Layered filling fissure seepage-erosion visualization experimental device and method

Abstract

The present application relates to the technical fields of rock mass fracture medium seepage experiment, in particular to a layered filling fracture seepage-erosion visualization experiment device, which comprises: a rack horizontally fixed on an experiment table; a plane light source horizontally fixed on the rack; adjustable supports distributed on both sides of the experiment table; a layered filling fracture model arranged on the two adjustable supports; a syringe arranged on the experiment table and communicated with a fluid inlet through a pipeline; a liquid collection bottle arranged below the fluid outlet; a mass monitoring module, a pressure monitoring module and an image acquisition module arranged on the experiment table. By segmentally filling the fracture model, a layered filling fracture model is made, which can reflect the layered characteristics of the soil body. By connecting a high-precision spiral pull rod pressure sensor, a mass monitoring system is constructed to realize real-time monitoring of the filling fracture. In combination with the pressure monitoring system and the image acquisition module, the visualization observation of the filling fracture seepage-erosion experiment is realized.

Description

Technical Field

[0001] The invention relates to the technical field of rock mass fissure medium seepage experiment, in particular to a layered filling fissure seepage-erosion visualization experiment device and method. Background Art

[0002] Filled fissures refer to the filling of natural rock fissures with unconsolidated, loose material due to water erosion, chemical erosion, and gravitational settling. Furthermore, due to geological processes such as sedimentation, erosion, and volcanic activity, the filling soil in these fissures can exhibit alternating layers of soil, with distinct stratification. The physical and chemical properties of adjacent layers often differ significantly.

[0003] The migration patterns of fluids and solutes within these layered filled fractures are very complex, and under the action of seepage, particles will migrate and lose in the filled fractures, further changing the seepage channels and permeability of the filled fractures. Conducting seepage research on filled fracture media with soil stratification characteristics is of great significance in many geological engineering projects. In geological engineering, the development of filled fractures forms weak zones and interlayers, constituting potential failure surfaces. Studying the seepage characteristics of filled fractures is of great significance for preventing geological disasters such as piping and landslides. In environmental science, filled fractures hinder the migration of pollutants compared to fracture media, which has a key impact on the study of the migration and diffusion process of pollutants.

[0004] The filling soil for cracks is composed of coarse and fine particles. The coarse particles form the basic skeleton of the filling medium, while the fine particles are loose particles dispersed within the skeleton space. When the fine particle size is smaller than the pore space formed by the coarse particle skeleton and the seepage pressure is greater than the frictional resistance between the particles, the fine particles can be lost through the pores of the coarse particle skeleton, causing erosion damage. For cracks filled with stratified soil, the different soil layers have different soil properties and significant differences in seepage characteristics. The permeability of soil layers with finer particles (such as clay layers) is relatively low, while the permeability of soil layers with coarser particles (such as sand layers) is relatively high. This seepage characteristic leads to uneven seepage paths, making the seepage characteristics of the filled cracks more complex.

[0005] Traditional seepage experiments involving filled fractures use filters at the sample end to prevent the loss of filling material. This neglects the effects of seepage erosion on soil particles during the seepage process and the impact of particle loss on the seepage pathways and permeability of the filled fractures. In particular, research on seepage in filled fractures in layered soils is limited. Furthermore, due to the opaque nature of the rock mass, traditional experiments are limited to obtaining basic fracture properties such as roughness, permeability, and relative permeability. This makes it difficult to visualize the seepage characteristics of the seepage-erosion process in layered filled fractures, and related research is urgently needed. Summary of the Invention

[0006] In order to overcome the shortcomings of the above-mentioned existing technologies, the present invention provides a device and method for visualizing the seepage and erosion of layered filling fractures. By connecting a high-precision spiral pull rod pressure sensor, a quality monitoring system is constructed to realize real-time quality monitoring of the seepage and erosion process of layered filling fractures. In combination with a pressure monitoring module and an image acquisition module, visual observation of the seepage and erosion process of filling fractures is realized.

[0007] According to one aspect of the present invention, a device for visualizing seepage and erosion in layered filling fractures is provided, comprising:

[0008] The stand is fixed horizontally on the laboratory table;

[0009] Plane light source, fixed horizontally on the stand;

[0010] Adjustable brackets, two adjustable brackets are distributed on both sides of the laboratory table;

[0011] A layered fracture filling model is provided on an adjustable bracket and is composed of multiple fracture filling segments spliced ​​together. The multiple fracture filling segments are spliced ​​and reinforced by a detachable segmented mounting box. A buffer box is provided at one end of the fracture filling segment and is connected thereto. An inlet cavity is provided at the end of the buffer box and is connected thereto. An outlet cavity is provided at the other end of the fracture filling segment.

