A simulated-actual synergistic test system and method for grouting in porous media considering percolation effect

Abstract

This invention relates to the field of grouting simulation testing technology, specifically disclosing a virtual-real grouting combined testing system and method for porous media considering the percolation effect. The system includes: a visualization formation simulation module, a temperature control module, a grouting module, and a main control module. The main control module includes a verification and optimization unit, used to construct momentum equations, continuity equations, temperature continuity equations, chemical reaction equations, temperature-percolation-time comprehensive viscosity equations, and grout-water two-phase fraction equations based on the test system data. Through coupled solving, numerical simulation results of grouting speed, pressure, grout viscosity, temperature, concentration, and grout diffusion morphology throughout the grouting process are obtained. The numerical simulation results are compared and verified with the experimental results, and the parameters of the three-dimensional model of the porous formation are optimized. This invention can simulate extreme formation temperatures such as high and low temperatures, thereby enabling the study of changes and influences on the percolation mechanism of porous media under extreme temperature conditions.

Description

Technical Field

[0001] This invention relates to the field of grouting simulation testing technology, and in particular to a virtual-real grouting synergistic testing system and method for porous media considering the percolation effect. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Porous media grouting technology is widely used in underground engineering, playing a crucial role, especially in tunnel construction, dam foundation reinforcement, foundation treatment, and disaster prevention. By injecting grout, it improves the physical and mechanical properties of underground soil and rock masses, enhancing the bearing capacity of the strata, reducing permeability, and controlling groundwater flow. With the acceleration of urbanization and the increasing number of high-rise buildings, underground spaces, and transportation tunnels, porous media grouting technology must adapt to more complex and variable geological environments. This necessitates a stronger demand for research into the mechanisms of porous media grouting reinforcement under complex and extreme conditions.

[0004] The main research methods for revealing the mechanism of grouting reinforcement in porous media formations include indoor model tests and numerical simulations. Indoor model tests simulate formation conditions to study the fluidity, diffusion characteristics, and solidification behavior of grouting materials. Compared to field tests, they offer a safer environment, facilitating systematic research and comparison of the effects of different parameters on grouting effectiveness. Numerical simulations use mathematical models and numerical algorithms to discretize physical phenomena, approximating solutions to complex engineering problems. However, existing research methods still have the following limitations:

[0005] (1) Difficulty in predicting the flow path and distribution of slurry: For porous media formations, due to the interaction between slurry and formation media and the complex geological structure, it is difficult to accurately predict and observe the flow path and final distribution of slurry.

[0006] (2) Numerical characterization of the permeation process of slurry in porous media is difficult: Most numerical simulation methods currently focus on the diffusion, mechanical response and changes in physical properties of slurry, but the importance of the permeation effect on slurry in porous media is often overlooked.

[0007] (3) Existing model tests often fail to fully consider the extreme temperature changes from low temperature to high temperature. Furthermore, the injected medium leads to low repeatability of manual laying during the model test. Existing porous media models have certain limitations in terms of pore size and morphology control, material physical and chemical property simulation, etc., resulting in low accuracy and reliability of the grouting mechanism revealed by the porous media model. Summary of the Invention

[0008] To address the aforementioned issues, this invention proposes a virtual-real co-operational test system and method for grouting in porous media that considers the percolation effect. Based on the microscopic structural image of natural strata, a three-dimensional pore structure model is constructed, and the pore structure is accurately reproduced using 3D printing technology. Considering the concentration change caused by the percolation of grout in the porous medium, a comprehensive viscosity equation coupled with temperature, percolation, and time is constructed. Numerical simulation is used to verify and optimize the visualized porous media percolation grouting test system.

[0009] In some implementations, the following technical solutions are adopted:

[0010] A simulated-actual grouting test system for porous media considering the percolation effect includes:

[0011] The visualization formation simulation module includes an experimental platform, on which a medium filling tank is provided. The medium filling tank includes multiple detachable filling units, each of which has a grouting hole at the bottom. The filling units can be connected or not connected as needed. A transparent top cover plate is provided on the top of the medium filling tank, and the top cover plate has a modular design.

[0012] The three-dimensional model of the porous formation within each filling unit is obtained through a medium formation reproduction module; the medium formation reproduction module performs three-dimensional modeling of the porous formation based on the microstructure image of the natural formation, and prints the three-dimensional model of the porous formation using 3D printing technology;

[0013] The temperature control module is used to control the temperature of the three-dimensional model of the porous formation in the medium filling tank.

[0014] The grouting module is connected to each filling unit through grouting pipelines;

[0015] The main control module includes a verification and optimization unit, which is used to construct momentum equations, continuity equations, temperature continuity equations, chemical reaction equations, temperature-percolation-time comprehensive viscosity equations, and slurry-water two-phase fraction equations based on experimental system data. Through coupled solution, numerical simulation results of grouting speed, pressure, slurry viscosity, temperature, concentration, and slurry diffusion morphology throughout the grouting process are obtained. The numerical simulation results are compared and verified with experimental results, and the parameters of the three-dimensional model of porous formation are optimized.

