Model box for groundwater system solute transport test, test method and device

Abstract

The invention provides a model box for an underground water system solute transport test. The model box comprises a transparent box body; the model layers comprise a pipeline layer, a single rough fracture layer and a matrix layer, the pipeline layer and the single rough fracture layer can be inserted into or pulled out of the transparent box body, and after the non-matrix model layers are installed in place, the space between every two adjacent non-matrix model layers is filled with a matrix to form the matrix layer; the inlet end and the outlet end of each model layer are respectively communicated with the corresponding water inlet channel and the water outlet channel on the side wall of the transparent box body; and the sensing unit comprises a plurality of pressure sensors which are uniformly distributed on the inner side of the side wall of the transparent box body, and is used for measuring pressure signals in each model layer. The invention further provides an underground water system solute transport test method and device based on the model box. According to the invention, a solute exchange process under a real condition can be simulated, a solute transport path and a fluid flow track are analyzed, and a test basis is provided for researching a solute transport rule in a complex underground water system.

Description

Technical Field

[0001] The invention relates to the technical field of karst groundwater system and solute migration, and in particular to a model box, a test method and a device for a groundwater system solute migration test. Background Art

[0002] Karst landforms are widely distributed throughout the world, such as in Yunnan, Guizhou, and Guilin in China and in Carlsbad Caverns abroad. They are unique geological structures formed by the dissolution of surface water and groundwater. These natural karsts are characterized by a complex groundwater system coupled with multi-scale fractures, multi-layered conduits, and a heterogeneous matrix. Solute transport is a hot topic in the field of groundwater systems. Studying groundwater flow characteristics and solute transport within karst areas is of great significance for local water resource development and pollutant control.

[0003] In karst systems, solute exchange between cracks, conduits, and the matrix of cracks plays a major role in controlling the solute transport process. In solute transport and exchange, cracks and conduits, as areas of high permeability, may form preferential flow, resulting in early solute arrival; while low permeability areas such as the matrix will delay the diffusion time of solute concentration, resulting in solute tailing. This abnormal migration phenomenon makes it impossible to control the solute migration law of groundwater flow, making it difficult to accurately predict solute transport and diffusion within the groundwater system. To this end, researchers conducted physical experiments to monitor the solute migration law. Most existing physical models only consider solute exchange between cracks and matrix or solute exchange between conduits and matrix, and lack a solute transport monitoring method under the coupling of the three situations. The solute transport process in the groundwater system is mainly affected by the flow characteristics of the fluid, but existing research still lacks a device and method for measuring fluid flow rate while monitoring solute exchange. 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 present invention adopts a visual research method and takes into account the highly heterogeneous geological structure of the karst system, simplifies the fracture network structure into a single-channel fracture, and thus proposes a model box, test method and device for solute migration test in groundwater system. The purpose is to simulate the solute exchange process under real conditions, analyze the solute migration path and fluid flow trajectory, provide high-precision and realistic test data for the numerical model research of the groundwater system, and provide an experimental basis for further research on the solute migration laws in complex groundwater systems.

[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 model box for a groundwater system solute transport test, comprising:

[0008] A transparent box body, the transparent box body having a top wall, a bottom wall and a plurality of side walls, a plurality of spaced chute grooves are provided on the inner sides of the first side wall and the second side wall respectively arranged opposite to each other, and a water inlet channel and a water outlet channel are respectively provided on the first side wall and the second side wall, protruding outward and parallel to the axis of the chute groove;

[0009] Several model layers, including a pipe layer, a single rough fracture layer, and a matrix layer, wherein the pipe layer and the single rough fracture layer cooperate with the corresponding chute to be inserted into or withdrawn from the transparent box from one side of the third side wall of the transparent box; after the non-matrix model layer is installed in place, a matrix is ​​filled between two adjacent non-matrix model layers to form the matrix layer; the inlet and outlet ends of each model layer are respectively connected to a corresponding water inlet channel and a water outlet channel; by combining and splicing different model layers, the influence of different geological structures on the non-Fickian migration of solutes in an actual environment is simulated;

[0010] The sensing unit includes a plurality of pressure sensors evenly distributed on the inner side of the fourth side wall of the transparent box, and is used to measure the pressure signals in each model layer.

[0011] In some embodiments, each water inlet channel is respectively provided with a first valve, and a plurality of water inlets connected to each water inlet channel are opened on the first side wall in contact with each water inlet channel; and a plurality of water outlets connected to each water outlet channel are opened on the second side wall in contact with each water outlet channel.

[0012] In some embodiments, the pipeline layer is composed of two transparent acrylic plates arranged one above the other, and first holes for solutes to pass through are formed on the upper and lower transparent acrylic plates. A channel for simulating the pipeline environment in the groundwater system is formed between the two transparent acrylic plates.

[0013] In some embodiments, the single rough fracture layer is composed of two upper and lower transparent rock layers, and a first rough fracture surface and a second rough fracture surface are respectively formed on the surfaces of the upper and lower transparent rock layers that are arranged opposite to each other. The gap channel formed between the two rough fracture surfaces is the fracture channel, and a second hole is formed on the upper and lower transparent rock layers that is arranged to penetrate along the height direction and is used for solutes to pass through.

[0014] In some embodiments, the upper and lower transparent rock layers are formed by casting or 3D printing, and the rough fracture surfaces thereon are rough surfaces obtained based on real rock fractures.

[0015] In some embodiments, a filler is attached to at least one rough fracture surface in two transparent rock layers to form a filled fracture; the filler is a colored soluble material with controllable dissolution rate, which is composed of a mixture of a transparent matrix, a dissolution rate controller and a dye.

[0016] In some embodiments, the transparent matrix is ​​a transparent resin, the dissolution rate controller is polyethylene glycol, polypropylene glycol, hydroxyethyl cellulose or polyvinyl pyrrolidone, and the dye is phenolphthalein, rhodamine B, fluorescein, beet red or indigo.