[0012] A syringe, the syringe being connected to an inlet cavity of the layered filling fracture model through a pipeline, and injecting fluid into the inlet cavity of the layered filling fracture model through the syringe;

[0013] A liquid collecting bottle is provided on the experimental table and is placed below the outlet cavity of the layered filling fracture model for collecting fluid;

[0014] Quality monitoring module, used to monitor the quality changes of the layered filling fracture model during the seepage process;

[0015] A pressure monitoring module, used to monitor the pressure of the injected fluid;

[0016] The image acquisition module is used to monitor the seepage process of the layered filling fracture model.

[0017] As a further technical scheme, the filling fissure section is formed by filling soil in the multi-section fissure section, the multi-section fissure section is formed by uniformly cutting the initial fissure model, the initial fissure model is formed by embedding the upper rough fissure surface and the lower rough fissure surface, opposite surfaces of the upper rough fissure surface and the lower rough fissure surface are respectively provided with the upper rough fissure surface connecting edge and the lower rough fissure surface connecting edge, the upper rough fissure surface connecting edge and the lower rough fissure surface connecting edge are attached by the rubber strip, and a fissure space with a fixed opening is formed between the upper rough fissure surface and the lower rough fissure surface to fill the soil.

[0018] As a further technical scheme, the other end of the inlet cavity is provided with a fluid inlet, the other end of the outlet cavity is provided with a fluid outlet with an arc-shaped outlet corner, the buffer tank is a hollow structure with open ends, the cavity of the buffer tank is filled with coarse gravel with a large particle size, and the particle size of the coarse gravel is greater than the fissure opening, and the connection between the buffer tank and the inlet cavity is provided with gauze.

[0019] As a further technical scheme, the detachable segmented installation tank is formed by splicing a plurality of installation tanks, and the length of the installation tank is equal to the length of the filling fissure section, the plurality of installation tanks are connected through a mortise and tenon structure, the mortise and tenon structure comprises a mortise and a tenon head matched with the mortise, the installation tank comprises a main tank body and a side plate, and the main tank body and the side plate are connected by screws through screw holes.

[0020] As a further technical scheme, the quality monitoring module comprises two spiral pull rod pressure sensors and a display control instrument, the two spiral pull rod pressure sensors are respectively arranged on two adjustable supports, one end of each of the two spiral pull rod pressure sensors is connected to the layered filling fissure model, and the two spiral pull rod pressure sensors are connected to the display control instrument.

[0021] As a further technical scheme, the pressure monitoring module comprises a pressure sensor and a reader, the pressure sensor is an over-flow type pressure sensor, one end of the pressure sensor is connected to the syringe through a pipeline, the other end of the pressure sensor is connected to the fluid inlet through a pipeline, the reader is connected to the pressure sensor and connected to a computer.

[0022] As a further technical scheme, the adjustable support comprises a base, a vertical rod, and a support plate that can move up and down on the outside of the vertical rod, the vertical rod is provided with a scale, and the edge of the support plate is provided with a screw hole for installing the spiral pull rod pressure sensor of the quality monitoring module.

[0023] As a further technical scheme, the syringe is installed on a syringe pump, the injection flow rate is adjusted by the syringe pump, and the reader and the display control instrument are connected to the computer.

[0024] According to one aspect of the present invention, a method for visualizing seepage and erosion in layered filling fractures is provided, comprising the following steps:

[0025] A layered filling fracture model is prepared and immersed in water for several hours, and then placed in a vacuum pump and allowed to stand for several hours under negative pressure to allow the soil to reach a saturated state;

[0026] After installing and adjusting each instrument, a visualization experiment of filled fracture seepage and erosion was conducted at a fixed flow rate. The syringe pump was turned on, and the fluid flowed out of the syringe, passed through the layered filled fracture model, and flowed into the liquid collection bottle.

[0027] The quality monitoring module records the quality changes during the seepage process in real time. The pressure monitoring module records the pressure at the inlet cavity of the layered filling fracture model in real time. The image acquisition module observes the seepage-erosion process of the filling fracture in real time.

[0028] As a further technical solution, the preparation method of the layered filling fracture model is as follows:

[0029] The upper and lower rough crack surfaces are prepared by casting and demoulding with a transparent epoxy resin material. Glue is applied to the connecting edges of the upper and lower rough crack surfaces. A rubber strip is placed between the two, and the upper and lower rough crack surfaces are fitted together to form a fixed and sealed connection. A crack space is formed between the upper and lower rough crack surfaces, and the cracks are left to stand for a period of time to solidify, thereby obtaining an initial crack model.

