A test device and test method for filling fissure seepage-erosion visualization

Abstract

The application discloses a test device and a test method for filling fissure seepage-erosion visualization, and the test device comprises a fissure flow model, a fluid flow control system and an image and pressure data acquisition and analysis system. The fissure flow model has the topography of a real rock fissure surface, and the opening degree can be quantitatively adjusted through a plug gauge gasket; the fluid flow control system utilizes a peristaltic pump and a stirrer to provide constant flow of fluid and particle input for the fissure flow model; the test device utilizes the light transmission principle to realize quantitative and visual observation and research on the filling fissure seepage-erosion process, and accurately obtains the particle erosion area shape and the permeability evolution data in the filling fissure.

Description

Technical Field

[0001] This invention relates to the field of rock fissure seepage and particle transport testing technology, specifically to a test device and test method for visualizing seepage-erosion in filled fissures. Background Technology

[0002] Rock masses in nature contain numerous joints, faults, fissures, and other rock structural surfaces, with a large amount of particles filling these surfaces. The seepage-erosion process within these fissures is a crucial scientific issue of common concern in fields such as energy, environment, water conservancy, and geosciences, possessing significant engineering application value and theoretical research significance. The invisibility of real rock structural surfaces severely restricts the study of the erosion process of particles filling fissures. Conventional experimental techniques have various limitations; for example, black-box experiments based on real rocks can only obtain permeability changes during the seepage-erosion process in fissures; using CT scanning to obtain particle distribution characteristics in fissures is costly and technically challenging; and while destructively separating the hanging wall and footwall of the real rock after the seepage-erosion process can reveal the spatial distribution of particles, it leads to difficulties in reproducibility. Visual experimental methods based on optical principles are widely used in the study of liquid-liquid two-phase seepage processes in fissure media, providing valuable technical support for the study of multiphase flow behavior in fissure media. However, there are relatively few visual models for studying seepage and particle transport processes in rock fissures. Therefore, researchers urgently need to develop a low-cost, easy-to-operate, and repeatable visualization test device and method for filling fractures to visualize seepage and erosion. Summary of the Invention

[0003] The purpose of this invention is to address the problems existing in the prior art by providing a test device and test method for visualizing seepage-erosion in filled fractures.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] On one hand, a test device for visualizing seepage-erosion in filled fractures is provided, including a device base, on which a transparent fracture flow model is mounted, and a fluid control system connected to the fracture flow model. The fracture flow model is also connected to an image and pressure data acquisition and analysis system. The fracture flow model includes a left model plate, a right model plate, and a feeler gauge shim located between the left and right model plates for adjusting the fracture opening. The left and right model plates are joined and sealed to form a flow channel interconnected with an inlet buffer tank, a fracture model flow channel, and an outlet buffer tank. The inlet buffer tank has a liquid inlet, and the outlet buffer tank has a liquid outlet. The fluid control system is connected to the liquid inlet to provide a constant flow rate of fluid and particle flow into the fracture flow model, and is connected to the liquid outlet to recover the output fluid and particles. The image and pressure data acquisition and analysis system is used to acquire and analyze images of the particle transport process and the fluid pressure at the inlet and outlet.

[0006] Furthermore, the device base is provided with a model support, and the model support is provided with multiple clamps. The clamps hold the fissure flow model. The fissure flow model is arranged vertically, with the inlet facing upward and the outlet facing downward.

[0007] Furthermore, the image and pressure data acquisition and analysis system includes a planar light source and a CCD camera disposed on both sides of the fracture flow model, and a hydraulic sensor connected to the fracture flow model. The CCD camera is connected to a computer via a line, and the hydraulic sensor is disposed at the inlet and outlet, respectively connected to the computer via lines. The computer is used to acquire image signals captured by the CCD camera and pressure signals acquired by the hydraulic sensor, and to analyze and process the image signals and pressure signals.

[0008] Furthermore, the planar light source is mounted on the device base via a planar light source bracket, and the CCD camera is mounted on the device base via a camera bracket. The center of the CCD camera lens is on the same straight line as the center of the rift flow model and the center of the planar light source.

