Multi-field coupling rock mass extraction and progressive instability simulation experimental device and method

Abstract

The present application relates to a kind of multi-field coupling rock mass extraction and progressive instability simulation experimental device and method, it is related to geotechnical engineering physical experiment simulation technical field, wherein device includes: the model box that can simulate the stress state of rock mass under deep ground condition, and is filled with rock sample;Water circulation device;Water tank with adjustable water pressure, model box is placed in water tank, and at least two side walls of model box are provided with first hole for fluid passing in water tank;Rock sample in model box is provided with second hole along vertical distribution, the outer wall of rock sample is tightly arranged with the inside of model box, top is provided with opening corresponding to second hole, is provided with pumping motor in, the output end of pumping motor is connected to the input end of water circulation device, output end is connected to the water inlet of water tank, the absolute height of water tank inner chamber top surface is slightly higher than the absolute height of model box inner chamber top surface.Compared with prior art, the present application can model the progressive instability state of rock mass in deep rock oil exploitation process.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering physical experiment simulation technology, and in particular to a multi-field coupled rock mass extraction and progressive instability simulation experimental device and method. Background Technology

[0002] Deep rock mass extraction is a core technology in oil and gas resource development, geothermal energy extraction, and CO2 geological storage. Its core challenge lies in the fracture propagation, fluid migration, and stability response of rock masses under the coupled effects of multiple physical fields (stress field, seepage field, temperature field, and chemical field). Existing experimental systems have significant limitations in simulating real engineering environments. Therefore, further development of multi-field coupled rock mass extraction simulation experimental devices is urgently needed.

[0003] Traditional experimental systems for research sampling have several significant problems, including:

[0004] 1. Existing model test systems cannot simulate the high confining pressure stress state and gradual instability process of deep rock masses.

[0005] 2. Existing model test systems lack the ability to simultaneously simulate high confining pressure stress and seepage effects. Traditional tests often do not apply high confining pressure to the rock mass if the seepage path of the reservoir is taken into account. Although fluid coupling can be achieved, the rock mass boundary is in a free state, which does not match the actual working conditions.

[0006] 3. Existing model test systems have limited consideration of temperature fields and often cannot simulate the high-temperature environment deep underground.

[0007] While some related fields offer simulation devices for reference, such as the experimental device disclosed in Chinese patent CN111220523A that can simulate geothermal extraction tests under complex load conditions, this prior art uses a pressure chamber to hold a rock sample and injects water into the sample through a permeable plate. However, this water injection method uses end injection, which cannot guarantee the stability of the pressure in the internal pores. Therefore, it still cannot simulate the high confining pressure stress state and gradual instability process of deep rock masses. The direct scouring of the end water flow can also lead to local changes in rock properties, resulting in significant errors in the test results. In addition, this technology does not address actual engineering practices, only analyzing the material properties of different rocks under seepage. The actual process is complex; under high pressure and the coupling effect of different fields, the structural response may not completely follow material changes, such as well wall collapse and instability. Summary of the Invention

[0008] The purpose of this invention is to provide a multi-field coupled rock mass extraction and progressive instability simulation experimental device and method to overcome the shortcomings of the prior art.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] A multi-field coupled rock mass extraction and progressive instability simulation experimental device includes:

[0011] A model box that can simulate the stress state of rock mass under deep-earth conditions, the model box being filled with rock samples;

[0012] Water circulation device;

[0013] Also includes:

[0014] A water tank with adjustable water pressure, wherein the model box is placed in the water tank, and at least two side walls of the model box are provided with first holes for fluid in the water tank to pass through;

[0015] Camera;

[0016] The rock sample in the model box has a second hole distributed vertically. The outer wall of the rock sample is tightly fitted to the inside of the model box. The top of the model box has an opening corresponding to the second hole. A water pump motor is installed at the opening. The input end of the water circulation device is connected to the output end of the water pump motor, and the output end is connected to the inlet of the water tank. The absolute height of the top surface of the inner cavity of the water tank is slightly higher than the absolute height of the top surface of the inner cavity of the model box. A first pressure sensor is installed in the second hole, and a second pressure sensor is installed in the water tank. A temperature control module is also installed at the bottom of the water tank. The camera is used to collect the seepage process in the second hole.