[0016] As a further option, it also includes:

[0017] The data acquisition module is used to collect grout temperature, grouting pressure and image data during the grouting process, and to visualize the data; wherein, the image data can display the grout diffusion pattern and grout-water-medium interface during the grouting process;

[0018] The data acquired by the data acquisition module is fed back to the main control module, which then performs intelligent control of the entire experimental system based on the received data.

[0019] As a further option, it also includes:

[0020] The intelligent head sensing and regulation module includes: a constant temperature water storage tank, a water level control unit, and a water pump; the water pump is connected to the constant temperature water storage tank and the medium filling tank through pipelines, and is used to inject water from the constant temperature water storage tank into the three-dimensional model of the porous formation to simulate dynamic water flow;

[0021] The constant temperature water storage tank integrates a PID-controlled intelligent heating element to keep the water tank temperature within the set temperature range. The water level control unit collects water level information through a water level sensor installed in the medium filling tank and controls the water injection start / stop valve to open or close based on the collected water level information.

[0022] As a further embodiment, the temperature control module includes at least one heating unit, at least one cooling unit, and temperature sensors disposed at different positions within the medium filling tank.

[0023] The heating unit is located at the bottom of the medium filling tank and can heat up the three-dimensional model of the porous formation in the medium filling tank by heating it.

[0024] The refrigeration unit is located at the bottom of the medium filling tank and can cool down the three-dimensional model of the porous formation in the medium filling tank through two-stage compression refrigeration.

[0025] As a further approach, the grouting rate, pressure, grout viscosity, temperature, and concentration throughout the grouting process are obtained through coupled solutions, specifically:

[0026] The verification and optimization unit constructs a fluid domain mesh based on the three-dimensional model of the porous formation and sets initial boundary conditions for grouting velocity, grouting pressure, grout temperature, and grout viscosity. Based on the grouting velocity, grouting pressure, phase fraction, and grout viscosity, it constructs continuity equations and momentum equations. Based on the continuity equations and momentum equations, it iteratively solves and iterates the grout pressure and grouting velocity to obtain the grouting pressure and grouting velocity v at the current time step.

[0027] The temperature continuity equation is established based on the grouting speed v at the current time step; the discretized heat transfer equation is coupled with the discretized temperature continuity equation to obtain the grout temperature and grouting speed.

[0028] A chemical reaction equation is established based on the slurry temperature. The discretized chemical reaction equation is coupled with the discretized temperature continuity equation to obtain the slurry temperature and viscosity.

[0029] Based on the slurry temperature and concentration, a temperature-percolation-time integrated viscosity equation is constructed. The discretized temperature-percolation-time integrated viscosity equation is coupled with the discretized chemical reaction equation, momentum equation and temperature continuity equation. Through iterative solution, the final slurry viscosity, temperature, concentration, grouting speed and grouting pressure are obtained.

[0030] As a further option, the discrete chemical reaction equation is specifically as follows:

[0031]

[0032] Among them, C (n+1) It is the slurry concentration at the next time step; C n Δt is the slurry concentration at the current time step; k is the time step length; r It is the rate constant of a chemical reaction; E a It is the minimum energy required to initiate a chemical reaction; R is the gas constant; T n It is the temperature value at the current time step.

[0033] As a further solution, the discretized temperature-percolation-time comprehensive viscosity equation is specifically as follows:

[0034]

[0035] Where, μ n The viscosity of the slurry at the current time step is given; μ0 is the initial viscosity; R is the gas constant; E is the activation energy of the chemical reaction; T is the slurry viscosity at the current time step. n β is the temperature at the current time step; α is the concentration effect coefficient; C is the correction coefficient for the effect of chemical product concentration on viscosity as a function of temperature; n γ is the slurry concentration at the current time step; γ is the reaction rate time constant, t n This represents the value of the time variable t at the nth time step.

[0036] In other embodiments, the following technical solutions are adopted:

[0037] A simulated-actual co-test method for porous media grouting considering the permeation effect, employing the aforementioned visualized porous media permeation grouting test system, includes:

[0038] Obtain microscopic structural images of natural strata, perform three-dimensional modeling of porous strata based on the microscopic structural images, and print the three-dimensional model of porous strata using 3D printing technology.

[0039] The diffusion of slurry in porous media was simulated by numerical simulation. The numerical simulation results were compared with the experimental results to optimize the parameters of the three-dimensional model of porous formation. The optimized three-dimensional model of porous formation was then placed in the filling unit of the medium filling tank as required.

[0040] Prepare the grout according to the test requirements, set the dynamic water level and temperature, and set the temperature, grouting speed and pressure parameters of the three-dimensional model; start grouting.

[0041] During the grouting process, the grout flow rate, the temperature of the injected medium, and the grouting pressure data are monitored in real time, and images of the three-dimensional model of the porous formation are acquired at the same time.

[0042] Based on the temperature data inside the 3D model, the changes in the temperature field during the grouting process are analyzed; based on the grouting pressure data, the changes in the pressure during the grouting process are monitored and analyzed; based on the image data, the diffusion mechanism of grout under different conditions is analyzed.

[0043] Based on the experimental system data, momentum equation, continuity equation, temperature continuity equation, chemical reaction equation, temperature-percolation-time comprehensive viscosity equation, and slurry two-phase fraction equation were constructed. Through coupled solution, numerical simulation results of grouting speed, pressure, slurry viscosity, temperature, slurry concentration, and slurry diffusion morphology throughout the grouting process were obtained. The numerical simulation results were then compared and verified with the experimental results.