[0009] Furthermore, the fluid control system includes a circulating liquid tank and a peristaltic pump mounted on the base of the device. The circulating liquid tank is adjacent to the inlet of the peristaltic pump via a flow pipe. The outlet of the peristaltic pump is connected to the inlet via an inlet pipe, and the outlet is connected to the bottom of the circulating liquid tank via an outlet pipe. The flow pipe connected to the upper part of the circulating liquid tank has its inlet located below the fluid surface and extends to the middle height of the circulating liquid tank.

[0010] Furthermore, the circulating liquid tank is equipped with a stirrer, and the circulating liquid tank contains liquid and particles. The blades of the stirrer are placed inside the circulating liquid tank to achieve stirring and suspension of the particles.

[0011] Furthermore, both the left and right disks of the model include a transparent replica of a rock fissure and a rigid, transparent channel auxiliary structure that seals and fixes the transparent replica of the rock fissure. The channel auxiliary structure includes a pair of fissure side fixing plates, with the transparent replica of the rock fissure disposed between the pair of fissure side fixing plates, and an inlet buffer groove structure and an outlet buffer groove structure located above and below the transparent replica of the rock fissure. The feeler gauge shim is disposed between the left and right fissure side fixing plates, and the left and right fissure side fixing plates are connected by a peelable sealant.

[0012] Furthermore, the transparent replica of the rock fissure includes a matching left-side transparent replica of the rock fissure and a matching right-side transparent replica of the rock fissure, with the two replicas forming a flow channel for the fissure model; the inlet buffer tank structure includes a matching left-side inlet buffer tank portion and a matching right-side inlet buffer tank portion, with the two replicas forming an inlet end buffer tank; the outlet buffer tank structure includes a matching left-side outlet buffer tank portion and a matching right-side outlet buffer tank portion, with the two replicas forming an outlet end buffer tank; the inlet end buffer tank and the outlet end buffer tank are both wedge-shaped structures, with their cross-sectional dimensions gradually decreasing towards the flow channel of the fissure model.

[0013] On the other hand, a test method is provided for a test apparatus for visualizing seepage-erosion in filled fractures, the test method comprising the following steps:

[0014] The fissure flow model is fabricated and installed on the device base. The circulating liquid tank and peristaltic pump on the fluid control system, as well as the planar light source, CCD camera, hydraulic sensor and computer in the image and pressure data acquisition and analysis system, are connected and installed.

[0015] Adjust the relative positions of the planar light source, the fissure flow model, and the CCD camera, and adjust the focal length, exposure intensity, and image acquisition frame rate of the CCD camera. Check and ensure that the hydraulic sensor is working properly.

[0016] The fluid control system performs the following steps: calculates and weighs the required test liquid and particles; pours the test liquid into the circulating liquid tank, turns on the peristaltic pump to saturate the flow pipe and the fracture flow model with the test liquid; turns off the peristaltic pump, operates the computer to control the CCD camera to capture and record an initial saturation image of the fracture flow model, pours the weighed particles into the circulating liquid tank, and turns on the stirrer in the circulating liquid tank to form a uniform suspension (fluid).

[0017] Prepare to fill the fracture flow model: Turn on the peristaltic pump to inject particles into the flow channel of the fracture model under the action of the suspension, and gradually block the flow channel of the fracture model. When the particle blockage area of ​​the flow channel of the fracture model no longer increases significantly as observed in real time in the image acquisition software, turn off the peristaltic pump and the agitator.

[0018] After the particles in the circulating liquid tank have completely settled, the fissure seepage-erosion test is started: the flow conditions of the peristaltic pump are set, the computer is operated to start recording the image data of the CCD camera and the pressure data of the hydraulic sensor, the peristaltic pump is turned on to inject the suspension into the fissure flow model at the set flow rate, and the fissure seepage-erosion process is started.

[0019] After the fissure filling seepage-erosion process is completed, stop recording the image data of the CCD camera and the pressure data of the hydraulic sensor, turn off the peristaltic pump, remove the fissure flow model, clean it with detergent and dry it, and collect and recycle the waste liquid. The test operation is then completed.