[0017] The model box includes a pressure chamber base, a pressure chamber rear wall, a pressure chamber front wall, a pressure chamber top cover, and two pressure chamber side walls. The pressure chamber rear wall and the pressure chamber front wall are arranged opposite each other. The pressure chamber rear wall, the pressure chamber front wall, and the two pressure chamber side walls are all vertically arranged and form a square frame. The bottom is connected to the pressure chamber base, and the top is connected to the pressure chamber top cover to form a sealed cavity. The pressure chamber base, the pressure chamber rear wall, the pressure chamber front wall, and the two pressure chamber side walls are all fixedly arranged. The pressure chamber top cover moves downward under the action of an external driving device to form a confining pressure on the rock sample inside the model box. The top of the water tank is provided with a water tank cover plate, which moves up and down synchronously with the pressure chamber top cover.

[0018] The pressure chamber has a first hole on its rear wall and on the two side walls of the pressure chamber.

[0019] The second hole is semi-cylindrical, with any radial cross-section being semi-circular, and the second hole is located on the first surface of the rock sample, with the axis of the second hole located in the plane of the first surface of the rock sample;

[0020] The first hole is not provided on the side wall of the first surface of the model box that contacts the rock sample, or the side wall of the first surface of the model box that contacts the rock sample is not in contact with the liquid in the water tank.

[0021] A test method for a multi-field coupled rock mass extraction and progressive instability simulation experimental device as described above includes:

[0022] Step S1: Prepare a rock sample containing a second hole and place the rock sample in a model box;

[0023] Step S2: Arrange the first pressure sensor in the second hole, and arrange the second pressure sensor and temperature control module in the water tank;

[0024] Step S3: Connect the model box and water tank to the water circulation device;

[0025] Step S4: Use an external drive device to increase the confining pressure inside the model box until the pre-configured target confining pressure is reached;

[0026] Step S5: Turn on the water circulation device and temperature control module. By observing the values ​​of the first pressure sensor and the second pressure sensor, ensure that the pressure in the water tank and at the second hole is equal and stable within the first target range, and that the temperature of the liquid in the water tank is stable and within the second target range.

[0027] Step S6: Turn on the camera to prepare to record the seepage process in the second hole, turn on the pump motor, control the pumping rate within the configured third target range, and record the value of the second pressure sensor in real time.

[0028] Step S7: After the continuous pumping operation reaches the expected time, turn off the pumping motor, obtain the seepage path based on the video recorded by the camera, and obtain the time series data of strain changing with pore pressure based on the pore pressure data collected by the second pressure sensor.

[0029] The liquid in the water tank contains a fluorescent agent.

[0030] The process of obtaining the seepage path based on the video recorded by the camera includes:

[0031] The model box is placed under an LED light source of a specified wavelength to excite fluorescence, and the images are captured by a camera equipped with an optical filter to obtain a sequence of photos, wherein the optical filter is used to filter out interference from the excitation light;

[0032] The seepage direction of each photo is obtained by converting the photo to grayscale, covering the rock background in the photo with a grayscale value of 0, cropping to obtain multiple continuous fluorescent regions, and generating directed line segments from the part with a large grayscale value to the part with a small grayscale value as the seepage direction based on each fluorescent region.

[0033] The seepage path is obtained by stitching together the directed line segments of each photo.

[0034] In step S6, the pumping rate of the pumping motor satisfies the condition that the water level in the tank drops within a pre-configured threshold range.

