Soluble rock fracture vortex visual monitoring device and method

Abstract

The invention provides a soluble rock fracture vortex visual monitoring device which comprises a soluble rock fracture model containing a first rock sample and a second rock sample, each rock sample is provided with a rough fracture surface consistent with the surface profile of a real rock fracture, and the two rough fracture surfaces are oppositely placed to form a soluble rock fracture; the rock clamping assembly is used for fixing the two rock samples and adjusting the initial opening degree of the crack; the injection unit is used for injecting a mixture which is used for simulating an underground water environment and contains dyeing tracer particles into the fracture so as to perform seepage; the waste liquid recovery unit is used for collecting the discharged waste liquid and measuring the concentration and flow of the waste liquid; the monitoring unit is used for continuously acquiring an image I1 based on a particle image velocity measurement technology and continuously acquiring an image I2 based on a laser scanning confocal microscope technology in a seepage process; and a data processing unit. The invention aims to research the erosion effect of the coupling seepage of the vortex region and the main flow region in the soluble rock on the fracture under the actual condition.

Description

Technical Field

[0001] The present invention relates to the field of rock fissure permeability research in geotechnical engineering, and in particular to a device and method for visually monitoring flow velocity, flow field and the presence of eddy currents during rock fissure seepage. Background Art

[0002] Soluble rocks such as salt rock and limestone are abundant in nature. These rocks are susceptible to dissolution and erosion under the action of water flow, affecting the flow capacity within rock fractures and significantly impacting groundwater flow, pollutant transport, and the stability of engineering structures. During seepage flow within soluble rock fractures, the presence of eddy zones creates a complex coupling relationship with the mainstream zone, significantly influencing the erosion of the rough rock fracture walls. High-speed flow in the mainstream zone induces eddies at geometric irregularities within the fracture, exacerbating dissolution and erosion. Dissolved products within the eddy zones are transferred to the mainstream zone, altering the flow characteristics of the mainstream zone. As the rough rock fracture walls undergo continuous dissolution and erosion, the fracture aperture and wall roughness change, further expanding the eddy zone area and influencing the distribution of the entire flow field, forming a dynamic coupled feedback mechanism. Therefore, research on monitoring the generation and presence of eddies within soluble fractures is essential.

[0003] In existing research, most research institutes use probe-type measurement as the eddy current monitoring method. By inserting the probe into the fluid to measure the local flow velocity or pressure, the presence of eddies is indirectly reflected. This detection method has obvious disadvantages: 1. The insertion of the probe will interfere with the flow field, change the local flow characteristics, and may form new eddies near the probe; 2. Probe measurement can only obtain the flow velocity near the probe tip, and it is difficult to obtain comprehensive information about the entire flow field; 3. Probe measurement itself has certain mechanical errors and requires frequent calibration under different conditions, which increases the complexity of the test. For changes in crack opening, measurements are generally made using a crack meter. However, this method can only measure changes in surface opening and cannot reflect changes in the opening of the rough wall within the crack. Summary of the Invention

[0004] The present invention aims to solve one of the technical problems existing in the prior art at least to a certain extent.

[0005] To this end, the purpose of the present invention is to provide a visual measurement device and method for flow velocity, flow field and eddy current in the seepage process of soluble rock fissures, aiming to study the erosion effect of the coupled seepage between the eddy zone and the mainstream zone in the soluble rock on the fissure under actual conditions. It mainly measures the changes of the eddy zone area in the soluble fissure with hydraulic gradient, fissure aperture, fissure roughness and fissure dissolution rate by adopting visualization research methods, particle image velocimetry technology (PIV technology) and related monitoring devices, and studies the changes of flow velocity under the coupling condition of the mainstream zone and the eddy zone in the fissure, so as to provide reliable experimental data for studying the seepage characteristics of soluble rocks (salt rock, limestone, karst) and the coupling effect and solute exchange between the eddy zone and the mainstream zone in the fissure.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A first aspect of the present invention provides a soluble rock eddy current visualization monitoring device, comprising:

[0008] A soluble rock fracture model includes a first rock sample and a second rock sample, each of which is made of a mixture of a transparent matrix and a soluble rock material, and each of which has a first rough fracture surface and a second rough fracture surface that are consistent with the surface contours of a real rock fracture. The first rough fracture surface and the second rough fracture surface are placed opposite each other to form a soluble rock fracture, and the soluble rock fracture has an inlet end and an outlet end.

[0009] a rock clamping assembly for fixing the first rock sample and the second rock sample and adjusting the initial opening of the soluble rock fracture;

[0010] an injection unit, configured to inject a mixture containing dyed tracer particles for simulating a groundwater environment into the soluble rock fissures through the inlet end to perform seepage;

[0011] a waste liquid recovery unit, used for collecting the waste liquid discharged from the outlet and measuring the concentration and flow of the waste liquid;

[0012] A monitoring unit, used for continuously collecting images I1 based on particle image velocimetry technology and continuously collecting images I2 based on laser scanning confocal microscopy technology during the seepage process;

[0013] A data processing unit is used to perform PIV calculation on the image I1 to obtain the flow field distribution in the soluble rock fracture, identify the eddy zone based on the flow field distribution, and observe the development process of the eddy zone; obtain the opening change of the soluble rock fracture based on the image I2; reflect the dissolution state of the fracture based on the concentration of the waste liquid discharged from the outlet end, and calculate the flow capacity of the soluble rock fracture based on the flow rate of the waste liquid discharged from the outlet end.