[0020] Furthermore, the experimental method also includes post-experiment image data processing, with the following steps:

[0021] Step a: Use the initial saturation image of the fracture flow model as the initial image P1;

[0022] Step b: Subtract the acquired images of the seepage-erosion test process of the filled fracture from the initial image P1 to obtain a grayscale image P2 with the background removed;

[0023] Step c: Take the average value of each cell in the grayscale image P2 at each time step over a time window to obtain an image P3 with enhanced grayscale contrast between the blocked and unblocked areas.

[0024] Step d: Binarize the image P3 to obtain image P4 where the particle blockage area is white and the particle erosion area is black;

[0025] Step e: Add the initial fracture morphology spatial distribution to the image P4 to obtain the particle erosion distribution data of the seepage-erosion process in the filled fracture.

[0026] Compared with the prior art, the beneficial effects of the present invention are: 1. This experimental device can realize the visual observation and full-process analysis of the seepage-erosion process in the filling fracture. The experimental device is simple and convenient to use and operate, can accurately identify the particle blockage area in the fracture, and displays the results intuitively and clearly. Moreover, the experimental device is easy to manufacture, low in cost, and highly repeatable; 2. Through the setting of the image and pressure data acquisition and analysis system, this experimental device can capture the movement process of particles in the fracture flow model, analyze the captured images, and monitor the fluid pressure at the inlet and outlet of the fracture flow model, acquire the fluid pressure, and perform data analysis; 3. The fluid control system not only monitors the flow of particles in the fracture... The flow model provides liquid and particles that enter with the liquid, while also recovering waste liquid flowing out of the fracture flow model, forming a fluid recycling system; 4. The fracture flow model is not only a fully transparent structure, but also a semi-detachable structure, which can be assembled for seepage and erosion tests, and can be disassembled for cleaning after the test; at the same time, this structure can be used with the feeler gauge shims to control the fracture opening and improve the applicability of the test; 5. The inlet buffer groove allows the fluid to fill the fracture model flow channel more evenly, and also plays a buffering role, avoiding large fluctuations in fluid flow, and preventing particles from accumulating at the inlet and outlet and causing blockage. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall structure of the experimental device for visualizing seepage-erosion in filling fractures according to the present invention.

[0028] Figure 2 This is a front view schematic diagram of the fracture flow model of the present invention;

[0029] Figure 3 for Figure 2 Schematic diagram of section A-A' of the flow model with a central fissure;

[0030] Figure 4 A schematic diagram of the fracture flow model;

[0031] Figure 5 A schematic diagram of the eroded area of ​​the filled crack obtained by image time window averaging and binarization method;

[0032] In the diagram: 1. Planar light source support; 2. Planar light source; 3. Fractal flow model; 4. Model support; 5. Fixture; 6. CCD camera; 7. Computer; 8. Stirrer; 9. Circulating liquid tank; 10. Flow pipe; 11. Peristaltic pump; 12. Hydraulic sensor; 13. Device base; 14. Liquid inlet; 15. Inlet buffer tank; 1501. Left plate inlet buffer tank section; 1502. Right plate inlet buffer tank section; 16. Fractal side fixing plate; 160 1. The fixing plate on the side of the fracture in the left plate of the model; 1602. The fixing plate on the side of the fracture in the right plate of the model; 17. Feeler gauge shim; 18. Transparent replica of the rock fracture; 1801. Transparent replica of the rock fracture in the left plate; 1802. Transparent replica of the rock fracture in the right plate; 19. Outlet buffer tank; 1901. Outlet buffer tank on the left plate; 1902. Outlet buffer tank on the right plate; 20. Liquid outlet; 21. Peelable sealing adhesive; 22. Flow channel of the fracture model; Figure 5 The numbers in the middle cells represent light intensity. Detailed Implementation

[0033] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] In the description of this invention, it should be noted that the terms "middle," "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] Example 1

[0036] This embodiment provides an experimental apparatus for visualizing seepage-erosion in filled fractures, such as... Figures 1-4As shown, the device includes a base 13, on which a transparent fissure flow model 3 is mounted, and a fluid control system connected to the fissure flow model 3. The fissure flow model is also connected to an image and pressure data acquisition and analysis system. The fissure flow model 3 includes a left model plate, a right model plate, and a feeler gauge shim 17 located between the left and right model plates for adjusting the fissure opening. The left and right model plates are joined and sealed to form an inlet buffer groove 15, a fissure model flow channel 22, and an outlet buffer groove 19, which are interconnected flow channels. The inlet buffer groove 15 is provided with an inlet port 14, and the outlet buffer groove 19 is provided with an outlet port 20. The fluid control system is connected to the inlet port 14 to provide a constant flow rate of fluid and particle flow into the fissure flow model 3, and is connected to the outlet port 20 to recover the output fluid and particles. The image and pressure data acquisition and analysis system is used to acquire and analyze images of the particle transport process and the fluid pressure at the inlet and outlet.

