Visual experiment device and method for seepage-erosion of layered filling fracture

Abstract

The invention relates to the technical field of rock mass fissure medium seepage experiments, in particular to a layered filling fissure seepage-erosion visual experiment device which comprises a rack horizontally fixed to an experiment table; the plane light source is horizontally fixed on the rack, the adjustable brackets are distributed on two sides of the experiment table, and the layered filling crack models are arranged on the two adjustable brackets; the injector is arranged on the experiment table and is communicated with the fluid inlet through a pipeline; the liquid collecting bottle is arranged below the fluid outlet; the quality monitoring module, the pressure monitoring module and the image acquisition module are arranged on the experiment table. A layered filling fracture model is manufactured by filling a fracture model in sections, the layering characteristic of a soil body can be reflected, and real-time monitoring of filling fractures is achieved by connecting a high-precision spiral pull rod pressure sensor and constructing a quality monitoring system. And a pressure monitoring system and an image acquisition module are matched to realize visual observation of the filled fracture seepage-erosion experiment.

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 natural rock fissures being filled with unconsolidated loose materials under the action of water scouring, chemical erosion and gravity sedimentation. In addition, under the geological action of sedimentation, erosion and volcanic activity, the filling soil in the fissures will present the form of alternating stacking of different soil layers, with obvious stratification, and the physical and chemical properties of adjacent soil layers often show significant differences.

[0003] The migration law of fluid and solute in such layered filling fractures is very complicated, and under the action of seepage, the migration and loss of particles will occur in the filling fractures, further changing the seepage channel and permeability of the filling fractures. It is of great significance to carry out the seepage research of the filling fracture medium with soil layering characteristics in many geological engineering projects. In geological engineering, the development of filling fractures forms weak zones and interlayers, which constitute potential failure surfaces. The study of the seepage characteristics of filling fractures is of great significance for preventing geological disasters such as pipe bursts and landslides. In environmental science, compared with fracture media, filling fractures will hinder the migration of pollutants, which has a key influence on the study of the migration and diffusion process of pollutants.

[0004] The filling soil of the cracks is composed of coarse particles and fine particles, of which the coarse particles constitute the basic skeleton of the filling medium, and the fine particles are loose particles dispersed in the skeleton space. When the particle size of the fine particles is smaller than the pore space size formed by the coarse particle skeleton, and the seepage pressure is greater than the friction resistance between the particles, the fine particles can flow out of the pores of the coarse particle skeleton, causing erosion damage. For the filling cracks with soil stratification characteristics, the soil properties of different soil layers are different, and the seepage characteristics will be significantly different. The permeability of the soil layer with finer particles (such as clay layer) is relatively small, while the permeability of the soil layer with coarser particles (such as sand layer) is relatively large. This seepage characteristic will lead to uneven seepage paths, making the seepage characteristics of the filling cracks more complicated.

[0005] Traditional filled fracture seepage experiments use filters at the end of the sample to prevent the loss of filling materials, ignoring the seepage erosion of soil particles during the seepage process and the effect of particle loss on the seepage channel and permeability of the filled fractures. In particular, there are few studies on the seepage of filled fractures in layered soil. And due to the opaque nature of the rock mass, traditional experiments are limited to obtaining basic physical parameters of fractures such as roughness, permeability and relative permeability, making it difficult to achieve visual observation of the seepage characteristics during the seepage-erosion process of layered filled fractures. Related work needs to be carried out urgently. Summary of the invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a visualization experimental device and method for seepage-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-erosion process of layered filling fractures. In combination with a pressure monitoring module and an image acquisition module, visualization observation of the seepage-erosion process of filling fractures is realized.