[0035] The strain is measured by a strain sensor.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. By placing the model box inside a sealed water tank and opening a first hole on the side of the model box for water infiltration, and by using the boundary constraints of all sides and bottom of the model box, a high confining pressure is applied to the rock sample inside the model box using the driving force of the external drive device. On the other hand, by increasing the pressure inside the water tank, combined with the second hole opened in the rock sample, the gradual instability state of the rock mass during the deep oil extraction process can be modeled.

[0038] 2. The first hole is provided on the rear wall of the pressure chamber and the two side walls of the pressure chamber, but the front wall of the pressure chamber does not contact the water tank. The second hole has a semi-circular radial cross section and is located on the surface of the front wall of the pressure chamber. This allows the overall size of the device to be reduced by utilizing the symmetry characteristics, thereby reducing space occupation. On the other hand, by using transparent material for the front wall of the pressure chamber, the quality of the photographs can be effectively improved, which is beneficial for obtaining the seepage path later.

[0039] 3. After ensuring that the pressure inside the water tank and at the second hole are equal and stable within the first target range, and that the temperature of the liquid inside the water tank is stable and within the second target range, start pumping water into the second hole. This ensures that the readings of the two pressure sensors are consistent and reduces fluctuations during the pumping process.

[0040] 4. By adding fluorescent agents and combining them with computer vision technology, the seepage direction is obtained by continuously dividing gray areas from large to small, and the seepage path is obtained by stitching together the seepage direction with time sequence information, which is accurate and fast. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the structure of the present invention;

[0042] Figure 2 for Figure 1 AA section cross-section view;

[0043] The components are: 1. Loading frame top plate, 2. Loading frame column, 3. Pressure chamber side wall, 4. Water tank side wall, 5. Second pressure sensor, 6. Support base, 7. Pumping motor, 8. Pressure chamber base, 9. Camera, 10. Servo cylinder, 11. Water pump, 12. Liquid extraction pipe, 13. Infusion pipe, 14. Liquid storage tank, 15. Storage tank support platform, 16. Water tank cover, 17. Pressure chamber top cover, 18. Temperature control module, 19. Pressure chamber rear wall, 20. Pressure chamber front wall, 21. First pressure sensor. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0045] A multi-field coupled rock mass extraction and progressive instability simulation experimental device, such as Figure 1 and Figure 2 As shown, it includes:

[0046] A model box that can simulate the stress state of rock mass under deep-earth conditions, with rock samples filling the inside of the model box;

[0047] Water circulation device;

[0048] Also includes:

[0049] A water tank with adjustable water pressure, a model box placed in the water tank, and at least two side walls of the model box are provided with first holes for fluid in the water tank to pass through;

[0050] The rock sample in the model box has a second hole distributed vertically. The outer wall of the rock sample is tightly attached to the inside of the model box. The top of the model box has an opening corresponding to the second hole. A water pump motor 7 is installed at the opening. The input end of the water circulation device is connected to the output end of the water pump motor 7, and the output end is connected to the water inlet of the water tank. The absolute height of the top surface of the water tank cavity is slightly higher than the absolute height of the top surface of the model box cavity.

[0051] The model box includes a pressure chamber base 8, a pressure chamber rear wall 19, a pressure chamber front wall 20, a pressure chamber top cover 17, and two pressure chamber side walls 3. The pressure chamber rear wall 19 and pressure chamber front wall 20 are arranged opposite each other. The pressure chamber rear wall 19, pressure chamber front wall 20, and two pressure chamber side walls 3 are all vertically arranged and form a square frame. The bottom is connected to the pressure chamber base 8, and the top is connected to the pressure chamber top cover 17 to form a sealed cavity. The pressure chamber base 8, pressure chamber rear wall 19, pressure chamber front wall 20, and two pressure chamber side walls 3 are all fixedly arranged. The pressure chamber top cover 17 moves downward under the action of an external driving device to form a confining pressure on the rock sample inside the model box. The top of the water tank is provided with a water tank cover 16, which moves up and down synchronously with the pressure chamber top cover 17.