[0044] Compared with the prior art, the beneficial effects of the present invention are:

[0045] (1) This invention constructs a three-dimensional model of porous formations by comprehensively considering the type of medium, distribution characteristics, and regional permeability properties. This method combines microscopy, CT scanning, and 3D printing technologies, and optimizes parameters based on numerical simulation, model experiments, and inversion analysis, achieving high-precision reproduction of the formation's pore structure. This innovation overcomes the difficulties in reproduction and the obstacles to mechanism exploration caused by the complexity and uncertainty of the medium's structure, providing a reliable method for studying the grouting, water plugging, and reinforcement mechanisms in porous media structures.

[0046] (2) This invention is based on a simulation and analysis verification method for porous media permeation grouting that integrates multiple disciplines such as thermodynamics, fluid mechanics, and materials science. In the numerical solution process, the heat exchange between the grout and the medium, the evolution of the hydration reaction, and the changes in the concentration field during permeation (i.e., considering the permeation effect) are comprehensively considered. By constructing chemical reaction equations and a temperature-permeation-time comprehensive viscosity equation, and combining it with governing equations such as momentum equations, continuity equations, and phase fraction equations, the precise characterization of grout viscosity changes and permeation mechanisms during porous media grouting is achieved, while effectively verifying the experimental mechanism.

[0047] (3) The experimental system of this invention sets the thickness of the three-dimensional model of the porous formation to 0-5 cm, which is thinner than a normal three-dimensional model. Combined with a transparent top cover, the diffusion process of the slurry can be observed quickly and clearly, simplifying the complexity of the experiment, enhancing the visualization effect, and making the slurry permeation behavior clearly visible under the transparent material, which is convenient for intuitive observation and analysis. The experimental system of this invention can simulate extreme formation temperatures such as high and low temperatures, thereby enabling the study of the changes and influences of the permeation mechanism of porous media under extreme temperature conditions.

[0048] Other features and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of the structure of the visual porous media permeation grouting test system in an embodiment of the present invention;

[0050] Figure 2 This is a schematic diagram of the filling unit assembly in an embodiment of the present invention;

[0051] The components include: 1. Medium filling tank; 2. Temperature control module; 3. Image acquisition device; 4. Flow sensor; 5. Grouting pipeline; 6. High-pressure constant-speed grouting pump; 7. Pressure sensor; 8. Grout storage tank; 9. Controller; 10. Data comprehensive analysis unit; 11. Central control unit; 12. Water tank; 13. First filling unit; 14. Second filling unit; 15. Third filling unit. Detailed Implementation

[0052] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0053] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0054] Example 1

[0055] In one or more embodiments, a pore medium grouting virtual-real synergistic test system considering the percolation effect is disclosed, combined with... Figure 1 Specifically, it includes:

[0056] (1) Visualized formation simulation module, including experimental platform. The experimental platform is used to support the experimental model. It is made of aluminum alloy and corrosion-resistant coating to ensure that it will not be corroded in long-term experiments and can withstand greater pressure. The experimental platform is equipped with a multi-functional support, which can freely adjust the height and tilt of the experimental platform to adapt to different types of experimental needs.

[0057] The experimental platform includes a media filling tank 1, which is constructed of double-layer stainless steel and a high thermal conductivity composite material to enhance corrosion resistance and thermal conductivity. An insulation layer is added to the tank wall to reduce external temperature interference. The media filling tank contains multiple detachable filling units, which can be freely assembled together. Figure 2 A structural diagram showing the assembly of the first filling unit 13, the second filling unit 14, and the third filling unit 15 is provided. Each filling unit can be individually filled with a printed medium model, enabling the simulation of various geological environments, and facilitating replacement and cleaning. The filling units can be connected or disconnected as needed.

[0058] Each filling unit can be completely independent, and different media models can be filled inside each filling unit. There is no physical connection between the filling units. Each filling unit is equipped with a grouting hole at the bottom, which can be grouted independently through the grouting pipeline 5.

[0059] Some or all of the filling units can also be connected to the permeation pipe through controllable channels, so that the grout can be exchanged or permeated between the filling units. At this time, grouting pipelines can be set up as needed.

[0060] The top of the media filling tank is equipped with a transparent upper cover plate. The upper cover plate is made of transparent acrylic material and coated with an anti-scratch coating to extend its service life and maintain long-term clarity. After the media is arranged in the media filling tank, the upper cover plate is fixed to the top of the filling tank to seal and fix the internal filling media. Multiple sensor interfaces are reserved on the upper cover plate, which can be used to install pressure, temperature or flow rate sensors to realize real-time acquisition of experimental data. The upper cover plate adopts a modular design. A threaded lifting device is installed at the four corners or edges of each modular upper cover plate. By rotating the screw rod, the height of the upper cover plate and the tilt angle are controlled to simulate different formation conditions.

