An experimental system and method for simulating slurry displacement and deposition in dynamic water fractures

Abstract

The present application relates to the technical field of coal mine grouting simulation, and discloses an experimental system and method for simulating slurry displacement and deposition in moving water fractures, comprising: a structure layer, which is made of light-cured 3D printing and corresponds to point cloud data obtained by three-dimensional laser scanning of a rock fracture sample. Compared with the prior art, the present application constructs a simulated fracture with a roughness close to that of an actual fracture wall, ensures the accuracy of the simulation results, eliminates the interference of pulse flow on the deposition process, and guarantees the reliability and repeatability of the experimental data; the present application realizes the synchronous acquisition of multiple physical signals such as pressure, flow rate, images, and sediment morphology, can intuitively and quantitatively evaluate the deposition effect, and guide the dynamic optimization of process parameters by the operator, thereby significantly improving the intelligent level of the experiment.

Description

Technical Field

[0001] This invention relates to the field of coal mine grouting simulation technology, and in particular to an experimental system and method for simulating grout displacement and deposition in dynamic water fractures. Background Technology

[0002] With the increasing depth of coal mining and its expansion into areas with complex geological structures, mines face increasingly severe threats of water inrush and seepage. Especially when roadways or working faces expose or approach water-rich faults, collapse columns, aquifers, or surface water bodies, high-pressure flowing water becomes a direct cause of mine water hazards. To effectively control mine water hazards and protect the lives of personnel and national property, grouting reinforcement and curtain interception technologies are widely used. This technology involves injecting materials such as cement, clay, and chemical grout into rock fissures or loose, fractured zones to solidify and fill them, forming an artificial seepage-proof curtain, thereby cutting off water-conducting channels and achieving safe pressurized mining or aquifer dewatering.

[0003] However, grouting under dynamic water conditions presents far greater technical challenges and safety risks than grouting under static or anhydrous conditions. From a macroscopic perspective, the migration of grouting materials (especially cement-based grouts) within fractures is driven not only by grouting pressure but also by overcoming complex mechanical forces such as water shearing, scouring, dilution, and entrainment. Microscopically, the grout and water flow undergo intense physicochemical interactions within the fracture network, manifesting as a dynamic conflict between the grout's particle settling, flocculation, hydration hardening, and the turbulent diffusion of the water flow. The direct consequence of this conflict is that a large amount of expensive grouting material is carried away by the water flow, prematurely lost before reaching the target area. This not only results in material loss but also incomplete grouting sealing, creating potential engineering hazards and even leading to the complete failure of the grouting project. For example, in open-pit mine curtain interception projects, if the slurry cannot be effectively deposited in the gravel layer fissures of the riverbed, the curtain will form a "skylight," and surface water will still bypass the curtain and flow into the mine. When tunneling underground through faults, if the slurry cannot form an effective regional seal, it is very likely to induce a water inrush and flooding accident.

[0004] Therefore, a deep understanding of the displacement and deposition mechanisms of grout in dynamic water fractures, and the accurate assessment and prediction of deposition effects, are of crucial theoretical and engineering value for guiding on-site grouting engineering design, optimizing construction parameters, and improving the reliability and economy of grouting water control projects. While existing physical simulation experiments can reproduce fractures and conduct dynamic water displacement and deposition experiments to a certain extent, they suffer from the following technical limitations: 1. The crack model does not have the roughness of an actual crack, and the crack is difficult to adjust to a preset width, resulting in unreliable experimental results.

[0005] 2. Grouting simulation typically involves injecting water into the fracture model using a liquid pump. However, the liquid pump inevitably generates pulse injections, resulting in pulsed flow during the water injection process. This can interfere with the deposition of dynamic water, leading to inaccurate experimental results.

[0006] 3. Although parameters such as dynamic water pressure and flow rate can be monitored during the experiment, the evaluation and analysis of the displacement and deposition of dynamic water in the fracture is generally carried out after the experiment, which is lagging and cannot evaluate the displacement and deposition results of dynamic water in the fracture in real time and dynamically.

[0007] 4. After the experiment, although the displacement and deposition mechanisms of dynamic water in the fracture can be evaluated through various parameters, they cannot be directly applied to engineering design guidance.

[0008] In view of this, how to partially or completely overcome the above-mentioned technical defects is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0009] The purpose of this invention is to provide an experimental system and method for simulating slurry displacement and deposition in dynamic water fractures, so as to solve the problems existing in the prior art.

[0010] To achieve the above objectives, the present invention provides an experimental system for simulating slurry displacement and deposition in dynamic water fractures, comprising: The structural layer is formed by three-dimensional laser scanning of rock fracture samples to obtain point cloud data. The structural layer is made by photopolymerization 3D printing and corresponds to the point cloud data. The structural layer has an upper structural layer and a lower structural layer that are separated from each other. The upper structural layer and the lower structural layer are columnar structures with the same cross-sectional shape. The upper structural layer is bonded to the upper cover plate and the lower structural layer is bonded to the lower cover plate. The upper sealing box is a cylindrical structure with a lower opening. The upper cover plate and the upper structural layer are arranged inside the upper sealing box, with the upper cover plate close to the top surface of the upper sealing box and the upper structural layer close to the lower opening of the upper sealing box. The lower sealing box is a cylindrical structure with an upper opening. The lower cover plate and the lower structural layer are arranged inside the lower sealing box, and the lower cover plate is in contact with the bottom surface of the lower sealing box, while the lower structural layer is close to the upper opening of the lower sealing box. The lower opening of the upper sealing box and the upper opening of the lower sealing box can be connected vertically. When the upper sealing box and the lower sealing box are connected, a sealing ring is set at the connection point. A simulated crack is defined between the upper structural layer and the lower structural layer. The sealing ring is provided with an inlet and an outlet. The inlet and outlet are respectively arranged close to the two ends of the simulated crack.

