path L is the critical hydraulic gradient ΔH / L of the rock and soil sample;

[0056] ⑧When simulating the shear deformation and failure of rock and soil, according to the shear deformation and failure mechanism, no liquid will be collected in the lower outlet collecting tank 5 at the beginning, and the pressure in the gas pressure liquid tank 9 will continue to be increased through the gas compressor 18. The rock and soil in the pressurized rock and soil tank 3 will produce structural damage under the action of pressure. When the pressure exceeds the compressive capacity of the rock and soil, the rock and soil will produce shear deformation and failure, and high-pressure liquid will be collected in the lower outlet collecting tank 5. The pressure indication in the pressure monitoring device 10 is the critical pressure at which the rock and soil sample undergoes structural collapse.

[0057] When conducting a rock rheology test or multiple acid fracturing tests where pressure is related to time (when the experiment is an acid fracturing test, it is recommended that the parts in contact with the acid be replaced with 316L stainless steel components), follow the steps below:

[0058] ① The setting of the pressure body A, close the second valve 4 and the fifth valve 22, open the sixth valve 26 and the first valve 2; when multiple rounds of acid fracturing tests are conducted, the arrangement of the permeable stones in the second permeable stone container 25 and the first permeable stone container 23 is selected as α; when the rock rheology experiment related to pressure and time is conducted, the arrangement of the permeable stones in the second permeable stone container 25 and the first permeable stone container 23 is selected as β. The rock and soil container 24 should be filled with experimental rock and soil.

[0059] ② The setting of the pressure liquid tank part B, close the second one-way valve 13, and open the first one-way valve 12. ③ The setting of the liquid supply part C, after the liquid tank is filled with liquid, open the third one-way valve 14, start the pump 15, the pump 15 drives the liquid in the liquid tank 16 to flow to the air pressure liquid tank 9, after the liquid in the air pressure liquid tank 9 is filled to the second preset depth, turn off the pump 15, and close the third one-way valve 14.

[0060] ④ The setting of the gas supply part D is to close the fourth valve 20 and open the third valve 19 so that the gas source after the gas compressor 18 is turned on is the air; when conducting a fracturing experiment of a special gas, open the fourth valve 20 and close the third valve 19 so that the gas source after the gas compressor 18 is turned on is the gas in the gas tank 21.

[0061] ⑤ The setting of the load change control center E, the required pressure and time relationship is input into the built-in single chip microcomputer of the load change control center E, the load change control center E controls to open the gas compressor 18, the air is pressurized and enters the gas pressure tank 9 through the first one-way valve 12, and contacts with the liquid therein. In this process, the pressure after air pressurization can be known through the pressure gauge 17, and the pressure in the gas pressure tank can be known through the pressure monitoring device 10. When the target pressure is reached, the load change control center E controls to close the gas compressor 18. The liquid in the gas pressure tank 9 is pressurized and enters the pressurized rock and soil tank 3 through the first valve 2. During this process, the load change control center part E monitors the pressure change in the pressure liquid tank 9 in real time through the pressure monitoring device 10. When it is detected that the internal pressure does not meet the required pressure, if the pressure is low, the pressure in the pressure liquid tank 9 is increased by controlling the opening of the gas compressor 18, and the gas compressor 18 is controlled to be closed after the pressure reaches the required pressure; if the pressure is high, the pressure in the pressure liquid tank 9 is reduced by controlling the opening of the second one-way valve 13, and the second one-way valve 13 is controlled to be closed after the pressure is reduced to the required pressure. The load change control center part E monitors the amount of liquid in the pressure liquid tank 9 through the liquid level monitoring device 11. When it is monitored that the liquid in the pressure liquid tank 9 is less than the first preset amount, which in this embodiment is 40% of the total amount of the pressure liquid tank 9, the pump 15 is controlled to open, and the pump pressure is increased to a level greater than the reading of the pressure monitoring device 10, and the liquid is pumped into the pressure liquid tank through the third one-way valve 14. When the liquid level monitoring device monitors that the liquid level is greater than the second preset amount, which in this embodiment is 60% of the total amount of the pressure liquid tank 9, the pump 15 is controlled to close.