[0017] In some embodiments, a filling mold is used to attach the filler to the rough crack surface, and the filling mold includes an outer frame and a plurality of filling heads;

[0018] The outer frame is a box-shaped structure with an open top, and a plurality of holes distributed in an array are provided on the bottom plate of the outer frame for mounting a corresponding filling head, and each hole is provided with an internal thread;

[0019] The filling head consists of a mounting portion and a silicone head fixed on the mounting portion at one end facing away from the base plate. The mounting portion and the silicone head are provided with through holes connected to each other. The length of the mounting portion is greater than the thickness of the base plate and the mounting portion is provided with an external thread. The filling head can be installed or removed by screwing the mounting portion into or out of the corresponding hole of the base plate; the filling mold is equipped with the silicone head of at least one shape.

[0020] The second aspect of the present invention provides a groundwater system solute transport test method based on the model box described in any embodiment of the first aspect of the present invention, comprising:

[0021] Step S1: A laser light source is provided outside the model box, and a test solution containing tracer particles for simulating a groundwater environment is injected into each water inlet channel, using the tracer particles as the solute. The solute concentration is reflected by the number of tracer particles. After each water inlet channel is fully filled, the first valve on the channel is opened to allow the test solution to enter each model layer, and a flow meter is provided on each water outlet channel.

[0022] Step S2: Turn on the laser light source and continuously collect path images I of the tracer particles flowing with the test solution. The displacement distance of the same tracer particle within a certain time range is calculated using the PIV method, thereby obtaining the flow velocity distribution of the flow field in the model box. A fluorescence imaging method is used on the image I to analyze the intensity of the fluorescence in the image I to obtain the distribution concentration of the solute in the model box, and the solute exchange occurring between different model layers is monitored in real time; the signal collected by the pressure sensor is obtained, and the pressure gradient change in the model box is obtained based on the signal; the test solution discharged from each outlet pipe is collected, and the water seepage and the concentration of the seepage solution of each model layer are measured;

[0023] Step S3: respectively change the flow rate of the water inlet channel, the solution concentration of the water inlet channel, the height of the non-matrix model layer, the initial porosity of the matrix layer, and the layout of each model layer in the model box, and study the influence of each factor on the solute transport in the groundwater system according to step S2.

[0024] A third aspect of the present invention provides a groundwater system solute transport test device, comprising:

[0025] The model box according to any embodiment of the first aspect of the present invention;

[0026] a fluid injection unit connected to each water inlet channel of the model box to inject a test solution containing tracer particles for simulating a groundwater environment into each model layer in the model box;

[0027] a fluid pressure acquisition unit, comprising a data collector connected to the sensing unit in the model box, for converting the analog signal measured by the pressure sensor into a digital signal;

[0028] An image acquisition unit, comprising a laser light source and a camera disposed on one side of the model box, for continuously acquiring images I of tracer particles flowing with the test solution during the test;

[0029] A waste liquid recovery unit is provided at the water outlet channel of the model box, and is used to collect the test solution discharged from each model layer and monitor the flow rate of the discharged solution in real time using a flow meter;

[0030] The data processing unit is used to calculate the displacement distance of the same tracer particle within a certain time range using the PIV method for the image I, thereby obtaining the flow velocity distribution of the flow field in the model box; using the fluorescence imaging method for the image I, by analyzing the intensity of the fluorescence in the image I, the distribution concentration of the solute in the model box is obtained, and the solute exchange occurring between different model layers is monitored in real time; the pressure gradient change in the model box is obtained according to the digital signal output by the sensing unit; and the water seepage amount and the concentration of the seepage solution of each model layer are measured according to the flow rate of the test solution discharged from each model layer.

[0031] Features and beneficial effects of the present invention:

[0032] Due to the complex and changeable structure of the groundwater system, there is still a lack of a method that can fully consider the seepage behavior and solute transport characteristics under real conditions (pipeline-crack-matrix coupling). The model box of the present invention can highly restore the complex and changeable geological structure in the groundwater system, especially the highly heterogeneous environment, by accurately adjusting the spatial position and internal materials of each layer of the model. Compared with the existing technology, the model box can more realistically simulate the coupling effect of cracks, matrix and pipelines, and provide seepage behavior data that is closer to the actual situation. In addition, the model box adopts a multi-level combination design to flexibly reproduce the groundwater flow environment under different geological conditions, so that when studying the impact of different geological structures on groundwater flow and solute transport, it is possible to fully consider a variety of interacting factors, which significantly improves the accuracy and adaptability of the simulation.

[0033] Furthermore, the experimental apparatus and methods based on this model box can effectively study non-Fickian transport phenomena in groundwater systems by injecting tracer particles to simulate solute migration behavior. Compared with traditional experimental methods, this experimental apparatus features real-time monitoring and visual analysis, enabling efficient acquisition of accurate data and reducing human error. Furthermore, the experimental method can systematically study the migration and diffusion characteristics of solutes under a variety of geological conditions and coupling scenarios, revealing the combined effects of natural fractures, artificial conduits, and the matrix. This comprehensive simulation capability not only enhances the comprehensiveness and depth of the experiments but also provides a more reliable scientific basis for groundwater pollution control and resource development. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] 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 limiting the present invention. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0035] Figure 1 1 is a front view of a model box for a groundwater system solute transport test according to an embodiment of the first aspect of the present invention;

[0036] Figure 2 2 is a rear view of a model box for a groundwater system solute transport test according to an embodiment of the first aspect of the present invention;

[0037] Figure 3 (a) and (b) are Figure 2 II and I'-I' cross-sections in.

[0038] Figure 4 yes Figure 2AA cross-section diagram in.

[0039] Figure 5 yes Figure 4 A partial enlarged schematic diagram of part B in the middle.

[0040] Figure 6 (a) and (b) are schematic structural diagrams of a filling mold and a filling head used in an embodiment of the present invention to fill a single crack.

[0041] Figure 7 It is a structural schematic diagram of a groundwater system solute transport test device provided by an embodiment of the third aspect of the present invention.