[0011] Furthermore, it also includes: An adjustment mechanism is installed inside the upper sealing box and connected to the upper cover plate. There is a moving gap between the upper cover plate and the top surface of the upper sealing box. The adjustment mechanism is used to drive the upper structural layer to move up and down and adjust the width of the simulated crack.

[0012] Furthermore, the adjustment mechanism includes: An adjusting support is provided, wherein an installation cavity is defined within the housing of the sealing box, the adjusting support is arranged within the installation cavity, and the installation cavity communicates with the upper sealing box, forming a through groove at the communication point; A lead screw is rotatably mounted on the adjusting support. A connecting block is provided on the lead screw. The outer side of the connecting block is in contact with the inner surface of the adjusting support to form a limit. The inner side extends from the through groove into the upper sealing box and is connected to the upper cover plate. The adjustment motor is connected to the lead screw drive to drive the lead screw to rotate, thereby moving the connecting block, the upper cover plate, and the upper structural layer up and down.

[0013] Furthermore, it also includes a water tank, a variable frequency drive water pump, a high-precision turbine flow meter, a manual shut-off valve, and an electric regulating valve connected in sequence. The electric regulating valve is connected to the water inlet, and the water tank is connected to the water outlet. Pressure sensors are installed at the water inlet and the water outlet.

[0014] Furthermore, it also includes: A diaphragm-type pressure vessel has a gas chamber and a liquid chamber, which are separated by an elastic diaphragm. A high-pressure nitrogen cylinder is connected to a gas chamber, and a pressure reducing valve and a pressure gauge are arranged at the outlet of the high-pressure nitrogen cylinder. A slurry storage tank is connected to a liquid chamber via a screw pump, and the liquid chamber is connected to a simulated fracture via a grouting pipe. Multiple fracture pressure sensors are arranged on the surface of the upper and / or lower structural layers to collect fracture pressure.

[0015] Furthermore, it also includes: The base, wherein the lower sealing box is disposed on the base; A mounting bracket is arranged above the base, and an industrial camera is mounted on the mounting bracket. The mounting frame has a slide rail arranged along the length of the simulated fracture. A laser displacement sensor is slidably mounted on the slide rail. The upper sealing box, lower sealing box, upper cover plate, and lower cover plate are all made of transparent material. The industrial camera is used to acquire images of slurry displacement and deposition in the simulated fracture. The laser displacement sensor is used to perform three-dimensional morphological scanning and measurement of the sediment. An industrial control computer is electrically connected to a data acquisition box, which integrates a data acquisition card and a signal conditioner. The control terminals of the variable frequency drive water pump, electric regulating valve, and screw pump are respectively connected to the digital I / O and analog output ports of the data acquisition box. The signal output terminals of the pressure sensor, crevice pressure sensor, and high-precision turbine flow meter, as well as the data output terminals of the industrial camera and laser displacement sensor, are all processed by the signal conditioner and then connected to the data acquisition card for synchronous acquisition and processing by the industrial control computer.

[0016] This invention also provides an experimental method for simulating slurry displacement and deposition in dynamic water fractures, using an experimental system that simulates slurry displacement and deposition in dynamic water fractures, comprising the following steps: S1: Three-dimensional laser scanning is used to obtain point cloud data of rock fracture samples. The structural layer is made by photopolymerization 3D printing. The structural layer corresponds to the point cloud data. The upper structural layer is bonded to the upper cover plate and the lower structural layer is bonded to the lower cover plate. The upper and lower sealing boxes are connected vertically. A sealing ring is set at the connection. The water tank is connected to the water outlet, the electric regulating valve is connected to the water inlet, and the grouting pipe is connected to the simulated fracture. Sensor mounting holes are reserved during the 3D printing of the structural layer. Fracture pressure sensors are arranged in the sensor mounting holes. S2: The upper structural layer is moved up and down by adjusting the mechanism and the width of the simulated crack is adjusted until the preset width is reached; S3: Fill the water tank with water, start the variable frequency drive water pump, manually adjust the opening of the electric regulating valve, and the industrial control computer's monitoring interface displays the real-time dynamic water pressure difference ΔP. Observe the real-time dynamic water pressure difference ΔP, and stabilize ΔP at the preset target pressure difference value ΔP by adjusting the electric regulating valve. set At this point, the reading of the turbine flow meter is the stable flow rate; S4: Start the screw pump to deliver slurry into the buffer tank at a constant speed. Simultaneously, set and maintain a constant back pressure in the gas chamber of the buffer tank through a high-pressure nitrogen cylinder and a pressure reducing valve, allowing the slurry to be injected into the simulated fracture without pulses, driven by this back pressure. At the start of injection, the industrial control computer synchronously starts the pressure sensor, fracture pressure sensor, industrial camera, and laser displacement sensor. The industrial control computer calculates the collected three-dimensional deposition volume V according to the preset deposition comprehensive index formula. d(t) A preliminary estimate is made, and the sedimentary composite index DCI(t) is calculated and displayed in real time. The sedimentary composite index is defined as: ; Where a and b are preset positive weighting coefficients, V d(t) σ represents the cumulative three-dimensional deposition volume at the current moment. d(t) D represents the standard deviation of the deposition thickness along the simulated fracture length at the current moment. avg(t)The average deposition thickness at the current moment; the deposition index is used to characterize the morphological development efficiency and spatial distribution uniformity during the grout injection process online, and the higher the value, the better the deposition effect; the operator observes the real-time DCI(t) value on the monitoring interface, and when DCI(t) reaches the predetermined peak or enters the plateau period, the corresponding dynamic water pressure difference ΔP and grouting pressure P are recorded. i , as the optimal combination of process parameters; S5: After the experiment stops, with the water flow completely still and no slurry injected, the final morphology of the sediment is recorded using an industrial camera; then, the laser displacement sensor is moved along the slide rail, moving at a set step size along the length of the simulated fracture. At each stop position, the cross-sectional profile height of the simulated fracture is measured by the laser displacement sensor, and the data is saved; after the operation is completed, a three-dimensional model of the sediment is reconstructed in the computer based on a set of cross-sectional data obtained from the scan. S6: Based on the three-dimensional model of the sediments obtained in step S5, calculate the final total sediment volume V. d Average deposition thickness D avg σ, standard deviation of deposition thickness d and the volume ratio R of the water flow channel v Substituting the weighting coefficient c, a final sedimentation composite index (DCI) is calculated. f ; ; Then, by analyzing multiple sets of different ΔP i , P i Measured values ​​of DCI under experimental conditions fi Regression analysis and data mining are performed to fit the final DCI. f With dynamic water pressure difference ΔP, grouting pressure P i The quantitative relationship between them is used to construct a method for predicting the value of any given ΔP and P. i A three-dimensional prediction model for slurry deposition effects under certain conditions: DCI fpred = f(ΔP, P i ).