[0014] In some embodiments, the first rock sample and the second rock sample are made by casting or 3D printing.

[0015] In some embodiments, the transparent matrix is ​​made of transparent epoxy resin, and the soluble rock material is selected according to the material of the simulated soluble rock fracture surface.

[0016] In some embodiments, the mass proportion of the transparent matrix in the rock sample is 70% to 90%.

[0017] In some embodiments, the rock clamping assembly includes a fixed frame and an acrylic plate sealed around the soluble rock crack, the fixed frame includes four adjustable columns and a number of fixing clamps connected thereto, the four adjustable columns are arranged at the four corners of the soluble rock crack model, the first fixing clamp is located at the front and rear sides of the first rock sample, the second fixing clamp is located at the front and rear sides of the second rock sample, the third fixing clamp is located at the front and rear sides of the soluble rock crack, and is fixedly connected to a corresponding first acrylic plate through a nut and a sealing gasket; the fourth fixing clamp is located at the inlet end and outlet end side of the soluble rock crack, and is fixedly connected to a second acrylic plate corresponding to the sealing gasket through a nut, and the second acrylic plate is provided with a number of holes connected to the inlet end or the outlet end.

[0018] In some embodiments, the injection unit includes an air compressor, a dye barrel, a colored tracer particle barrel and a transparent water tank; the air compressor is connected to the transparent water tank through a conduit with a pressure reducing valve, the colored tracer particle barrel is used to supply colored tracer particles into the transparent water tank, and the dye barrel is used to supply dye into the transparent water tank to dye the rough crack surface after dissolution, and the transparent water tank is connected to the inlet end through a water inlet pipe with a flow meter.

[0019] In some embodiments, the dye is rhodium B or phenolphthalein; and the colored tracer particles are green tracer particles.

[0020] In some embodiments, the monitoring unit includes a laser scanning confocal microscope, a camera and a laser light source; the laser light source and the camera are arranged vertically, a first excitation filter is installed in front of the laser light source, and a first emission filter is installed in front of the camera, and the camera is used to collect the image I1 containing colored tracer particles in real time; the laser scanning confocal microscope is arranged on one side of the soluble rock crack, a second excitation filter is installed at the light source of the laser scanning confocal microscope, and a second emission filter is installed at the camera system of the laser scanning confocal microscope. The laser scanning confocal microscope scans at a set frequency and collects the image I2 containing the rough crack surface that has been eroded, dissolved and stained in real time.

[0021] In some embodiments, the data processing unit includes a computer connected to the camera and the laser scanning confocal microscope, the computer performs PIV calculation on the image I1 to obtain the flow field distribution in the soluble rock cracks, and observes the eddy current zone and its development process based on the convolutional neural network; the computer performs three-dimensional reconstruction on the image I2, and obtains the range of change of the crack opening by comparing the changes in the coordinate values ​​of the rough crack surface in the two frames of images before and after.

[0022] A second aspect of the present invention provides a method for visually monitoring eddy currents in soluble rocks, comprising:

[0023] Step 1: Prepare a soluble rock fracture model, comprising a first rock sample and a second rock sample, each of which is made of a mixture of a transparent matrix and a soluble rock material, and each of which has a first rough fracture surface and a second rough fracture surface that are consistent with the surface contours of a real rock fracture. The first rough fracture surface and the second rough fracture surface are placed relative to each other to form a soluble rock fracture, wherein the soluble rock fracture has an inlet end and an outlet end; and the initial opening of the soluble rock fracture is set using a rock clamping assembly.

[0024] Step 2: injecting a mixture containing tracer particles for simulating a groundwater environment into the soluble rock fissure through the inlet end to perform seepage; during the seepage process, continuously collecting images I1 based on particle image velocimetry technology and continuously collecting images I2 based on laser scanning confocal microscopy technology, performing PIV calculation on image I1 to obtain the flow field distribution in the soluble rock fissure, identifying the eddy zone based on the flow field distribution and observing the development process of the eddy zone; obtaining the change in the opening of the soluble rock fissure based on image I2; reflecting the dissolution state of the fissure based on the concentration of the waste liquid discharged from the outlet end, and calculating the flow capacity of the soluble rock fissure based on the flow rate of the waste liquid discharged from the outlet end;

[0025] Step 3: Change the hydraulic gradient and flow rate at the inlet, as well as the initial opening, roughness and dissolution rate of the soluble rock fractures, and study the influence of each factor on the eddy current interval generated in the soluble rock fractures according to step 2.

