Porous media grouting test system and method taking temperature effects into consideration

Abstract

A porous media grouting test system and method taking temperature effects into consideration. The system comprises a porous media formation simulation model (1), a grouting system (2), a water level adjustment system, a formation temperature control system and a data analysis system, wherein the porous media formation simulation model (1) is used for simulating a porous media formation; the water level adjustment system and the formation temperature control system are used for simulating the conditions of different water saturation levels and different water temperatures and ground temperatures; and the data analysis system is used for comparing different time-series data collected by sensors such as a temperature sensor and a pressure sensor with data such as temperature data and pressure data that is obtained by means of coupled solving of a heat transfer equation and a momentum equation, so as to verify and analyze a grouting diffusion path. Free simulation of different water saturation levels is realized by means of a water level adjustment system, and simulation of different ground temperatures is realized by means of a formation temperature control system, thereby realizing the research on grouting diffusion under different water levels and different water temperatures and ground temperatures.

Description

A porous medium grouting test system and method considering temperature effect

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] The present invention claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on December 11, 2023, with application number 202311705174.3 and invention name “A grouting test system and method for porous media considering temperature effects”, the entire contents of which are incorporated by reference into the present invention and constitute a part of the present invention for all purposes. Technical Field

[0003] The present invention belongs to the technical field related to porous medium grouting tests, and in particular relates to a porous medium grouting test system and method taking temperature effects into consideration. Background Art

[0004] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0005] During tunnel construction, water damage is a common and significant problem, affecting construction quality, delaying progress, increasing costs, and even leading to serious accidents. Grouting is the most commonly used method for water damage prevention and control. Grouting gradually transforms from a liquid to a solid phase over time, sealing water channels and effectively reinforcing the ground, playing a vital role in tunnel construction.

[0006] Geological environments vary significantly from region to region. Designing flood control strategies for different geological conditions requires tailoring these characteristics. Leakage formations filled with porous media such as sand and gravel are common in alluvial fan plains, such as the Chengdu Plain and the Beijing Small Plain. These porous media have unstable mechanical properties, making grout loss during grouting a frequent occurrence. This often results in significantly increased grouting volume without effectively stabilizing the formation. Currently, no satisfactory solution exists, and the only effective approach is to minimize the impact by using multiple drilling holes, multiple grouting injections, or fast-setting grouts. In some areas, porous media formations are affected by high-temperature hot springs and high ground temperatures. Conventional grouting materials are susceptible to failure in these environments, and the presence of high-temperature water further complicates flood control. Therefore, understanding the grouting and diffusion mechanisms of grouting in these environments is crucial. Current model tests for grouting in porous media have not fully considered the grouting diffusion mechanism under the coupled conditions of multiple factors, such as the water-richness of the porous formation, water temperature, and ground temperature effects. Furthermore, accurate visualization of the grouting diffusion process during grouting in porous media formations is not possible. In terms of conducting model tests, the existing grouting equipment also cannot meet the requirements of controllable constant-speed grouting and the convenience of grout storage and cleaning. Summary of the Invention

[0007] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a porous medium grouting test system and method that takes into account the water-geothermal effect. The free simulation of different water richness and different water temperatures is achieved through the water level regulation system, and the simulation of different ground temperatures is achieved through the formation temperature control system, thereby realizing the study of grouting diffusion under different water levels, water temperatures and ground temperatures.

[0008] To achieve the above-mentioned object, a first aspect of the present invention provides a porous medium grouting test system considering temperature effects, comprising: a porous medium formation simulation model, a grouting system, a water level regulation system, a formation temperature control system, and a data analysis system;

[0009] The porous medium formation simulation model includes a test box filled with porous medium;

[0010] The grouting system is connected to the grouting port pipeline of the porous medium formation simulation model, and provides a grouting method with controllable grouting rate and grouting pressure for the porous medium formation simulation model;

[0011] The water level regulating system is connected to the pipeline of the porous medium formation simulation model, and provides a water injection method with adjustable water volume and controllable water temperature for the porous medium formation simulation model;

[0012] The formation temperature control system includes a heating device and a temperature monitoring sensor. The temperature monitoring sensor is arranged inside the porous medium formation simulation model. The heating device is used to heat the interior of the porous medium formation simulation model to simulate different ground temperatures.

[0013] The data acquisition device includes a plurality of temperature sensors and pressure sensors, and the temperature sensors and pressure sensors are respectively arranged at different positions in the porous medium formation simulation model;

[0014] The data analysis system is signal-connected to the data acquisition device and is used to compare the different time series data collected by the temperature sensor and pressure sensor with the temperature data and pressure data solved by coupling the heat transfer equation and the momentum equation, so as to verify and analyze the grouting diffusion path.