[0052] By placing the model box inside a sealed water tank and opening a first hole on the side of the model box for water infiltration, and by using the boundary constraints of all sides and bottom of the model box, a high confining pressure is applied to the rock sample inside the model box using the driving force of an external drive device. On the other hand, by increasing the pressure inside the water tank, combined with the second hole opened in the rock sample, the gradual instability state of the rock mass during the deep oil extraction process can be modeled.

[0053] In addition, this embodiment also includes a loading frame, which includes a support base 6, a loading frame column 2 and a loading frame top plate 1. The support base 6 and the loading frame top plate 1 are connected by the loading frame column 2. The model box and the water tank are both located inside the loading frame and placed on the support base 6.

[0054] The water circulation device includes a water pump 11, a suction pipe 12, a delivery pipe 13, a liquid storage tank 14, and a storage tank support platform 15. The output end of the suction pipe 12 is connected to the liquid storage tank 14, and the input end is connected to the pumping motor 7, used to deliver the liquid drawn by the pumping motor 7 from the second hole to the liquid storage tank 14. The input end of the delivery pipe 13 is connected to the liquid storage tank 14, and the output end is connected to a water tank. The water pump 11 is mounted on the delivery pipe 13, used to draw liquid from the liquid storage tank 14 and inject it into the water tank to increase the hydraulic pressure in the water tank. In this embodiment, as shown... Figure 1 As shown, there are multiple sets of infusion pipes 13 and water pumps 11. The connection points of each infusion pipe 13 to the water tank are evenly distributed around the model box on the horizontal plane, which can improve the uniformity of water pressure around the model box.

[0055] In this embodiment, the rear wall 19 of the pressure chamber and the two side walls 3 of the pressure chamber are each provided with a first hole, such as Figure 2As shown, the second hole is semi-cylindrical, with any radial cross-section being semi-circular. The second hole is located on the first surface of the rock sample, and the axis of the second hole is located in the plane of the first surface of the rock sample. The side wall of the model box that contacts the first surface of the rock sample does not have the first hole, or the side wall of the model box that contacts the first surface of the rock sample does not contact the liquid in the water tank. Thus, on the one hand, the symmetry characteristics can be used to reduce the size of the overall device and reduce space occupation. On the other hand, by using transparent material for the front wall 20 of the pressure chamber, the quality of the photographs can be effectively improved, which is beneficial for obtaining the seepage path later.

[0056] The second hole is equipped with a first pressure sensor 21, and the water tank is equipped with a second pressure sensor 5. The support base 6 near the bottom of the water tank is also equipped with a temperature control module 18.

[0057] In this embodiment, the pressure chamber sidewall 3, the bearing base 6, and the pressure chamber rear wall 19 are made of steel, with pre-drilled bolt holes for easy mutual fixing and fixing of the pressure chamber base 8, and rubber rings to ensure sealing; the pressure chamber sidewall 3 and the pressure chamber rear wall 19 have pre-drilled first dispersion holes to ensure that the liquid in the water tank can seep into the rock sample; the pressure chamber top cover 17 and the pressure chamber front wall 20 are made of transparent material to maintain high transparency and facilitate observation of the liquid seepage during the test; the mud in the liquid storage tank 14 is filled with fluorescent material to facilitate recording the liquid seepage during the sample preparation process.

[0058] Therefore, this application also provides a test method for the multi-field coupled rock mass extraction and progressive instability simulation experimental device as described above, including:

[0059] Step S1: Prepare a rock sample containing a second hole, place the rock sample in the model box, and use the pressure chamber side wall 3, pressure chamber rear wall 19, and pressure chamber base 8 to constrain the five-sided displacement of the rock mass. All components are connected with sealing rings and bolts to ensure good sealing.

