Pore medium grouting virtual-real cooperative test system and method considering percolation effect

Abstract

The invention relates to the technical field of grouting simulation tests, and particularly discloses a pore medium grouting virtual-real cooperative test system and method considering the percolation effect, the system comprises a visual stratum simulation module, a temperature control module, a grouting module and a main control module, the main control module comprises a verification and optimization unit, and the verification and optimization unit comprises a verification and optimization unit. The equation building module is used for building a momentum equation, a continuity equation, a temperature continuity equation, a chemical reaction equation, a temperature-infiltration-time comprehensive viscosity equation and a slurry-water two-phase fraction equation according to data of a test system; numerical simulation results of the grouting speed, the grouting pressure, the slurry viscosity, the slurry temperature, the slurry concentration and the slurry diffusion form in the whole grouting process are obtained through coupling solution; and performing comparison verification on a numerical simulation result and a test result, and optimizing parameters of the pore stratum three-dimensional model. Extreme formation temperatures such as high temperature and low temperature can be simulated, so that the change and influence of a pore medium permeation mechanism under the extreme temperature condition can be researched.

Description

Technical Field

[0001] The invention relates to the technical field of grouting simulation test, and in particular to a porous medium grouting virtual-real coordinated test system and method taking into account the percolation effect. Background Art

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

[0003] Porous medium stratum grouting technology is widely used in the field of underground engineering, especially in tunnel construction, dam foundation reinforcement, foundation treatment and disaster prevention and control projects, playing a vital role. By injecting slurry, the physical and mechanical properties of underground rock and soil can be improved, the bearing capacity of the stratum can be increased, the permeability can be reduced, and the flow of groundwater can be controlled. With the acceleration of urbanization, the number of high-rise buildings, underground spaces, and transportation tunnels is increasing. The porous medium stratum grouting technology must adapt to a more complex and changeable geological environment. This has led to an increasingly strong demand for the exploration of the porous medium stratum grouting reinforcement mechanism under complex and extreme conditions.

[0004] The main research methods to reveal the grouting reinforcement mechanism of porous medium formations are 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 with field tests, indoor model tests have a safer environment for conducting systematic research and comparison of the effects of different parameters on grouting effects. Numerical simulations discretize physical phenomena through mathematical models and numerical algorithms to approximate solutions to complex engineering problems. However, existing research methods still have the following problems:

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

[0006] (2) It is difficult to numerically characterize the infiltration process of slurry in porous media: Currently, most numerical simulation methods focus on the diffusion, mechanical response and changes in physical properties of slurry. However, the importance of the influence of infiltration on slurry in porous media is often overlooked.

[0007] (3) Existing model tests often fail to fully consider the changes in extreme temperature conditions from low temperature to high temperature. In addition, during the model test, the injected medium leads to low repeatability of artificial laying. The existing porous medium model has certain limitations in terms of pore size and morphology control, material physical and chemical properties simulation, etc., resulting in low accuracy and reliability of the grouting mechanism revealed by the porous medium model. Summary of the invention

[0008] In order to solve the above problems, the present invention proposes a virtual-reality collaborative test system and method for porous medium grouting considering the infiltration effect. Based on the microstructure image of the natural stratum, a three-dimensional structure model of the pores is constructed, and the accurate reproduction of the pore structure is achieved through 3D printing technology. Considering the concentration change caused by the penetration of slurry in the porous medium, a comprehensive viscosity equation coupled with temperature, infiltration and time is constructed, and the verification and optimization of the visualized porous medium infiltration grouting test system are realized through numerical simulation.

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

[0010] A porous medium grouting virtual-real collaborative test system considering the percolation effect, comprising:

[0011] The visual formation simulation module includes an experimental platform, on which a medium filling tank is provided, the medium filling tank includes a plurality of detachable filling units, each of which has a grouting hole at the bottom; the filling units can be connected or disconnected as required; a transparent upper cover plate is provided on the top of the medium filling tank, and the upper cover plate is modularly designed;

[0012] The three-dimensional model of the porous stratum in each filling unit is obtained by a medium stratum reproduction module; the medium stratum reproduction module performs three-dimensional modeling of the porous stratum based on the microscopic structure image of the natural stratum, and prints the three-dimensional model of the porous stratum by 3D printing technology;

[0013] A temperature control module is used to realize temperature control of a three-dimensional model of a porous formation in a medium-filled slot;

[0014] A grouting module, connected with each filling unit through a grouting pipeline;

[0015] The main control module includes a verification and optimization unit, which is used to construct a momentum equation, a continuity equation, a temperature continuity equation, a chemical reaction equation, a temperature-percolation-time comprehensive viscosity equation and a slurry-water two-phase phase fraction equation according to the test system data, and obtain the numerical simulation results of the grouting speed, pressure, slurry viscosity, temperature, concentration and slurry diffusion morphology of the whole grouting process through coupling solution; the numerical simulation results are compared and verified with the test results, and the parameters of the porous formation three-dimensional model are optimized.