[0062] ⑥ In this process, the data of the stabilized flow and pressure monitoring device 10 in the upper outlet collection tank 1 are recorded, and the permeability k of the rock and soil at different times can be calculated according to the Darcy experimental principle formula and the permeability coefficient and permeability conversion formula, thereby obtaining the rock rheology or the changes in the rock and soil properties during multiple rounds of acid fracturing.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A variable pressure rock and soil deformation and failure simulation experimental device, characterized by: The device comprises a pressure-bearing main body part A, a pressure liquid tank part B, a liquid supply part C, a gas supply part D and a load change control center part E; the pressure-bearing main body part A comprises an upper outlet collecting tank (1), a first valve (2), a pressure rock and soil tank (3), a second valve (4), a lower outlet collecting tank (5), a three-way pipe (6) and a connecting pipeline; the pressure liquid tank part B comprises a safety valve (7), an exhaust device (8), a pressure liquid tank (9), a pressure monitoring device (10), a liquid level monitoring device (11), a first one-way valve (12), a second one-way valve (13) and a connecting pipeline; the liquid supply part C comprises a third one-way valve (14), a pump (15) and a liquid tank (16); the gas supply part D comprises a pressure gauge (17), A gas compressor (18), a third valve (19), a fourth valve (20) and a gas tank (21); the load change control center part E has a built-in single chip processor, which is connected to the second one-way valve (12) and the liquid level monitoring device (11), the gas compressor (18) and the pump (15) and the third one-way valve (14) through a line and a pressure monitoring device (10) for coordinated control; the three-way pipe (6) is connected to the lower liquid outlet of the gas pressure liquid tank (9) through a connecting pipe; the upper outlet of the gas pressure liquid tank (9) is connected to the pressure gauge (17) through a connecting pipe, and the exhaust to the outside is controlled by the exhaust device (8); the left outlet of the gas pressure liquid tank (9) is connected to the gas compressor (18) through a connecting pipe, and is controlled by the first one-way valve (12).

2. The variable pressure rock and soil deformation and failure simulation experimental device according to claim 1, characterized in that: The pressure rock and soil tank (3) comprises a fifth valve (22), a first permeable stone container (23), a rock and soil container (24), a second permeable stone container (25) and a sixth valve (26); the top end of the first permeable stone container (23) is connected to the fifth valve (22), and the bottom end is connected to the top end of the rock and soil container (24); the top end of the second permeable stone container (25) is connected to the bottom end of the rock and soil container (24), and the bottom end is connected to the sixth valve (26); according to different experimental purposes, the first permeable stone container (23) and the second permeable stone container (25) can select the α or β permeable stone filling method.

3. The variable pressure rock and soil deformation and failure simulation experimental device according to claim 1, characterized in that: The first one-way valve (12) is used to control the flow of fluid from the gas compressor (18) to the gas pressure liquid tank (9) through the pressure gauge (17), the second one-way valve (13) is used to control the flow of fluid from the gas pressure liquid tank (9) to the outside, and the third one-way valve (14) is used to control the flow of fluid from the pump (15) to the gas pressure liquid tank (9).

4. The variable pressure rock and soil deformation and failure simulation experimental device according to claim 1, characterized in that: The third one-way valve (14) is used to control the pump (15) to flow liquid into the air pressure liquid tank part B.

5. The variable pressure rock and soil deformation and failure simulation experimental device according to claim 1, characterized in that: The first valve (2) and the second valve (4) are used to control the flow of liquid in the pressure rock and soil tank (3). When the first valve (2) is closed and the second valve (4) is opened, the liquid only flows into the pressure rock and soil tank (3) from the bottom; when the second valve (4) is closed and the first valve (2) is opened, the liquid only flows into the pressure rock and soil tank (3) from the top; when the first valve (2) and the second valve (4) are opened at the same time, the liquid enters the pressure rock and soil tank (3) from both the top and the bottom.

6. The variable pressure rock and soil deformation and failure simulation experimental device according to claim 1, characterized in that: The third valve (19) and the fourth valve (20) are used to control the gas source of the gas compressor (18). When the third valve (19) is opened and the fourth valve (20) is closed, the gas source of the gas compressor (18) is air; when the third valve (19) is closed and the fourth valve (20) is opened, the gas source of the gas compressor (18) is the gas in the gas tank (21).

7. The variable pressure rock and soil deformation and failure simulation experimental device according to claim 2, characterized in that: The fifth valve (22) and the sixth valve (26) are used to control the flow of liquid into the upper outlet collection tank (1) and the lower outlet collection tank (5), respectively; when the liquid is required to enter the pressure rock and soil tank (3) from bottom to top, the sixth valve (26) is closed and the fifth valve (22) is opened; when the liquid is required to enter the pressure rock and soil tank (3) from top to bottom, the fifth valve (22) is closed and the sixth valve (26) is opened; when the liquid is required to enter the pressure rock and soil tank (3) from both sides, the fifth valve (22) and the sixth valve (26) are closed.