[0007] According to one aspect of the present invention, a layered filling fracture seepage-erosion visualization experimental device is provided, comprising:

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

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

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

[0011] A layered filling fracture model is arranged on an adjustable bracket and is formed by splicing a plurality of filling fracture sections, wherein the plurality of filling fracture sections are spliced ​​and reinforced by a detachable segmented mounting box, a buffer box connected thereto is arranged at one end of the filling fracture section, an inlet cavity connected thereto is arranged at the end of the buffer box, and an outlet cavity connected thereto is arranged at the other end of the filling fracture section;

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

[0013] A liquid collecting bottle is arranged on the experimental table and is placed below the outlet cavity in the layered filling fracture model to collect 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 solution, the filled fracture section is formed by filling soil in multiple fracture sections, and the multiple fracture sections are formed by evenly cutting the initial fracture model. The initial fracture model is formed by the mosaic of an upper rough fracture surface and a lower rough fracture surface. The opposing surfaces of the upper rough fracture surface and the lower rough fracture surface are respectively provided with an upper rough fracture surface connecting edge and a lower rough fracture surface connecting edge. The upper rough fracture surface connecting edge and the lower rough fracture surface connecting edge are fitted together by a rubber strip, and a fracture space with a fixed opening is formed between the upper rough fracture surface and the lower rough fracture surface for filling soil.

[0018] As a further technical solution, a fluid inlet is provided at the other end of the inlet cavity, and a fluid outlet with an arc-shaped outlet corner is provided at the other end of the outlet cavity. The buffer box is a hollow structure with openings at both ends, and its cavity is filled with coarse gravel with large particle size, and the particle size thereof is larger than the crack opening. Gauze is provided at the connection between the buffer box and the inlet cavity.

[0019] As a further technical solution, the detachable segmented installation box is spliced ​​together by multiple segments of installation boxes, and the length is equal to the length of the crack filling segment. The multiple segments of installation boxes are connected by a mortise and tenon structure, and the mortise and tenon structure includes a mortise groove and a tenon matching therewith. The installation box includes a main box body and a side panel, and the main box body and the side panel are connected by screws through threaded holes.

[0020] As a further technical solution, the quality monitoring module includes two spiral tie rod pressure sensors and a display control instrument. The two spiral tie rod pressure sensors are respectively arranged on two adjustable brackets, one end of the two spiral tie rod pressure sensors is connected to the layered filling fracture model, and the two spiral tie rod pressure sensors are connected to the display control instrument.

[0021] As a further technical solution, the pressure monitoring module includes a pressure sensor and a reader. The pressure sensor is a flow-through pressure sensor. One end of the pressure sensor is connected to the syringe through a pipeline, and the other end is connected to the fluid inlet through a pipeline. The reader is connected to the pressure sensor and to a computer.

[0022] As a further technical solution, the adjustable bracket includes a base, a vertical pole, and a support plate that can move up and down on the outside of the vertical pole. The vertical pole is provided with a scale, and screw holes are provided at the edge of the support plate for installing the spiral pull rod pressure sensor of the quality monitoring module.

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

[0024] According to one aspect of the present invention, a layered filling fracture seepage-erosion visualization experimental method is provided, comprising the following steps:

[0025] A layered filling fracture model is made, and the layered filling fracture model is immersed in water and left to stand for several hours, and then placed in a vacuum pump and left 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-erosion was conducted at a fixed flow rate. The injection 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 is used to record the quality changes during the seepage process in real time. The pressure monitoring module is used to record the pressure at the inlet cavity of the layered filling fracture model in real time. The image acquisition module is used to observe 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 rough crack surface and the lower rough crack surface are prepared by casting and demoulding with a transparent epoxy resin material, glue is applied on the connecting edge of the upper rough crack surface and the connecting edge of the lower rough crack surface, and a rubber strip is placed between the two, and the upper and lower rough crack surfaces are fitted together to make the upper rough crack surface and the lower rough crack surface fixedly sealed and connected, and a crack space is formed between the upper rough crack surface and the lower rough crack surface, and the crack surface is left to stand for a period of time to solidify, thereby obtaining an initial crack model;

[0030] The prepared initial fracture model is uniformly cut into a plurality of fracture segments, and the experimental soil is filled into the fracture space of the fracture segment to form a filled fracture segment according to the experimental needs;

[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, and 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] The second section main box, the third section main box and the fourth section main box are connected in sequence, the second section filling crack section, the third section filling crack section and the buffer box are bonded in sequence, and the side panels are fixed to the corresponding main boxes;

[0034] Place the weight block on the top of the assembly to compact the multiple sections of the crack filling, let it stand for a while, and remove the installation box after the glue solidifies;

[0035] The inlet cavity is glued to the front end of the buffer box with glue, and the outlet cavity is glued to the rear end of the first section of the crack filling section. After being left to stand for a period of time to solidify, 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. The pressure monitoring system and image acquisition module were used to realize the visual observation of the filled crack seepage-erosion experiment.