[0026] The present invention has the following beneficial effects:

[0027] The seepage process in the fissure is often accompanied by the generation of vortices. The existence of vortex zones affects the entire seepage process, and most seepage monitoring devices fail to accurately monitor the generation of vortices in the fissure seepage process and the influence of vortex zones on the seepage capacity of the fissure. Therefore, the present invention proposes a soluble transparent rock fissure vortex visualization monitoring device and method, which can not only be used to monitor the generation of vortex zones in real time, but also can be used to study the solute exchange between vortex zones and mainstream areas. Advantages of this device: 1. Particle image velocimetry (PIV) is used to measure the flow field distribution during the seepage process, with high measurement accuracy, good data quality and real-time monitoring; 2. Laser scanning confocal microscopy technology is used to monitor changes in fissure opening, which has the advantages of non-contact and real-time performance; 3. A transparent rock fissure model is made by casting, and the rock properties can be changed by changing the additives to simulate different types of rock masses, such as adding sodium chloride to simulate salt rock, adding calcium carbonate to simulate limestone, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limitations on the present invention. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 1 is an overall schematic diagram of a soluble transparent rock fissure eddy current visualization monitoring device provided by an embodiment of the first aspect of the present invention;

[0030] Figure 2 yes Figure 1 A structural diagram of the rock clamping assembly in the monitoring device shown;

[0031] Figure 3 yes Figure 2 Detail of the rock clamping assembly used in the soluble transparent fracture model;

[0032] In the figure: 1, air compressor, 2, pressure reducing valve, 3, dye barrel, 4, colored tracer particle barrel, 5, water tank, 6, water inlet pipe, 7, first sampling port, 8, flow meter, 9, laser scanning confocal microscope, 10, soluble transparent fracture model, 101, first rock sample, 102, second rock sample, 103, inlet end, 104, outlet end, 11, water outlet pipe, 12, green laser light source, 13, camera, 14, liquid collection box, 15, second sampling port, 16, computer, a, first rough fracture surface, b, second rough fracture surface, c, first hole, d, second hole, e, third hole, f, fourth hole, g, fifth hole;

[0033] 20. Rock clamping assembly, 201. Threaded vertical rod, 202. Base, 203. Adjusting nut, 204. First fixing fixture, 205. Second fixing fixture, 206. Third fixing fixture, 207. Fourth fixing fixture, 208. First acrylic plate, 209. Second acrylic plate. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of this application more clearly understood, this application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0035] On the contrary, this application covers any alternatives, modifications, equivalents, and solutions made within the spirit and scope of this application as defined by the claims. Furthermore, to facilitate a better understanding of this application, certain specific details are described in detail below in the detailed description of this application. Those skilled in the art will be able to fully understand this application without these details.

[0036] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for understanding and reading by those familiar with this technology. They are not used to limit the conditions for implementation of this application and therefore have no substantial technical significance. Any modification of the structure, change in the proportion relationship, or adjustment of the size should still fall within the scope of the technical content disclosed in this application without affecting the efficacy and purpose that can be achieved by this application. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of implementation of this application. Changes or adjustments in their relative relationships should also be regarded as the scope of implementation of this application without substantially changing the technical content.

[0037] See also Figures 1 to 3 The first embodiment of the present invention provides a soluble rock eddy current visualization monitoring device, comprising:

[0038] The soluble rock fracture model 10 includes a first rock sample 101 and a second rock sample 102. The first rock sample 101 and the second rock sample 102 are both made of a mixture of a transparent matrix and a soluble rock material and have a first rough fracture surface a and a second rough fracture surface b, respectively, that are consistent with the surface profile of a real rock fracture. The first rough fracture surface a and the second rough fracture surface b are placed relative to each other to form a soluble rock fracture. The soluble rock fracture has an inlet end 103 and an outlet end 104.

[0039] Rock clamping assembly 20 (the rock clamping assembly 20 is Figure 1 (not shown), used to fix the first rock sample 101 and the second rock sample 102 and adjust the initial opening of the soluble rock fracture;

[0040] An injection unit, configured to inject a mixture containing dyed tracer particles for simulating groundwater environment into the soluble rock fissures through the inlet end 103 to induce seepage;

[0041] A waste liquid recovery unit is provided at the outlet port 104 and is used to collect the waste liquid discharged from the outlet port 104 and measure the concentration and flow rate of the waste liquid;

[0042] A monitoring unit, used for continuously acquiring images I1 based on particle image velocimetry (PIV) technology and continuously acquiring images I2 based on confocal laser scanning microscopy (CLSM) technology during the seepage process;

[0043] The data processing unit is used to perform PIV calculation on image I1 to obtain the flow field distribution in the soluble rock fracture, identify the eddy zone based on the flow field distribution, and observe the development process of the eddy zone; obtain the opening change of the soluble rock fracture based on image I2; reflect the dissolution state of the fracture based on the concentration of the waste liquid discharged from the outlet end 104, and calculate the flow capacity of the soluble rock fracture based on the flow rate of the waste liquid discharged from the outlet end 104.