[0042] In the picture:

[0043] 100, transparent box, 111, first side wall, 112, second side wall, 113, third side wall, 114, fourth side wall, 114a, mounting hole, 115, chute, 116, water inlet, 116a, water inlet, a, first valve, 117, water outlet, 117a, water outlet, 120, top wall, 130, bottom wall; 210, pipe layer, 211, acrylic plate, 212, first hole, 220, single rough crack layer, 2 21. Transparent rock layer, 221a. First rough fracture surface, 221b. Second rough fracture surface, 222. Second hole, 230. Matrix layer, 231. Matrix; 310. Pressure sensor; 410. Outer frame, 411. Side plate, 412. Bottom plate, 412a. Hole position, 420. Filling head, 421. Mounting portion, 422. Silicone head, 422a. Frustum-shaped silicone head, 422b. Rectangular silicone head, 422c. Semicircular silicone head;

[0044] 1. Water supply port, 2. Filling port, 3. Water tank, 4. Water intake port, 5. Drain port, 6. Injection pump, b. Second valve: 7. Flow meter, 8. Injection pipe, 9. Model box, 10. Data collector, 11. Output pipe, 12. Flow meter, 13. Recovery box, 14. Communication cable, 15. Laser light source, 16. Camera, 17. Computer, etc. DETAILED DESCRIPTION

[0045] 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.

[0046] 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.

[0047] 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.

[0048] See also Figures 1 to 5 The first embodiment of the present invention provides a model box for a groundwater system solute transport test, comprising:

[0049] The transparent box 100 has a top wall 120, a bottom wall 130, and several side walls. A plurality of spaced chutes 115 are provided on the inner sides of the first and second side walls 111, 112, which are arranged opposite each other. The axial direction of the chutes 115 is perpendicular to the direction of solute migration. An inlet channel 116 and an outlet channel 117 are provided on the first and second side walls 111, 112, respectively, protruding outward and parallel to the axial direction of the chutes 115. A test solution for simulating a groundwater environment is introduced into the transparent box 100 through the inlet channel 116, and the fluid in the transparent box 100 is discharged through the outlet channel 117.

[0050] Several model layers, including a pipe layer 210, a single rough fracture layer 220, and a matrix layer 230, wherein the pipe layer 210 and the single rough fracture layer 220 cooperate with corresponding chutes 115 to be inserted into or withdrawn from the transparent box 110 from the third side wall 113 of the transparent box 110, and the third side wall 113 is detachably connected to the first side wall 111 or the second side wall 112. After the model layer of the non-matrix layer is installed in place, a matrix is ​​filled between the model layers of two adjacent non-matrix layers to form a matrix layer 210. The inlet and outlet ends of each model layer are respectively connected to a corresponding water inlet channel 116 and a water outlet channel 117. By combining and splicing different model layers, the influence of different geological structures on the non-Fickian migration of solutes in an actual environment can be simulated;

[0051] The sensing unit includes a plurality of strain gauge pressure sensors 310 evenly distributed on the inner side of the fourth side wall 114 of the transparent box 100 , and is used to measure the pressure signal in each model layer.

[0052] For the convenience of description, the solute migration direction is defined as the length direction of the model box (i.e. Figure 1 The left and right directions shown in the figure are defined as the height direction of the model box (i.e. Figure 1 The width direction of the model box is defined as the plane direction perpendicular to the length direction and the height direction.

[0053] In some embodiments, the side walls, top plate, and bottom plate of the transparent box 100 are all made of colorless, transparent acrylic sheets, which have good transparency, high strength, and are easy to install and process. The first side wall 111 (i.e., the left side wall) and the second side wall 112 (i.e., the right side wall) are arranged opposite each other, with the spacing between them being the length of the model box; the third side wall 113 (i.e., the front side wall) and the fourth side wall 114 (i.e., the rear side wall) are arranged opposite each other, with the spacing between them being the width of the model box. The third side wall 113 is detachably connected to the first side wall 111 or the second side wall 112 to facilitate the installation of each model layer.

[0054] Furthermore, a plurality of outwardly protruding water inlet channels 116 are provided on the first side wall 111 of the transparent box 100. Each water inlet channel 116 is a pipe with a rectangular cross-section extending along the width of the model box. Each water inlet channel 116 is provided with a first valve a. A plurality of water inlets 116a are provided on the first side wall 111, which contacts each water inlet channel 116, and are connected to each water inlet channel 116. The water inlets 116a are formed by drilling holes at equal intervals along the width of the model box or drilling holes along the entire length of the model box. When the water inlet channels 116 are filled with a test solution for simulating a groundwater environment, the first valve a is opened, allowing water to flow more evenly into each model layer, reducing measurement errors. The second sidewall 112 of the transparent box 100 is provided with a plurality of outwardly protruding water outlet channels 117. Each water outlet channel 117 is a pipe with a rectangular cross-section extending along the width of the model box. A plurality of water outlet ports 117a are provided on the second sidewall 112 in contact with each water outlet channel 117. The provision of the water outlet ports 117a facilitates the collection and monitoring of the outlet flow rate of each model layer, thereby studying the flow capacity and solution concentration of each model layer. The water inlet 116a and the water outlet port 117a can be formed by laser drilling.

[0055] Furthermore, a number of equally spaced chutes 115 are provided on the first and second side walls 111, 112, respectively. These serve as support structures for the various model layers within the model box and facilitate the insertion and removal of each model layer along the width of the model box, thereby facilitating the layout of the model layers within the model box to simulate different working conditions. The chutes 115 are configured as U-shaped grooves, which not only provide excellent guidance but also prevent the model layers from tilting during insertion or removal. Furthermore, the guiding structure and locking device can secure and ensure the precise positioning of the model layers. The chutes 115 should be positioned away from the water inlet 116a on the first side wall 111 and the water outlet 117a on the second side wall 112. The spacing between adjacent chutes 115 on the same side wall is generally determined by their proportional relationship to the model box height; the spacing between adjacent chutes 115 can be set to one-tenth of the model box height. This facilitates adjusting the proportions of different model layers. For example, if the model box height is 1200 mm, the chutes should be spaced 120 mm apart. The model box used in the present invention has a height of 300 mm, and the chute spacing is 30 mm.

[0056] Furthermore, a number of equally spaced mounting holes 114a are formed on the fourth side wall 114 of the transparent box 100 by laser drilling for mounting the strain gauge pressure sensor 310 in the sensing unit. The mounting location should be sealed to prevent liquid in the box from leaking out.