[0030] The prepared initial fracture model is evenly cut into multiple fracture segments, and the experimental soil is filled into the fracture spaces of the fracture segments according to experimental requirements to form filled fracture segments;

[0031] First, stick the tape on the lower part of the first section of the crack filling section, and place it inside the first section of the main box. Fix the first section of the side panel to the first section of the main box with screws;

[0032] Then insert the tenon of the second main box into the tenon groove of the first main box, apply a proper amount of glue on the surface of the second crack filling section, and adhere it to the first crack filling section, and then fix the second side panel to the second main box with screws;

[0033] Connect the second section of the main box, the third section of the main box and the fourth section of the main box in sequence, adhere the second section of the crack filling section, the third section of the crack filling section and the buffer box in sequence, and fix the side panels to the corresponding main boxes;

[0034] Place the weight block on the top of the assembly to compact the multiple sections of crack filling. Let it sit for a while until the glue solidifies and then remove the installation box.

[0035] Use glue to stick the inlet cavity to the front end of the buffer box, and stick the outlet cavity to the rear end of the first section of the crack filling section. Let it stand for a while to solidify, and the layered crack filling model is completed.

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

[0037] 1. By filling the crack model in sections, a layered filling crack model was made, which can reflect the layered characteristics of the soil and observe the seepage characteristics of different soils. By connecting a high-precision spiral pull rod pressure sensor, a quality monitoring system was constructed to achieve real-time monitoring of the filled cracks. In conjunction with the pressure monitoring system and image acquisition module, visual observation of the filled crack seepage-erosion experiment was achieved.

[0038] 2. The fracture segments are directly cut from the initial fracture model. This is because the fracture opening is small. This operation can ensure that each fracture segment has good fit and avoid blocking the fracture opening during the fracture segment assembly process, which affects the seepage-erosion experiment.

[0039] 3. The assembly of each fissure segment is coordinated through the detachable segmented installation box, and the internal cavity size of the detachable segmented installation box is completely consistent with the external size of the filled fissure segment, which can ensure that each fissure segment has good fit and further avoid blocking the fissure opening during the assembly process of the fissure segment.

[0040] 4. The fluid outlet of the outlet cavity is set as an open outlet, and the turning point is set as a curved surface to prevent the lost particles from being retained inside the outlet cavity during the filling fracture seepage experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction will be given below to the drawings used in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1 This is a schematic diagram of the structure of the fracture filling seepage-erosion experimental device of the present invention.

[0043] Figure 2 Schematic diagram of the layered crack filling model of the present invention.

[0044] Figure 3 Schematic diagram of the initial crack model of the present invention.

[0045] Figure 4 This is a schematic diagram of the crack filling section and buffer box of the present invention.

[0046] Figure 5This is a schematic diagram of the detachable segmented installation box of the present invention.

[0047] Figure 6 This is a schematic diagram of the second section installation box and mortise and tenon structure of the present invention.

[0048] In the figure: 1. Upper rough crack surface; 2. Lower rough crack surface; 3. Upper rough crack surface connecting edge; 4. Lower rough crack surface connecting edge; 5. Rubber strip; 6. Crack space; 61. Soil body 1; 62. Soil body 2; 63. Soil body 3; 71. First section of crack filling section; 72. Second section of crack filling section; 73. Third section of crack filling section; 8. Buffer box; 9. Coarse gravel; 101. First section of main box; 102. Second section of main box; 103. Third section of main box; 104. Fourth section of main box; 111. First section of side panel; 112. Second section of side panel; 113. Third section of side panel; 114. Fourth section of side panel; 12. Mortise and tenon; 13. Tenon; 141. Threaded hole one; 142. Threaded hole two; 15. Inlet cavity; 16. Outlet cavity; 17. Fluid inlet; 18. Fluid outlet; 19. Layered filling fracture model; 20. Stand; 21. Plane light source; 22. Adjustable bracket; 221. Base; 222. Vertical pole; 223. Support plate; 23. Screw-type pull rod pressure sensor; 24. Display control instrument; 25. Pressure sensor; 26. Reader; 27. Camera; 28. Syringe; 29. ​​Syringe pump; 30. Computer; 31. Liquid collection bottle; 32. Weight block. DETAILED DESCRIPTION

[0049] The terms "including" and "having" and any variations thereof in the description and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions, for example, a process, method, system, product or apparatus that includes a series of steps or units is not necessarily limited to the steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0050] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In addition, the technical features in the various embodiments or single embodiments provided by the present invention are arbitrarily combined with each other to form a new technical solution. This combination is not restricted by the sequence of steps and / or structural composition mode, but must be based on the ability of ordinary technicians in this field to implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that this combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0051] Existing methods for filling fracture seepage experiments include core experiment technology, which involves filling the split fractured rock mass with filling materials and placing it in a seepage device. After sealing, water is injected into the rock mass to simulate the seepage process of the filled fractures. The pore space distribution of the filled fractures after the seepage experiment is observed by scanning with technologies such as CT and X-ray.