[0044] For the convenience of description below, the direction along the opening of the soluble rock fracture is defined as the height direction of the soluble rock fracture model 10 (i.e., along the up and down direction in the figure), the mainstream direction of the fluid in the soluble rock fracture is defined as the length direction of the soluble rock fracture model 10 (i.e., along the left and right direction in the figure), and the direction perpendicular to the paper in the figure is defined as the width direction of the soluble rock fracture model 10.

[0045] In some embodiments, the first rock sample 101 and the second rock sample 102 in the soluble rock fracture model 10 can be made by casting or 3D printing, and the first rough fracture surface a and the second rough fracture surface b thereon are rough surfaces obtained based on real rock fractures.

[0046] For the casting method, the real rock fracture surface is first cleaned to ensure the surface is clean, and then a solution that facilitates demolding and a silicone solution are sprayed on the real rock fracture surface. After the silicone solidifies, a natural fracture silicone mold is obtained; a transparent matrix is ​​poured into the natural fracture silicone mold and a soluble rock material is used as an additive. The two are fully mixed and evenly mixed. After solidification and demolding, one of the rock samples can be obtained; then the natural fracture silicone mold is used to make another rock sample.

[0047] For the 3D printing method, a developer is first sprayed on the surface of the upper and lower real rock cracks to improve scanning accuracy. The upper and lower real cracks are scanned by a 3D scanner to obtain the 3D morphological point cloud data of the real rock cracks. The 3D morphological point cloud data is then imported into a 3D printer, and two rock samples are printed using a mixture of a transparent matrix and a soluble rock material.

[0048] Preferably, the transparent matrix in the first and second rock samples 101 and 102 is made of a transparent epoxy resin (polyvinyl alcohol, PVA). After curing, it exhibits high transparency and strength, facilitating accurate capture of seepage velocity and changes in fracture aperture. The transparent matrix accounts for 70% to 90% of the total mass of the rock sample. The soluble rock material is selected based on the material of the simulated soluble rock fracture surface. For example, sodium chloride (NaCl) or potassium chloride (KCl) can be used to simulate rock salt or salt domes, with a mass ratio (transparent matrix:soluble rock material) of 85:15, and the salt crystal size is 100 mesh or less. Calcium carbonate (CaCO3) plus kaolin can be used to simulate argillaceous rock, with a mass ratio (transparent matrix:soluble rock material) of 75:20:5, with the kaolin typically comprising 10% to 25%. Gypsum (CaSO4·2H2O) can be used to simulate gypsum rock layers, with a mass ratio (transparent matrix: soluble rock material) of 90:10 and a gypsum particle size greater than 200 mesh. Dolomite (CaMg(CO3)2) can be used to simulate dolomitic calcareous rock, with a mass ratio (transparent matrix: soluble rock material) of 80:20. The magnesium oxide (MgO) content in the dolomite should be greater than 18%. Calcite (CaCO3) can be used to simulate pure limestone, with a mass ratio (transparent matrix: soluble rock material) of 70:30 and a CaCO3 purity greater than 99%.

[0049] In some embodiments, see Figure 2 、 Figure 3The rock clamping assembly 20 comprises a fixed frame and an acrylic plate that seals the perimeter of the soluble rock fracture. The fixed frame comprises four adjustable columns and several fixtures connected thereto. The four adjustable columns are located at the four corners of the soluble rock fracture model 10. Each adjustable column has an identical structure, consisting of a threaded vertical rod 201, an internally threaded base 202, and an adjustment nut 203. The bottom of the threaded vertical rod 201 is inserted into the base 202. The adjustment nut 203 on the base 202 adjusts the length of the threaded vertical rod 201 by screwing it in or out of the base 202, thereby adjusting the fracture opening. The first fixing clamp 204 is located on the front and rear sides of the first rock sample 101 and is fixedly connected to the first rock sample 101 through a nut. The second fixing clamp 205 is located on the front and rear sides of the second rock sample 102 and is fixedly connected to the second rock sample 102 through a nut. The third fixing clamp 206 is located on the front and rear sides of the soluble rock crack and is fixedly connected to a corresponding first acrylic plate 208 through a nut and a sealing gasket. The two first acrylic plates 208 are respectively sealed on the front and rear sides of the soluble rock crack; the fourth fixing clamp 207 is located on the left and right sides of the soluble rock crack and is fixedly connected to a second acrylic plate 209 corresponding to the sealing gasket through a nut. The two second acrylic plates 209 are respectively sealed on the left and right sides of the soluble rock crack, and are respectively provided with a plurality of holes connected to the inlet end 103 and the outlet end 104. When using the rock clamping assembly 20 of this embodiment, first connect the four acrylic plates to the corresponding fixing fixtures, then use the second fixing fixture 205 and the matching nut to fix them to the second rock sample 102, then use the first fixing fixture 204 and the matching nut to fix them to the first rock sample 101, and then tighten the nuts on the third fixing fixture 206 and the fourth fixing fixture 207 to tightly connect the acrylic plates to the soluble rock fracture model 10. Finally, perform the fracture flow characteristic test to prevent water from flowing out from other parts except the inlet end 103 and the outlet end 104.