[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 a 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 part 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 is 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 It is a schematic diagram of the layered filling fracture model of the present invention.

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

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

[0046] Figure 5It 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 filling crack section; 72, second section filling crack section; 73, third section filling crack section; 8, buffer box; 9, coarse gravel; 101, first section main box; 102, second section main box; 103, third section main box; 104, fourth section main box; 111, first section side plate; 112, second section side plate; 113, third section side plate; 114, The fourth section of the 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, spiral pull rod pressure sensor; 24, display control instrument; 25, pressure sensor; 26, reader; 27, camera; 28, syringe; 29, injection pump; 30, computer; 31, liquid collection bottle; 32, weight block. DETAILED DESCRIPTION

[0049] The terms "including" and "having" and any variations thereof in the specification 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 comprising 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 in the present invention, all other embodiments obtained by ordinary technicians in this field without 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 the structural composition mode, but must be based on the ability of ordinary technicians in this field to achieve. When the combination of technical solutions is contradictory or cannot be achieved, it should be considered that this combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0051] Existing filled fracture seepage experimental methods include core experiment technology, which fills the split fractured rock mass with filling materials and places it in a seepage device. After sealing, water is injected into the rock mass to simulate the seepage process of filling the 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] Most of the existing filled fracture seepage experiments 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 influence of particle loss on the seepage channel and permeability of the filled fracture. And due to the opaque characteristics of natural rock mass, most experiments cannot observe the seepage process of the filling medium and the evolution of the seepage channel in real time. Therefore, the present invention proposes a filled fracture seepage-erosion visualization experimental device and method, and makes a transparent layered filled fracture model with real geometric morphology. The quality of the filled fracture seepage process is monitored in real time by a spiral pull rod pressure sensor, and the pressure sensor is used to monitor the filling fracture inlet cavity pressure to achieve the purpose of real-time monitoring of the permeability evolution during the seepage process. Different constant flow rates are provided for the seepage by an injection pump, and combined with a high-resolution camera, the purpose of fine capture of the filled fracture seepage-erosion behavior is achieved.

[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, a layered filling crack model 19 arranged on a pair of adjustable brackets 22, and a syringe 28, a quality monitoring module, a pressure monitoring module and an image acquisition module are also arranged on the laboratory table.

[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 arranged on the stand 20 below the fracture outlet of the layered filling fracture model 19, and the liquid flowing out of the layered filling fracture model 19 is collected by the liquid collecting bottle 31. 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 during the seepage process, the pressure of the injected fluid and the seepage process of the layered filling fracture model 19.

[0055] In this embodiment, Figure 2 As shown, the layered filling fracture model 19 is formed by splicing a plurality of filling fracture sections, one end of the filling fracture section 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 other end of the filling fracture section 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 initial fracture model can be uniformly cut into multiple ends. Moreover, since the fracture opening is small, the initial fracture model is directly uniformly cut to form multiple fracture sections, which 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 grading 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 mosaic of an upper rough fracture surface 1 and a lower rough fracture surface 2, and 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, and 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, and 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 fitted and connected to make it fit better, a detachable segmented installation box is introduced in this embodiment. The detachable segmented installation box assists in the splicing and reinforcement of multiple sections of filled crack segments. The detachable segmented installation box is spliced ​​by multiple sections of installation boxes, and its length is equal to the length of the filled crack segment.

[0060] Among them, the detachable segmented installation box is used to assist in the assembly of each crack section; and the detachable segmented installation box is spliced ​​by multiple sections of installation boxes, and the length is equal to the length of the filling crack section, and each section of the installation box is fixedly connected by a mortise and tenon structure, and the mortise and tenon structure includes a tenon 13 and a tenon groove 12 matching therewith. The first section of the installation box is not provided with a tenon 13, and the bottom is sealed, the last section of the installation box is not provided with a tenon groove 12, and the middle installation box is provided with a tenon groove 12 and a tenon 13, and the installation box also includes a main box body and side panels, and the main box body and the side panels are fixedly connected by screws through threaded holes 142.