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

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

[0018] The data collected by the data acquisition module is fed back to the main control module, and the main control module realizes intelligent control of the entire test system based on the received data.

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

[0020] The water head intelligent sensing and regulating 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 in the constant temperature water storage tank into the three-dimensional model of the porous formation to simulate the dynamic water flow;

[0021] The constant temperature water storage tank integrates a PID-controlled intelligent heating element to control the water tank temperature to always remain within the set temperature range; the water level control unit collects water level information through a water level sensor arranged in the medium filling tank, and controls the water injection start-stop valve to open or close according to the collected water level information.

[0022] As a further solution, the temperature control module includes at least one heating unit, at least one cooling unit, and temperature sensors arranged at different positions in the medium filling tank;

[0023] The heating unit is arranged at the bottom of the medium filling tank, and can heat the three-dimensional model of the porous formation in the medium filling tank by heating;

[0024] The refrigeration unit is arranged 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 solution, the grouting speed, pressure, slurry viscosity, temperature and concentration of the whole grouting process are obtained through coupling solution, specifically:

[0026] The verification and optimization unit constructs a fluid domain grid according to the three-dimensional model of the porous formation, and sets initial boundary conditions of grouting velocity, grouting pressure, slurry temperature and slurry viscosity; constructs a continuity equation and a momentum equation according to the grouting velocity, grouting pressure, phase fraction and slurry viscosity, and repeatedly solves and iterates the slurry pressure and grouting velocity based on the continuity equation and the momentum equation to obtain the grouting pressure and grouting velocity v of the current time step;

[0027] A temperature continuity equation is established according to the grouting speed v of the current time step; the discretized heat transfer equation is coupled with the discretized temperature continuity equation to obtain the slurry temperature and the grouting speed;

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

[0029] The temperature-infiltration-time comprehensive viscosity equation is constructed based on the slurry temperature and concentration. The discretized temperature-infiltration-time comprehensive viscosity equation is coupled with the discretized chemical reaction equation, momentum equation and temperature continuity equation. After iterative solution, the final slurry viscosity, temperature, concentration, grouting speed and grouting pressure are obtained.

[0030] As a further solution, the discretized chemical reaction equation is specifically:

[0031]

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

[0033] As a further solution, the discrete temperature-filtration-time comprehensive viscosity equation is specifically:

[0034]

[0035] Among them, μ n is the slurry viscosity at the current time step; μ0 is the initial viscosity; R is the gas constant; E is the chemical reaction activation energy; T n is the temperature of the current time step; β is the concentration influence coefficient; α is the correction coefficient of the influence of chemical product concentration on the viscosity changing with temperature; C n is the slurry concentration at the current time step; γ is the reaction rate time constant, t n 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 porous medium grouting virtual-real collaborative test method considering the percolation effect adopts the above-mentioned visualized porous medium permeation grouting test system, comprising:

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

[0039] By means of numerical simulation, the diffusion of slurry in porous media is simulated, the numerical simulation results are compared with the test results, and the parameters of the porous formation three-dimensional model are optimized; the optimized porous formation three-dimensional model is placed in the filling unit of the medium filling tank as required;

[0040] Prepare slurry according to test requirements, set dynamic water level and temperature, set 3D model temperature, grouting speed and pressure parameters; start grouting;

[0041] During the grouting process, the slurry 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 collected at the same time;

[0042] Based on the temperature data inside the 3D model, the change analysis of the temperature field during the grouting process can be realized. Based on the grouting pressure data, the monitoring and analysis of the pressure change during the grouting process can be realized. Based on the image data, the analysis of the slurry diffusion mechanism under different conditions can be realized.

[0043] According to the test system data, the momentum equation, continuity equation, temperature continuity equation, chemical reaction equation, temperature-percolation-time comprehensive viscosity equation and slurry-water two-phase phase fraction equation are constructed. The grouting velocity, pressure, slurry viscosity, temperature, slurry concentration and slurry diffusion morphology of the whole grouting process are obtained by coupling solution. The numerical simulation results are compared and verified with the test results.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The present invention constructs a three-dimensional model of porous strata by comprehensively considering the type of media, distribution characteristics and regional permeability properties. This method combines microscopy and CT scanning with 3D printing technology, optimizes parameters based on numerical simulation, model testing and inversion analysis, and achieves high-precision reproduction of stratum pore structure. This innovation breaks through the reproduction difficulties and mechanism exploration obstacles caused by the complexity and uncertainty of medium structure, and provides a reliable method for studying grouting water blocking and reinforcement mechanisms in porous medium structures.