[0060] Step S2: Arrange the first pressure sensor 21 in the second hole, and arrange the second pressure sensor 5 and temperature control module 18 in the water tank. Arrange the temperature control module 18 on the support base 6. Arrange the second pressure sensor 5 on the inner side of the water tank side wall 4 and place it on the support base 6. Fix the water tank cover plate 16 to the top of the water tank, ensuring that its position is slightly higher than the pressure chamber top cover 17.

[0061] Step S3: Connect the model box and water tank to the water circulation device, connect the water pump 11 to the infusion pipe 13, and place the infusion pipe 13 into the water tank through the hole reserved in the water tank cover.

[0062] Step S4: Use an external drive device to increase the confining pressure inside the model box until the pre-configured target confining pressure is reached;

[0063] Step S5: Turn on the water circulation device and temperature control module 18. By observing the values ​​of the first pressure sensor 21 and the second pressure sensor 5, ensure that the pressure in the water tank and at the second hole is equal and stable within the first target range, and that the temperature of the liquid in the water tank is stable and within the second target range. The first target range is the pressure of the deep rock mass to be simulated, and the second target range is the temperature of the deep rock mass to be simulated.

[0064] Step S6: Turn on camera 9 to prepare to record the seepage process in the second hole, and turn on pump motor 7 to control the pumping rate within the configured third target range, and record the value of second pressure sensor 5 in real time. Camera 9 is positioned in a suitable location to ensure that the situation in the second hole can be captured.

[0065] Step S7: After the continuous pumping operation reaches the expected time, the pumping motor 7 is turned off. The seepage path is obtained based on the video recorded by the camera 9, and the time series data of strain changing with pore pressure is obtained based on the pore pressure data collected by the second pressure sensor 5. In this embodiment, the strain is measured by a strain sensor.

[0066] In this embodiment, the process of obtaining the seepage path based on the video recorded by camera 9 includes:

[0067] (1) The model box is placed under an LED light source of a specified wavelength to excite fluorescence. The image is captured by a camera 9 equipped with an optical filter to obtain a sequence of photos. The optical filter is used to filter out interference from the excitation light. Generally, the wavelength of the LED light source needs to be combined with a fluorescent agent. Different fluorescent agents have different excitation wavelengths. In addition, since the image captured by the camera 9 contains the fluorescence excited under the LED light source and the light of the LED light source itself, a filter is needed to filter out the light of the LED light source itself to obtain the fluorescence excited under the LED light source. Of course, in specific implementation, in order to reduce costs, the filter can generally only filter some narrower bands, thus still retaining the reflected light of the background rocks.

[0068] (2) Based on each photo, the seepage direction of each photo is obtained: the photo is grayscaled, the rock background in the photo is covered with grayscale value 0, multiple continuous fluorescent areas are cropped, and a directed line segment from the part with large grayscale value to the part with small grayscale value is generated based on each fluorescent area as the seepage direction.

[0069] In some embodiments, a monochrome camera can be used directly, thus eliminating the need for grayscale conversion, since the captured image is already grayscale. In other embodiments, grayscale conversion can be achieved using existing conversion formulas. It is recommended to directly use a monochrome camera to capture grayscale images to reduce errors.

[0070] In the process of covering the rock background in the photo with a gray value of 0, the method used in this embodiment is to directly determine whether it is a rock based on the gray value of each pixel. Simply put, a threshold gray value is set, and all pixels with gray values ​​less than the threshold gray value are regarded as rock background. Of course, in other embodiments, the corresponding area can also be obtained by target detection.

[0071] The key step in this process is to generate directed line segments from areas with high grayscale values ​​to areas with low grayscale values, based on each fluorescent region, as the seepage direction. Specifically, one or more fluorescent regions are first obtained through distance constraints. The specific process includes:

[0072] Any pixel among all non-zero pixels that are not included in any fluorescent region is selected as the current seed pixel.