[0017] Furthermore, in step S4, the acquired three-dimensional deposition volume V is... d(t) The method for making a preliminary estimate is as follows: The industrial control computer extracts the pixel area S(t) of the deposited region from the background using an image segmentation algorithm based on the grayscale image captured by the industrial camera at time t, and combines this with the reference value h of the fracture aperture. ref Using formula V d(t) ≈ k×S(t)× h ref An estimate is made, where k is a correction factor related to image resolution and camera calibration.

[0018] Furthermore, in step S6, DCI fpred It is obtained by fitting the training dataset using the multiple linear regression analysis method, and its model form is as follows: DCI fpred = k1 × ΔP + k2 × P i + k0; Where k1, k2, and k0 are empirical coefficients determined through regression analysis.

[0019] Furthermore, the values ​​of a, b, and c are determined using the analytic hierarchy process (AHP) based on the total sediment volume V. d , deposition uniformity and the smoothness of water flow channels R v The relative importance of these three indicators in engineering applications is determined.

[0020] The present invention discloses the following technical effects: (1) The present invention uses three-dimensional laser scanning to obtain point cloud data of rock fracture samples, and then uses photopolymerization 3D printing to make structural layers, which correspond to the point cloud data. Compared with the prior art, the present invention constructs a simulated fracture with a high degree of roughness close to the actual fracture wall, ensuring the accuracy of the simulation experiment results.

[0021] (2) A stable and precisely controllable dynamic water flow field is achieved by using a variable frequency water pump in conjunction with an electric regulating valve; by utilizing the gas-liquid isolation structure of the screw pump and the nitrogen buffer tank, constant pressure and pulse-free injection of the slurry are achieved, eliminating the interference of pulse flow on the deposition process and ensuring the reliability and repeatability of experimental data.

[0022] (3) It realizes the synchronous acquisition of multiple physical signals such as pressure, flow rate, image, and sediment morphology, and can capture the dynamic information of the entire process of slurry displacement and deposition completely and accurately, providing a high-quality data foundation for in-depth analysis.

[0023] (4) The concept of “Deposition Comprehensive Index (DCI)” was innovatively proposed. Through online real-time calculation, the deposition effect can be evaluated intuitively and quantitatively, and operators can be guided to dynamically optimize process parameters, which significantly improves the level of intelligence of the experiment.