[0037] This experimental device enables the visual observation and full-process analysis of the seepage-erosion process in the filling of fissures. The device is simple and convenient to use, can accurately identify the particle blockage area in the fissure, and displays the results intuitively and clearly. Moreover, the device is easy to manufacture, low in cost, and highly repeatable.

[0038] This experimental device, through the setup of the image and pressure data acquisition and analysis system, can capture images of the movement of particles in the fissure flow model 3, analyze the captured images, and also monitor the fluid pressure at the inlet and outlet of the fissure flow model 3, acquire the fluid pressure, and perform data analysis.

[0039] The fluid control system not only provides liquid to the fissure flow model 3, but also provides particles that enter with the liquid, and can also recover waste liquid flowing out of the fissure flow model 3, forming a fluid recycling system.

[0040] The fissure flow model 3 is not only a fully transparent structure, but also a detachable structure. When assembled, it forms a flow channel containing an inlet 14, an inlet buffer tank 15, a fissure model flow channel 22, an outlet buffer tank 19, and an outlet 20, to facilitate seepage and erosion tests. After the test, it can be disassembled for cleaning. At the same time, this structure can be used in conjunction with the feeler gauge shim 17 to control the fissure opening and improve the applicability of the test. The feeler gauge shim 17 is available in various sizes.

[0041] The inlet buffer trough 15 is designed to accommodate a certain amount of fluid, allowing the fluid to fill the flow channel of the fracture model more evenly. It also serves as a buffer to prevent large fluctuations in fluid flow. Furthermore, the buffer trough facilitates the entry and flow of particles, reducing the risk of particles adhering to the inner wall of the channel and the inlet, thus preventing blockage.

[0042] Furthermore, the device base 13 is provided with a model support 4, and the model support 4 is provided with a plurality of clamps 5. The clamps 5 hold the fissure flow model. The fissure flow model is arranged vertically, with the liquid inlet facing upward and the liquid outlet facing downward.

[0043] The clamps 5 hold the rift flow model 3 from both sides of its edge. The clamps 5 are symmetrically arranged on a pair of model supports 4, suspending the rift flow model 3 between them. This arrangement reduces obstruction of the rift flow model 3 by external objects and ensures the entire rift is within the lens of the light source and CCD camera for accurate image acquisition. The vertical arrangement of the rift flow model 3 also saves space on the device base and facilitates the placement of the planar light source and CCD camera.

[0044] In some embodiments, the model support 4 is a vertical pole, one end of the clamp 5 is sleeved on the vertical pole and can be raised and lowered and adjusted, and can be fastened by locking screws, and the other end of the clamp is a claw or clamp that can hold and fix the fissure flow model.

[0045] Furthermore, the image and pressure data acquisition and analysis system includes a planar light source 2 and a CCD camera 6 disposed on both sides of the fracture flow model 3, and a hydraulic sensor 12 connected to the fracture flow model 3. The CCD camera 6 is connected to a computer 7 via a line, and the hydraulic sensor 12 is disposed at the inlet 14 and the outlet 20, respectively, and is connected to the computer 7 via lines. The computer 7 is used to acquire the image signals captured by the CCD camera 6 and the pressure signals acquired by the hydraulic sensor 12, and to analyze and process the image signals and pressure signals.

[0046] Furthermore, the planar light source 2 is mounted on the device base 13 via the planar light source bracket 1, and the CCD camera 6 is mounted on the device base 13 via the camera bracket. The center of the lens of the CCD camera 6 is on the same straight line as the center of the fissure flow model 3 and the planar light source 2. The planar light source 2 is arranged parallel to the fissure flow model 3, and its area is not less than the area of ​​the fissure flow model 3, so as to ensure that all positions in the fissure can be equally illuminated by the light source.