[0073] Search for non-zero pixels within a range of 1 pixel interval around it. If there are any, then form a fluorescent region by combining the current seed pixel, all the searched pixels, and the interval pixels.

[0074] Continue to diffuse outwards in the fluorescent region, searching for non-zero pixels within a range of 1 pixel intervals. If a non-zero pixel is found, the current fluorescent region, all the searched pixels, and the interval pixels are superimposed to update the current fluorescent region until no non-zero pixels are found within a range of 1 pixel intervals.

[0075] Continue to use any pixel among all non-zero pixels that have not been included in any fluorescent region as the current seed pixel, and repeat the above process until there are no non-zero pixels that have not been included in any fluorescent region, thereby obtaining multiple consecutive fluorescent regions.

[0076] Next, all obtained continuous fluorescent regions need to be filtered to remove some that are too small. Then, for all the remaining continuous fluorescent regions, multiple cluster centers are obtained by clustering. Based on the principle of the average gray value of each cluster group from large to small, a directed line segment is generated from the cluster center of the part with the large gray value to the cluster center of the part with the small gray value as the seepage direction. In this embodiment, two cluster centers are obtained for each fluorescent region. Of course, in some cases, when a continuous fluorescent region is relatively large and exhibits obvious band-like characteristics (width is less than length), a directed broken line segment consistent with the direction of the fluorescent region can be generated.

[0077] (3) The seepage path is obtained by stitching together the directed line segments of each photo. Specifically, all directed line segments are superimposed, including:

[0078] Set the interval pixel to 1;

[0079] Merging steps: If the distance between the endpoint of any directed line segment and another directed graphic (the initial directed image is a directed line segment or a directed polyline segment) is less than the interval pixel, then the directed line segment is superimposed on the directed graphic to obtain the updated directed graphic.

[0080] Increase the interval pixels and return to the merging step until the interval pixels reach the upper limit. Generally, the upper limit needs to be determined based on the size of the second hole.

[0081] Furthermore, in step S6, the pumping rate of the pumping motor 7 satisfies the following condition: the rate of decrease in the water level in the tank is within a pre-configured threshold range. The pumping rate should not be too high, but should result in a significant drop in the water level in the tank. After the liquid is pumped out, a pressure difference will be generated at the wall of the second hole, which will lead to an increase in the seepage rate. The value of the first pressure sensor 21 at the wall of the second hole will fluctuate significantly, stabilizing after a certain period of pumping.

[0082] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A multi-field coupling rock mass extraction and progressive instability simulation experimental device, comprising: a model box capable of simulating the stress state of rock mass under deep geological conditions, the model box being filled with a rock sample in the middle; a water circulation device; characterized in that further comprising: a water tank capable of adjusting water pressure, the model box being placed in the water tank, and at least two side walls of the model box being provided with first holes for the fluid in the water tank to pass through; a camera (9); a second hole being provided on the rock sample in the model box and being vertically distributed, an outer wall of the rock sample being tightly arranged with the inside of the model box, and a top of the model being provided with an opening corresponding to the second hole, the opening being provided with a water pumping motor (7), an input end of the water circulation device being connected to an output end of the water pumping motor (7), an output end being connected to a water inlet of the water tank, an absolute height of a top surface of an inner cavity of the water tank being slightly higher than an absolute height of a top surface of an inner cavity of the model box; a first pressure sensor (21) being provided in the second hole, and a second pressure sensor (5) being provided in the water tank, a temperature control module (18) being further provided at a bottom of the water tank, and the camera (9) collecting a seepage process in the second hole; the water circulation device further comprising a water pump (11), a liquid delivery pipe (13), and a liquid storage tank (14), an input end of the liquid delivery pipe (13) being connected to the liquid storage tank (14), an output end being connected to the water tank, and the water pump (11) being arranged on the liquid delivery pipe (13) and used for pumping liquid in the liquid storage tank (14) and injecting the liquid into the water tank to increase the hydraulic pressure in the water tank; the model box comprising a pressure chamber base (8), a pressure chamber back wall (19), a pressure chamber front wall (20), a pressure chamber top cover (17), and two pressure chamber side walls (3), the pressure chamber back wall (19) and the pressure chamber front wall (20) being oppositely arranged, the pressure chamber back wall (19), the pressure chamber front wall (20), and the two pressure chamber side walls (3) being vertically arranged and surrounding a square frame, the bottom being connected to the pressure chamber base (8), and the top being connected to the pressure chamber top cover (17) to form a closed cavity, the pressure chamber base (8), the pressure chamber back wall (19), the pressure chamber front wall (20), and the two pressure chamber side walls (3) being fixedly arranged, the pressure chamber top cover (17) being driven downward by an external driving device to form confining pressure on the rock sample in the model box, and the water tank being provided with a water tank cover plate (16), the water tank cover plate (16) moving up and down synchronously with the pressure chamber top cover (17). 2.The multi-field coupling rock mass extraction and progressive failure simulation experimental device according to claim 1, characterized in that, The pressure chamber back wall (19) and the two pressure chamber side walls (3) are each provided with a first hole.