[0061] (2) Medium formation reproduction module: Based on the microstructure image of natural formation, three-dimensional modeling of porous formation is performed, and the three-dimensional model of porous formation is printed by 3D printing technology;

[0062] In this embodiment, the 3D model of the porous formation within each filling unit is created using a medium formation reproduction module. Microscopic images of the natural formation's microstructure are acquired using microscopy and CT scanning techniques, digitized, and reconstructed to obtain the 3D model of the porous formation. Settings including interface thickness, interface material, and printing speed are configured. The 3D printer is then prepared, ensuring the print bed is clean and leveled as needed. Suitable printing material is loaded, and the sliced ​​files are uploaded to the 3D printer to complete the 3D printing of the porous formation model. 3D printing technology allows for better differentiation of interfaces between formations, providing a more realistic simulation of formation conditions.

[0063] The thickness of the three-dimensional porous formation model in this embodiment is 0-5cm. Compared with the normal geological three-dimensional model with a thickness of 20-30cm, the thickness of the three-dimensional porous formation model in this embodiment is thinner. Combined with a transparent top cover plate, the diffusion process of the slurry can be observed quickly and clearly. This simplifies the complexity of the experiment, enhances the visualization effect, and makes the slurry infiltration behavior clearly visible under the transparent material, which is convenient for intuitive observation and analysis.

[0064] (3) Temperature control module 2 is used to realize temperature control of the three-dimensional model of the porous formation in the medium filling tank.

[0065] The temperature control module of this embodiment includes at least one heating unit, at least one cooling unit, and temperature sensors disposed at different positions in the medium filling tank.

[0066] The heating unit is located at the bottom of the medium filling tank and can heat the three-dimensional model of the porous formation inside the medium filling tank by heating it. The heating unit can use various heating methods such as heating plates, resistance wires, and water baths. The heating unit can achieve precise and rapid heating from ambient temperature to 120°C according to the experimental temperature requirements. Multiple heating units can divide the medium filling tank into multiple independent heating blocks. Through zone control, the temperature of each area can be independently adjusted and rapidly heated to meet the needs of different experiments.

[0067] The refrigeration unit is located at the bottom of the medium filling tank and includes a cavity at the bottom of the medium filling tank and a two-stage compression refrigeration device. The two-stage compression refrigeration device can output gas (such as nitrogen) cooled to a set temperature, which can cool the three-dimensional model of the porous formation in the medium filling tank.

[0068] This embodiment achieves precise temperature control through primary compression for rapid cooling, followed by secondary fine adjustment, ensuring rapid and accurate cooling of the system, allowing the model temperature to drop from ambient temperature to -20°C. The refrigeration unit can also adopt a modular design, allowing for free combination and expansion according to experimental scale and cooling capacity requirements, improving flexibility and adaptability, and suitability for rapid temperature adjustment under various experimental conditions. Multiple refrigeration units can divide the media filling tank into multiple independent refrigeration blocks, enabling independent adjustment and rapid cooling of each area through zone control, adapting to the needs of different experiments.

[0069] By arranging multiple high-precision temperature sensors at different locations within the medium filling tank, temperature changes are monitored, enabling comprehensive real-time data feedback and ensuring uniform temperature control within the experimental model.

[0070] A stable power supply can be provided to the temperature control module through the distribution box. Through functions such as power distribution, overload and short circuit protection, leakage protection and equipment control, the safe operation of the power system and the stable power supply of the equipment are ensured.

[0071] (4) Grouting module, which is connected to each filling unit through grouting pipeline.

[0072] The grouting module includes a grout storage tank 8 and a high-pressure constant-speed grouting pump 6, and the grout storage tank 8 and the high-pressure constant-speed grouting pump 6 are connected by a grouting pipeline;

[0073] The high-pressure constant-speed grouting pump is connected to each filling unit through multiple grouting pipelines. The high-pressure constant-speed grouting pump supports multiple flow rate adjustments. The multiple grouting pipelines adopt a wear-resistant and corrosion-resistant multi-channel grouting pipeline design, allowing multiple grouting points to work simultaneously, realizing flexible adjustment of grout injection rate and grout injection of each filling unit.

[0074] Flow sensor 4 and pressure sensor 7 are installed on the grouting pipeline to monitor flow changes and pressure fluctuations in real time during the grouting process.

[0075] The start-up, shutdown, and speed settings of the high-pressure constant-speed grouting pump can be controlled by controller 9, enabling precise grouting throughout the entire test process.

[0076] (5) Intelligent head sensing and adjustment module, including: constant temperature water storage tank 12, water level control unit and water pump; the water pump is connected to the constant temperature water storage tank and the medium filling tank through pipelines respectively, and is used to inject water in the constant temperature water storage tank into the three-dimensional model of the porous formation to simulate dynamic water flow.

[0077] The constant-temperature water storage tank integrates a PID-controlled intelligent heating element to maintain the water temperature within the set range and features automatic power-off protection against overheating. It provides water for the dynamic flow of water within porous media. The tank employs a double-layer stainless steel structure, with an inner layer of corrosion-resistant material and an outer layer of high-efficiency heat-insulating material, with insulation material filling the space between the two layers to ensure stable temperature and effectively prevent heat loss. To ensure uniform water temperature distribution and prevent localized overheating or underheating, a circulation pump is installed inside the tank.

[0078] The water level control unit includes a water pressure sensor, a water level control device, a water injection start / stop valve, and a pressure relief device. It collects water level information by means of a water level sensor installed in the medium filling tank, and controls the water injection start / stop valve to open or close based on the collected water level information.