[0046] (2) The present invention is a porous media infiltration grouting simulation and analysis verification method based on the integration of multiple disciplines such as thermodynamics, fluid mechanics and materials science. In the numerical solution process, the heat exchange between the slurry and the medium, the evolution of the hydration reaction, and the change of the concentration field during the infiltration process (i.e., the percolation effect) are comprehensively considered. By constructing the chemical reaction equation and the temperature-percolation-time comprehensive viscosity equation, and combining the momentum equation, continuity equation and phase fraction equation and other control equations, the accurate characterization of the slurry viscosity change and the permeation mechanism during the porous media grouting process is achieved, and the experimental mechanism is effectively verified.

[0047] (3) The thickness of the porous stratum three-dimensional model set in the test system of the present invention is 0-5 cm, which is thinner than that of the normal three-dimensional model. Combined with the transparent overlying plate, the diffusion process of the slurry can be observed quickly and clearly, which can simplify the complexity of the experiment and enhance the visualization effect, so that the slurry penetration behavior is clearly visible under the transparent material, which is convenient for intuitive observation and analysis. The test system of the present invention can simulate extreme formation temperatures such as high temperature and low temperature, so as to study the changes and influences of the porous medium penetration mechanism under extreme temperature conditions.

[0048] Other features and advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of the structure of a visual porous medium penetration grouting test system in an embodiment of the present invention;

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

[0051] Among them, 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. slurry 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 DESCRIPTION

[0052] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0053] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0054] Embodiment 1

[0055] In one or more embodiments, a porous medium grouting virtual-real collaborative test system considering the infiltration effect is disclosed, combined with Figure 1 , including:

[0056] (1) Visual formation simulation module, including an experimental platform. The experimental platform is used to carry the test model. It is made of aluminum alloy and treated with corrosion-resistant coating to ensure that it will not be corroded during long-term experiments and can withstand high pressure. The test platform is equipped with a multi-functional bracket that can freely adjust the height and inclination of the test platform to meet the needs of different types of experiments.

[0057] The experimental platform is provided with a medium filling tank 1, which is made of double-layer stainless steel and high thermal conductivity composite materials to improve corrosion resistance and thermal conductivity, and add a heat insulation layer on the tank wall to reduce external temperature interference; the medium filling tank is provided with multiple detachable filling units, and each filling unit can be freely spliced. Figure 2 A schematic diagram of the structure of the first filling unit 13, the second filling unit 14 and the third filling unit 15 is provided. Each filling unit can be filled with a printed medium model separately, which can realize the simulation of various geological environments and is easy to replace and clean; the filling units can be connected or disconnected as needed, that is:

[0058] Each filling unit can be completely independent, and different medium models can be filled in each filling unit. There is no physical connection between the filling units. A grouting hole is provided at the bottom of each filling unit, and grouting can be performed independently through the grouting pipeline 5.

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

[0060] A transparent cover plate is provided on the top of the medium filling tank. The cover plate is made of transparent visible acrylic material and is coated with a scratch-resistant coating to extend the service life and maintain long-term clarity. After the medium in the medium filling tank is arranged, the cover plate is fixed to the upper part of the filling tank to seal and fix the filling medium inside. Multiple sensor interfaces are reserved on the cover plate, and pressure, temperature or flow rate sensors can be installed to realize real-time collection of experimental data. The cover plate adopts a modular design, and a threaded lifting device is installed at the four corners or edges of each modular cover plate. By rotating the spiral rod, the height lifting and tilting angle of the cover plate are controlled to simulate the distribution of different formation conditions.

[0061] (2) The medium formation reproduction module performs three-dimensional modeling of porous formations based on the microstructure image of natural formations and prints the three-dimensional model of porous formations through 3D printing technology;

[0062] In this embodiment, the three-dimensional model of the porous stratum in each filling unit is made by the medium stratum reproduction module. The microstructure image of the natural stratum is obtained by microscope and CT scanning technology, and it is digitized and three-dimensionally reconstructed to obtain the three-dimensional model of the porous stratum; the settings include interface thickness, interface material, printing speed, etc., and the 3D printer is further prepared to ensure the cleanliness of the printing bed, and level it as needed, load the appropriate printing material, upload the sliced ​​file to the 3D printer, and complete the 3D printing of the three-dimensional model of the porous stratum. 3D printing technology can better distinguish the interface conditions between strata and simulate the stratum conditions more realistically.