[0050] In some embodiments, see Figure 1The injection unit includes an air compressor 1, a dye barrel 3, a colored tracer particle barrel 4, and a transparent water tank 5. The water tank 5 is made entirely of a transparent acrylic sheet, which has the advantages of good transparency and high strength. A first hole c, a second hole d, and a third hole e are provided on the top plate of the water tank 5, and a fourth hole f and a fifth hole g are provided on the right side wall of the water tank 5. The first hole c is connected to the air compressor 1 through a conduit with a high-precision pressure reducing valve 2. The maximum output pressure of the air compressor 1 is 50kPa, and the outlet pressure is set to 45kPa in the experiment; the pressure reducing valve 2 reduces the inlet pressure to 5kPa output to meet the working conditions. Then, during the experiment, the pressure at the inlet is controlled by adjusting the pressure reducing valve 2. The air compressor 1 and the pressure reducing valve 2 cooperate to provide a certain pressure to the water tank 5 to ensure that the water flow can be smoothly injected into the soluble rock cracks. The second hole d and the third hole e are connected to the dye barrel 3 and the colored tracer particle barrel 4, respectively. The colored tracer particles in the colored tracer particle barrel 4 are dyed green with fluorescein isothiocyanate (FITC). The dye barrel 3 is filled with rhodium B dye (phenolphthalein can also be used as a dye), which is used to dye the solution in the water tank 5 red. The following purposes are: 1. To facilitate observation of the seepage process of the solution within the soluble rock fractures; 2. To dye the rough fracture surface after dissolution with the red solution, making it easier to monitor the aperture value using the CLSM instrument; 3. To facilitate high-resolution camera capture and processing of the image I1 to detect eddy currents. A magnetic fluid agitator (not shown) is installed inside the water tank 5 to stir the mixture in the water tank 5 and ensure thorough mixing. The fourth hole f on the right side wall of the water tank 5 is connected to the inlet end 103 of the soluble rock fissure through the water inlet pipe 6 with a flow meter 8. The flow meter 8 is used to detect the flow velocity entering the soluble rock fissure; the first sampling port 7 is set in the fifth hole g on the right side wall of the water tank 5 to collect the mixed solution and observe the mixing of the tracer particles and the solution.

[0051] In some embodiments, the monitoring unit mainly monitors the flow velocity changes and the dynamic evolution of the opening in the soluble rock fracture in real time based on PIV and CLSM. Specifically, the monitoring unit includes a laser scanning confocal microscope (CLSM) 9, a high-resolution camera 13 and a green laser light source 12. The green laser light source 12 and the camera 13 are arranged vertically, and a 495nm excitation filter is installed in front of the green laser light source 12, and a 520nm emission filter is installed in front of the camera 13. It is mainly used to collect images I1 containing green tracer particles in real time, and then capture the green fluorescent tracer particles distributed in the soluble rock fracture through PIV calculation, so as to obtain the flow velocity distribution in the soluble rock fracture; the layout position of the laser scanning confocal microscope 9 is generally selected according to the research focus, (1) if the capture of the initial dissolution front formation process is considered, it is arranged at the fracture entrance area. (2) if the relationship between the dynamic change of the opening and the flow velocity is quantitatively analyzed, it is arranged in the middle section of the fracture. (3) if the migration of dissolution products and secondary precipitation are detected, it is arranged at the fracture outlet area. In this example, a sensor was placed in the deformation-sensitive area in the middle of the crack and scanned at 2-minute intervals to analyze the relationship between changes in crack aperture and flow rate. A 550nm excitation filter was installed in the CLSM's built-in light source, and a 580nm emission filter was installed in the CLSM's built-in camera system. These sensors were primarily used to capture real-time I2 images of the rough crack surface, which had been dissolved and stained by the red solution. These I2 images were then processed to capture the rough crack surface and calculate the dynamic changes in crack aperture.

[0052] In some embodiments, the recovery unit includes an outlet pipe 11, a liquid collection tank 14, and a second sampling port 15. The liquid collection tank 14 is made of an acrylic plate with a hole on its upper side. The outlet pipe 11 is connected to the outlet end 104 of the soluble rock fracture and is connected to the outlet end 104 of the soluble rock fracture. The flow rate of the discharged waste liquid is collected by the flow meter and subsequently used to calculate the seepage capacity of the soluble rock fracture. The liquid collection tank 14 has a hole and a second sampling port 15 installed on it, which is mainly used to collect the outflow solution, detect the solution concentration, and understand the dissolution state of the fracture.