[0052] Existing seepage experiments on filled fractures mostly use the method shown above, which is limited to obtaining basic fracture parameters such as roughness, permeability, relative permeability, etc., and ignores the seepage erosion caused to soil particles during the seepage process and the impact of particle loss on the seepage channels and permeability of the filled fractures. Moreover, due to the opaque characteristics of natural rock masses, most experiments are unable to observe the seepage process of the filling medium and the evolution of the seepage channels in real time. Therefore, the present invention proposes a visualization experimental device and method for seepage-erosion of filled fractures, and produces a transparent layered filled fracture model with a real geometric morphology. A spiral pull rod pressure sensor is used to monitor the quality of the filled fracture seepage process in real time, and a pressure sensor is used to monitor the pressure of the filling fracture inlet cavity to achieve the purpose of real-time monitoring of the permeability evolution during the seepage process. An injection pump is used to provide different constant flow rates for the seepage, and a high-resolution camera is combined to achieve the purpose of finely capturing the seepage-erosion behavior of the filled fractures.

[0053] See also Figure 1-6 The present invention provides a layered filling crack seepage-erosion visualization experimental device, which includes a stand 20 horizontally fixed on a laboratory table, a plane light source 21 horizontally arranged on the stand 20, adjustable brackets 22 arranged on both sides of the stand 20, and a layered filling crack model 19 set on a pair of adjustable brackets 22. The laboratory table is also provided with a syringe 28, a quality monitoring module, a pressure monitoring module and an image acquisition module.

[0054] During the experiment, the syringe 28 is connected to the fracture inlet of the layered filling fracture model 19 through a pipeline, and fluid is injected into the fracture of the layered filling fracture model 19 through the syringe 28. A liquid collecting bottle 31 is also provided on the stand 20 below the fracture outlet of the layered filling fracture model 19. The liquid flowing out of the layered filling fracture model 19 is collected through the liquid collecting bottle 31, and the quality monitoring module, the pressure monitoring module and the image acquisition module respectively monitor the mass change of the layered filling fracture model 19, the pressure of the injected fluid and the seepage process of the layered filling fracture model 19 during the seepage process.

[0055] In this embodiment, Figure 2 As shown, the layered filling fracture model 19 is composed of multiple filling fracture segments, the end of the filling fracture segment at one end is provided with a buffer box 8 connected thereto, the end of the buffer box 8 is provided with an inlet cavity 15 connected thereto, and the end of the filling fracture segment at the other end is provided with an outlet cavity 16 connected thereto.

[0056] Among them, the filled fracture section is formed by filling soil in multiple fracture sections, and the multiple fracture sections are formed by uniformly cutting the initial fracture model. According to experimental needs, the above-mentioned initial fracture model can be uniformly cut into multiple ends. Moreover, since the fracture opening is small, directly uniformly cutting the initial fracture model to form multiple fracture sections can ensure that each fracture section has good fit and avoid blocking the fracture opening during the fracture section assembly process.

[0057] The number of fracture sections can also be reasonably selected according to experimental needs, and soil parameters such as the gradation of the filling soil need to be prepared according to experimental needs.

[0058] Further, such as Figure 3 As shown, the initial fracture model is formed by the upper rough fracture surface 1 and the lower rough fracture surface 2. The opposite surfaces of the upper rough fracture surface 1 and the lower rough fracture surface 2 are respectively provided with an upper rough fracture surface connecting edge 3 and a lower rough fracture surface connecting edge 4. The upper rough fracture surface connecting edge 3 and the lower rough fracture surface connecting edge 4 are fitted together by a rubber strip 5. A fracture space 6 with a fixed opening is formed between the upper rough fracture surface 1 and the lower rough fracture surface 2 for filling soil.

[0059] Further, such as Figure 5-6 As shown, in order to facilitate the installation of the layered filling crack model 19 during the experiment and ensure that each crack segment is tightly connected to make it fit better, this embodiment introduces a detachable segmented installation box, which assists in the splicing and reinforcement of multiple filling crack segments. The detachable segmented installation box is spliced ​​by multiple installation boxes, and its length is equal to the length of the filling crack segment.

[0060] The detachable sectional installation box is used for assisting assembly of each fracture section; the detachable sectional installation box is spliced by multiple installation boxes, and the length of the detachable sectional installation box is equal to the length of the filled fracture section; each installation box is fixedly connected through a mortise and tenon structure; the mortise and tenon structure comprises a tenon 13 and a mortise 12 matched with the tenon 13; the first installation box is not provided with the tenon 13, and the bottom is sealed; the last installation box is not provided with the mortise 12; the middle installation boxes are all provided with the mortise 12 and the tenon 13; and the installation box further comprises a main box body and a side plate, and the main box body and the side plate are fixedly connected through a threaded hole two 142.

[0061] The internal cavity size of the detachable sectional installation box is completely consistent with the external size of the filled fracture section, so that the fitting of each fracture section is good, and the opening of the fracture section is further prevented from being blocked during assembly of the fracture section.