[0063] The thickness of the porous stratum three-dimensional model of this embodiment is 0-5 cm. Compared with the normal 20-30 cm thick geological three-dimensional model, the thickness of the porous stratum three-dimensional model of this embodiment is thinner. Combined with the transparent overlying plate, the diffusion process of the slurry can be observed quickly and clearly, which can simplify the experimental complexity and enhance the visualization effect, so that the slurry penetration behavior is clearly visible under the transparent material, which is convenient for intuitive observation and analysis.

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

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

[0066] Among them, the heating unit is arranged at the bottom of the medium filling tank, and can heat the porous formation three-dimensional model in the medium filling tank by heating; the heating unit can be heated by a variety of methods such as heating plate, resistance wire, water bath, etc. The heating unit can realize accurate and rapid heating from ambient temperature to 120°C according to the test temperature environment requirements; multiple heating units can divide the medium filling tank into multiple independent heating blocks, and through zone control, the temperature of each area can be independently adjusted and quickly heated to meet the needs of different tests.

[0067] The refrigeration unit is arranged at the bottom of the medium filling tank, including a cavity arranged 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, and can cool the three-dimensional model of the porous formation in the medium filling tank.

[0068] This embodiment achieves precise temperature control through rapid cooling through first-stage compression and fine adjustment through second-stage, ensuring that the system can quickly and accurately cool down the model temperature from ambient temperature to -20°C. The refrigeration unit can also adopt a modular design, which can be freely combined and expanded according to the experimental scale and cooling demand, improve flexibility and adaptability, and be suitable for rapid temperature adjustment under various experimental conditions. Multiple refrigeration units can divide the medium filling tank into multiple independent refrigeration blocks, and through zoning control, independent adjustment and rapid cooling of each area can be achieved to meet the needs of different experiments.

[0069] By arranging multiple high-precision temperature sensors at different positions in the medium filling tank, the temperature changes are monitored and all-round real-time data feedback is achieved to ensure uniform temperature control in the experimental model.

[0070] The distribution box can provide a stable power supply for the temperature control module, and ensure the safe operation of the power system and the stable power supply of the equipment through functions such as power distribution, overload short circuit protection, leakage protection and equipment control.

[0071] (4) A grouting module connected to each filling unit through a grouting pipeline.

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

[0073] The high-pressure constant-speed grouting pump is connected to each filling unit through a multi-channel grouting pipeline; the high-pressure constant-speed grouting pump supports multi-speed flow adjustment, and the multi-channel grouting pipeline adopts a wear-resistant and corrosion-resistant multi-channel grouting pipeline design, allowing multiple grouting points to work at the same time, realizing flexible adjustment of the slurry injection rate and slurry injection of each filling unit.

[0074] A flow sensor 4 and a pressure sensor 7 are arranged on the grouting pipeline to monitor the flow change and pressure fluctuation in real time during the grouting process.

[0075] The start, stop and gear position of the high-pressure constant-speed grouting pump can be controlled by the controller 9 to achieve accurate grouting throughout the entire test process.

[0076] (5) A water head intelligent sensing and regulating module, comprising: a constant temperature water storage tank 12, 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 in the constant temperature water storage tank into the three-dimensional model of the porous formation to simulate the dynamic water flow.

[0077] The constant temperature water tank integrates PID-controlled intelligent heating elements to control the water tank temperature to always remain within the set temperature range, and has an over-temperature automatic power-off protection function; the constant temperature water tank provides water for the dynamic water flow process in the porous medium. The water tank adopts a double-layer stainless steel structure, with the inner layer made of corrosion-resistant material and the outer layer made of high-efficiency heat-insulating material, and insulation material is filled between the two layers to ensure that the temperature in the water tank is stable and effectively prevent heat loss. In order to make the water temperature in the tank evenly distributed and avoid local temperature being too high or too low, a circulation pump is added inside the water 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. The water level information is collected by the water level sensor arranged in the medium filling tank, and the water injection start-stop valve is controlled to be opened or closed according to the collected water level information.

[0079] Water pressure sensors are respectively set at the water outlet of the water tank and the dynamic water injection port of the model to transmit water pressure information to the water level control device, which is set in the water tank to collect, feedback and regulate water pressure. The water injection port is located on the tank wall and connected to the water tank through a water supply pipeline. The water pump in the water tank injects water into the test model; the water supply pipeline is composed of a hose made of high-temperature and corrosion-resistant composite materials, and all pipe joints are designed with quick connection for easy installation and disassembly; at the same time, automatic pressure relief devices are set at key nodes.