[0057] In certain embodiments, the model layer of configuration in the model box includes three types, namely, a pipe layer 210, a single rough fracture layer 220 and a matrix layer 230. The pipe layer 210 is used to simulate the pipe environment in the groundwater system, the single rough fracture layer 220 is used to simulate the single fracture environment in the groundwater system, and the matrix layer 230 is used to simulate the matrix environment in the groundwater system. When each model layer is installed, first the non-matrix model layer (i.e., any one or both of the pipe layer 210 and the single rough fracture layer 220, the number of each non-matrix model layer can be selected according to the working condition of the simulation) is inserted into the corresponding chute 115 in the transparent box 100, and then the transparent particles or transparent blocks used to simulate the matrix 231 are filled between the model layers of adjacent two non-matrix layers to form the matrix layer 230. The pipeline layer 210 is composed of two transparent acrylic plates 211 arranged one above the other. Laser drilling is performed on these plates 211 to form first holes 212. The channel formed between the two transparent acrylic plates 211 is used to simulate the pipeline environment within the groundwater system. The single rough fracture layer 220 is composed of two transparent rock layers 221, one above the other. A first rough fracture surface 221a and a second rough fracture surface 221b are formed on the opposing surfaces of these two transparent rock layers. The gap formed between the two rough fracture surfaces is the fracture channel. Laser drilling is performed on the two transparent rock layers 221 to form second holes 222 extending vertically through the layers. Solute exchange between the different model layers is achieved through the first and second holes 212, 222, and the pores within the matrix layer. This allows for the study of solute migration trajectories under different geological structures under different flow conditions.

[0058] Furthermore, the upper and lower transparent rock layers 221 in the single rough fracture layer 220 can be formed by casting or 3D printing, and the rough fracture surfaces thereon are rough surfaces obtained based on real rock fractures.

[0059] As 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 is sprayed on the real rock fracture surface to make a fracture silicone mold. Colorless epoxy resin is poured into the fracture silicone mold. After it is cured and demolded, one of the transparent rock layer bodies can be obtained. Then, the fracture silicone mold is used to make another transparent rock layer body. Finally, the two transparent rock layer bodies are laser drilled to obtain two transparent rock layers 221.

[0060] For the 3D printing method, a developer is first sprayed on the surface of the upper and lower real rock cracks to improve the scanning accuracy. The upper and lower real cracks are scanned by a 3D scanner to obtain the three-dimensional morphological point cloud data of the real rock cracks. The three-dimensional morphological point cloud data is then imported into a 3D printer, and the upper and lower transparent rock layer bodies are printed using colorless and transparent epoxy resin. Finally, the two transparent rock layer bodies are laser drilled to obtain two transparent rock layers 221.

[0061] Furthermore, the fracture channels in the single rough fracture layer 220 are filled to obtain filled fractures. A filler is attached to at least one of the rough fracture surfaces of the two transparent rock layers 221. The filler is a colored soluble material with a controllable dissolution rate, which is composed of a transparent matrix, a dissolution rate controller, and a dye, and is used to simulate the filling material in real rock fractures. Among them, the transparent matrix is ​​preferably a transparent resin, which mainly plays a structural support role and should account for more than 65% by weight; the dissolution rate controller can be polyethylene glycol (PEG), polypropylene glycol (PPG), hydroxyethyl cellulose (HEC) or polyvinyl pyrrolidone (PVP), etc., accounting for 20%-30%; the dye can be phenolphthalein, rhodamine B, fluorescein, beet red or indigo, etc., accounting for 3%-7% by weight. In a specific embodiment of the present invention, the transparent resin is heated until it melts, and polyethylene glycol and phenolphthalein solution are added, stirred to fully mix, and the filling material is obtained, which is then placed in a syringe for standby use. A filling mold is used to make the filling material adhere to at least one rough fracture surface in the two transparent rock layers 221. Figure 6 In (a), the filling mold includes an outer frame 410 and several filling heads 420. The outer frame 410 is a box-shaped structure with an open top, consisting of four side panels 411 and a bottom panel 412. The bottom panel 412 of the outer frame 410 is provided with a plurality of holes 412a distributed in an array for mounting a corresponding filling head 420. Each hole 412a is provided with an internal thread. Figure 6 In (b), the filling head 420 consists of a mounting portion 421 and a silicone head 422 fixed to the end of the mounting portion 421 facing away from the base plate 412. The mounting portion 421 and the silicone head 422 have through holes that communicate with each other. The length of the mounting portion 421 is greater than the thickness of the base plate 412, and the mounting portion 421 is provided with external threads. The filling head 420 is installed or removed by screwing the mounting portion 421 into or out of the corresponding hole 412a of the base plate 412. In order to simulate filling materials of different shapes, the filling mold is equipped with a variety of silicone heads 422 of different shapes, see Figure 6 In (b), a truncated cone-shaped silicone head 422a, a rectangular silicone head 422b, and a semicircular silicone head 422c are shown. In addition to using silicone heads of regular shapes, silicone heads of irregular shapes can also be used. Taking one of the transparent rock layers 221 as an example, the specific steps of the filling process using the filling mold are described:

[0062] Select a suitable silicone head 422 and install it on the mounting portion 421 at the end facing away from the base plate 412. Insert the mounting portion 421 into the hole 412a of the outer frame 410. Place the roughened cracked surface of the transparent rock layer 221 facing upward. Place the filling mold upside down on the roughened cracked surface, with the silicone head 422 facing the roughened cracked surface. Tighten the mounting portion 421 until the silicone head 422 is firmly attached to the roughened cracked surface. Then, insert the needle of a syringe containing filler material into the through hole of the mounting portion 421 to inject the filler material into the silicone head 422. After the filler material solidifies, unscrew the mounting portion 421 to separate the silicone head 422 from the roughened cracked surface of the transparent rock layer 221. Remove the filling mold, and the filler is formed on the roughened cracked surface of the transparent rock layer 221. Optionally, to enhance the adhesion between the filler and the roughened cracked surface of the transparent rock layer 221, an adhesive may be applied between the two.