[0047] Furthermore, the fluid control system includes a circulating liquid tank 9 and a peristaltic pump 11 disposed on the device base 13. The circulating liquid tank 9 is adjacent to the inlet of the peristaltic pump 11 through a flow pipe 10. The outlet of the peristaltic pump 11 is connected to the inlet port 14 through an inlet pipe. The outlet port 20 is connected to the bottom of the circulating liquid tank 9 through an outlet pipe.

[0048] The peristaltic pump 11 can pump the liquid or liquid-particle mixture in the circulating liquid tank 9 from the inlet into the fissure flow model 3. The liquid or liquid-particle mixture flowing out from below the fissure flow model 3 can be discharged back into the circulating liquid tank 9. They can be mixed evenly in the circulating liquid tank and reused.

[0049] Furthermore, an agitator 8 is provided above the circulating liquid tank 9. The circulating liquid tank 9 contains liquid and particles, and the blades of the agitator 8 are placed inside the circulating liquid tank to achieve stirring and suspension of the particles.

[0050] The stirrer 8 can stir and mix the liquid and particles in the circulating liquid tank to form a uniform suspension. Through this system, particle-liquid mixing can be achieved, enabling crack filling in the early stage of the erosion test.

[0051] The flow pipe connected to the upper part of the circulating liquid tank 9 has its inlet located below the fluid surface and extending to the middle height of the circulating liquid tank 9. This ensures that particles deposited at the bottom of the circulating liquid tank 9 will not enter the flow channel when the stirrer 8 is not turned on. The purpose of this design is to allow pure liquid to be pumped into the fracture flow model 3 even when the stirrer is not turned on, so as to obtain the first fracture flow image. After the stirrer is turned on, mixed suspensions can also be pumped in. The pumping of the two different fluids can be done simply by turning the peristaltic pump on and off, without the need for additional operation or liquid supply, making the operation simpler.

[0052] Furthermore, both the left and right disks of the model include a transparent replica of a rock fissure 18 and a rigid, transparent channel auxiliary structure that seals and fixes the transparent replica of the rock fissure 18. The channel auxiliary structure includes a pair of fissure side fixing plates 16, with the transparent replica of the rock fissure 18 disposed between the pair of fissure side fixing plates 16, and an inlet buffer groove structure and an outlet buffer groove structure located above and below the transparent replica of the rock fissure 18. The feeler gauge shim 17 is disposed between the left and right fissure side fixing plates 16, which are connected by a peelable sealant. The clamp can also clamp the fissure flow model, both for clamping the entire fissure flow model and for further clamping the left and right fissure side fixing plates.

[0053] The number of parts on the left and right plates of the model is basically the same, but the shapes of the transparent replicas 18 of the rock fissures on the left and right plates are different. Although the left and right plates of the model are detachable structures in half, they are not symmetrical and exactly the same. There are differences in thickness and shape between the two. This setting allows the surface where the fissure is located to be on the same surface as the parting surface (the mating surface of the fissure side fixing plate) where the left and right plates are spliced. This makes the integrity of the flow channel of the fissure model better and the sealing better, reducing the influence of the model itself on the fissure. At the same time, it also allows the inlet and outlet to be on a complete buffer tank structure, rather than a separate spliced ​​structure.

[0054] Furthermore, the transparent replica of the rock fissure 18 includes a matching left-side transparent replica of the rock fissure 1801 and a right-side transparent replica of the rock fissure 1802, forming a flow channel 22 for the fissure model between the left-side transparent replica of the rock fissure 1801 and the right-side transparent replica of the rock fissure 1802; the inlet buffer tank structure includes a matching left-side inlet buffer tank portion 1501 and a right-side inlet buffer tank portion 1502, the left-side inlet buffer tank portion 1501 and the right-side... The inlet buffer trough 15 is formed between the inlet buffer trough portions 1502; the outlet buffer trough structure includes a matching left plate outlet buffer trough portion 1901 and a right plate outlet buffer trough portion 1902, and the outlet buffer trough 19 is formed between the left plate outlet buffer trough portion 1901 and the right plate outlet buffer trough portion 1902; the inlet buffer trough 15 and the outlet buffer trough 19 are wedge-shaped structures, and their cross-sectional dimensions are gradually reduced towards the direction of the crack model flow channel 22.