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

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

[0082] The image acquisition device is set on the beam above the test model to capture the slurry diffusion morphology and slurry-water-medium interface during the grouting process in real time and transmit the image to the main control module.

[0083] In addition, the data acquisition module also includes a temperature sensor in the medium filling tank, a temperature sensor in the constant temperature water storage tank, a water level sensor, a pressure sensor, a flow sensor on the slurry supply pipeline, a pressure sensor, etc.; it is 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 of this embodiment mainly includes:

[0085] The central control unit 11 is used to realize intelligent regulation of the entire system, for example: intelligently controlling the water temperature in the water tank according to the temperature data transmitted by the data acquisition unit, and realizing internal temperature control by starting and stopping the heating device when the water temperature reaches the set temperature; intelligently controlling the water head height in the water head regulating device according to the water level data transmitted by the data acquisition unit, automatically detecting the water level in the water head regulating box and adjusting the lifting unit under the water tank to achieve the specified water level height and control the dynamic water flow rate.

[0086] The data comprehensive analysis unit 10 is used to comprehensively analyze the received data, integrate and analyze the temperature, pressure, and image data, depict the temperature field changes during the grouting process, monitor the 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 the momentum equation, continuity equation, temperature continuity equation, chemical reaction equation, temperature-percolation-time comprehensive viscosity equation and slurry-water two-phase phase fraction equation according to the test system data, and obtain the numerical simulation results of the grouting velocity, pressure, slurry viscosity, temperature, concentration and slurry diffusion morphology of the whole grouting process through coupling solution; compare and verify the numerical simulation results with the test results, and optimize the parameters of the porous formation three-dimensional model.

[0088] In this embodiment, a consolidation strength mechanical simulation experiment is carried out to simulate the process of solidification of the slurry after being injected into the porous medium, and verify the bonding performance and solidification characteristics of the material. Further, according to the initial parameters such as the thickness of the stratum interface, the interface material, and the printing speed, the physical model is printed, and the model test under the same conditions as the numerical calculation is carried out. According to the error value of the test results, the material parameters are repeatedly adjusted to gradually optimize the simulation accuracy. Finally, through multiple iterations and experimental verification, it is ensured that the simulation and inversion analysis are highly consistent with the actual data, so as to determine the optimal material parameters. At the same time, by selecting a combination of different particles and binders and adjusting the proportions to simulate the medium characteristics under various geological conditions, the final three-dimensional model is finally printed.

[0089] As a specific example, the grouting speed, pressure, slurry viscosity, temperature, and concentration of the entire grouting process are obtained through coupling solution. The specific process is as follows:

[0090] ① The verification and optimization unit constructs the fluid domain grid according to the three-dimensional model of the porous formation, and sets the initial boundary conditions of grouting velocity, grouting pressure, slurry temperature and slurry viscosity; the continuity equation and momentum equation are constructed according to the grouting velocity, grouting pressure, phase fraction and slurry 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 through experiments, g is the gravitational acceleration, F st is the surface tension.

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

[0094]

[0095] Where v is the fluid velocity vector, ρ is the density; ρ n+1 v n+1 and ρ n v n are the product of density and velocity at the new and old time steps, V CV is the volume of the control volume, S face The control volume is the area vector of the control volume surface. The control volume is a basic unit for dividing space in numerical calculations and is usually used in methods such as the finite volume method to discretize the conservation equations of fluids or other physical fields. n is the pressure at the current time step, is the viscous stress at the current time step, g is the gravitational acceleration, is the surface tension and Δt is the time step.

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

[0097] Based on the continuity equation and momentum equation, the slurry pressure and grouting speed are repeatedly solved and iterated to obtain the grouting pressure and grouting speed v of the current time step;

[0098] ② Establish the temperature continuity equation according to the grouting speed V of the current time step:

[0099]

[0100] Discretize the equation:

[0101]

[0102] Among them, T (n+1) is the temperature value of the next time step; T n is the temperature value of the current time step; ρ is the density; c p 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 is the heat exchange coefficient between the fluid and the medium; A i is the surface area of ​​contact between fluid and medium;∑ i hi A i (T i -T) is the heat exchange term, which indicates the heat exchange amount between the fluid and different media, where T i represents the temperature at the boundary of the control volume; u represents the velocity vector of the fluid, Represents the temperature gradient, which is used to describe the rate of change of temperature in space.