[0063] In a specific embodiment of the present invention, the transparent box 100 is a rectangular box with overall dimensions of 600mm long, 400mm wide, and 300mm high. The filling mold primarily comprises an outer frame 410 and several filling heads 420. The outer frame's side panels 411 measure 600mm long, 300mm high, and 5mm thick, respectively, while the base plate 412 measures 600mm long, 400mm wide, and 5mm thick, respectively. Holes 412a are evenly distributed on the base plate 412, each with a diameter of 10mm and a spacing of 50mm. These holes are arranged in an array to ensure stable installation of the filling heads 420. Holes 412a are internally threaded, using the M10 standard, to precisely mate with the external threads of the filling heads 420. The filling heads 42 have mounting portions 421 with a diameter of 8mm and a height of 20mm. Inside the transparent box 100, the model layers are inserted and removed along the width of the box via slides 115. The slides 115 between each layer are spaced 40 mm apart, which is one-tenth the height of the box (300 mm), ensuring ample support and operating space. Furthermore, each layer is made of durable, transparent glass, 3 mm thick, and is equipped with locating pins to ensure alignment during sliding to prevent misalignment. The specific manufacturing and assembly process for the model box of this embodiment is as follows:

[0064] Step 1: Making the pipeline layer 210: Take two transparent acrylic plates 211 and use laser to punch a number of holes as first holes 212 for achieving solute exchange.

[0065] Step 2: Make a single rough fracture layer 220: Use silicone to make a real fracture surface mold. After obtaining the corresponding silicone mold, pour transparent epoxy resin into the mold. After solidification, demold it to obtain a transparent rock layer body. Use laser drilling technology to drill holes in the upper and lower transparent rock layer bodies to form a second hole 222 for solute exchange.

[0066] Step 3: Laser-drill the transparent box 100, made of transparent acrylic sheet. First, several holes are drilled on the fourth rear sidewall 114 for mounting the strain gauge pressure sensor 310. Five strip-shaped holes are then drilled on the first and second sidewalls 111, 112, on either side, to serve as water inlets 116a and 117a. A strip-shaped water inlet channel 116 is fixed to the first sidewall 111 at each water inlet 116a, and a strip-shaped water outlet channel 117 is fixed to the second sidewall 112 at each water outlet 117a. The connections between the water inlet and outlet channels 116, 117, and the sidewalls are sealed. The third front sidewall 113 is designed to be removable for mounting subsequent model layers.

[0067] Step 4: Install the pipe layer 210 and the single rough fractured layer 220: Place the transparent box 100 with the fourth sidewall 114 facing downward and the third sidewall 113 facing upward. Because the box's interior is designed to be pull-out, with multiple horizontal surfaces formed by the chute 115 on the first and second sidewalls 111, 112 of the transparent box 100, the pipe layer 210 and the single rough fractured layer 220 are inserted into the corresponding chute 115 one after the other, and sealed with sealant.

[0068] Step 5: Fill the remaining matrix layers: Use organic glass blocks or glass particles as the matrix 231 and fill it into the remaining three model layers.

[0069] Step 6: After installing the third side wall 113 and sealing it with sealant, put the entire model box upright, that is, the fourth side wall 114 is at the back and the third side wall 113 is at the front.

[0070] A second embodiment of the present invention provides a groundwater system solute transport test method based on the above-mentioned model box, comprising the following steps:

[0071] Step S1: A laser light source is provided outside the model box. A test solution containing tracer particles, used to simulate a groundwater environment, is injected into each water inlet channel 116. The tracer particles are used as the solute, and the solute concentration is reflected by the number of tracer particles. After each water inlet channel 116 is fully filled, the first valve a thereon is opened to allow the test solution to enter each model layer through the water inlet 116a. A flow meter is then provided on each water outlet channel 117.

[0072] Step S2: Turn on the laser light source and continuously collect path images I of the tracer particles flowing with the test solution. Particle Image Velocimetry (PIV) is used to calculate the displacement distance of the same tracer particle within a certain time range, thereby obtaining the velocity distribution of the flow field in the model box. Fluorescence imaging is used on image I to analyze the intensity of fluorescence in image I to obtain the distribution concentration of solute in the model box, and solute exchange between different model layers is monitored in real time. The signal collected by the strain gauge pressure sensor 310 is obtained, and the pressure gradient change in the model box is obtained based on the signal. The test solution discharged from each outlet pipe 117 is collected, and the water seepage and the concentration of the seepage solution of each model layer are measured.

[0073] Step S3: respectively change the flow rate of the water inlet channel, the solution concentration of the water inlet channel, the height of the non-matrix model layer, the initial porosity of the matrix layer, and the layout of each model layer in the model box, and study the influence of each factor on the solute transport in the groundwater system according to step S2.

[0074] Furthermore, in step S2, the fluorescence intensity of the tracer particles between different model layers is used to determine the concentration of the solutes contained in each model layer. The migration and diffusion trajectories of the solutes under the action of water flow are analyzed to study the solute diffusion rates reflected in different structures. Furthermore, by dyeing the tracer particles in different model layers with different colors, the solute exchange trajectories between different model layers can be captured.

[0075] Furthermore, by monitoring the solution concentration distribution at the fracture outlet in real time, the non-Fickian transport characteristics of solutes in groundwater systems, namely early arrival and tailing, can be further studied. By considering the concentration variation trend at the fracture outlet under different working conditions (breakthrough curve, BTC), the influence of multiple coupling factors on solute transport can be analyzed.

[0076] Furthermore, when the fractures in the single rough fracture layer are filled fractures, step S3 also includes respectively changing the initial distribution density and initial morphology of the filling, and then studying the influence of the initial distribution density and initial morphology of the filling on the solute migration in the groundwater system according to step S2.

[0077] Furthermore, for solute transport characteristics, the velocity field is used to analyze solute transport rates, and the concentration distribution (concentration field) in the image is used to analyze solute diffusion phenomena. The velocity field and concentration field are used to explain the non-Fickian transport behavior of solutes (abnormal transport phenomena). In addition, the above-mentioned multiple measurement data can comprehensively characterize the solute transport characteristics in the groundwater system and reveal solute diffusion, retention, and abnormal transport phenomena.