[0053] In some embodiments, the data processing unit in this embodiment includes a computer 16 and a communication cable 17. The camera 13 and the laser scanning confocal microscope 9 are connected to the computer 16 via the communication cable 17, and the images I1 and I2 taken by them are processed in real time. The computer 16 is loaded with a PIV calculation module (PIV software in a specific embodiment of the present invention) and a three-dimensional image reconstruction module (IMageJ software in a specific embodiment of the present invention). First, the image I1 collected by the camera 13 is processed using the PIV calculation module to obtain the flow field distribution in the soluble rock cracks, and then the "U-Net eddy segmentation + PIV-Net velocity field generation" joint framework in the convolutional neural network algorithm is used to monitor the generation of eddy current zones in real time. Subsequently, the image I2 returned by the CLSM is three-dimensionally reconstructed by the three-dimensional image reconstruction module, and the range of change of the crack opening is obtained by comparing the changes in the coordinate values ​​of the rough crack surface in the two frames before and after.

[0054] As can be understood, the embodiments of the present invention employ visualization research methods to propose a visualization research device for real-time monitoring of the flow field and eddy zones during seepage within soluble fractures. This device enables precise monitoring and analysis of flow velocity, flow field, and eddy zone area within fractures, providing more accurate and reliable experimental data for a variety of studies, including those investigating eddy zone formation, eddy zone variation with fracture aperture, and solute exchange between eddy zones and the mainstream.

[0055] A second embodiment of the present invention provides a method for monitoring eddy currents in soluble transparent rock fractures, comprising the following steps:

[0056] Step 1: Prepare a soluble rock fracture model, which is the soluble rock fracture model 10 used in the embodiment of the first aspect of the present invention, and use a rock clamping assembly 20 to set an initial opening between a first rock sample 101 and a second rock sample 102;

[0057] Step 2: Inject a mixture containing tracer particles for simulating a groundwater environment into the soluble rock fissure through the inlet port 103 to perform seepage. During the seepage process, continuously collect images I1 based on particle image velocimetry (PIV) technology and I2 based on confocal laser scanning microscopy (CLSM) technology, perform PIV calculation on image I1, obtain the flow field distribution within the soluble rock fissure, identify the eddy zone based on the flow field distribution, and observe the development process of the eddy zone; obtain the aperture change of the soluble rock fissure based on image I2; reflect the dissolution state of the fissure based on the concentration of the waste liquid discharged from the outlet port 104, and calculate the flow capacity of the soluble rock fissure based on the flow rate of the waste liquid discharged from the outlet port 104;

[0058] Step 3: respectively change the hydraulic gradient of the inlet end 103, the flow rate of the inlet end 103, the initial opening of the soluble rock fissure, the roughness of the soluble rock fissure, and the dissolution rate of the soluble rock fissure, and study the influence of each factor on the vortex interval generated in the soluble rock fissure according to step 2.

[0059] In some embodiments, step 1 specifically includes:

[0060] Step 11: Make a soluble transparent rock crack model

[0061] Step 11A: Use a brush to clean the upper and lower surfaces of the real rock cracks, pour a silicone solution on the surface, and wait for it to solidify to obtain a silicone mold;

[0062] Step 11B: Pour transparent epoxy resin (polyvinyl alcohol, PVA) into the silicone mold prepared in step 11A, and select additives (sodium chloride crystals or calcium carbonate) to simulate different types of rock masses;

[0063] Step 11C: After the resin in the mold solidifies, remove it and obtain the first rock sample 101; repeat step 11B to produce the second rock sample 102;

[0064] Step 12: Install the soluble rock crack using the rock clamping assembly 20

[0065] Step 12A: Then, four transparent acrylic plates (208, 209) are taken out and placed around the crack surface. The second acrylic plate 209, which is parallel to the rough surface in width, is laser-punched with holes of approximately 1 mm in radius to connect the inlet end 103 and the outlet end 104 respectively.

[0066] Step 12B: Place the first rock sample 101 and the second rock sample 102 in the rock clamping assembly 20 respectively, and fix the rock samples with corresponding bolts;

[0067] Step 12C: Turn the adjusting nut 203 to adjust the height of the first rough fracture surface a so that a flow channel is formed between the first rough fracture surface a and the second rough fracture surface b. Then, tighten the bolts covering the first acrylic plate 208 in the length direction and the second acrylic plate 209 in the width direction of the first and second rock samples to ensure that the acrylic plates are closely attached to the fractures.

[0068] Step 12D: Perform a watertightness test to prevent water leakage during the experiment.

[0069] Step 2: Conduct seepage experiment

[0070] Step 21: Set up the injection unit for experiment

[0071] Step 21A: using fluorescein isothiocyanate to dye polystyrene microsphere particles green as tracer particles;

[0072] Step 21B: Open the valve of the dye barrel 3 containing Rhodium B, adjust the dye ratio using the scale on the outer wall of the dye barrel 3, and then open the valve to inject Rhodium B into the water tank 5. Similarly, for the colored tracer particle barrel 4, adjust the ratio and then open the valve of the colored tracer particle barrel 4 to inject the colored tracer particles into the water tank 5.