[0015] A second aspect of the present invention provides a porous medium grouting test method taking temperature effects into account, comprising:

[0016] injecting water of a preset water-richness and a preset water temperature into the porous medium formation simulation model through a water level regulating system; wherein the porous medium formation simulation model is filled with porous medium;

[0017] heating the interior of the porous medium formation simulation model to a preset ground temperature through a formation temperature control system;

[0018] Grouting is performed into the porous medium stratum simulation model through a grouting port provided below the porous medium stratum simulation model by a grouting system;

[0019] The temperature and pressure data during the grouting process are collected through the data acquisition system and transmitted to the data analysis system;

[0020] The data analysis system compares the temperature data and pressure data of different time series collected by the temperature sensor and pressure sensor with the temperature data and pressure data solved by coupling the heat transfer equation with the momentum equation, thereby realizing verification analysis of the grouting diffusion path.

[0021] One or more of the above technical solutions have the following beneficial effects:

[0022] In the present invention, free simulation of different water richness is achieved through the water level regulation system, and simulation of different ground temperatures is achieved through the formation water bath temperature control system, which can realize the study of grouting diffusion under different water levels, water temperatures and ground temperatures.

[0023] In the present invention, the heat transfer equation is coupled with the momentum equation to realize the simulation of grouting temperature, slurry velocity and slurry diffusion morphology. Based on the comparison of simulation data with experimental measured data and the slice analysis of the stone body, the accurate evolution of the slurry diffusion path in the porous formation is realized.

[0024] In this invention, a screw-connected piston, in conjunction with a speed control module and an air pressure regulation module, enables rapid slurry storage, cleaning, and constant-rate grouting. Compared to traditional air pressure-driven constant-rate grouting methods, this allows for precise constant-rate slurry injection throughout the entire process, facilitating slurry storage and cleaning.

[0025] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0027] FIG1 is a diagram of a porous medium grouting test device considering temperature effects in Example 1 of the present invention;

[0028] FIG2 is a layout diagram of a porous medium grouting test model considering temperature effects in Example 1 of the present invention;

[0029] 3 is a structural diagram of a grouting system lifter of a porous medium grouting test device considering temperature effects in Example 1 of the present invention;

[0030] FIG4 is a flow chart of a porous medium grouting test method considering temperature effects in Example 2 of the present invention;

[0031] Among them, 1. Porous medium formation simulation system; 2. Dual-liquid grouting system; 3. Slurry storage tank; 4. Waste liquid outflow pipe; 5. Waste liquid collection container; 6. Heating device; 7. Upper baffle; 8. Waste liquid discharge pipe; 9. Pebble cushion; 10. Pressure sensor; 11. Seepage pressure sensor; 12. Rubber cushion; 13. Motor; 14. Speed ​​regulating valve; 15. First air pressure valve; 16. Air pressure regulating channel at the screw platform; 17. Screw platform; 18. Second air pressure valve; 19. Screw; 20. Air pressure regulating channel at the piston; 21. Piston. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0033] It should be noted that the terms used herein are for describing particular embodiments only and are not intended to limit the exemplary embodiments according to the present invention.

[0034] In the absence of conflict, the embodiments of the present invention and the features thereof may be combined with each other.

[0035] Example 1

[0036] As shown in FIG1 , this embodiment discloses a porous medium grouting test system considering temperature effects, comprising: a porous medium formation simulation model, a grouting system, a water level regulation system, a formation temperature control system, and a data analysis system;

[0037] The porous medium formation simulation model includes a test box filled with porous medium;

[0038] The grouting system is connected to the grouting port pipeline of the porous medium formation simulation model, and provides a grouting method with controllable grouting rate and grouting pressure for the porous medium formation simulation model;

[0039] The water level regulating system is connected to the pipeline of the porous medium formation simulation model, and provides a water injection method with adjustable water volume and controllable water temperature for the porous medium formation simulation model;

[0040] The formation temperature control system includes a heating device and a temperature monitoring sensor. The temperature monitoring sensor is arranged inside the porous medium formation simulation model. The heating device is used to heat the interior of the porous medium formation simulation model to simulate different ground temperatures.

[0041] The data acquisition device includes a plurality of temperature sensors and pressure sensors, and the temperature sensors and pressure sensors are respectively arranged at different positions in the porous medium formation simulation model;

[0042] The data analysis system is signal-connected to the data acquisition device and is used to compare the different time series data collected by the temperature sensor and pressure sensor with the temperature data and pressure data solved by coupling the heat transfer equation and the momentum equation, so as to verify and analyze the grouting diffusion path.