[0062] Further, as shown in Figure 2 , the other end of the inlet cavity 15 is provided with a fluid inlet 17, and the other end of the outlet cavity 16 is provided with a fluid outlet 18 with an arc-shaped outlet corner. The outlet corner of the fluid outlet 18 is arranged in an arc shape, which can effectively prevent the loss of particles from being retained in the outlet cavity 16 during the filling fracture seepage-erosion experiment.

[0063] The injector 28 is communicated with the fluid inlet 17 through a pipeline, and injects fluid into the fracture space 6 through the inlet cavity 15. The injector 28 can also be installed on the injection pump 29, and the injection flow rate is adjusted through the injection pump 29 to provide a stable injection flow rate for the experiment.

[0064] During the experiment, the injection flow rate is controlled by the injection pump 29, the injector 28 injects fluid into the fracture space 6 through the inlet cavity 15, and finally the fluid is discharged through the fluid outlet 18.

[0065] Further, as shown in Figure 2 , 4 , the buffer tank 8 is a hollow structure with openings at both ends, and the cavity is filled with large-diameter coarse gravel 9, and the particle size is greater than the fracture opening. The connection between the buffer tank 8 and the inlet cavity 15 is provided with gauze.

[0066] Specifically, the buffer tank 8 is a groove-shaped structure with an internal cavity, and the two ends are respectively communicated with the fracture section and the inlet cavity 15. The cavity cross-sectional area of the buffer tank 8 can completely cover the interface of the inlet cavity 15 and the interface of the fracture space 6. The main function of the buffer tank 8 is to buffer the water flow in the inlet cavity, so that the water flow enters the fracture space 6 smoothly. The internal filling of the buffer cavity is large-diameter coarse gravel 9, and the particle size needs to be greater than the fracture opening to prevent the internal filling of the buffer cavity from entering the fracture space 6 and interfering with the experimental results. The connection between the buffer tank 8 and the inlet cavity 15 is provided with gauze to prevent the internal filling of the buffer tank 8 from entering the inlet cavity 15.

[0067] In this embodiment, the quality monitoring module is used to monitor the quality changes of the layered filling fracture model 19 during the seepage process. Specifically, the quality monitoring module includes two spiral tie rod pressure sensors 23 and a display control instrument 24. The two spiral tie rod pressure sensors 23 are respectively arranged on two adjustable brackets 22. One end of the two spiral tie rod pressure sensors 23 is connected to the layered filling fracture model 19, and the two spiral tie rod pressure sensors 23 are connected to the display control instrument 24.

[0068] In this embodiment, the pressure monitoring module is used to monitor the pressure of the injected fluid. Specifically, the pressure monitoring module includes a pressure sensor 25 and a reader 26. The pressure sensor 25 is a flow-through pressure sensor. One end of the pressure sensor 25 is connected to the syringe 28 through a pipeline, and the other end is connected to the inlet cavity 15 of the layered filling fracture model 19 through a pipeline. The reader 26 is connected to the pressure sensor 25 and to the computer 30.

[0069] In this embodiment, the image acquisition module is used to monitor the seepage process. Specifically, the image acquisition module includes a camera 27. The image acquisition module is set above the layered filling fracture model 19, and the axis of the camera 27 is always perpendicular to the surface of the filling fracture model.

[0070] The camera 27 is a high-resolution camera, which is arranged directly above the layered filling fracture model 19 , and the axis of the camera 27 is always perpendicular to the surface of the layered filling fracture model 19 .

[0071] It should be noted that the quality monitoring module, the pressure monitoring module and the image acquisition module are all connected to the computer 30 via lines to achieve real-time data acquisition.

[0072] In this embodiment, the adjustable bracket 22 includes a base 221, a vertical pole 222, and a support plate 223. The vertical pole 222 is designed with a scale, and the support plate 223 can move up and down on the vertical pole 222. The support plate 223 is locked to the vertical pole 222 by bolts to maintain the same height. Screw holes are provided at the edge of the support plate 223 to facilitate the installation of the spiral pull rod pressure sensor 23 in the quality monitoring module.

[0073] During installation, since a threaded hole 141 is provided at the upper end of the inlet cavity 15 at the end of the layered filling fracture model 19 and the upper end of the outlet cavity 16 at the other end of the layered filling fracture model 19, one end of the two spiral pull rod pressure sensors 23 can be respectively installed on the two ends of the layered filling fracture model 19. Before installing the quality monitoring module, the support plates 223 on both sides should be adjusted to the same scale height in advance, and then one end of the spiral pull rod pressure sensor 23 should be fixed to the support plate 223, and the other end should be fixed to the layered filling fracture model 19.