[0079] Water pressure sensors are installed at the water tank outlet and the model's dynamic water inlet, transmitting water pressure information to the water level control device. This device, located inside the water tank, collects, provides feedback on, and regulates the water pressure. The water inlet is located on the tank wall and connected to the water tank via a water supply pipeline. A water pump in the tank injects water into the test model. The water supply pipeline is made of flexible hoses made of high-temperature and corrosion-resistant composite materials. All pipeline joints feature quick-connect designs for easy installation and disassembly. Automatic pressure relief devices are also installed at key points.

[0080] (6) Data acquisition module, used to collect grout temperature, grouting pressure and image data during the grouting process, and to visualize the data.

[0081] The data acquisition module includes pressure sensors, temperature sensors, and flow rate sensors installed on the upper cover plate, as well as an image acquisition device 3 (such as a camera or camera) set above the three-dimensional model of the porous formation; it can collect the temperature and grouting pressure information of the injected medium in real time and convert it into a unified format to upload to the main control module.

[0082] The image acquisition device is installed on the crossbeam above the test model to capture the grout diffusion pattern and grout-water-medium interface in real time during the grouting process, and transmit the images to the main control module.

[0083] In addition, the data acquisition module also includes temperature sensors installed in the medium filling tank, temperature sensors in the constant temperature water storage tank, water level sensors, pressure sensors, flow sensors and pressure sensors on the slurry supply pipeline, etc.; used to detect relevant data at each location in real time and feed it back to the main control module.

[0084] (7) Main control module, the main control module in this embodiment mainly includes:

[0085] The central control unit 11 is used to realize intelligent regulation of the entire system. For example, it can intelligently control the water temperature in the water storage tank based on the temperature data transmitted by the data acquisition unit. When the water temperature reaches the set temperature, the internal temperature is controlled by starting and stopping the heating device. Based on the water level data transmitted by the data acquisition unit, it can intelligently control the water head height in the water head regulating device, automatically detect the water level in the water head regulating tank and adjust the lifting unit under the water tank to control the water flow rate at the specified water level.

[0086] The data integration and analysis unit 10 is used to integrate and analyze the received data, combine and analyze temperature, pressure and image data, depict the temperature field changes during grouting, monitor pressure changes and analyze the diffusion mechanism under different conditions, and transmit the results to the visualization system.

[0087] The verification and optimization unit is used to construct momentum equations, continuity equations, temperature continuity equations, chemical reaction equations, temperature-percolation-time comprehensive viscosity equations, and slurry two-phase fraction equations based on experimental system data. Through coupled solutions, numerical simulation results of grouting speed, pressure, slurry viscosity, temperature, concentration, and slurry diffusion morphology throughout the grouting process are obtained. The numerical simulation results are compared and verified with experimental results, and the parameters of the three-dimensional model of porous formation are optimized.

[0088] In this embodiment, a consolidation strength mechanical simulation experiment was conducted to simulate the solidification process of the slurry after injection into the porous medium, verifying the material's bonding performance and solidification characteristics. Furthermore, based on initial parameters such as the thickness of the formation interface, the interface material, and the printing speed, a physical model was printed, and model experiments were conducted under the same conditions as the numerical calculations. Based on the error values ​​of the experimental results, the material parameters were repeatedly adjusted to gradually optimize the simulation accuracy. Finally, through multiple iterations and experimental verification, the simulation and inversion analysis were ensured to be highly consistent with the actual data, thereby determining the optimal material parameters. Simultaneously, by selecting different combinations of particles and binders and adjusting their proportions, the medium characteristics under various geological conditions were simulated, ultimately resulting in the final three-dimensional model being printed.

[0089] As a specific example, the grouting speed, pressure, grout viscosity, temperature, and concentration throughout the grouting process are obtained through coupled solution. The specific process is as follows:

[0090] ① The verification and optimization unit constructs a fluid domain mesh based on the three-dimensional model of the porous formation and sets initial boundary conditions for grouting velocity, grouting pressure, grout temperature, and grout viscosity; it then constructs continuity and momentum equations based on the grouting velocity, grouting pressure, phase fraction, and grout viscosity.

[0091]

[0092] Where v is the fluid velocity vector, ρ is the density, p is the pressure, μ is the viscosity function characterized by time t and slurry temperature T (which can be obtained experimentally), g is the acceleration due to gravity, and F... st Surface tension.

[0093] The continuity equation and momentum equation after coupling and discretization are as follows:

[0094]

[0095] Where v is the fluid velocity vector, and ρ is the density; ρ n+1 v n+1 With ρ n v n These are the density and velocity products of the new and old time steps, respectively, V CV It is the volume that controls the volume, S face To control the area vector of a volume surface, the control volume is a basic unit for partitioning space in numerical computation, commonly used in methods such as the finite volume method, to discretize the conservation equations of fluids or other physical fields. n Due to the pressure of the current time step, Let g be the viscous stress at the current time step, and g be the gravitational acceleration. Δt represents the surface tension, and Δt represents the time step.

[0096] Among them, the control volume is a basic unit for dividing space in numerical calculations. It is usually used in methods such as the finite volume method to discretize the conservation equations of fluids or other physical fields.