[0043] A porous medium grouting test system considering temperature effect of this embodiment is described in detail below with reference to FIG. 1 .

[0044] A porous medium grouting test system considering temperature effects in this embodiment includes a test platform, a porous medium formation simulation system 1, a dual-liquid grouting system 2, a water level adjustment system, a formation temperature control system, a waste liquid treatment system, a data acquisition system, a data analysis system and a visualization system.

[0045] Specifically, as shown in Figure 2, the porous medium formation simulation system 1 includes a test box / barrel and porous media, which provide an environment and a medium-filled foundation for the grouting test; the upper and lower parts of the test box / barrel are respectively an upper baffle 7 and a lower bottom plate, a slurry-permeable partition is provided at the upper position inside the test box / barrel, and the slurry outlet is located in the middle of the upper baffle 7, and a pebble cushion layer 9 is filled between the slurry-permeable partition and the upper baffle 7. The function of the pebble cushion layer 9 is to prevent the diffusion of slurry from driving the medium out of the outlet during the grouting process, and to ensure that the slurry has an outflow channel to avoid excessive internal pressure; the middle part of the upper baffle 7 is the slurry outlet, the position of the slurry outlet can be adjusted according to actual needs, and sensor placement holes and internal sensor wire outlet holes are provided around the slurry outlet; a grouting hole and a water injection port are provided in the middle of the lower bottom plate, and the water injection port realizes water level adjustment of the water richness; a rubber cushion layer 12 is provided on the inner wall of the test box / barrel, the function of which is to facilitate demoulding after grouting is completed.

[0046] As shown in Figure 3, the dual-liquid grouting system 2 includes a grouting module and a control module. The grouting module includes: a screw 19, a piston 21, a speed regulating valve 14, a motor 13, an air pressure regulating module and a slurry storage tank 3; the upper part of the screw 19 is set through the screw platform 17, and the lower end of the screw 19 is connected to the piston 21. The screw 19 is located in the center of the device and extends into the slurry storage tank 3; under the driving action of the motor 13 and the speed regulating valve 14, the screw 19 applies a stable pressure to the slurry in the slurry storage tank 3 to achieve constant speed slurry discharge, and the piston 21 must ensure good air tightness; the speed regulating valve 14 is set on the screw platform 17, which is used to adjust the lifting rate of the screw 19; the motor 13 is connected to the speed regulating valve 14 to provide stable power for the operation of the grouting system.

[0047] The air pressure regulating module is arranged on the opening between the piston 21 and the screw platform 17 to realize the air pressure regulation during the grouting process and the slurry storage process. It can also serve as a slurry storage channel and a cleaning channel after the grouting is completed. Specifically, the first opening of the piston 21 is connected to the opening of the screw platform 17 by a pipe to form an air pressure regulating channel 16 at the screw platform. The second opening of the piston 21 forms an air pressure regulating channel 20 at the piston. A first air pressure valve 15 is set on the air pressure regulating channel 16 at the screw platform, and a second air pressure valve 18 is set on the air pressure regulating channel 20 at the piston. When storing slurry, the two air pressure valves are opened and the slurry is poured in from the top. After the injected slurry reaches the specified position and stabilizes, the slurry storage is completed. When grouting, the two air pressure valves are closed to achieve a sealed environment for the grouting process. The motor 13 drives the piston 21 to push the slurry in the slurry storage tank 3 out to complete the grouting, and cooperates with the speed regulating valve to meet different grouting rate requirements to achieve a closed grouting process for smooth grouting. The slurry storage tank 3 is located below the screw platform 17 and is fixed on the screw platform 17 for storing slurry. After the grouting is completed, the air pressure regulating module is opened and high-pressure water is injected through the opening to facilitate cleaning inside the slurry storage tank. The control module is used to start and stop the various functions of the grouting module and adjust the gear position, ultimately achieving precise grouting throughout the entire test process.

[0048] The water level regulation system includes a water injection module and a water level control module. The water injection module includes a water tank, water pipes, a water pump, a water injection valve, and a water level sensor. The water injection port of the test box / barrel in the porous medium formation simulation system is connected to the water tank via the water pipe. The water pump in the water tank injects water into the porous medium formation simulation system 1. The water level control module includes a water level sensor, a water level control device, and a water injection start-stop valve. The water level sensors are installed around the test box / barrel to sense water level changes and transmit water level information to the water level control device, which enables real-time water injection and stopping through the water injection valve.