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

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

[0105]

[0106] Discretize the equation:

[0107]

[0108] Among them, C (n+1) is the slurry concentration at the next time step; C n is the slurry concentration at the current time step; Δt is the time step; k r is the rate constant of the chemical reaction; E a is the minimum energy required to start a chemical reaction; R is the gas constant; T n 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 solution and iteration of the slurry temperature and concentration until the slurry temperature and viscosity are obtained after reaching the number of iterations.

[0110] ④Construct the temperature-filtration-time comprehensive viscosity equation

[0111]

[0112] Discretize the equation:

[0113]

[0114] Among them, μ n is the viscosity of the current time step; μ0 is the initial viscosity; R is the gas constant; E is the activation energy of the chemical reaction; T n is the temperature of the current time step; β is the concentration influence coefficient, which is determined based on empirical data; α is the correction coefficient for the influence of chemical product concentration on the change of viscosity with temperature; C n 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 slurry in the entire slurry volume, and viscosity is the internal resistance encountered by the slurry during the flow process, which is a parameter that reflects the difficulty of slurry flow.

[0116] The discretized comprehensive viscosity equation is coupled with the chemical reaction equation, momentum equation and temperature continuity equation to realize the repeated solution and iteration of slurry viscosity, temperature, concentration and speed. After reaching the number of iterations, the slurry viscosity, temperature, concentration and grouting speed and pressure are obtained.

[0117] According to the grouting velocity v of the current time step, the discretized slurry-water two-phase phase fraction equation is constructed. The slurry diffusion morphology in the porous medium is obtained by solving the phase fraction equation. The slurry-water two-phase phase fraction equation is:

[0118]

[0119] Among them, α represents the volume proportion occupied by a specific phase in a given volume;

[0120] By repeatedly iteratively solving the above equations, the grouting velocity, pressure and diffusion morphology of the whole grouting process can be fully captured. Based on the comparative verification of the numerical solution results and the model tests carried out at typical time steps, the parameters of the three-dimensional model of porous formations can be optimized. At the same time, through the mutual verification of the two results, a comprehensive analysis of the grouting mechanism and law capture of porous media can be achieved.

[0121] Embodiment 2

[0122] In one or more embodiments, a method for virtual-real collaborative testing of porous media grouting considering the percolation effect is disclosed, using the visualized porous media permeation grouting test system described in Example 1, specifically including the following process:

[0123] (1) Obtaining microstructure images of natural strata, performing three-dimensional modeling of porous strata based on the microstructure images, and printing the three-dimensional model of porous strata by 3D printing technology;

[0124] (2) simulating the diffusion of slurry in porous media by numerical simulation, comparing the numerical simulation results with the test results, and optimizing the parameters of the porous formation three-dimensional model; placing the optimized porous formation three-dimensional model 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 medium stratum, a model test is carried out, and the medium parameters are optimized based on the digital model. The specific process is: the microstructure image of the natural stratum is obtained through a microscope and CT scanning technology, the accuracy of the initial parameters is verified by numerical simulation and physical experiments, the numerical simulation is compared with the actual data through grouting diffusion and consolidation strength experiments, the material parameters and printing conditions are adjusted according to the error value, and the optimization is iterated repeatedly. Finally, when the numerical simulation, inversion analysis and actual data are consistent and stable, the optimal parameters are determined and the final model is printed.

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

[0127] In this embodiment, according to the research requirements, the slurry selection and ratio, the water-rich condition of the formation, the dynamic water flow rate, the dynamic water temperature, and the porous medium characteristics are determined; according to the slurry selection and ratio, the slurry is prepared and injected into the slurry storage tank 8, the slurry can be single-liquid or double-liquid slurry, and the material can be selected as cement slurry, or specified materials such as water glass and new materials according to the needs; the water level control module is adjusted according to the head height; the water temperature of the water 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 groove and the overlying plate is sealed on the groove. According to the test purpose, the pressure and temperature data monitoring elements are arranged at the reserved opening of the overlying plate of the "pseudo three-dimensional" formation model, the elements are connected to the data acquisition device, the image acquisition and transmission module is turned on, and the grouting is started.

[0128] (4) Real-time monitoring of slurry flow rate, temperature and pressure data during grouting, while simultaneously collecting images of the 3D model of the porous formation;

[0129] (5) Based on the temperature data inside the three-dimensional model, the changes in the temperature field during the grouting process can be analyzed. Based on the grouting pressure data, the pressure changes during the grouting process can be monitored and analyzed. Based on the image data, the slurry diffusion mechanism under different conditions can be analyzed.