[0074] The present invention also provides a layered filling crack seepage-erosion experimental method, comprising the following steps:

[0075] S1, making a layered filling fracture model 19, and immersing the layered filling fracture model 19 in water and letting it stand for 24 hours, then placing it in a vacuum pump and letting it stand for 12 hours under negative pressure to allow the soil to reach a saturated state;

[0076] S2, install and adjust the quality monitoring module, connect one end of the spiral tie rod pressure sensor 23 to the support plate 223, and the other end to the layered filling fracture model 19, and connect the display control instrument 24 to the spiral tie rod pressure sensor 23 through a line and communicate with the computer 30;

[0077] S4, install and adjust the pressure monitoring module, connect the syringe 28, the pressure sensor 25 and the fluid inlet 17 through a pipeline, so that the fluid flows from the syringe 28 through the pressure sensor 25 and is injected into the layered filling fracture model 19, and the reader 26 is connected to the pressure sensor 25 through a line connection and communicated with the computer 30;

[0078] S5, install and adjust the image acquisition module, connect the camera 27 and the computer 30, turn on the plane light source 21, adjust the working distance between the camera 27 and the layered filling fracture model 19, and complete the imaging quality adjustment process after the image is clear;

[0079] S6, conduct a visualization experiment of filled fracture seepage-erosion at a fixed flow rate, turn on the quality monitoring system, and record the quality changes during the seepage process in real time; turn on the pressure monitoring system, and record the pressure at the inlet cavity 15 of the layered filling fracture model 19 in real time, turn on the camera 27, and observe the filled fracture seepage-erosion process in real time; after ensuring that all systems are working normally, turn on the injection pump 29, and the fluid flows out of the syringe 28, passes through the layered filling fracture model 19 and flows into the liquid collection bottle 31. After the experiment is completed, turn off the injection pump 29, turn off the camera 27 and the computer 30, and the experiment is completed.

[0080] This embodiment also provides a method for preparing a layered filling fracture model, comprising the following steps:

[0081] S1: Prepare an initial crack model, cast and demould with a transparent epoxy resin material to prepare an upper rough crack surface 1 and a lower rough crack surface 2, apply glue on the upper rough crack surface connecting edge 3 and the lower rough crack surface connecting edge 4, then place a rubber strip 5 in the middle of the connecting edge, fit the upper and lower parts together, so that the two crack surfaces are fixed and sealed, and a crack space 6 with a fixed opening is formed between the two crack surfaces, and then stand for 24 hours to cure;

[0082] S2: Preparation of filling fracture section, the initial fracture model prepared in S1 is uniformly cut into 3 sections to obtain fracture sections, and soil body one 61, soil body two 62 and soil body three 63 are filled into each fracture section according to the experimental requirements to obtain a first section filling fracture section 71, a second section filling fracture section 72 and a third section filling fracture section 73;

[0083] S3: The first section filling fracture section 71, the second section filling fracture section 72 and the third section filling fracture section 73 are reinforced and formed by a detachable segmented installation box. The adhesive tape is pasted at the lower part of the first section filling fracture section 71 to prevent the internal filling soil from flowing out, and the first section filling fracture section 71 is placed in the first section main box body 101, and the first section side plate 111 is fixed with the first section main box body 101 by screws;

[0084] S4: The tenon 13 of the second section main box body 102 is inserted into the mortise 12 of the first section main box body 101, and an appropriate amount of glue is applied to the surface of the second section filling fracture section 72 to adhere to the first section filling fracture section 71, and then the second section side plate 112 is fixed with the second section main box body 102 by screws;

[0085] S5: The third section main box body 103 is connected with the second section main box body 102 through the mortise and tenon structure, an appropriate amount of glue is applied to the surface of the third section filling fracture section 73 to adhere to the second section filling fracture section 72, and then the third section side plate 113 is fixed with the third section main box body 103 by screws;

[0086] S6: The fourth section main box body 104 is connected with the third section main box body 103 through the mortise and tenon structure, an appropriate amount of glue is applied to the surface of the buffer box 8 to adhere to the third section filling fracture section 73, and then the fourth section side plate 114 is fixed with the fourth section main box body 104 by screws;

[0087] S7: The weight block 32 is placed at the top of the assembled body for compaction, further ensuring the tight connection at the connecting section to prevent water leakage at the connecting section, and the installation box is detached after 24 hours of standing for glue curing;

[0088] S8: The inlet cavity 15 is pasted to the front end of the buffer box 8 by using glue, and the outlet cavity 16 is pasted to the rear end of the first section filling fracture section 71, and the layered filling fracture model 19 is prepared after 24 hours of standing for curing.