[0078] See also Figure 7The third embodiment of the present invention provides a groundwater system solute transport test device based on the above-mentioned model box, comprising:

[0079] The model box 9 adopts the model box provided by the embodiment of the first aspect of the present invention;

[0080] A fluid injection unit is connected to each water inlet channel 116 of the model box 9 to inject a test solution containing tracer particles for simulating the groundwater environment into each model layer in the model box 9;

[0081] The fluid pressure acquisition unit includes a data acquisition device 10 connected to each pressure sensor 310 in the model box 9 via a communication cable 14, and is used to convert the analog signal measured by the pressure sensor 310 into a digital signal;

[0082] An image acquisition unit, comprising a laser light source 15 and a high-resolution camera 16 disposed on one side of the model box 9, for continuously acquiring path images I of the tracer particles flowing with the test solution during the test;

[0083] The waste liquid recovery unit is provided at the water outlet channel 117 of the model box 9 and is used to collect the test solution discharged from each model layer in the model box 9 and monitor the flow rate of the discharged solution in real time using a flow meter;

[0084] The data processing unit is used to calculate the displacement distance of the same tracer particle within a certain time range using the PIV method for image I, thereby obtaining the flow velocity distribution of the flow field in the model box; using the fluorescence imaging method for image I, by analyzing the intensity of the fluorescence in image I, the distribution concentration of the solute in the model box is obtained, and the solute exchange occurring between different model layers is monitored in real time; the pressure gradient change in the model box is obtained based on the digital signal output by the fluid pressure acquisition unit; and the water seepage and the concentration of the seepage solution of each model layer are measured based on the flow rate of the test solution discharged from each model layer.

[0085] In some embodiments, water as a solvent and sodium chloride as a solute are mixed to simulate the actual groundwater environment and characteristics, and tracer particles are added to the sodium chloride solution. The tracer particles are obtained by fluorescently staining polystyrene microspheres with rhodamine B and serve as the main experimental tool for studying solute transport.

[0086] In some embodiments, the fluid injection unit includes a transparent water tank 3 and an injection pump 6. The side walls, top plate, and bottom plate of the water tank 3 are all made of transparent glass plates. A water supply port 1 and a filling port 2 are provided on the top plate of the water tank 3. A water intake port 4 is provided on the side wall of the water tank 3 near the bottom plate. A drain port 5 is provided on the bottom plate of the water tank 3. The water supply port 1 serves as a water source to ensure continuous water supply for the experiment. The filling port 2 is mainly used to add sodium chloride solute and dyed polystyrene balls to the water tank 3 to form tracer particles. The purposes of using fluorescent dyed tracer particles are: 1) to monitor the seepage characteristics of the fluid in the groundwater system through the PIV method and calculate the flow velocity to obtain the flow field; 2) to use the fluorescence imaging method to calculate the fluorescence intensity of the particles to obtain the distribution concentration of the solute in the groundwater system, monitor the solute exchange between different media in real time, and provide more data for studying the solute convection and diffusion phenomenon. The water intake port 4 is mainly used to monitor whether the concentration of the mixed solution meets the requirements and whether the tracer particles are mixed evenly. An injection pipe 8 connects the water outlet of the water tank 3 to the injection pump 6, transferring the test solution from the water tank 3 to the water inlet channel 116 of the model box 9. A main channel connecting the water outlet of the water tank 3 and the water inlet channel 116 of the model box 9 is divided into several branch channels (five branch channels are provided in this embodiment) via a plurality of three-pronged pipes. The test solution is then fed into the corresponding model layer. A second valve b and a flow meter 7 are installed in each branch channel to control the flow rate of the test solution. The flow rate is adjusted by controlling the size of the second valve b.

[0087] In some embodiments, the data acquisition device 10 is generally selected from the NIUSB-6211 data acquisition device (DAQ) in the National Instruments (NI) series. The pressure sensor is connected to the data acquisition device DAQ via a communication cable to convert the analog signal into a digital signal, and a computer 17 and data analysis related software are used to record the pressure data and perform data processing and analysis.

[0088] In some embodiments, the waste liquid recovery unit includes an output pipe 11, a flow meter 12, and a recovery tank 13. The output pipe 11 is connected to the water outlet channel 117 of the model tank 9 and is used to output the test solution discharged from the model tank 9 to the recovery tank 13. The flow meter 12 is set on the output pipe 11 to monitor the output flow rate in real time.

[0089] In some embodiments, the image acquisition unit includes a high-resolution camera 16 and two 532nm green laser light sources 15. The two laser light sources 15 are respectively placed on the upper and lower sides of the model box 9, and a 532nm excitation filter is arranged in front of the laser light source 15 to irradiate light of a set wavelength into the model box 9 to ensure that the fluorescent tracer particles in the model box 9 are fully irradiated. The high-resolution camera 16 is arranged on the front side of the model box 9, and the shooting angle is perpendicular to the light emitted from the upper and lower parts, and a 580nm emission filter is installed in front of the lens of the camera 16, which is mainly used to filter out other light so that the required light is reflected into the camera. The camera 16 is connected to the data processing unit through a communication cable 14, and the images taken by the camera 16 are processed in real time to obtain the flow field and concentration field.

[0090] In some embodiments, the data processing unit includes a computer 17, which is connected to the data acquisition device 10 and the camera 16 via a communication cable 14 and is used to process the data transmitted by them. Computer 17 is equipped with a PIV module, a fluorescence imaging module, and a pressure signal processing module. The PIV module is used to capture tracer particles flowing in the fluid based on the image I captured by the camera 16 to calculate the velocity field. The fluorescence imaging module is used to analyze the intensity of fluorescence in the image I to obtain the distribution and concentration of solutes within the model box, thereby monitoring the solute exchange between different model layers in real time. The pressure signal processing module is used to receive and process the pressure signal from the pressure sensor 310 to calculate the pressure gradient changes within the model box. The multiple sets of real-time measurement data such as the velocity field, concentration distribution, pressure gradient changes, and water seepage can be used to comprehensively characterize the solute transport characteristics in the groundwater system. This not only reflects the solute transport path and rate in the geological medium, but also further reveals the mechanism of abnormal transport phenomena (non-Fickian phenomena) such as solute diffusion and retention in the groundwater system. This provides relevant scientific basis and data sources for the subsequent establishment and optimization of transport models.

[0091] The specific working process of the groundwater system solute transport test device provided by the third embodiment of the present invention is described in detail below:

[0092] Step 1: Treat the solution required for the test

[0093] Step 1A: Use fluorescent rhodamine B to dye polystyrene microsphere particles as tracer particles.

[0094] Step 1B: Open the water supply port 1 so that the water tank 3 is filled with 2 / 3 of water, first add sodium chloride solute at the filling port 2 to mix the solution thoroughly, and open the water intake port 4 to take part of the solution to test the concentration.

[0095] Step 1C: Add tracer particles from the filling port 2 and observe whether the particle distribution is uniform from the water intake port 4.