[0130] According to the test requirements, different grouting pressures are set according to different grouting rate ratios. After the setting is completed, grouting begins. The injection process tracks and records the monitoring data such as grouting flow rate, temperature, and pressure in real time. The collected data is analyzed, and the change analysis of the temperature field during the grouting process is realized based on the temperature data inside the three-dimensional model; the monitoring and analysis of the pressure change during the grouting process is realized based on the grouting pressure data; according to the transmitted image information, the law of the slurry diffusion mechanism under different medium filling, different dynamic water flow rates and other conditions during the grouting process is analyzed, and the various experimental data are converted into visual charts through comprehensive data analysis to display the temperature field, pressure changes and slurry diffusion morphology, and monitor in real time on the system display screen.

[0131] (6) Based on the test system data, the momentum equation, continuity equation, temperature continuity equation, chemical reaction equation, temperature-percolation-time comprehensive viscosity equation and slurry-water two-phase phase fraction equation are constructed. Through coupled solution, the numerical simulation results of the grouting velocity, pressure, slurry viscosity, temperature, concentration and slurry diffusion morphology of the whole grouting process are obtained; the numerical simulation results are compared and verified with the test results.

[0132] In this embodiment, numerical test verification is carried out. According to the test model, a fluid domain grid is constructed, and initial boundary conditions are set. The initial boundary conditions include grouting velocity, grouting pressure, slurry temperature and slurry viscosity. Energy equation, continuity equation, temperature continuity equation, chemical reaction equation and temperature-percolation-time comprehensive viscosity equation are constructed, and coupled discrete solutions are performed to obtain all-round information on grouting velocity, pressure and diffusion morphology of the whole grouting process. The numerical solution results are compared and verified with the model test carried out at a typical time step.

[0133] After the verification is completed, the slurry plugging rules and mechanisms under single variable conditions or multi-condition coupling conditions such as different medium temperatures, different porous medium formations, different dynamic water flow rates, different dynamic water temperatures, and different slurry selections are obtained through data analysis results.

[0134] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it 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 on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A porous medium grouting virtual-real collaborative test system considering the infiltration effect, characterized in that: include: The visual formation simulation module includes an experimental platform, on which a medium filling tank is provided, the medium filling tank includes a plurality of detachable filling units, each of which has a grouting hole at the bottom; the filling units can be connected or disconnected as required; a transparent upper cover plate is provided on the top of the medium filling tank, and the upper cover plate is modularly designed; The three-dimensional model of the porous stratum in each filling unit is obtained by a medium stratum reproduction module; the medium stratum reproduction module performs three-dimensional modeling of the porous stratum based on the microscopic structure image of the natural stratum, and prints the three-dimensional model of the porous stratum by 3D printing technology; A temperature control module is used to realize temperature control of a three-dimensional model of a porous formation in a medium-filled slot; A grouting module, connected with each filling unit through a grouting pipeline; The main control module includes a verification and optimization unit, which is used to construct a momentum equation, a continuity equation, a temperature continuity equation, a chemical reaction equation, a temperature-percolation-time comprehensive viscosity equation and a slurry-water two-phase phase fraction equation according to the test system data, and obtain the numerical simulation results of the grouting speed, pressure, slurry viscosity, temperature, concentration and slurry diffusion morphology of the whole grouting process through coupling solution; the numerical simulation results are compared and verified with the test results, and the parameters of the porous formation three-dimensional model are optimized.

2. A porous medium grouting virtual-real collaborative test system considering the infiltration effect as claimed in claim 1, characterized in that: Also includes: A data acquisition module is used to collect slurry temperature, grouting pressure and image data during the grouting process, and to visualize the data; wherein the image data can display the slurry diffusion morphology and slurry-water-medium interface during the grouting process; The data collected by the data acquisition module is fed back to the main control module, and the main control module realizes intelligent control of the entire test system based on the received data.

3. A porous medium grouting virtual-real collaborative test system considering the infiltration effect as claimed in claim 1, characterized in that: Also includes: Water head intelligent sensing and regulating module, including: constant temperature water storage tank, 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, and is used to inject water in the constant temperature water storage tank into the three-dimensional model of the porous formation to simulate the dynamic water flow; The constant temperature water storage tank integrates a PID-controlled intelligent heating element to control the water tank temperature to always remain within the set temperature range; the water level control unit collects water level information through a water level sensor arranged in the medium filling tank, and controls the water injection start-stop valve to open or close according to the collected water level information.

4. A porous medium grouting virtual-real collaborative test system considering the infiltration effect as claimed in claim 3, characterized in that: The constant temperature water storage tank adopts a double-layer stainless steel structure, the inner layer is made of corrosion-resistant material, the outer layer is made of high-efficiency heat-insulating material, and heat-insulating material is filled between the two layers.