[0024] (5) By conducting in-depth analysis of the experimental data, a final deposition effect (DCI) was constructed. fpred The Quantitative Prediction Model (DCI) between the key engineering parameters (hydrodynamic pressure difference, grouting pressure) and the engineering key parameters (hydrodynamic pressure difference, grouting pressure) fpred = f(ΔP, P i This has enabled a leap from "experimental data" to "engineering design guidance," providing strong and forward-looking decision support for on-site grouting construction. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 for Figure 1 Rear view; Figure 3 This is a schematic diagram of the internal structure of the lower sealing box; Figure 4 This is a schematic diagram of the assembly of the structural layers; The components are as follows: 1. Upper structural layer; 2. Lower structural layer; 3. Upper cover plate; 4. Lower cover plate; 5. Upper sealing box; 6. Lower sealing box; 7. Sealing ring; 8. Inlet; 9. Outlet; 10. Movement clearance; 11. Adjusting support; 12. Lead screw; 13. Connecting block; 14. Adjusting motor; 15. Water tank; 16. Variable frequency drive water pump; 17. High-precision turbine flow meter; 18. Manual shut-off valve; 19. Electric regulating valve; 20. Diaphragm pressure stabilizing tank; 21. High-pressure nitrogen cylinder; 22. Slurry storage tank; 23. Crack pressure sensor; 24. Base; 25. Mounting bracket; 26. Slide rail; 27. Industrial camera; 28. Laser displacement sensor; 29. ​​Industrial computer; 30. Data acquisition box; 31. Screw pump. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Those skilled in the art will understand that the term "comprising" as used in this application means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements present. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figures 1 to 4 As shown, this embodiment of the invention provides an experimental system for simulating slurry displacement and deposition in dynamic water fractures, comprising: The structural layer is made by three-dimensional laser scanning of rock fracture samples to obtain point cloud data. The structural layer is made by photopolymerization 3D printing and corresponds to the point cloud data. The structural layer has an upper structural layer 1 and a lower structural layer 2 that are separated from each other. The upper structural layer 1 and the lower structural layer 2 are columnar structures with the same cross-sectional shape. The upper structural layer 1 is bonded to the upper cover plate 3 and the lower structural layer 2 is bonded to the lower cover plate 4. The upper sealing box 5 is a cylindrical structure with a lower opening. The upper cover plate 3 and the upper structural layer 1 are arranged inside the upper sealing box 5, with the upper cover plate 3 close to the top surface of the upper sealing box 5 and the upper structural layer 1 close to the lower opening of the upper sealing box 5. The lower sealing box 6 is a cylindrical structure with an upper opening. The lower cover plate 4 and the lower structural layer 2 are arranged inside the lower sealing box 6, with the lower cover plate 4 in contact with the bottom surface of the lower sealing box 6 and the lower structural layer 2 close to the upper opening of the lower sealing box 6. The lower opening of the upper sealing box 5 and the upper opening of the lower sealing box 6 can be connected in the vertical direction. When the upper sealing box 5 and the lower sealing box 6 are connected, a sealing ring 7 is set at the connection point. A simulated crack is defined between the upper structural layer 1 and the lower structural layer 2. An inlet 8 and an outlet 9 are opened on the sealing ring 7. The inlet 8 and the outlet 9 are respectively arranged close to the two ends of the simulated crack.

[0031] In this embodiment, it also includes: An adjustment mechanism is installed inside the upper sealing box 5 and connected to the upper cover plate 3. There is a moving gap 10 between the upper cover plate 3 and the top surface of the upper sealing box 5. The adjustment mechanism is used to drive the upper structural layer 1 to move up and down and adjust the width of the simulated crack.

[0032] In this embodiment, the adjustment mechanism includes: Adjustable support 11 defines an installation cavity within the housing of the sealing box. The adjustable support 11 is arranged within the installation cavity, which is connected to the upper sealing box 5, forming a through groove at the connection point. The lead screw 12 is rotatably mounted on the adjusting support 11. A connecting block 13 is provided on the lead screw 12. The outer side of the connecting block 13 is in contact with the inner surface of the adjusting support 11 to form a limit. The inner side extends from the through groove into the upper sealing box 5 and is connected to the upper cover plate 3. Adjustment motor 14 is connected to lead screw 12 for driving lead screw 12 to rotate, so that connecting block 13, upper cover plate 3 and upper structural layer 1 move up and down.

[0033] In this embodiment, the system also includes a water tank 15, a variable frequency drive water pump 16, a high-precision turbine flow meter 17, a manual shut-off valve 18, and an electric regulating valve 19, all connected in sequence. The electric regulating valve 19 is connected to the inlet 8, and the water tank 15 is connected to the outlet 9. Pressure sensors are installed at both the inlet 8 and the outlet 9. Specifically, the water tank 15 has a volume of 50L and is made of PVC material. The variable frequency drive water pump 16 has a power of 1.5KW and a maximum flow rate of 5m³ / h. 3 / h, the manual shut-off valve 18 is a DN25 butterfly valve, and the high-precision turbine flow meter 17 is a DN25 turbine flow meter.

[0034] In this embodiment, it also includes: The diaphragm-type pressure vessel 20 has a gas chamber and a liquid chamber, which are separated by an elastic diaphragm. High-pressure nitrogen cylinder 21 is connected to the gas chamber, and a pressure reducing valve and a pressure gauge are arranged at the outlet end of high-pressure nitrogen cylinder 21. The slurry storage tank 22 is connected to the liquid chamber via a screw pump 31, and the liquid chamber is connected to the simulated fracture via a grouting pipe. Multiple fracture pressure sensors 23 are arranged on the surface of the upper structural layer 1 and / or the lower structural layer 2 to collect fracture pressure.

[0035] In this embodiment, the elastic diaphragm is made of PTFE material. The specific pressure stabilization principle of the diaphragm-type pressure stabilizing tank 20 is existing technology and will not be described in detail here. The slurry storage tank 22 has a volume of 10L, and the pressure range of the high-pressure nitrogen cylinder 21 is 0-1MPa.