[0096] Step 2: Install the model box required for the test

[0097] The specific steps are as mentioned above and will not be repeated here.

[0098] Step 3: Use the fluid injection unit to inject the test solution into the model box for testing

[0099] Step 3A: Use the injection pump 6 to absorb the test solution in the water tank 3 and inject it into the water inlet channels 116 of the model box 9 through the injection pipe 8.

[0100] Step 3B: By adjusting each second valve b on the injection pipe 8, the value of the flow meter 7 corresponding to each model layer in the model box 9 is observed to keep the value as consistent as possible.

[0101] Step 3C: observe the state of each water inlet channel 116 in the model box 9, and open the first valve a after the test solution fully fills the water inlet channel 116 to allow the test solution to enter each corresponding model layer.

[0102] Step 4: Solute migration path observation

[0103] Step 4A: Turn on the 532 nm laser light source 15 and the high-resolution camera 16 to capture an image I of the path of the fluorescent tracer particles flowing along the solution, and transmit the image to the computer 17 via the communication cable 14 .

[0104] Step 4B: The captured image I is analyzed and processed by the data processing module within the computer 17. The PIV module is used to calculate the displacement distance between particles, thereby obtaining the fluid flow field. A fluorescence imaging module is then used to analyze the intensity of the fluorescence within the image to obtain the corresponding tracer particle concentration distribution, that is, the solute concentration distribution. A fluid pressure module is used to monitor the pressure gradient. A strain gauge pressure sensor is connected to a reserved hole and connected to a data acquisition device (DAQ) via a cable. This is then connected to a computer, converting the analog signal into a digital signal. The pressure gradient is monitored in real time on the computer, and the dynamic changes in the seepage field in the groundwater system can be understood in real time by analyzing the pressure gradient trend. The seepage volume and solute concentration of each model layer are calculated, and the solution seeped from each model layer is collected using a recovery device. The flowmeter on the output pipeline then measures the amount of water seepage within each model layer. The solution within each model layer is collected and recovered, and analyzed to obtain the concentration of the seepage solution in each model layer. The solute transfer rate can be calculated by analyzing the seepage volume, and then the migration time of the solute from the injection point to the discharge point can be evaluated; and by collecting the concentration data of the seepage solution, not only the solute release process can be reversed, but it can also be used to verify and calibrate the seepage and solute transport models.

[0105] Step 5: Solute transport test under different test conditions

[0106] Step 5A: Study the relationship between the model box inlet flow rate and solute transport: In step 3B, adjust the size of each second valve b and observe the value of the flow meter 7 to change the model box inlet flow rate. Repeat steps 3 and 4 to control the concentration of the test solution, the fracture aperture, the channel aperture, and the initial porosity of the matrix to study the relationship between flow rate and solute transport.

[0107] Step 5B: Study the relationship between test solution concentration and solute transport: Adjust the amount of sodium chloride added and the number of tracer particles in Steps 1B and 1C to adjust the test solution concentration. Repeat Steps 3-4 to control the model box inlet flow rate, fracture aperture, channel aperture, and initial matrix porosity to study the relationship between solution concentration and solute transport.

[0108] Step 5C: Study the relationship between crack opening and solute transport. In step 2, adjust the upper and lower crack surfaces to different levels to adjust the crack opening. Repeat steps 3-4 to control the model box inlet flow rate, test solution concentration, pipe opening, and initial porosity of the matrix to study the relationship between crack opening and solute transport.

[0109] Step 5D: Study the relationship between channel aperture and solute transport. In step 2, adjust the channel aperture by placing the upper and lower acrylic plates within the channel layer at different levels. Repeat steps 3-4, controlling the model box inlet flow rate, test solution concentration, fracture aperture, and initial matrix porosity to study the relationship between channel aperture and solute transport.

[0110] Step 5E: Study the relationship between matrix porosity and solute transport. In step 2, select organic glass blocks of different sizes and fill the matrix layer to adjust the initial porosity. Repeat steps 3-4, controlling the model box inlet flow rate, test solution concentration, pipe aperture, and fracture aperture to study the relationship between matrix porosity and solute transport.

[0111] Step 5F: Study the relationship between the presence of fillers (filled fractures) and solute transport. In step 2, the initially open fractures are filled with a filling mold. At the same time, the distribution density and morphological characteristics of the fillers are further changed by filling with silicone joints. All other conditions are kept unchanged. Steps 3-4 are repeated to study the effects of different fracture geometric characteristics on solute transport in the groundwater system.

[0112] Step 6: Study the relationship between model layer arrangement and solute transport

[0113] Step 6A: In step 2, adjust the upper fracture layer to a complete, unperforated fracture model. In step 3, close the valves in the fracture layer and the underlying matrix layer, allowing solution injection only into the pipeline layer and the matrix layers on either side. Repeat steps 2-4 to investigate the relationship between various factors and solute transport in the pipeline-matrix coupled system.

[0114] Step 6B: Study solute transport in the fracture-matrix coupling system: In step 2, replace the lower pipe layer with a complete, unperforated acrylic plate. In step 3, close the valves in the pipe layer and the matrix layer above it, allowing only solution injection into the fracture layer and the matrix layers on either side. Repeat steps 2-4 to study fracture-matrix solute exchange.

[0115] Step 6C: Study fracture-channel solute exchange: In step 2, install the channel layer adjacent to the fracture layer. Adjust the upper channel layer to a complete, unperforated acrylic sheet, and the lower fracture layer to a complete, unperforated, transparent fracture surface. Allow solution injection only into the channel and fracture layers. Repeat steps 2-4 to study fracture-channel solute exchange.

[0116] In summary, the present invention provides a model chamber, test method, and apparatus for testing solute transport in groundwater systems. This method simulates solute exchange within real karst fissures, conduits, and matrix, and employs visualization, PIV, and fluorescence imaging techniques to simultaneously monitor solute exchange concentrations and fluid flow characteristics within the karst system. This method accurately monitors changes in solute concentration, fluid flow rate, and corresponding pressure gradients during solute transport, providing reliable experimental data for analyzing and predicting solute exchange trajectories within groundwater systems.

[0117] 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.