3. The multi-field coupling rock mass extraction and progressive failure simulation experiment device according to claim 1, characterized in that, The second hole is a semi-cylindrical shape, any radial cross section of which is a semicircle, and the second hole is located on a first surface of the rock sample, and an axis of the second hole is located in a plane of the first surface of the rock sample. The side wall of the model box contacting the first surface of the rock sample is not provided with a first hole, or the side wall of the model box contacting the first surface of the rock sample is not in contact with the liquid in the water tank.

4. The method of the multi-field coupling rock mass extraction and progressive failure simulation experiment device according to claim 3, characterized in that, ​ Step S1: preparing a rock sample containing a second hole, and placing the rock sample in a model box; Step S2: arranging a first pressure sensor (21) in the second hole, and arranging a second pressure sensor (5) and a temperature control module (18) in a water tank; Step S3: connecting the model box and the water tank to a water circulation device; Step S4: increasing the confining pressure in the model box by using an external driving device until a preconfigured target confining pressure is reached; Step S5: opening the water circulation device and the temperature control module (18), and ensuring that the pressure in the water tank and at the second hole is equal and stable within a first target range, and the temperature of the liquid in the water tank is stable and within a second target range, by observing the values of the first pressure sensor (21) and the second pressure sensor (5); Step S6: opening a camera (9) to record the seepage process in the second hole, and opening a water pumping motor (7) to control the pumping rate within a preconfigured third target range, and recording the value of the second pressure sensor (5) in real time; Step S7: after the continuous pumping operation reaches a preconfigured time, the water pumping motor (7) is turned off, the seepage path is obtained based on the video recorded by the camera (9), and the time series data of the strain change with the hole pressure is obtained based on the hole pressure data collected by the second pressure sensor (5).

5. The method of claim 4, wherein, The liquid in the water tank contains a fluorescent agent.

6. The method of claim 5, wherein, The process of obtaining the seepage path based on the video recorded by the camera (9) includes: placing the model box under a LED light source of a specified wavelength to excite fluorescence, and taking a photo sequence by the camera (9) equipped with an optical filter, wherein the optical filter is used to filter the excitation light interference; obtaining the seepage direction of each photo based on the photo: graying the photo, covering the rock background in the photo with a gray value of 0, cutting to obtain a plurality of continuous fluorescent regions, and generating a directed line segment from a part with a large gray value to a part with a small gray value as the seepage direction based on each fluorescent region; splicing the directed line segments of each photo to obtain the seepage path.

7. The method of claim 4, wherein, The pumping rate of the water pumping motor (7) in step S6 meets the requirement that the water level in the water tank decreases at a speed within a preconfigured threshold range.

8. The method of claim 4, wherein, The strain is measured by a strain sensor.

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