5. A porous medium grouting virtual-real collaborative test system considering the infiltration effect as claimed in claim 1, characterized in that: The temperature control module includes at least one heating unit, at least one cooling unit and temperature sensors arranged at different positions in the medium filling tank; The heating unit is arranged at the bottom of the medium filling tank, and can heat the three-dimensional model of the porous formation in the medium filling tank by heating; The refrigeration unit is arranged 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. A porous medium grouting virtual-real collaborative test system considering the infiltration effect as claimed in claim 1, characterized in that: The transparent upper cover plate is connected to the medium filling slot via a lifting device, and the lifting device can adjust the height and inclination of the transparent upper cover plate.

7. A porous medium grouting virtual-real collaborative test system considering the infiltration effect as claimed in claim 1, characterized in that: The grouting speed, pressure, slurry viscosity, temperature and concentration of the whole grouting process are obtained through coupling solution, specifically: The verification and optimization unit constructs a fluid domain grid according to the three-dimensional model of the porous formation, and sets initial boundary conditions of grouting velocity, grouting pressure, slurry temperature and slurry viscosity; constructs a continuity equation and a momentum equation according to the grouting velocity, grouting pressure, phase fraction and slurry viscosity, and repeatedly solves and iterates the slurry pressure and grouting velocity based on the continuity equation and the momentum equation to obtain the grouting pressure and grouting velocity v of the current time step; A temperature continuity equation is established according to the grouting speed v of the current time step; the discretized heat transfer equation is coupled with the discretized temperature continuity equation to obtain the slurry temperature and the grouting speed; A chemical reaction equation is established based on the slurry temperature, and the discretized chemical reaction equation is coupled with the discretized temperature continuity equation to obtain the slurry temperature and viscosity; The temperature-infiltration-time comprehensive viscosity equation is constructed based on the slurry temperature and concentration. The discretized temperature-infiltration-time comprehensive viscosity equation is coupled with the discretized chemical reaction equation, momentum equation and temperature continuity equation. After iterative solution, the final slurry viscosity, temperature, concentration, grouting speed and grouting pressure are obtained.

8. A porous medium grouting virtual-real collaborative test system considering the infiltration effect as claimed in claim 7, characterized in that: The discretized chemical reaction equation is specifically: Among them, C (n+1) is the slurry concentration at the next time step; C n is the slurry concentration at the current time step; Δt is the time step; k r is the rate constant of the chemical reaction; E a is the minimum energy required to start a chemical reaction; R is the gas constant; T n is the temperature value at the current time step.

9. A porous medium grouting virtual-real collaborative test system considering the infiltration effect as claimed in claim 7, characterized in that: The discrete temperature-filtration-time comprehensive viscosity equation is specifically: Among them, μ n is the slurry viscosity at the current time step; μ0 is the initial viscosity; R is the gas constant; E is the chemical reaction activation energy; T n is the temperature of the current time step; β is the concentration influence coefficient; α is the correction coefficient of the influence of chemical product concentration on the viscosity changing with temperature; C n is the slurry concentration at the current time step; γ is the reaction rate time constant, t n Represents the value of the time variable t at the nth time step.

10. A method for virtual-real collaborative testing of porous media grouting considering the infiltration effect, using the visualized porous media permeability grouting test system according to any one of claims 1 to 9, characterized in that: include: Obtain microstructure images of natural strata, perform three-dimensional modeling of porous strata based on the microstructure images, and print the three-dimensional model of porous strata using 3D printing technology; By means of numerical simulation, the diffusion of slurry in porous media is simulated, the numerical simulation results are compared with the test results, and the parameters of the porous formation three-dimensional model are optimized; the optimized porous formation three-dimensional model is placed in the filling unit of the medium filling tank as required; Prepare slurry according to test requirements, set dynamic water level and temperature, set 3D model temperature, grouting speed and pressure parameters; start grouting; During the grouting process, the slurry 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 collected at the same time; Based on the temperature data inside the 3D model, the change analysis of the temperature field during the grouting process can be realized. Based on the grouting pressure data, the monitoring and analysis of the pressure change during the grouting process can be realized. Based on the image data, the analysis of the slurry diffusion mechanism under different conditions can be realized. According to the test system data, the momentum equation, continuity equation, temperature continuity equation, chemical reaction equation, temperature-percolation-time comprehensive viscosity equation and slurry-water two-phase phase fraction equation are constructed. The grouting velocity, pressure, slurry viscosity, temperature, slurry concentration and slurry diffusion morphology of the whole grouting process are obtained by coupling solution. The numerical simulation results are compared and verified with the test results.

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