[0036] In this embodiment, it also includes: The lower sealing box 6 is mounted on the base 24; Mounting bracket 25 is arranged above base 24, and industrial camera 27 is mounted on mounting bracket 25; The slide rail 26 and the mounting bracket 25 are arranged along the length of the simulated fracture. A laser displacement sensor 28 is slidably mounted on the slide rail 26. The upper sealing box 5, the lower sealing box 6, the upper cover plate 3 and the lower cover plate 4 are all made of transparent material. The industrial camera 27 is used to collect images of slurry displacement and deposition in the simulated fracture. The laser displacement sensor 28 is used to perform three-dimensional morphological scanning and measurement of the sediment. The industrial control computer 29 is electrically connected to the data acquisition box 30. The data acquisition box 30 integrates a data acquisition card and a signal conditioner. The control terminals of the variable frequency drive water pump 16, electric regulating valve 19, and screw pump 31 are respectively connected to the digital I / O and analog output ports of the data acquisition box 30. The signal output terminals of the pressure sensor, the fissure pressure sensor 23, and the high-precision turbine flow meter 17, as well as the data output terminals of the industrial camera 27 and the laser displacement sensor 28, are all processed by the signal conditioner and then connected to the data acquisition card, where the industrial control computer 29 performs synchronous acquisition and processing.

[0037] In this embodiment, the industrial computer 29 is an IPC-610L industrial computer, which has a PCIe-1710 data acquisition card installed inside. This data acquisition card has 16 channels of 16-bit differential analog input, 4 channels of D / A output, and multiple digital I / O channels.

[0038] This invention also provides an experimental method for simulating slurry displacement and deposition in dynamic water fractures, using an experimental system that simulates slurry displacement and deposition in dynamic water fractures, comprising the following steps: S1: Three-dimensional laser scanning is performed on rock fracture samples to obtain point cloud data. After data processing and smoothing using Geomagic Studio software, the data is converted into a three-dimensional CAD model. Then, the structural layer is fabricated by photopolymerization 3D printing. The printing material is a transparent photosensitive resin material with high mechanical strength and chemical stability. A high-fidelity structural layer is printed at a 1:1 scale. The upper structural layer 1 is bonded to the upper cover plate 3, and the lower structural layer 2 is bonded to the lower cover plate 4. The upper cover plate 3 and the lower cover plate 4 can be made of acrylic sheets, and the bonding material is high-strength epoxy resin. The upper cover plate 3 is bolted to the connecting block 13, and the lower cover plate 4 is directly connected to the bottom surface of the lower sealing box 6. The upper sealing box 5 and the lower sealing box 6 are connected vertically, and a sealing ring 7 is set at the connection. The water tank 15 is connected to the water outlet 9, the electric regulating valve 19 is connected to the water inlet 8, and the grouting pipe is connected to the simulated fracture. Sensor mounting holes are reserved during the 3D printing of the structural layer, and fracture pressure sensors 23 are arranged in the sensor mounting holes.

[0039] S2: The upper structural layer 1 is moved up and down by the adjustment mechanism to adjust the width of the simulated crack until the preset width is reached. It should be noted that the height of the upper structural layer 1 is greater than the height of the lower structural layer 2, and the bottom of the upper structural layer 1 extends downwards from the upper sealed box 5. Therefore, the simulated crack is actually located primarily within the lower sealed box 6. The preset width of the simulated crack is 1.5mm-2.5mm. The simulated crack is a non-uniform, slightly narrower wedge-shaped crack to simulate the water flow constriction effect in a real crack. During the adjustment of the simulated crack width, a feeler gauge can be used to verify the opening at multiple points to ensure that the local opening is within the range of 2.0±0.05mm and the overall shape meets expectations.

[0040] S3: Fill water tank 15 with water, start the variable frequency drive water pump 16, set the frequency to 40Hz, manually adjust the opening of electric regulating valve 19 to 30%, and monitor the water pressure in real time at the pressure sensors at inlet 8 and outlet 9. The real-time dynamic water pressure difference ΔP (the difference between the pressure measured by the two pressure sensors) is displayed on the monitoring interface of industrial control computer 29. Observe the real-time dynamic water pressure difference ΔP, and stabilize ΔP at the preset target pressure difference value ΔP by adjusting electric regulating valve 19. set In this embodiment, the target differential pressure is 5 kPa, at which point the turbine flow meter reading (1.5 m) is... 3 The steady flow rate ( / h) represents the dynamic water conditions for this experiment.

[0041] S4: Start the screw pump 31 and set its rotation speed to 200 r / min to deliver slurry into the buffer tank at a constant speed. In this embodiment, the slurry is an anti-dispersion slurry with a water-cement ratio of 0.5. Simultaneously, a constant back pressure is set and maintained in the gas chamber of the buffer tank through the high-pressure nitrogen cylinder 21 and the pressure reducing valve. In this embodiment, the back pressure is 0.3 MPa, which is the grouting pressure P. i The slurry is injected into the simulated fracture without pulses, driven by the back pressure. At the start of injection, the industrial control computer 29 simultaneously activates the pressure sensor, fracture pressure sensor 23, industrial camera 27, and laser displacement sensor 28. The industrial control computer 29 calculates the collected three-dimensional deposition volume V according to the preset deposition comprehensive index formula. d(t) A preliminary estimate is made, and the sedimentary composite index DCI(t) is calculated and displayed in real time. The sedimentary composite index is defined as: ; Where a and b are preset positive weighting coefficients, V d(t) σ represents the cumulative three-dimensional deposition volume at the current moment. d(t) D represents the standard deviation of the deposition thickness along the simulated fracture length at the current moment. avg(t)The average deposition thickness at the current moment; the deposition index is used to characterize the morphological development efficiency and spatial distribution uniformity during the slurry injection process online, with a higher value indicating better deposition effect; the weighting coefficients a and b are determined according to the specific application scenario of this invention. In this experiment focusing on "water plugging," the slurry plugging volume V is given priority consideration. d To ensure the uniformity of sedimentation, an analytic hierarchy process (AHP) was used to select a combination of a=0.6 and b=0.4, assigning a value to the total volume V. d The highest weight is 0.6 because it directly relates to the integrity of the curtain; the second highest weight is given to deposition uniformity at 0.4 because it affects the overall strength and water pressure resistance of the sealing body. Operators observed on the monitoring interface that the DCI(t) curve reached its peak 60 seconds after grouting began, and then entered a slowly rising plateau phase. Operators observed the real-time updated DCI(t) values ​​on the monitoring interface, and when DCI(t) reached the predetermined peak or entered the plateau phase, they recorded the corresponding hydrodynamic pressure difference ΔP and grouting pressure P. i This represents the optimal combination of process parameters under the experimental conditions.