[0061] Since the internal cavity size of the detachable segmented installation box is completely consistent with the external size of the filled crack segment, it can ensure that each crack segment fits well, further avoiding blocking of the crack opening during the assembly process of the crack segment.

[0062] Further, such as Figure 2 As shown, a fluid inlet 17 is provided at the other end of the inlet cavity 15, and a fluid outlet 18 with an arc-shaped outlet corner is provided at the other end of the outlet cavity 16. The outlet corner of the fluid outlet 18 is set to be arc-shaped, which can effectively prevent the lost particles from being retained inside the outlet cavity 16 during the filling fracture seepage-erosion experiment.

[0063] The syringe 28 is connected to the fluid inlet 17 through a pipeline, and the fluid is injected into the crack space 6 through the inlet cavity 15. The syringe 28 can also be installed on the injection pump 29, and the injection flow rate is adjusted by the injection pump 29 to provide a stable injection flow rate for the experiment.

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

[0065] Further, such as Figure 2 , 4 As shown, the buffer box 8 is a hollow structure with openings at both ends, and its cavity is filled with coarse gravel 9 with large particle size, and the particle size is larger than the crack opening. Gauze is provided at the connection between the buffer box 8 and the inlet cavity 15.

[0066] Specifically, the buffer box 8 is a groove-shaped structure with an internal cavity, and its two ends are respectively connected to the crack section and the inlet cavity 15, and the cavity cross-sectional area of ​​the buffer box 8 can completely cover the interface of the inlet cavity 15 and the interface of the crack space 6. The main function of the buffer box 8 is to buffer the water flow in the inlet cavity so that the water flow enters the crack space 6 smoothly; the internal filler of the buffer cavity is large-diameter coarse gravel 9, and the particle size must be larger than the crack opening to prevent the internal filler of the buffer cavity from entering the crack space 6 and interfering with the experimental results; gauze is provided at the connection between the buffer box 8 and the inlet cavity 15 to prevent the internal filler of the buffer box 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 arranged 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 through 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 on the vertical pole 222 by bolts to maintain the same height. Screw holes are set 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 two side support plates 223 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 leaving it to stand for 24 hours, and then placing it in a vacuum pump and leaving it to 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 and fix one end of the spiral 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 rod pressure sensor 23 through the line, and communicate with the computer 30;

[0077] S4, installing and adjusting the pressure monitoring module, connecting 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, use transparent epoxy resin material to cast and demould 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 fixedly sealed and connected, and a crack space 6 with a fixed opening is formed between the two crack surfaces, and then stand for 24 hours to solidify;

[0082] S2: preparing the filled fracture sections, cutting the initial fracture model prepared in S1 into three sections uniformly to obtain fracture sections, and filling soil body 1 61, soil body 2 62 and soil body 3 63 into each fracture section according to the experimental requirements, to obtain the first filled fracture section 71, the second filled fracture section 72 and the third filled fracture section 73;

[0083] S3: The first section filling crack section 71, the second section filling crack section 72 and the third section filling crack section 73 are reinforced and formed by using a detachable segmented installation box. First, an adhesive tape is attached to the lower part of the first section filling crack section 71 to prevent the internal filling soil from being lost, and the first section filling crack section 71 is placed inside the first section main box 101. The first section side plate 111 is fixed to the first section main box 101 by screws;

[0084] S4: insert the tenon 13 of the second main box 102 into the tenon groove 12 of the first main box 101, apply a proper amount of glue on the surface of the second crack filling section 72, adhere it to the first crack filling section 71, and then fix the second side panel 112 to the second main box 102 with screws;

[0085] S5: Connect the third section main box 103 and the second section main box 102 through the mortise and tenon structure, apply a proper amount of glue on the surface of the third section filling crack section 73, adhere it to the second section filling crack section 72, and then fix the third section side panel 113 and the third section main box 103 with screws;

[0086] S6: Connect the fourth section main box 104 to the third section main box 103 through the mortise and tenon structure, apply a proper amount of glue on the surface of the buffer box 8, adhere it to the third section filling crack section 73, and then fix the fourth section side panel 114 to the fourth section main box 104 with screws;

[0087] S7: Place a weight block 32 on the top of the assembly to compact it, further ensure a tight connection at the connection section, and prevent water leakage at the connection. Leave it for 24 hours until the glue is cured and then remove the installation box.