[0118] 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 model box for groundwater system solute transport test, characterized in that: include: A transparent box body, the transparent box body having a top wall, a bottom wall and a plurality of side walls, a plurality of spaced chute grooves are provided on the inner sides of the first side wall and the second side wall respectively arranged opposite to each other, and a water inlet channel and a water outlet channel are respectively provided on the first side wall and the second side wall, protruding outward and parallel to the axis of the chute groove; Several model layers, including a pipe layer, a single rough fracture layer, and a matrix layer, wherein the pipe layer and the single rough fracture layer cooperate with the corresponding chute to be inserted into or withdrawn from the transparent box from one side of the third side wall of the transparent box; after the non-matrix model layer is installed in place, a matrix is ​​filled between two adjacent non-matrix model layers to form the matrix layer; the inlet and outlet ends of each model layer are respectively connected to a corresponding water inlet channel and a water outlet channel; by combining and splicing different model layers, the influence of different geological structures on the non-Fickian migration of solutes in an actual environment is simulated; The sensing unit includes a plurality of pressure sensors evenly distributed on the inner side of the fourth side wall of the transparent box, and is used to measure the pressure signals in each model layer.

2. The model box according to claim 1, characterized in that Each water inlet channel is respectively provided with a first valve, and a plurality of water inlets connected to each water inlet channel are opened on the first side wall in contact with each water inlet channel; a plurality of water outlets connected to each water outlet channel are opened on the second side wall in contact with each water outlet channel.

3. The model box according to claim 1, characterized in that The pipeline layer is composed of two transparent acrylic plates arranged one above the other. First holes for solutes to pass through are formed on the upper and lower transparent acrylic plates, and a channel for simulating the pipeline environment in the groundwater system is formed between the two transparent acrylic plates.

4. The model box according to claim 1, characterized in that The single rough fracture layer is composed of two upper and lower transparent rock layers, and a first rough fracture surface and a second rough fracture surface are respectively formed on the surfaces of the upper and lower transparent rock layers that are arranged opposite to each other. The gap channel formed between the two rough fracture surfaces is the fracture channel, and a second hole is formed on the upper and lower transparent rock layers, which is set through in the height direction and is used for solutes to pass through.

5. The model box according to claim 4, characterized in that: The upper and lower transparent rock layers are formed by casting or 3D printing, and the rough crack surfaces thereon are rough surfaces obtained based on real rock cracks.

6. The model box according to claim 4, characterized in that: A filler is attached to at least one rough crack surface in two transparent rock layers to form a filled crack; the filler is a colored soluble material with controllable dissolution rate, which is composed of a mixture of a transparent matrix, a dissolution rate controller and a dye.

7. The model box according to claim 6, characterized in that: The transparent matrix is ​​selected from transparent resin, the dissolution rate controller is selected from polyethylene glycol, polypropylene glycol, hydroxyethyl cellulose or polyvinyl pyrrolidone, and the dye is selected from phenolphthalein, rhodamine B, fluorescein, beetroot red or indigo.

8. The model box according to claim 6, characterized in that: A filling mold is used to make the filler adhere to the rough crack surface, and the filling mold includes an outer frame and a plurality of filling heads; The outer frame is a box-shaped structure with an open top, and a plurality of holes distributed in an array are provided on the bottom plate of the outer frame for mounting a corresponding filling head, and each hole is provided with an internal thread; The filling head consists of a mounting portion and a silicone head fixed on the mounting portion at one end facing away from the base plate. The mounting portion and the silicone head are provided with through holes connected to each other. The length of the mounting portion is greater than the thickness of the base plate and the mounting portion is provided with an external thread. The filling head can be installed or removed by screwing the mounting portion into or out of the corresponding hole of the base plate; the filling mold is equipped with the silicone head of at least one shape.

9. A method for testing solute transport in a groundwater system based on the model box according to any one of claims 1 to 8, characterized in that: include: Step S1: A laser light source is provided outside the model box, and a test solution containing tracer particles for simulating a groundwater environment is injected into each water inlet channel, using the tracer particles as the solute. The solute concentration is reflected by the number of tracer particles. After each water inlet channel is fully filled, the first valve on the channel is opened to allow the test solution to enter each model layer, and a flow meter is provided on each water outlet channel. Step S2: Turn on the laser light source and continuously collect path images I of the tracer particles flowing with the test solution. The displacement distance of the same tracer particle within a certain time range is calculated using the PIV method, thereby obtaining the flow velocity distribution of the flow field in the model box. A fluorescence imaging method is used on the image I to analyze the intensity of the fluorescence in the image I to obtain the distribution concentration of the solute in the model box, and the solute exchange occurring between different model layers is monitored in real time. The signal collected by the pressure sensor is obtained, and the pressure gradient change in the model box is obtained based on the signal. Collect the test solutions discharged from each outlet pipe and measure the water seepage volume and seepage solution concentration of each model layer; Step S3: respectively change the flow rate of the water inlet channel, the solution concentration of the water inlet channel, the height of the non-matrix model layer, the initial porosity of the matrix layer, and the layout of each model layer in the model box, and study the influence of each factor on the solute transport in the groundwater system according to step S2.

10. A groundwater system solute transport test device, characterized in that: include: The model box according to any one of claims 1 to 8; a fluid injection unit connected to each water inlet channel of the model box to inject a test solution containing tracer particles for simulating a groundwater environment into each model layer in the model box; a fluid pressure acquisition unit, comprising a data collector connected to the sensing unit in the model box, for converting the analog signal measured by the pressure sensor into a digital signal; An image acquisition unit, comprising a laser light source and a camera disposed on one side of the model box, for continuously acquiring images I of tracer particles flowing with the test solution during the test; A waste liquid recovery unit is provided at the water outlet channel of the model box, and is used to collect the test solution discharged from each model layer and monitor the flow rate of the discharged solution in real time using a flow meter; The data processing unit is used to calculate the displacement distance of the same tracer particle within a certain time range using the PIV method for the image I, thereby obtaining the flow velocity distribution of the flow field in the model box; using the fluorescence imaging method for the image I, by analyzing the intensity of the fluorescence in the image I, the distribution concentration of the solute in the model box is obtained, and the solute exchange occurring between different model layers is monitored in real time; the pressure gradient change in the model box is obtained according to the digital signal output by the sensing unit; and the water seepage amount and the concentration of the seepage solution of each model layer are measured according to the flow rate of the test solution discharged from each model layer.

Images