[0089] Further, the manufacturing process of the upper rough fracture surface 1 and the lower rough fracture surface 2 is as follows:

[0090] First, the square original rock is split to obtain the upper rough fracture surface 1 and the lower rough fracture surface 2, and the acrylic plate is fixed to the two sides of the rock fracture surface by using glue to form a connecting edge for subsequent glue coating to fix and seal the connection of the fracture surface;

[0091] The original fracture surface is replicated using a flexible epoxy resin material according to the method of the remolding technology to obtain an upper rough fracture surface 1 having an upper rough fracture surface connecting edge 3 and a lower rough fracture surface 2 having a lower rough fracture surface connecting edge 4;

[0092] Glue is applied on the connecting edges on both sides of the upper rough crack surface 1 and the lower rough crack surface 2, and a rubber strip 5 is placed between the connecting edge 3 of the upper rough crack surface and the connecting edge 4 of the lower rough crack surface to control the crack opening. The upper and lower surfaces are fitted together so that the upper rough crack surface 1 and the lower rough crack surface 2 are fixedly sealed and connected, and a crack space 6 is formed between the upper rough crack surface 1 and the lower rough crack surface 2 so that liquid leakage from the side will not occur.

[0093] The present invention adopts a transparent fracture model with the geometric morphology of natural rock fractures as the experimental object, and realizes the visual observation of the filled fracture seepage-erosion experiment through the quality monitoring module, the pressure monitoring module and the image acquisition module.

[0094] In other embodiments, the injection pump 29 can be replaced with a lifting frame and a Malvern flask to study the seepage-erosion behavior of filled fractures under constant water head conditions, and the spiral pull rod pressure sensor 23 can be replaced with a cantilever beam sensor.

[0095] In summary, the present invention adopts a transparent fracture model as an experimental object to ensure that the fracture geometry can reflect the geometric morphology of real rock fractures; compared with traditional seepage experiments, the present invention provides a layered filling fracture model that can reflect the layered characteristics of the soil, and sets the outlet cavity as an open outlet, and the lower surface as an arc surface to avoid the loss of particles trapped inside the outlet cavity 16 during the filling fracture seepage experiment, and uses the spiral pull rod pressure sensor 23 to monitor the seepage-erosion process of the filling fracture in real time, and further quantify the particle loss during the seepage-erosion process; traditional seepage experiments use CT and X-rays to observe the spatial distribution of fracture pores, which has a long scanning time, high equipment cost, and cannot realize real-time observation of the seepage erosion process. The transparent fracture used in the present invention can observe the seepage-erosion process in real time through the camera 27, and has the advantages of high acquisition frame rate, low equipment cost, and strong repeatability.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. A layered filling crack seepage-erosion visualization experimental device, characterized in that: include: A stand (20) is fixed horizontally on the experimental table; A planar light source (21) is horizontally fixed on the stand (20); Adjustable brackets (22), two adjustable brackets (22) are distributed on both sides of the experimental table; A layered filling fracture model (19) is arranged on an adjustable bracket (22) and is formed by splicing a plurality of filling fracture segments, wherein the plurality of filling fracture segments are spliced ​​and reinforced by a detachable segmented mounting box, wherein a buffer box (8) is provided at one end of the filling fracture segment in communication therewith, and an inlet cavity (15) is provided at the end of the buffer box (8) in communication therewith, and an outlet cavity (16) is provided at the other end of the filling fracture segment in communication therewith; A syringe (28), wherein the syringe (28) is connected to the inlet cavity (15) of the layered filling fracture model (19) through a pipeline, and a fluid is injected into the inlet cavity (15) of the layered filling fracture model (19) through the syringe (28); A liquid collecting bottle (31) is provided on a laboratory table and is placed below the outlet cavity (16) in the layered filling fracture model (19) for collecting fluid; The quality monitoring module is used to monitor the quality changes of the layered filling fracture model (19) during the seepage process; A pressure monitoring module, used to monitor the pressure of the injected fluid; The image acquisition module is used to monitor the seepage process of the layered filling fracture model (19).

2. The layered filling crack seepage-erosion visualization experimental device according to claim 1 is characterized in that: The multiple filled fracture sections are formed by filling soil in the multiple fracture sections. The multiple fracture sections are evenly cut from the initial fracture model. The initial fracture model is formed by the interlocking of an upper rough fracture surface (1) and a lower rough fracture surface (2). The upper rough fracture surface (1) and the lower rough fracture surface (2) are respectively provided with an upper rough fracture surface connecting edge (3) and a lower rough fracture surface connecting edge (4) on the opposite sides. The upper rough fracture surface connecting edge (3) and the lower rough fracture surface connecting edge (4) are fitted together by a rubber strip (5). A fracture space (6) with a fixed opening is formed between the upper rough fracture surface (1) and the lower rough fracture surface (2) for filling soil.

3. The layered filling crack seepage-erosion visualization experimental device according to claim 1 is characterized in that: The other end of the inlet cavity (15) is provided with a fluid inlet (17), and the other end of the outlet cavity (16) is provided with a fluid outlet (18) with an arc-shaped outlet corner. The buffer box (8) is a hollow structure with both ends open, and its cavity is filled with coarse gravel (9) with large particle size, and the particle size of the gravel is larger than the crack opening. Gauze is provided at the connection between the buffer box (8) and the inlet cavity (15).