[0042] S5: After the experiment stops, with the water flow completely still and no slurry injected, the final morphology of the sediment is recorded by the industrial camera 27. Then, the laser displacement sensor 28 is moved along the slide rail 26 in a set step size (1cm) along the length of the simulated fracture. At each stop position, the cross-sectional profile height of the simulated fracture is measured by the laser displacement sensor 28 and the data is saved. When saving the data, a three-dimensional rectangular coordinate axis can be established to facilitate the coordinateization of the data. For example, a rectangular coordinate system can be established with the length of the simulated fracture as the x-axis and the vertical direction as the z-axis. After the operation is completed, the cross-sectional data in CSV format is imported into MATLAB software based on a set of cross-sectional data obtained by scanning. The griddata function is used for interpolation to finally generate a three-dimensional model of the sediment.

[0043] S6: Based on the three-dimensional model of the sediments obtained in step S5, calculate the final total sediment volume V. d Average deposition thickness D avg σ, standard deviation of deposition thickness d and the volume ratio R of the water flow channel v Substituting the weighting coefficient c, a final sedimentation composite index (DCI) is calculated. f ; ; In this embodiment, the total deposition volume V d = 125.6 cm 3 Average deposition thickness D avg = 0.8 cm, standard deviation of deposition thickness σd = 0.3 cm, water flow channel volume ratio R v = 0.75. Set a=0.6, b=0.4, c=0.2 (assigning a volume ratio R of the water flow channel). v A moderate weight of 0.2 is used to avoid undesirable high stresses caused by excessive grout expansion during the pursuit of complete sealing. Substitute into the final formula: DCI f = (0.6 × 125.6) - (0.4 × 0.3 / 0.8) + (0.2 ×0.75) = 75.36 - 0.15 + 0.15 = 75.36.

[0044] This data point (ΔP=5.0, P) i =0.3, DCI f =75.36) is stored as a sample point in the database. Then, by analyzing multiple groups (at least ten groups) with different ΔP... i , P i Measured values ​​of DCI under experimental conditions fi Regression analysis and data mining are performed to fit the final DCI. f With dynamic water pressure difference ΔP, grouting pressure P i The quantitative relationship between them is used to construct a method for predicting the value of any given ΔP and P. i A three-dimensional prediction model for slurry deposition effects under certain conditions: DCI fpred = f(ΔP, P i ). (Referring to ΔP and P) i After converting the units to kPa and MPa respectively, the model can be used to predict the comprehensive deposition index of grout under any dynamic water pressure and grouting pressure, thereby providing suggestions for the optimal parameter combination for on-site construction.

[0045] In this embodiment, in step S4, the acquired three-dimensional deposition volume V is... d(t) The method for making a preliminary estimate is as follows: The industrial control computer 29 extracts the pixel area S(t) of the deposited region from the background using an image segmentation algorithm based on the grayscale image captured by the industrial camera 27 at time t, and combines this with the reference value h of the fracture aperture. ref Using formula V d(t) ≈ k×S(t)× h ref An estimate is made, where k is a correction factor related to image resolution and camera calibration.

[0046] In this embodiment, in step S6, DCI fpred It is obtained by fitting the training dataset using the multiple linear regression analysis method, and its model form is as follows: DCI fpred = k1 × ΔP + k2 × P i + k0; Where k1, k2, and k0 are empirical coefficients determined through regression analysis. In this embodiment, DCI fpred = 8.12 ×ΔP + 102.5 × P i - 25.4.

[0047] In this embodiment, the values ​​of a, b, and c are determined using the analytic hierarchy process (AHP) based on the total deposition volume V. d , deposition uniformity and the smoothness of water flow channels R v The relative importance of these three indicators in engineering applications is determined.