8. The variable pressure rock and soil deformation and failure simulation experimental device according to claim 1, characterized in that: The load change control center part E is connected to the pressure monitoring device (10), the second one-way valve (13), the gas compressor (18), the pump (15), and the third one-way valve (14) through lines; the built-in single-chip microcomputer obtains the pressure condition in the gas pressure liquid tank (9) through the pressure monitoring device (10), releases the pressure of the gas pressure liquid tank (9) by controlling the opening of the second one-way valve (13), supplies liquid to the gas pressure liquid tank (9) by opening the third one-way valve (14) and the pump (15), and pressurizes the gas pressure liquid tank (9) by controlling the opening of the gas compressor (18).

9. A variable pressure rock and soil deformation and failure simulation experimental device as claimed in claims 1 to 8, characterized in that: When the device is used to conduct a rock and soil deformation and failure experiment, the arrangement of the permeable stones in the second permeable stone container (25) and the first permeable stone container (23) can be changed to achieve simulation of different deformation and failure mechanisms of the rock and soil body. The specific steps are as follows: ① Setting of the pressure-bearing main body A, opening the second valve (4) and the fifth valve (22), closing the sixth valve (26) and the first valve (2); filling the experimental rock and soil in the rock and soil container (24). When the simulation of rock and soil seepage deformation failure is selected, the arrangement of the permeable stones in the second permeable stone container (25) and the first permeable stone container (23) is selected as α, and when the simulation of rock and soil shear deformation failure is selected, the arrangement of the permeable stones in the second permeable stone container (25) and the first permeable stone container (23) is selected as β; ② The setting of the pressure liquid tank part B, opening the second one-way valve (12), and closing the second one-way valve (13); ③ The setting of the liquid supply part C, after the liquid tank (16) is filled with water, the third one-way valve (14) is opened, and the pump (15) is turned on, and the pump (15) drives the water in the liquid tank (16) to flow to the air pressure liquid tank (9), and after the water in the air pressure liquid tank (9) is filled to a first preset depth, the pump (15) is turned off; ④ Setting of the gas supply part D, closing the fourth valve (20) and opening the third valve (19), so that the gas source after the gas compressor (18) is turned on is air, and at this time, there is no need to turn on the load change control center part E; ⑤ Turn on the gas compressor (18), and the pressurized air passes through the first one-way valve (12) and enters the gas pressure liquid tank (9), and contacts the water therein. During this process, the pressure of the pressurized air is obtained through the pressure gauge (17), and the pressure in the gas pressure liquid tank (9) is obtained through the pressure monitoring device (10); ⑥ According to the different lithology in the geotechnical container (24), the exhaust and infiltration time are different. After the exhaust and infiltration are completed, the second valve (4) and the fifth valve (22) are closed, and the first valve (2) and the sixth valve (26) are opened to change the direction of the liquid entering after being pressurized to flow from top to bottom, and finally enter the lower outlet collection tank (5); ⑦ When simulating the seepage deformation and damage of the rock and soil mass, according to the seepage deformation and damage mechanism, liquid will be collected in the lower outlet collection tank (5), and at this time, the data of the stabilized flow rate and the pressure monitoring device (10) in the outlet collection tank (5) will be recorded; after a period of stabilization, the pressure in the gas pressure liquid tank (9) will be increased by the gas compressor (18), and the increase in pressure will increase the entrainment of the particles by the seepage flow, further causing the destruction of the rock and soil mass structure, and the data of the stabilized flow rate and the pressure monitoring device (10) in the collection tank (5) will be collected, and the above operation will be repeated; According to the Darcy experimental principle: Q = KA (ΔH / L), the stable flow rate Q is obtained, where K is the permeability coefficient, A is the water flow cross-sectional area, L is the permeability path, that is, the length of the geotechnical container (24) along the water flow direction, and ΔH is the pressure in the gas pressure liquid tank (9); The water passes through the geotechnical container (24) under pressure, flows from top to bottom, and flows out from the water outlet at the bottom thereof; the pressure in the gas pressure tank (9) is increased, so that the geotechnical sample in the geotechnical container (24) is subjected to a certain osmotic pressure difference. When the critical hydraulic / pressure state is reached, the geotechnical sample will be osmotically deformed and damaged, and the water will carry the geotechnical sample out from the water outlet at the bottom of the geotechnical container (24); According to the above principle, when the change of the stable flow Q in the lower outlet collection tank (5) and the change of the pressure H in the pressure monitoring device (10) change, it means that the permeability coefficient K changes. At this time, the reading in the pressure monitoring device (10) minus the permeability path L is the critical hydraulic gradient ΔH / L of the rock and soil sample; ⑧ When simulating the shear deformation failure of the rock and soil mass, according to the shear deformation failure mechanism, no liquid will be collected in the lower outlet collection tank (5) at the beginning. The pressure in the gas pressure liquid tank (9) is continuously increased through the gas compressor (18). The rock and soil mass in the pressurized rock and soil tank (3) will produce structural damage under the action of pressure. When the pressure exceeds the compressive capacity of the rock and soil mass, the rock and soil mass will produce shear deformation failure. High-pressure liquid will be collected in the lower outlet collection tank (5). The pressure reading in the pressure monitoring device (10) is the critical pressure at which the rock and soil sample will undergo structural collapse.