4. The layered filling crack seepage-erosion visualization experimental device according to claim 1, characterized in that: The detachable segmented installation box is formed by splicing multiple segmented installation boxes, and the length is equal to the length of the crack filling section. The multiple segmented installation boxes are connected by a mortise and tenon structure, and the mortise and tenon structure includes a mortise groove (12) and a tenon (13) matched therewith. The installation box includes a main box body and side panels, and the main box body and the side panels are connected by screws through threaded holes (142).

5. The layered filling crack seepage-erosion visualization experimental device according to claim 1, characterized in that: The quality monitoring module includes two spiral tie rod pressure sensors (23) and a display control instrument (24), wherein the two spiral tie rod pressure sensors (23) are respectively arranged on two adjustable brackets (22), one end of the two spiral tie rod pressure sensors (23) is connected to the layered filling fracture model (19), and the two spiral tie rod pressure sensors (23) are connected to the display control instrument (24).

6. The layered filling crack seepage-erosion visualization experimental device according to claim 1, characterized in that: The pressure monitoring module includes a pressure sensor (25) and a reader (26). The pressure sensor (25) is a flow-through pressure sensor. One end of the pressure sensor (25) is connected to the syringe (28) through a pipeline, and the other end is connected to the fluid inlet (17) through a pipeline. The reader (26) is connected to the pressure sensor (25) and to the computer (30).

7. The layered filling crack seepage-erosion visualization experimental device according to claim 1, characterized in that: The adjustable bracket (22) comprises a base (221), a vertical rod (222), and a support plate (223) that can move up and down outside the vertical rod (222), the vertical rod (222) is provided with a scale, and a screw hole is provided at the edge of the support plate (223) for installing a screw rod pressure sensor (23) of a quality monitoring module.

8. The layered filling crack seepage-erosion visualization experimental device according to claim 6, characterized in that: The syringe (28) is mounted on a syringe pump (29), and the injection flow rate is adjusted by the syringe pump (29). The reader (26) and the display control instrument (24) are connected to a computer (30).

9. A method for visualizing seepage and erosion in layered filling fractures, characterized in that: The following steps are involved: A layered filling fracture model (19) is prepared, and the layered filling fracture model (19) is immersed in water and allowed to stand for several hours, and then placed in a vacuum pump and allowed to stand for several hours under negative pressure to allow the soil to reach a saturated state; After installing and adjusting each instrument, a filling fracture seepage-erosion visualization experiment was conducted at a fixed flow rate. The syringe pump (29) was turned on, and the fluid flowed out of the syringe (28), passed through the layered filling fracture model (19), and flowed into the liquid collection bottle (31). The quality monitoring module records the quality changes during the seepage process in real time. The pressure monitoring module records the pressure at the inlet cavity (15) of the layered filling fracture model (19) in real time. The image acquisition module observes the filling fracture seepage-erosion process in real time.

10. The layered filling crack seepage-erosion visualization experimental method according to claim 9, characterized in that: The preparation method of the layered filling fracture model (19) is as follows: A transparent epoxy resin material is used to cast and demould to prepare an upper rough crack surface (1) and a lower rough crack surface (2), glue is applied to the upper rough crack surface connection edge (3) and the lower rough crack surface connection edge (4), and a rubber strip (5) is placed between the two, and the upper and lower rough crack surfaces are fitted together to make the upper rough crack surface (1) and the lower rough crack surface (2) fixed and sealed. A crack space (6) is formed between the upper rough crack surface (1) and the lower rough crack surface (2), and the crack space (6) is formed between the upper rough crack surface (1) and the lower rough crack surface (2). The crack surface is left to stand for a period of time to solidify, thereby obtaining an initial crack model; The prepared initial fracture model is uniformly cut into multiple fracture segments, and the experimental soil is filled into the fracture space (6) of the fracture segment according to the experimental requirements to form a filled fracture segment; First, stick the tape on the lower part of the first section filling crack section (71), and place it inside the first section main box (101), and fix the first section side plate (111) to the first section main box (101) with screws; Then, the tenon (13) of the second main box (102) is inserted into the tenon groove (12) of the first main box (101), and an appropriate amount of glue is applied to the surface of the second crack filling section (72) to adhere to the first crack filling section (71), and then the second side panel (112) is fixed to the second main box (102) by screws; The second main box (102), the third main box (103) and the fourth main box (104) are sequentially connected, the second crack filling section (72), the third crack filling section (73) and the buffer box (8) are sequentially bonded, and the side panels are fixed to the corresponding main boxes; Place the weight block (32) on the top of the assembly to compact the multiple sections of the filling cracks, let it stand for a while, and remove the installation box after the glue solidifies; The inlet cavity (15) is glued to the front end of the buffer box (8) using glue, and the outlet cavity (16) is glued to the rear end of the first section of the crack filling section (71). After being left to stand for a period of time to solidify, the layered crack filling model (19) is prepared.

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