[0049] The formation temperature control system includes a heating device 6, a temperature monitoring device, and a temperature control device; the heating device 6 can adopt a circulating water bath temperature control method outside the model, the inlet of the circulating water heating device is connected to the constant temperature water tank, the outlet is connected to the pipeline, the pipeline is connected to the heating water tank, the heating water tank realizes the heating position of the water temperature and is close to the constant temperature water tank, which is used to prevent the temperature loss of water during the flow of the pipeline. After the water temperature is heated to the set temperature, it is injected into the constant temperature water tank to keep the water temperature constant. The above steps are repeated to realize water bath temperature control and realize the temperature control of the porous medium. The temperature data is recorded in real time by the internal temperature monitoring sensor. After reaching the specified temperature, it is instructed by the temperature control device to maintain the current temperature.

[0050] The waste liquid treatment system includes a waste liquid outflow pipe 4 and a waste liquid collection container 5; the waste liquid collection container 5 can realize the orderly separation of water and slurry; the waste liquid in the test box / barrel flows into the waste liquid collection container 5 through the waste liquid discharge pipe 8 and the waste liquid outflow pipe 4, and then the solid-liquid separation of slurry and water is realized through the filter plate in the waste liquid collection container 5.

[0051] The data acquisition system includes a temperature sensor and a pressure sensor 10; the temperature sensor is arranged in the porous medium to monitor the temperature, ensure that the temperature in the model meets the preset temperature, and transmit real-time temperature data to the data analysis system; the pressure sensor 10 is divided into a soil pressure sensor and a seepage pressure sensor 11. The soil pressure sensor is arranged around the inside of the model and on the slurry-permeable partition to monitor the pressure changes in the model; the seepage pressure sensor 11 is buried in the porous medium to monitor the pore water pressure inside the medium in real time, and transmits real-time data to the data analysis system to obtain the law of internal pressure changes during the grouting process.

[0052] The data analysis system includes a thermal analysis module and a pressure analysis module. The thermal analysis module solves the temperature and grouting rate based on parameters such as the thermal conductivity, thermal diffusion coefficient, initial boundary conditions and slurry injection temperature of the underground medium by coupling the heat transfer equation with the energy equation, and compares the results with data such as the temperature and pressure time series changes captured by the temperature and pressure sensors to realize diffusion path verification analysis. The pressure analysis module can realize slurry pressure analysis in the medium, analyze the changing laws of the confining pressure and seepage pressure inside the medium, and obtain the appropriate pressure range for grouting and plugging of porous media under the influence of temperature effect and water richness.

[0053] The visualization system includes a slurry diffusion visualization module, a temperature field visualization display module, and a pressure field visualization display module; the slurry diffusion visualization module realizes the dynamic display of the slurry diffusion path, as well as the dynamic display of the temperature field and pressure field.

[0054] Example 2

[0055] As shown in FIG4 , this embodiment provides a porous medium grouting test method considering temperature effects, including:

[0056] injecting water of a preset water-richness and a preset water temperature into the porous medium formation simulation model through a water level regulating system; wherein the porous medium formation simulation model is filled with porous medium;

[0057] heating the interior of the porous medium formation simulation model to a preset ground temperature through a formation temperature control system;

[0058] Grouting is performed into the porous medium stratum simulation model through a grouting port provided below the porous medium stratum simulation model by a grouting system;

[0059] The temperature and pressure data during the grouting process are collected through the data acquisition system and transmitted to the data analysis system;

[0060] The data analysis system compares the temperature data and pressure data of different time series collected by the temperature sensor and pressure sensor with the temperature data and pressure data solved by coupling the heat transfer equation with the momentum equation, thereby realizing verification analysis of the grouting diffusion path.

[0061] Specifically, the test method includes the following steps:

[0062] Step 1: According to the water richness of the formation required for the test, the water level is injected to the designated position, which is equipped with a water level control device to ensure the stability of the water level and realize the autonomous adjustment of the water level;

[0063] Step 2: Heat the temperature inside the test model to the specified temperature and keep the temperature constant. To ensure the visualization of the internal grouting process and the constant temperature control effect, the heating adopts the model external circulation water bath temperature control method. The inlet of the circulating water heating device is connected to the constant temperature water tank, and the outlet is connected to the pipeline. The pipeline is connected to the heating water tank. The heating water tank is located close to the constant temperature water tank to prevent the water from losing temperature during the flow of the pipeline. After the water temperature is heated to the original set temperature, it is injected into the constant temperature water tank to keep the water temperature constant. The above steps are repeated to achieve water bath temperature control;