[0073] Step 21C: After stirring the solution in the water tank 5, the first sampling port 7 is opened to collect part of the solution and detect the mixed concentration of the solution;

[0074] Step 21D: Set the pressure of the air compressor 1 to the pressure required for the experiment, change the pressure value by adjusting the pressure reducing valve 2, and record the flow rate value measured by the flow meter 8 at the water inlet pipe 6;

[0075] Step 22: Seepage process monitoring

[0076] Step 22A: Turn on the green laser light source 12 equipped with a 495 nm filter and the camera 13 equipped with a 520 nm emission filter to capture an image I1 to capture the flow state of the tracer particles during the seepage process.

[0077] Step 22B: Turn on the laser confocal microscope 9 equipped with a 550 nm excitation filter and a 580 nm emission filter to collect an image I2 to monitor the change in the opening of the rough surface of the crack that has been dissolved by the solution and dyed red;

[0078] Step 22C: import the image I1 captured by the camera 13 into the PIV software for processing, and calculate the flow field distribution in the soluble rock fracture;

[0079] Step 22D: import the obtained flow field distribution into the convolutional neural network eddy current area identification algorithm to calculate the generated eddy current area and its size;

[0080] Step 22E: Import the image I2 obtained by CLSM into ImageJ software to reconstruct a three-dimensional model, calculate the coordinate values ​​of the three-dimensional model, and obtain the change in the crack opening by comparing the changes in the coordinate values ​​before and after;

[0081] Step 22F, processing and mapping the data of the monitored crack opening and the generation and expansion of the eddy current zone, and studying the effect of the crack opening on the eddy current zone as the dissolution time changes;

[0082] Step 23: Process the waste liquid in the liquid collecting box 14, collect part of the waste liquid through the second sampling port 15, and detect the change in the concentration of the waste liquid; process the solution in the entire liquid collecting box 14 and calculate the seepage volume of the fracture.

[0083] Step 3: Study the relationship between various factors and eddy current range:

[0084] Step 3A: Study the relationship between flow velocity and vortex interval: In step 21D, adjust the size of pressure reducing valve 2 and observe the value of flow meter 6 to change the flow velocity. Repeat steps 21 to 23 to control the initial opening, roughness, and dissolution rate of the soluble rock fracture to study the relationship between the inlet flow velocity and the vortex interval.

[0085] Step 3B: Study the relationship between the initial fracture opening and the eddy current range: In step 12D, rotate the adjusting nut 203 to adjust the height of the first rock sample 101 to change the initial fracture opening of the soluble rock. Repeat steps 21 to 23 to control the hydraulic gradient, as well as the roughness and dissolution rate of the soluble rock fracture to study the relationship between the initial fracture opening and the eddy current range.

[0086] Step 3C: Study the relationship between soluble rock fracture roughness and eddy flow range: In step 11A, select different natural fractures to create silicone molds with different roughness to change the fracture surface roughness. Repeat steps 1 and 2, controlling the hydraulic gradient, initial fracture opening, and dissolution rate to study the relationship between rock fracture roughness and eddy flow range.

[0087] Step 3D: Study the relationship between the dissolution rate of soluble rock fractures and the eddy flow range: Different additives selected in Step 11B result in different rock types, which in turn alter the dissolution rate of the roughened fracture surfaces of the soluble rock. The hydraulic gradient, initial aperture, and roughness of the soluble rock fractures were manipulated to study the relationship between the dissolution rate of the soluble rock fractures and the eddy flow range.

[0088] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, illustrative uses of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0089] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A visual monitoring device for soluble rock eddy current, characterized in that: include: A soluble rock fracture model includes a first rock sample and a second rock sample, each of which is made of a mixture of a transparent matrix and a soluble rock material, and each of which has a first rough fracture surface and a second rough fracture surface that are consistent with the surface contours of a real rock fracture. The first rough fracture surface and the second rough fracture surface are placed opposite each other to form a soluble rock fracture, and the soluble rock fracture has an inlet end and an outlet end. a rock clamping assembly for fixing the first rock sample and the second rock sample and adjusting the initial opening of the soluble rock fracture; an injection unit, configured to inject a mixture containing dyed tracer particles for simulating a groundwater environment into the soluble rock fissures through the inlet end to perform seepage; a waste liquid recovery unit, used for collecting the waste liquid discharged from the outlet and measuring the concentration and flow of the waste liquid; A monitoring unit, used for continuously collecting images I1 based on particle image velocimetry technology and continuously collecting images I2 based on laser scanning confocal microscopy technology during the seepage process; A data processing unit is used to perform PIV calculation on the image I1 to obtain the flow field distribution in the soluble rock fracture, identify the eddy zone based on the flow field distribution, and observe the development process of the eddy zone; obtain the opening change of the soluble rock fracture based on the image I2; reflect the dissolution state of the fracture based on the concentration of the waste liquid discharged from the outlet end, and calculate the flow capacity of the soluble rock fracture based on the flow rate of the waste liquid discharged from the outlet end.