[0097] The grout pressure and grouting speed are repeatedly solved and iterated based on the continuity equation and momentum equation to obtain the grouting pressure and grouting speed v at the current time step.

[0098] ②Establish the temperature continuity equation based on the grouting rate V at the current time step:

[0099]

[0100] Discretize the equation:

[0101]

[0102] Among them, T (n+1) The temperature value for the next time step; T n The current time step temperature is ρ; density is c. p It is the specific heat capacity of the fluid; T is the temperature of the flow field; k is the thermal conductivity; Q is the internal heat source or external heating; h i It is the heat exchange coefficient between the fluid and the medium; A i It is the surface area of ​​the fluid in contact with the medium; ∑ i hi A i (T i -T) is a heat exchange term, representing the amount of heat exchanged between the fluid and different media, where T i The temperature at the control volume boundary is represented by u; u represents the fluid velocity vector. The temperature gradient is used to describe the rate of temperature change in space.

[0103] The discretized heat transfer equation is coupled with the temperature continuity equation to realize the repeated solution and iteration of slurry temperature and grouting speed until the number of iterations is reached, and then the slurry temperature and grouting speed are obtained.

[0104] ③ Considering the concentration change of the slurry during the permeation process in the porous medium, the chemical reaction equation is established:

[0105]

[0106] Discretize the equation:

[0107]

[0108] Among them, C (n+1) It is the slurry concentration at the next time step; C n Δt is the slurry concentration at the current time step; k is the time step length; r It is the rate constant of a chemical reaction; E a It is the minimum energy required to initiate a chemical reaction; R is the gas constant; T n It is the temperature value at the current time step.

[0109] The discretized chemical reaction equation is coupled with the temperature continuity equation to achieve repeated solutions and iterations of slurry temperature and concentration until the number of iterations is reached, at which point the slurry temperature and viscosity are obtained.

[0110] ④ Construct a temperature-percolation-time integrated viscosity equation

[0111]

[0112] Discretize the equation:

[0113]

[0114] Where, μ n The viscosity at the current time step is μ0; the initial viscosity is μ0; R is the gas constant; E is the activation energy of the chemical reaction; T is the viscosity at the current time step. n The temperature is at the current time step; β is the concentration influence coefficient, determined based on empirical data; α is the correction coefficient for the influence of chemical product concentration on viscosity as a function of temperature; C n γ is the slurry concentration at the current time step; γ is the reaction rate time constant.

[0115] Among them, concentration refers to the proportion of solid matter in the total volume of slurry, and viscosity is the internal resistance encountered by the slurry during flow, which is a parameter reflecting the ease or difficulty of slurry flow.

[0116] The discretized comprehensive viscosity equation is coupled with the chemical reaction equation, momentum equation, and temperature continuity equation to achieve repeated solutions and iterations of slurry viscosity, temperature, concentration, and velocity until the number of iterations is reached, at which point the slurry viscosity, temperature, concentration, grouting velocity, and pressure are obtained.

[0117] Based on the grouting velocity v at the current time step, a discrete two-phase fractional equation for the grout and water is constructed. By solving the fractional equation, the diffusion pattern of the grout in the porous medium is obtained. The two-phase fractional equation for the grout and water is as follows:

[0118]

[0119] Where α represents the proportion of a specific phase in a given volume;

[0120] By iteratively solving the above equations, the grouting speed, pressure, and diffusion morphology of the entire grouting process can be captured in all aspects. Based on the comparison and verification of the numerical solution results and the model test conducted at typical time steps, the parameters of the three-dimensional model of porous formation can be optimized. At the same time, the comprehensive analysis of the grouting mechanism and law of porous media can be achieved through the mutual verification of the two results.

[0121] Example 2

[0122] In one or more embodiments, a simulated-actual co-test method for porous media grouting considering the permeation effect is disclosed, employing the visualized porous media permeation grouting test system described in Example 1, specifically including the following process:

[0123] (1) Obtain microstructure images of natural strata, perform three-dimensional modeling of porous strata based on microstructure images, and print three-dimensional models of porous strata using 3D printing technology.

[0124] (2) The diffusion of slurry in porous media is simulated by numerical simulation. The numerical simulation results are compared with the experimental results to optimize the parameters of the three-dimensional model of porous formation. The optimized three-dimensional model of porous formation is placed in the filling unit of the medium filling tank as required.

[0125] In this embodiment, the printing equipment is initially set up and printed according to the characteristics of the porous media formation. Model experiments are conducted, and the media parameters are optimized based on the digital model. The specific process is as follows: microscopic images of the natural strata are obtained using microscopy and CT scanning technology; the accuracy of the initial parameters is verified using numerical simulation and physical experiments; numerical simulation and actual data are compared through grouting diffusion and consolidation strength experiments; material parameters and printing conditions are adjusted according to the error value, and optimization is iterated repeatedly. Finally, when the numerical simulation, inversion analysis, and actual data reach consistency and stability, the optimal parameters are determined, and the final model is printed.

[0126] (3) Prepare the grout according to the test requirements, set the dynamic water level and temperature, and set the model temperature, grouting speed and pressure parameters; start grouting.