[0055] A pair of fracture side fixing plates, the transparent replica of the rock fracture on the left plate, the inlet buffer groove of the left plate, and the outlet buffer groove of the left plate are fixedly connected together with AB adhesive to form a complete model left plate. The inlet 14 is provided at the top center of the inlet buffer groove 1501 of the left plate, and the outlet 20 is provided at the bottom center of the outlet buffer groove 1901 of the left plate. Similarly, a pair of fracture side fixing plates, the transparent replica of the rock fracture on the right plate, the inlet buffer groove of the right plate, and the outlet buffer groove of the right plate are fixedly connected together with AB adhesive to form a complete model right plate. The model left plate and the model right plate are connected by a peelable sealant (such as glass glue) to form the entire model structure. This allows for separation after the test for internal cleaning, and also facilitates the setting of feeler gauge shims of different thicknesses and adjustment of the fracture opening.

[0056] Example 2

[0057] This embodiment provides a test method for the test device for visualizing seepage-erosion in filled fractures as described in Embodiment 1. The test method includes the following steps:

[0058] Step 1: Fabricate the fissure flow model 3, install the fissure flow model 3 on the device base 13, and connect and install the circulating liquid tank 9 and peristaltic pump 11 on the fluid control system, as well as the planar light source 2, CCD camera 6, hydraulic sensor 12 and computer 7 in the image and pressure data acquisition and analysis system;

[0059] Specifically, the transparent replicas of rock fissures 18, made by silicone molding and epoxy resin casting of the surfaces of two real rock fissures obtained from rock splitting, and the auxiliary structure of the fissure model channel; the dimensions of the transparent replicas of rock fissures on the left and right sides of the fissure model are 10cm long, 5cm wide, and about 2cm thick.

[0060] Step 2: Adjust the relative positions of the planar light source 2, the fissure flow model 3, and the CCD camera 6, and adjust the focal length, exposure intensity, and image acquisition frame rate of the CCD camera 6 to ensure good imaging effect. Check and ensure that the hydraulic sensor 12 is working properly.

[0061] Step 3: Sample injection by the fluid control system: Calculate and weigh the test liquid and particles required for the test; pour the test liquid into the circulating liquid tank 9, turn on the peristaltic pump 11 to saturate the flow pipe and the fracture flow model 3 with the test liquid; turn off the peristaltic pump 11, operate the computer to control the CCD camera 6 to take and record an initial saturation image of the fracture flow model, pour the weighed particles into the circulating liquid tank 9, turn on the stirrer 8 in the circulating liquid tank to form a uniform suspension (fluid).

[0062] Step 4: Prepare to fill the fracture flow model: Turn on the peristaltic pump 11 to inject the particles into the fracture model flow channel 22 under the action of the suspension, and gradually fill the fracture model flow channel 22. When the particle filling (blockage) area of ​​the fracture model flow channel observed in real time in the image acquisition software no longer increases significantly, turn off the peristaltic pump 11 and the agitator 8.

[0063] Step 5: After the particles in the circulating liquid tank 9 have completely settled, start the fissure seepage-erosion test: Set the flow rate of the peristaltic pump 11, operate the computer to start recording the image data of the CCD camera 6 and the pressure data of the hydraulic sensor 12, turn on the peristaltic pump to inject the suspension into the fissure flow model 3 at the set flow rate, and start the fissure seepage-erosion process.

[0064] Step 6: After the filling of the fissure seepage-erosion process is completed, stop recording the image data of the CCD camera 6 and the pressure data of the hydraulic sensor 12, turn off the peristaltic pump 11, remove the fissure flow model 3, clean it with detergent and dry it, collect and recycle the waste liquid, and the test operation is completed.

[0065] The above method makes it easy to study the seepage and particle transport process in rock fissures. A transparent fissure replica sample, combined with a channel auxiliary structure, has wedge-shaped inlet and outlet buffer tanks arranged at the inlet and outlet to visualize the particle transport process and the smooth transport of liquid and particles in the fissure. It can accurately identify the blockage area of ​​particles in the fissure flow channel and display the test results intuitively and clearly.