2. The soluble rock eddy current visualization monitoring device according to claim 1 is characterized in that: The first rock sample and the second rock sample are made by casting or 3D printing.

3. The soluble rock eddy current visualization monitoring device according to claim 1, characterized in that: The transparent matrix is ​​made of transparent epoxy resin, and the soluble rock material is selected according to the material of the simulated soluble rock fracture surface.

4. The soluble rock eddy current visualization monitoring device according to claim 1, characterized in that: The mass proportion of the transparent matrix in the rock sample is 70% to 90%.

5. The soluble rock eddy current visualization monitoring device according to claim 1, characterized in that: The rock clamping assembly includes a fixed frame and an acrylic plate sealed around the soluble rock crack. The fixed frame includes four adjustable columns and several fixing clamps connected thereto. The four adjustable columns are arranged at the four corners of the soluble rock crack model. The first fixing clamp is located at the front and rear sides of the first rock sample, the second fixing clamp is located at the front and rear sides of the second rock sample, and the third fixing clamp is located at the front and rear sides of the soluble rock crack, and is fixedly connected to a corresponding first acrylic plate through a nut and a sealing gasket; the fourth fixing clamp is located at the inlet end and outlet end of the soluble rock crack, and is fixedly connected to a second acrylic plate corresponding to the sealing gasket through a nut, and the second acrylic plate is provided with several holes connected to the inlet end or the outlet end.

6. The soluble rock eddy current visualization monitoring device according to claim 1, characterized in that: The injection unit includes an air compressor, a dye barrel, a colored tracer particle barrel and a transparent water tank; the air compressor is connected to the transparent water tank through a conduit with a pressure reducing valve, the colored tracer particle barrel is used to supply colored tracer particles into the transparent water tank, and the dye barrel is used to supply dye into the transparent water tank to dye the rough crack surface after dissolution. The transparent water tank is connected to the inlet end through a water inlet pipe with a flow meter.

7. The soluble rock eddy current visualization monitoring device according to claim 6, characterized in that: The dye is rhodium B or phenolphthalein; and the colored tracer particles are green tracer particles.

8. The soluble rock eddy current visualization monitoring device according to claim 1, characterized in that: The monitoring unit includes a laser scanning confocal microscope, a camera and a laser light source; the laser light source and the camera are arranged vertically, a first excitation filter is installed in front of the laser light source, and a first emission filter is installed in front of the camera, and the camera is used to collect an image I1 containing colored tracer particles in real time; the laser scanning confocal microscope is arranged on one side of the soluble rock crack, a second excitation filter is installed at the light source of the laser scanning confocal microscope, and a second emission filter is installed at the camera system of the laser scanning confocal microscope. The laser scanning confocal microscope scans at a set frequency and collects an image I2 containing a rough crack surface that has been eroded, dissolved and stained in real time.

9. The soluble rock eddy current visualization monitoring device according to claim 8, characterized in that: The data processing unit includes a computer connected to the camera and the laser scanning confocal microscope. The computer performs PIV calculation on the image I1 to obtain the flow field distribution in the soluble rock cracks, and observes the eddy current zone and its development process based on the convolutional neural network; the computer performs three-dimensional reconstruction on the image I2, and obtains the range of change of the crack opening by comparing the changes in the coordinate values ​​of the rough crack surface in the two frames of images before and after.

10. A method for visual monitoring of soluble rock eddy currents, characterized in that: include: Step 1: Prepare a soluble rock fracture model, comprising a first rock sample and a second rock sample, each of which is made of a mixture of a transparent matrix and a soluble rock material, and each of which has a first rough fracture surface and a second rough fracture surface that are consistent with the surface contours of a real rock fracture. The first rough fracture surface and the second rough fracture surface are placed relative to each other to form a soluble rock fracture, wherein the soluble rock fracture has an inlet end and an outlet end; and the initial opening of the soluble rock fracture is set using a rock clamping assembly. Step 2: injecting a mixture containing tracer particles for simulating a groundwater environment into the soluble rock fissure through the inlet end to perform seepage; during the seepage process, continuously collecting images I1 based on particle image velocimetry technology and continuously collecting images I2 based on laser scanning confocal microscopy technology, performing PIV calculation on image I1 to obtain the flow field distribution in the soluble rock fissure, identifying the eddy zone based on the flow field distribution and observing the development process of the eddy zone; obtaining the change in the opening of the soluble rock fissure based on image I2; reflecting the dissolution state of the fissure based on the concentration of the waste liquid discharged from the outlet end, and calculating the flow capacity of the soluble rock fissure based on the flow rate of the waste liquid discharged from the outlet end; Step 3: Change the hydraulic gradient and flow rate at the inlet, as well as the initial opening, roughness and dissolution rate of the soluble rock fractures, and study the influence of each factor on the eddy current interval generated in the soluble rock fractures according to step 2.

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