[0127] In this embodiment, based on research requirements, the slurry selection and proportion, formation water abundance, dynamic water flow rate, dynamic water temperature, and porous media characteristics are determined. The slurry is prepared according to the selected slurry proportion and injected into the slurry storage tank 8. The slurry can be a single-component or two-component slurry. Materials can be selected according to requirements, such as cement slurry, or specified materials like water glass and new materials. The water level control module is adjusted according to the water head height. The water temperature in the storage tank is adjusted according to the set dynamic water temperature. The model temperature is set according to the formation temperature. The printed formation model is fixed in the medium filling tank, and the upper cover plate is sealed on the tank. According to the experimental purpose, pressure and temperature data monitoring elements are arranged at the reserved openings on the upper cover plate of the "pseudo-3D" formation model. The elements are connected to the data acquisition device, the image acquisition and transmission module is turned on, and grouting begins.

[0128] (4) During the grouting process, monitor the grout flow rate, temperature and pressure data in real time, and collect images of the three-dimensional model of the porous formation at the same time;

[0129] (5) Based on the temperature data inside the three-dimensional model, the temperature field changes during the grouting process are analyzed; based on the grouting pressure data, the pressure changes during the grouting process are monitored and analyzed; based on the image data, the diffusion mechanism of grout under different conditions is analyzed.

[0130] Based on experimental requirements, different grouting pressures were set according to different grouting rate ratios. After setting, grouting began, and monitoring data such as grouting flow rate, temperature, and pressure were recorded in real time during the injection process. The collected data were analyzed. Temperature data from the 3D model was used to analyze the temperature field changes during the grouting process; grouting pressure data was used to monitor and analyze pressure changes during the grouting process; and based on transmitted image information, the diffusion mechanism of the grout under different filling media and different dynamic water flow velocities was analyzed. Through comprehensive data analysis, the experimental data were transformed into visual charts to display the temperature field, pressure changes, and grout diffusion morphology, which were then monitored in real time on the system display screen.

[0131] (6) Based on the experimental system data, construct the momentum equation, continuity equation, temperature continuity equation, chemical reaction equation, temperature-percolation-time comprehensive viscosity equation and slurry two-phase fraction equation, and obtain the numerical simulation results of grouting speed, pressure, slurry viscosity, temperature, concentration and slurry diffusion morphology throughout the grouting process through coupled solution; compare and verify the numerical simulation results with the experimental results.

[0132] This embodiment conducts numerical experimental verification. Based on the experimental model, a fluid domain mesh is constructed, and initial boundary conditions are set, including grouting velocity, grouting pressure, grout temperature, and grout viscosity. Energy equations, continuity equations, temperature continuity equations, chemical reaction equations, and temperature-percolation-time comprehensive viscosity equations are constructed and coupled and discretized to obtain comprehensive information on grouting velocity, pressure, and diffusion morphology throughout the grouting process. The numerical solution results are compared and verified with the model test conducted at typical time steps.

[0133] After verification, the slurry plugging rules and mechanisms under single or multiple coupled conditions, such as different medium temperatures, different porous media formations, different dynamic water flow velocities, different dynamic water temperatures, and different slurry types, are obtained through data analysis.

[0134] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A simulated-actual grouting test system for porous media considering the percolation effect, characterized in that, include: The visualization formation simulation module includes an experimental platform, on which a medium filling tank is provided. The medium filling tank includes multiple detachable filling units, each of which has a grouting hole at the bottom. The filling units can be connected or not connected as needed. A transparent top cover plate is provided on the top of the medium filling tank, and the top cover plate has a modular design. The three-dimensional model of the porous formation within each filling unit is obtained through a medium formation reproduction module; the medium formation reproduction module performs three-dimensional modeling of the porous formation based on the microstructure image of the natural formation, and prints the three-dimensional model of the porous formation using 3D printing technology; The temperature control module is used to control the temperature of the three-dimensional model of the porous formation in the medium filling tank. The grouting module is connected to each filling unit through grouting pipelines; The main control module includes a verification and optimization unit, which is used to construct momentum equations, continuity equations, temperature continuity equations, chemical reaction equations, temperature-percolation-time comprehensive viscosity equations, and slurry-water two-phase fraction equations based on experimental system data. Through coupled solution, numerical simulation results of grouting speed, pressure, slurry viscosity, temperature, concentration, and slurry diffusion morphology throughout the grouting process are obtained. The numerical simulation results are compared and verified with experimental results, and the parameters of the three-dimensional model of porous formation are optimized.

2. The grouting virtual-real synergistic test system for porous media considering the percolation effect as described in claim 1, characterized in that, Also includes: The data acquisition module is used to collect grout temperature, grouting pressure and image data during the grouting process, and to visualize the data; wherein, the image data can display the grout diffusion pattern and grout-water-medium interface during the grouting process; The data acquired by the data acquisition module is fed back to the main control module, which then performs intelligent control of the entire experimental system based on the received data.

3. The grouting virtual-real synergistic test system for porous media considering the percolation effect as described in claim 2, characterized in that, Also includes: The intelligent head sensing and adjustment module includes: a constant temperature water storage tank, a water level control unit, and a water pump; The water pump is connected to the constant temperature water storage tank and the medium filling tank through pipelines, and is used to inject water from the constant temperature water storage tank into the three-dimensional model of the porous formation to simulate dynamic water flow. The constant temperature water storage tank integrates a PID-controlled intelligent heating element to keep the water tank temperature within the set temperature range. The water level control unit collects water level information through a water level sensor installed in the medium filling tank and controls the water injection start / stop valve to open or close based on the collected water level information.