[0066] Furthermore, the experimental method also includes post-experiment image data processing. Using self-written Matlab code, the images are processed to remove background, homogenize time, and binarize. The morphological characteristics of the eroded area during the seepage-erosion process in the filled fractures are statistically analyzed. The steps are as follows:

[0067] Step a: Use the initial saturation image of the fracture flow model as the initial image P1;

[0068] Step b: Subtract the acquired images of the seepage-erosion test process of the filled fracture from the initial image P1 to obtain a grayscale image P2 with the background removed;

[0069] Step c: Take the average value of each cell in the grayscale image P2 at each time step over a time window to obtain an image P3 with enhanced grayscale contrast between the blocked and unblocked areas.

[0070] Step d: Binarize the image P3 to obtain image P4 where the particle blockage area is white and the particle erosion area is black;

[0071] Step e: Add the initial fracture morphology spatial distribution to the image P4 to obtain data on the particle erosion distribution during the seepage-erosion process in the filled fractures, such as... Figure 5 As shown.

[0072] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A test apparatus for visualizing seepage-erosion in filled fractures, characterized in that, The device includes a base on which a transparent fracture flow model is mounted, and a fluid control system connected to the fracture flow model. The fracture flow model is also connected to an image and pressure data acquisition and analysis system. The fracture flow model includes a left model plate, a right model plate, and a feeler gauge shim located between the left and right model plates for adjusting the fracture opening. The left and right model plates are joined and sealed to form an interconnected flow channel consisting of an inlet buffer tank, a fracture model flow channel, and an outlet buffer tank. The inlet buffer tank has a liquid inlet, and the outlet buffer tank has a liquid outlet. The fluid control system connects to the liquid inlet to provide a constant flow rate of fluid and particle flow to the fracture flow model, and connects to the liquid outlet to recover the output flow. The system includes a fluid control system for collecting and analyzing images of particle transport, inlet and outlet fluid pressures, and a model support on the device base. The model support has multiple clamps that hold the fracture flow model, which is vertically arranged with the inlet facing upwards and the outlet facing downwards. The fluid control system includes a circulating liquid tank and a peristaltic pump mounted on the device base. The circulating liquid tank is adjacent to the inlet of the peristaltic pump via a flow pipe. The outlet of the peristaltic pump is connected to the inlet via an inlet pipe, and the outlet is connected to the bottom of the circulating liquid tank via an outlet pipe. The flow pipe connected to the upper part of the circulating liquid tank has its inlet below the fluid surface and extends to the middle of the circulating liquid tank.

2. The experimental apparatus for visualizing seepage-erosion in filled fractures according to claim 1, characterized in that, The image and pressure data acquisition and analysis system includes a planar light source and a CCD camera disposed on both sides of the fracture flow model, and a hydraulic sensor connected to the fracture flow model. The CCD camera is connected to a computer via a line, and the hydraulic sensor is disposed at the inlet and outlet, respectively, and is connected to the computer via lines. The computer is used to acquire image signals captured by the CCD camera and pressure signals acquired by the hydraulic sensor, and to analyze and process the image signals and pressure signals.

3. The experimental apparatus for visualizing seepage-erosion in filled fractures according to claim 2, characterized in that, The planar light source is mounted on the device base via a planar light source bracket, and the CCD camera is mounted on the device base via a camera bracket. The center of the CCD camera lens is on the same straight line as the center of the rift flow model and the center of the planar light source.

4. The experimental apparatus for visualizing seepage-erosion in filled fractures according to claim 1, characterized in that, The circulating liquid tank is equipped with a stirrer, and the circulating liquid tank contains liquid and particles. The blades of the stirrer are placed inside the circulating liquid tank to achieve stirring and suspension of the particles.