[0048] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0049] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0050] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0051] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An experimental system for simulating slurry displacement and deposition in dynamic water fractures, characterized in that, include: The structural layer is made by three-dimensional laser scanning of rock fracture samples to obtain point cloud data, and the structural layer corresponds to the point cloud data. The structural layer has an upper structural layer (1) and a lower structural layer (2) that are separated from each other. The upper structural layer (1) and the lower structural layer (2) are columnar structures with the same cross-sectional shape. The upper structural layer (1) is bonded to the upper cover plate (3), and the lower structural layer (2) is bonded to the lower cover plate (4). The upper sealing box (5) is a cylindrical structure with a lower opening. The upper cover plate (3) and the upper structural layer (1) are arranged inside the upper sealing box (5), and the upper cover plate (3) is close to the top surface of the upper sealing box (5) and the upper structural layer (1) is close to the lower opening of the upper sealing box (5). The lower sealing box (6) is a cylindrical structure with an upper opening. The lower cover plate (4) and the lower structural layer (2) are arranged inside the lower sealing box (6), and the lower cover plate (4) is in contact with the bottom surface of the lower sealing box (6), and the lower structural layer (2) is close to the upper opening of the lower sealing box (6). The lower opening of the upper sealing box (5) and the upper opening of the lower sealing box (6) can be connected in the vertical direction. When the upper sealing box (5) and the lower sealing box (6) are connected, a sealing ring (7) is provided at the connection point. A simulated crack is defined between the upper structural layer (1) and the lower structural layer (2). An inlet (8) and an outlet (9) are provided on the sealing ring (7). The inlet (8) and the outlet (9) are respectively arranged close to the two ends of the simulated crack. The industrial control computer (29) calculates the collected three-dimensional sediment volume according to the preset sedimentation comprehensive index calculation formula. V d(t) Preliminary estimates are made, and the comprehensive sedimentary index is calculated and displayed in real time. DCI (t), the sedimentation comprehensive index is defined as: ； in, a and b These are preset positive weighting coefficients. V d(t) The cumulative three-dimensional deposition volume at the current moment. σ d(t) This represents the standard deviation of the deposition thickness along the simulated fracture length at the current moment. D avg(t) The average deposition thickness at the current moment; the deposition index is used to characterize the morphological development efficiency and spatial distribution uniformity during the slurry injection process online, with a higher value indicating better deposition results; operators observe the real-time data on the monitoring interface. DCI (t) value, when DCI (t) When the predetermined peak value is reached or the plateau period is entered, record the corresponding dynamic water pressure difference Δ. P and grouting pressure P i This is the optimal combination of process parameters.

2. The experimental system for simulating slurry displacement and deposition in dynamic water fractures according to claim 1, characterized in that, Also includes: An adjustment mechanism is set inside the upper sealing box (5) and connected to the upper cover plate (3). There is a moving gap (10) between the upper cover plate (3) and the top surface of the upper sealing box (5). The adjustment mechanism is used to drive the upper structural layer (1) to move up and down and adjust the width of the simulated crack.

3. The experimental system for simulating slurry displacement and deposition in dynamic water fractures according to claim 2, characterized in that, The adjustment mechanism includes: Adjustable support (11), the housing of the sealing box defines an installation cavity, the adjustable support (11) is arranged in the installation cavity, the installation cavity is connected to the upper sealing box (5), and a through groove is formed at the connection; The lead screw (12) is rotatably mounted on the adjusting support (11). A connecting block (13) is provided on the lead screw (12). The outer side of the connecting block (13) is connected to the inner surface of the adjusting support (11) to form a limit. The inner side extends from the through groove into the upper sealing box (5) and is connected to the upper cover plate (3). Adjustment motor (14) is connected to lead screw (12) for driving lead screw (12) to rotate, so that connecting block (13), upper cover plate (3) and upper structural layer (1) move up and down.

4. The experimental system for simulating slurry displacement and deposition in dynamic water fractures according to claim 2, characterized in that, It also includes a water tank (15), a variable frequency drive water pump (16), a high-precision turbine flow meter (17), a manual shut-off valve (18), and an electric regulating valve (19) connected in sequence. The electric regulating valve (19) is connected to the inlet (8), and the water tank (15) is connected to the outlet (9). Pressure sensors are provided at the inlet (8) and the outlet (9).

5. The experimental system for simulating slurry displacement and deposition in dynamic water fractures according to claim 4, characterized in that, Also includes: A diaphragm-type pressure vessel (20) has a gas chamber and a liquid chamber, which are separated by an elastic diaphragm. A high-pressure nitrogen cylinder (21) is connected to a gas chamber, and a pressure reducing valve and a pressure gauge are arranged at the outlet end of the high-pressure nitrogen cylinder (21). The slurry storage tank (22) is connected to the liquid chamber via a screw pump (31), and the liquid chamber is connected to the simulated fracture via a grouting pipe; Multiple fracture pressure sensors (23) are arranged on the surface of the upper structural layer (1) and / or the lower structural layer (2) for collecting fracture pressure.

6. The experimental system for simulating slurry displacement and deposition in dynamic water fractures according to claim 5, characterized in that, Also includes: The base (24) and the lower sealing box (6) are disposed on the base (24); Mounting bracket (25) is arranged above base (24), and an industrial camera (27) is mounted on the mounting bracket (25). The slide rail (26) is arranged along the length of the simulated fracture. A laser displacement sensor (28) is slidably mounted on the slide rail (26). The upper sealing box (5), lower sealing box (6), upper cover plate (3), and lower cover plate (4) are all made of transparent material. The industrial camera (27) is used to collect images of slurry displacement and deposition in the simulated fracture. The laser displacement sensor (28) is used to perform three-dimensional morphological scanning and measurement of the sediment. The industrial control computer (29) is electrically connected to the data acquisition box (30). The data acquisition box (30) integrates a data acquisition card and a signal conditioner. The control terminals of the variable frequency drive water pump (16), electric regulating valve (19), and screw pump (31) are respectively connected to the digital I / O and analog output ports of the data acquisition box (30). The signal output terminals of the pressure sensor, the crack pressure sensor (23), and the high-precision turbine flow meter (17), as well as the data output terminals of the industrial camera (27) and the laser displacement sensor (28), are all processed by the signal conditioner and then connected to the data acquisition card, which is then synchronously acquired and processed by the industrial control computer (29).