4. The grouting virtual-real synergistic test system for porous media considering the percolation effect as described in claim 3, characterized in that, The constant temperature water tank adopts a double-layer stainless steel structure, with the inner layer being a corrosion-resistant material and the outer layer being a high-efficiency heat insulation material, and heat insulation material is filled between the two layers.

5. The grouting virtual-real synergistic test system for porous media considering the percolation effect as described in claim 1, characterized in that, The temperature control module includes at least one heating unit, at least one cooling unit, and temperature sensors disposed at different positions within the medium filling tank. The heating unit is located at the bottom of the medium filling tank and can heat up the three-dimensional model of the porous formation in the medium filling tank by heating. The refrigeration unit is located at the bottom of the medium filling tank and can cool down the three-dimensional model of the porous formation in the medium filling tank through two-stage compression refrigeration.

6. The grouting virtual-real synergistic test system for porous media considering the percolation effect as described in claim 1, characterized in that, The transparent upper cover is connected to the medium filling tank via a lifting device, which can adjust the height and tilt angle of the transparent upper cover.

7. The grouting virtual-real synergistic test system for porous media considering the percolation effect as described in claim 1, characterized in that, The grouting rate, pressure, grout viscosity, temperature, and concentration throughout the entire grouting process are obtained through coupled solutions. The verification and optimization unit constructs a fluid domain mesh based on a three-dimensional model of the porous formation and sets initial boundary conditions for grouting velocity, grouting pressure, grout temperature, and grout viscosity. Based on the grouting velocity, grouting pressure, phase fraction, and grout viscosity, it constructs continuity and momentum equations. Based on these equations, it iterative solutions and iterations are performed to obtain the grouting pressure and grouting velocity at the current time step. ; Based on the grouting speed at the current time step Establish the temperature continuity equation; couple the discretized heat transfer equation with the discretized temperature continuity equation to obtain the slurry temperature and grouting rate. A chemical reaction equation is established based on the slurry temperature. The discretized chemical reaction equation is coupled with the discretized temperature continuity equation to obtain the slurry temperature and viscosity. Based on the slurry temperature and concentration, a temperature-percolation-time integrated viscosity equation is constructed. The discretized temperature-percolation-time integrated viscosity equation is coupled with the discretized chemical reaction equation, momentum equation and temperature continuity equation. Through iterative solution, the final slurry viscosity, temperature, concentration, grouting speed and grouting pressure are obtained.

8. The grouting virtual-real synergistic test system for porous media considering the percolation effect as described in claim 7, characterized in that, The discrete chemical reaction equation is as follows: ； in, It is the slurry concentration at the next time step; It is the slurry concentration at the current time step; It is the time step; It is the rate constant of a chemical reaction; It is the minimum energy required to initiate a chemical reaction; It is the gas constant; It is the temperature value at the current time step.

9. The grouting virtual-real synergistic test system for porous media considering the percolation effect as described in claim 7, characterized in that, The discretized temperature-percolation-time comprehensive viscosity equation is as follows: ； in, It is the viscosity of the slurry at the current time step; It is the initial viscosity; It is the gas constant; It is the activation energy of a chemical reaction; It is the temperature at the current time step; It is the concentration influence coefficient; It is a correction factor for the effect of chemical product concentration on viscosity as a function of temperature. It is the slurry concentration at the current time step; It is the reaction rate time constant. This represents the value of the time variable 𝑡 at the nth time step.

10. A method for combined virtual and real grouting tests of porous media considering the percolation effect, employing the combined virtual and real grouting test system of porous media considering the percolation effect as described in claim 3, characterized in that, include: Obtain microscopic structural images of natural strata, perform three-dimensional modeling of porous strata based on the microscopic structural images, and print the three-dimensional model of porous strata using 3D printing technology. The diffusion of slurry in porous media was simulated by numerical simulation. The numerical simulation results were compared with the experimental results to optimize the parameters of the three-dimensional model of porous formation. The optimized three-dimensional model of porous formation was then placed in the filling unit of the medium filling tank as required. Prepare the grout according to the test requirements, set the dynamic water level and temperature, and set the temperature, grouting speed and pressure parameters of the three-dimensional model; start grouting. During the grouting process, the grout flow rate, the temperature of the grout being injected, and the grouting pressure data are monitored in real time, and images of the three-dimensional model of the porous formation are acquired at the same time. Based on the temperature data inside the 3D model, the changes in the temperature field during the grouting process are analyzed; based on the grouting pressure data, the changes in the pressure during the grouting process are monitored and analyzed; based on the image data, the diffusion mechanism of grout under different conditions is analyzed. Based on the experimental system data, momentum equation, continuity equation, temperature continuity equation, chemical reaction equation, temperature-percolation-time comprehensive viscosity equation, and slurry two-phase fraction equation were constructed. Through coupled solution, numerical simulation results of grouting speed, pressure, slurry viscosity, temperature, slurry concentration, and slurry diffusion morphology throughout the grouting process were obtained. The numerical simulation results were then compared and verified with the experimental results.

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