[0088] S8: Use glue to stick the inlet cavity 15 to the front end of the buffer box 8, and stick the outlet cavity 16 to the rear end of the first section of the crack filling section 71. Let it stand for 24 hours to solidify, and the layered crack filling model 19 is completed.

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

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

[0091] The original fracture surface is replicated using a flexible epoxy resin material according to the method of mold remodeling technology, so as 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 fracture surface 1 and the lower rough fracture surface 2, and a rubber strip 5 is placed between the upper rough fracture surface connecting edge 3 and the lower rough fracture surface connecting edge 4 to control the fracture opening. The upper and lower surfaces are fitted together so that the upper rough fracture surface 1 and the lower rough fracture surface 2 are fixedly sealed and connected, and a fracture space 6 is formed between the upper rough fracture surface 1 and the lower rough fracture surface 2 so that liquid leakage will not occur from the side.

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

[0094] In other embodiments, the injection pump 29 can be replaced with a lifting frame and a Martens 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 the traditional seepage experiment, the present invention provides a layered filling fracture model, which can reflect the layered characteristics of the soil, and sets the outlet cavity as an open outlet, and the lower surface is set as an arc surface to avoid the lost particles from being retained inside the outlet cavity 16 during the filling fracture seepage experiment, and the seepage-erosion process of the filling fracture is monitored in real time by the spiral pull rod pressure sensor 23, and the particle loss in the seepage-erosion process is further quantified; the traditional seepage experiment uses CT and X-rays to observe the spatial distribution of fracture pores, which has a long scanning time and 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 fracture 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 and is connected thereto, wherein an inlet cavity (15) is provided at the end of the buffer box (8) and is connected thereto, and an outlet cavity (16) is provided at the other end of the filling fracture segment; 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 arranged on a laboratory table and is placed below an outlet cavity (16) in the layered filling fracture model (19) for collecting fluid; A 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; An image acquisition module is used to monitor the seepage process of the layered filling fracture model (19).

2. The layered filling fracture 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 formed by uniformly cutting the initial fracture model. The initial fracture model is formed by the mosaic 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 fracture seepage-erosion visualization experimental device according to claim 1, 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 openings at both ends, and its cavity is filled with coarse gravel (9) with a 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 fracture seepage-erosion visualization experimental device according to claim 1, characterized in that: The detachable segmented installation box is formed by splicing multiple segment installation boxes, and the length is equal to the length of the crack filling segment. The multiple segment 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 a side panel, and the main box body and the side panel are connected by screws through a second threaded hole (142).

5. The layered filling fracture seepage-erosion visualization experimental device according to claim 1, characterized in that: The quality monitoring module comprises 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).

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

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

8. The layered filling fracture seepage-erosion visualization experimental device according to claim 6, characterized in that: The syringe (28) is installed on the 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 the computer (30).

9. A layered filling fracture seepage-erosion visualization experimental method, 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 is conducted at a fixed flow rate. The injection pump (29) is turned on, 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); The quality monitoring module is used to record the quality changes during the seepage process in real time. The pressure monitoring module is used to record the pressure at the inlet cavity (15) of the layered filling fracture model (19) in real time. The image acquisition module is used to observe the filling fracture seepage-erosion process in real time.

10. The layered filling fracture 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: An upper rough crack surface (1) and a lower rough crack surface (2) are prepared by casting and demoulding with a transparent epoxy resin material, 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 (1) and the lower rough crack surface (2) 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), and the cracks are 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 a plurality of 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, an adhesive tape is attached to the lower part of the first crack filling section (71), and the first crack filling section (71) is placed inside the first main box (101), and the first side panel (111) is fixed to the first main box (101) by screws; Then, the tenon (13) of the second main box body (102) is inserted into the tenon groove (12) of the first main box body (101), and a suitable 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 body (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 a weight block (32) on the top of the assembly to compact the multiple sections of the filling cracks, leave it for a while, and remove the installation box after the glue is cured; The inlet cavity (15) is glued to the front end of the buffer box (8), and the outlet cavity (16) is glued to the rear end of the first fissure filling section (71). The mixture is left to stand for a period of time to solidify, and the layered fissure filling model (19) is prepared.

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