5. The experimental apparatus for visualizing seepage-erosion in filled fractures according to claim 1, characterized in that, Both the left and right disks of the model include a transparent replica of a rock fissure and a rigid, transparent channel auxiliary structure that seals and fixes the transparent replica of the rock fissure. The channel auxiliary structure includes a pair of fissure side fixing plates, with the transparent replica of the rock fissure disposed between the pair of fissure side fixing plates, and an inlet buffer groove structure and an outlet buffer groove structure located above and below the transparent replica of the rock fissure. The feeler gauge shim is disposed between the left and right fissure side fixing plates, and the left and right fissure side fixing plates are connected by a peelable sealant.

6. The experimental apparatus for visualizing seepage-erosion in filled fractures according to claim 5, characterized in that, The transparent replica of the rock fissure includes a matching left-side transparent replica of the rock fissure and a right-side transparent replica of the rock fissure, with a flow channel for the fissure model formed between the left-side transparent replica of the rock fissure and the right-side transparent replica of the rock fissure; the inlet buffer tank structure includes a matching left-side inlet buffer tank portion and a right-side inlet buffer tank portion, with an inlet end buffer tank formed between the left-side inlet buffer tank portion and the right-side inlet buffer tank portion; The outlet buffer groove structure includes a matching left disk outlet buffer groove portion and a right disk outlet buffer groove portion, and the outlet end buffer groove is formed between the left disk outlet buffer groove portion and the right disk outlet buffer groove portion. The inlet buffer groove and the outlet buffer groove are both wedge-shaped structures, with their cross-sectional dimensions gradually decreasing towards the flow channel of the crack model.

7. A test method for visualizing seepage-erosion in filled fractures, applied to the test apparatus for visualizing seepage-erosion in filled fractures as described in any one of claims 1 to 6, characterized in that, The experimental method includes the following steps: The fissure flow model is fabricated and installed on the device base. The circulating liquid tank and peristaltic pump on the fluid control system, as well as the planar light source, CCD camera, hydraulic sensor and computer in the image and pressure data acquisition and analysis system, are connected and installed. Adjust the relative positions of the planar light source, the fissure flow model, and the CCD camera, and adjust the focal length, exposure intensity, and image acquisition frame rate of the CCD camera. Check and ensure that the hydraulic sensor is working properly. The fluid control system performs the following steps: calculates and weighs the required test liquid and particles; pours the test liquid into the circulating liquid tank, turns on the peristaltic pump to saturate the flow pipe and the fracture flow model with the test liquid; turns off the peristaltic pump, operates the computer to control the CCD camera to capture and record an initial saturation image of the fracture flow model, pours the weighed particles into the circulating liquid tank, and turns on the stirrer in the circulating liquid tank to form a uniform suspension. Prepare to fill the fracture flow model: Turn on the peristaltic pump to inject particles into the flow channel of the fracture model under the action of the suspension, and gradually block the flow channel of the fracture model. When the particle blockage area of ​​the flow channel of the fracture model no longer increases significantly as observed in real time in the image acquisition software, turn off the peristaltic pump and the agitator. After the particles in the circulating liquid tank have completely settled, the fissure seepage-erosion test is started: the flow conditions of the peristaltic pump are set, the computer is operated to start recording the image data of the CCD camera and the pressure data of the hydraulic sensor, the peristaltic pump is turned on to inject the suspension into the fissure flow model at the set flow rate, and the fissure seepage-erosion process is started. After the fissure filling seepage-erosion process is completed, stop recording the image data of the CCD camera and the pressure data of the hydraulic sensor, turn off the peristaltic pump, remove the fissure flow model, clean it with detergent and dry it, and collect and recycle the waste liquid. The test operation is then completed.

8. The experimental method for visualizing seepage-erosion in filled fractures according to claim 7, characterized in that, The experimental method also includes post-experiment image data processing, the steps of which are as follows: Step a: Use the initial saturation image of the fracture flow model as the initial image P1; Step b: Subtract the acquired images of the seepage-erosion test process of the filled fracture from the initial image P1 to obtain a grayscale image P2 with the background removed; Step c: Take the average value of each cell in the grayscale image P2 at each time step over a time window to obtain an image P3 with enhanced grayscale contrast between the blocked and unblocked areas. Step d: Binarize the image P3 to obtain image P4 where the particle blockage area is white and the particle erosion area is black; Step e: Add the initial fracture morphology spatial distribution to the image P4 to obtain the particle erosion distribution data of the seepage-erosion process in the filled fracture.

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