10. A variable pressure rock and soil deformation and failure simulation experimental device as claimed in claims 1 to 8, characterized in that: When using the device to conduct rock rheology-related or multi-round acid fracturing tests with pressure and time correlation, the specific steps are as follows: ① The pressure-bearing main body A is set up, the second valve (4) and the fifth valve (22) are closed, and the sixth valve (26) and the first valve (2) are opened; wherein, when multiple rounds of acid fracturing tests are conducted, the arrangement of the permeable stones in the second permeable stone container (25) and the first permeable stone container (23) is selected as α; when a rock rheology experiment related to pressure and time is conducted, the arrangement of the permeable stones in the second permeable stone container (25) and the first permeable stone container (23) is selected as β; the rock and soil container (24) is filled with experimental rock and soil; ② The pressure tank part B is set up, the second one-way valve (13) is closed, and the first one-way valve (12) is opened; ③ The setting of the liquid supply part C, after the liquid tank (16) is filled with liquid, the third one-way valve (14) is opened, and the pump (15) is turned on, and the pump (15) drives the liquid in the liquid tank (16) to flow to the air pressure liquid tank (9), and after the liquid in the air pressure liquid tank (9) is filled to a second preset depth, the pump (15) is turned off, and the one-way valve (14) is closed; ④ The setting of the gas supply part D, the fourth valve (20) is closed, and the third valve (19) is opened, so that the gas source after the gas compressor (18) is turned on is air; when conducting a fracturing experiment of a special gas, the fourth valve (20) is opened, and the third valve (19) is closed, so that the gas source after the gas compressor (18) is turned on is the gas in the gas tank (21); ⑤ Setting of the load change control center E. The required pressure and time relationship is input into the built-in single chip microcomputer of the load change control center E. The load change control center E controls the opening of the gas compressor (18). After the air is pressurized, it passes through the first one-way valve (12) and enters the gas pressure tank (9) to contact the liquid therein. During this process, the pressure after the air is pressurized is obtained through the pressure gauge (17). The pressure in the gas pressure tank (9) is obtained through the pressure monitoring device (10). When the target pressure is reached, the load change control center E controls the closing of the gas compressor (18). The liquid in the gas pressure tank (9) is pressurized and enters the pressurized rock and soil tank (3) through the first valve (2). During this process, the load change control center E monitors the pressure change in the gas pressure tank (9) in real time through the pressure monitoring device (10). When it is detected that the pressure inside the gas pressure tank (9) is different from the pressure inside the pressure monitoring device (10), the load change control center E controls the closing of the gas compressor (18). When the preset pressure is not met, if the pressure is too low, the pressure in the gas pressure tank (9) is increased by controlling the opening of the gas compressor (18), and the pressure is controlled to be closed after the pressure reaches the preset pressure; if the pressure is too high, the pressure in the gas pressure tank (9) is reduced by controlling the opening of the second one-way valve (13), and the pressure is controlled to be closed after the pressure reaches the preset pressure; the load change control center part E monitors the amount of liquid in the gas pressure tank (9) through the liquid level monitoring device (11), and when it is monitored that the amount of liquid in the gas pressure tank (9) is less than the first preset amount, the pump (15) is controlled to be opened, and when the pressure of the pump (15) is increased to a value greater than the reading of the pressure monitoring device (10), the liquid is pumped into the gas pressure tank (9) through the third one-way valve (14), and when the liquid level monitoring device (11) monitors that the liquid level is greater than the second preset amount, the pump (15) is controlled to be closed; ⑥ In this process, the data of the stabilized flow rate and pressure monitoring device (10) in the upper outlet collection tank (1) are recorded, and the permeability k of the rock and soil at different times can be calculated according to the Darcy experimental principle formula and the permeability coefficient and permeability conversion formula, thereby obtaining the rock rheology or the changes in the rock and soil properties during multiple rounds of acid fracturing.

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