7. An experimental method for simulating slurry displacement and deposition in dynamic water fractures, characterized in that, The experimental system for simulating slurry displacement and deposition in dynamic water fractures as described in claim 6 includes the following steps: S1: Three-dimensional laser scanning is performed on rock fracture samples to obtain point cloud data. The structural layer is made by photopolymerization 3D printing. The structural layer corresponds to the point cloud data. The upper structural layer (1) is bonded to the upper cover plate (3), and the lower structural layer (2) is bonded to the lower cover plate (4). The upper sealing box (5) and the lower sealing box (6) are connected in the vertical direction. A sealing ring (7) is set at the connection. The water tank (15) is connected to the outlet (9), the electric regulating valve (19) is connected to the inlet (8), and the grouting pipe is connected to the simulated fracture. Sensor installation holes are reserved during the 3D printing of the structural layer. A fracture pressure sensor (23) is arranged in the sensor installation holes. S2: Drive the upper structural layer (1) up and down by adjusting the mechanism and adjust the width of the simulated crack until the preset width is reached; S3: Fill the water tank (15) with water, start the variable frequency drive water pump (16), manually adjust the opening of the electric regulating valve (19), and the monitoring interface of the industrial control computer (29) displays the real-time dynamic water pressure difference ΔP. Observe the real-time dynamic water pressure difference ΔP, and stabilize ΔP at the preset target pressure difference value Δ by adjusting the electric regulating valve (19). P set At this point, the reading of the turbine flow meter is the stable flow rate; S4: Start the screw pump (31) to deliver slurry into the buffer tank at a constant speed. At the same time, set and maintain a constant back pressure in the gas chamber of the buffer tank through the high-pressure nitrogen cylinder (21) and the pressure reducing valve, so that the slurry is injected into the simulated fracture without pulses using the back pressure as the driving force. At the start of injection, the industrial control computer (29) simultaneously starts the pressure sensor, fracture pressure sensor (23), industrial camera (27) and laser displacement sensor (28). The industrial control computer (29) calculates the collected three-dimensional deposition volume according to the preset deposition comprehensive index calculation formula. V d(t) Preliminary estimates are made, and the comprehensive sedimentary index is calculated and displayed in real time. DCI (t), the sedimentation comprehensive index is defined as: ； in, a and b These are preset positive weighting coefficients. V d(t) The cumulative three-dimensional deposition volume at the current moment. σ d(t) This represents the standard deviation of the deposition thickness along the simulated fracture length at the current moment. D avg(t) The average deposition thickness at the current moment; the deposition index is used to characterize the morphological development efficiency and spatial distribution uniformity during the slurry injection process online, with a higher value indicating better deposition results; operators observe the real-time data on the monitoring interface. DCI (t) value, when DCI (t) When the predetermined peak value is reached or the plateau period is entered, record the corresponding dynamic water pressure difference Δ. P and grouting pressure P i , as the optimal combination of process parameters; S5: After the experiment stops, with the water flow completely still and no slurry injected, the final shape of the sediment is recorded by an industrial camera (27); then the laser displacement sensor (28) is moved along the slide rail (26) to move along the simulated fracture length direction at a set step size. At each stop position, the cross-sectional profile height of the simulated fracture is measured by the laser displacement sensor (28), and the data is saved; after the operation is completed, a three-dimensional model of the sediment is reconstructed in the computer based on a set of cross-sectional data obtained by scanning. S6: Based on the three-dimensional model of the sediments obtained in step S5, calculate the final total sediment volume. V d Average deposition thickness D avg Standard deviation of deposition thickness σ d and water flow channel volume ratio R v And substitute the weighting coefficients c A final comprehensive sedimentation index is calculated. DCI f ; ； Then, by analyzing multiple sets of different Δ P i , P i Measurements under experimental conditions DCI fi Perform regression analysis and data mining to fit the final result. DCI f With dynamic water pressure difference Δ P Grouting pressure P i The quantitative relationship between them is used to construct a method for predicting the value of any given Δ. P and P i A three-dimensional prediction model for slurry deposition effects under the given conditions: DCI fpred = f (Δ P , P i ).

8. The experimental method for simulating slurry displacement and deposition in dynamic water fractures according to claim 7, characterized in that, In step S4, the acquired three-dimensional deposition volume is... V d(t) The method for making a preliminary estimate is as follows: The industrial computer (29) based on the industrial camera (27) in t The grayscale images captured in real time are used to extract the pixel area of ​​the deposited region from the background using an image segmentation algorithm. S ( t ), and combined with the reference value of fracture aperture. h ref Using the formula V d(t) ≈ k × S ( t )× h ref To make an estimate, among which k These are correction factors related to image resolution and camera calibration.

9. The experimental method for simulating slurry displacement and deposition in dynamic water fractures according to claim 7, characterized in that, In step S6, DCI fpred It is obtained by fitting the training dataset using the multiple linear regression analysis method, and its model form is as follows: DCI fpred = k 1 × D P + k 2 × P i + k 0; in, k 1. k 2. k 0 is the empirical coefficient determined through regression analysis.

10. The experimental method for simulating slurry displacement and deposition in dynamic water fractures according to claim 7, characterized in that, a, b, c The value is determined by the analytic hierarchy process based on the total sediment volume. V d , deposition uniformity and the smoothness of water flow channels R v The relative importance of these three indicators in engineering applications is determined.

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