[0064] Step 3: After the temperature is constant, prepare single grouting liquid or double grouting liquid according to the experimental requirements and material ratio. The material can be selected as cement slurry or specified materials such as water glass and new materials according to the requirements;

[0065] Step 4: Inject the prepared slurry into the grouting system, open the air pressure control valve of the grouting system slurry storage tank and the grouting inlet valve, and inject the slurry into the slurry storage tank from the upper end of the grouting channel inside the screw. After the injected slurry reaches the designated position, close the grouting inlet valve and the air pressure control valve. Inject water glass or new materials into another grouting system in the same way;

[0066] Step 5: Adjust the rate of the dual-liquid grouting system, turn on the switch to inject dual-liquid or single-liquid into the porous medium model, track and record the pressure monitoring data in real time during the injection process, record the pressure of the grouting port and the side wall of the model, and avoid excessive pressure inside the medium model to cause danger.

[0067] Step 6: Based on the test model, construct the fluid domain grid and set the initial boundary conditions, which include grouting velocity, grouting pressure, slurry temperature, and slurry viscosity. Build a momentum prediction equation based on the grouting velocity, grouting pressure, phase fraction, and slurry viscosity, and predict the grouting velocity by solving the momentum equation.

[0068] The momentum equation is:

[0069] Where ρ is density, p is pressure, μ is the viscosity function characterized by time t and slurry temperature T, which can be obtained through experiments, g is the acceleration of gravity, F st is the surface tension.

[0070] The predicted grouting velocity is solved by the discretized momentum prediction equation:

[0071] Among them, ρ n+1 v n+1 and ρ n v n are the density and velocity products of the new and old time steps, V CV is the volume of the control volume, S face The area vector of the control volume surface, p n is the pressure at the current time step, is the viscous stress at the current time step, g is the acceleration due to gravity, is the surface tension and Δt is the time step.

[0072] Furthermore, the slurry water continuity equation is:

[0073] Where v is the fluid velocity vector.

[0074] The discretized continuity equation is coupled with the momentum equation to realize the repeated solution and iteration of the slurry pressure and grouting velocity. After the number of iterations is reached, the obtained grouting pressure and grouting velocity are the grouting pressure and grouting velocity v of the current time step.

[0075] Furthermore, the slurry water heat transfer equation is established according to the grouting velocity v of the current time step: Q=-ΔH rxn r

[0076] Where T is temperature, c p is the specific heat capacity of the fluid, k is the thermal conductivity of the porous medium, Q represents the heat generated and released during the solidification phase change of the slurry, ΔH rxn is the heat released per mole of reaction, which can be an empirical value, r is the rate of chemical reaction, which can be an empirical value, and v is the fluid velocity vector.

[0077] The predicted slurry temperature can be predicted by solving the discretized prediction equation:

[0078] Among them, T new With T old are the temperatures of the old and new time steps respectively, Δt is the time step length, V CV is the volume of the control volume, S faceis the area vector of the control volume face, pointing normal to the face and outward.

[0079] The discretized heat transfer equation is coupled with the momentum equation to realize the repeated solution and iteration of the slurry temperature and grouting velocity until the number of iterations is reached and the slurry temperature and grouting velocity v are obtained.

[0080] The discretized slurry-water two-phase phase fraction equation is constructed according to the grouting velocity v of the current time step. 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:

[0081] Here, α represents the volume fraction occupied by a specific phase within a given volume.

[0082] According to the repeated iterations of the above equations, the slurry diffusion path is finally visualized through the phase fraction equation.

[0083] After the simulation is completed, the temperature field data and grouting pressure data of the current time step are compared with the actual test data. If the temperature field data, grouting pressure and velocity data are consistent with the test data, the accurate simulation of the slurry diffusion morphology and the capture of the slurry diffusion path in the porous medium are achieved.

[0084] Step 7: After the grouting is completed, the obtained pressure data and temperature field data are displayed and further analyzed. The pressure data is further analyzed to obtain the grouting plugging material ratio and grouting pressure range suitable for porous media under the influence of temperature effect and water richness.

[0085] Step 8: De-mold the stone body inside the model and perform a three-dimensional scan on the whole body. Pre-mark the slice position to slice the stone body, and further compare the slurry diffusion path images of each cross-section of the stone body. If the cross-section shows the full penetration form of the slurry, the penetration time calculated by the penetration rate is time-matched with the simulation result. If they are consistent, it can be considered that the diffusion result of this simulation is the slurry diffusion form; if there are some areas where the slurry has not penetrated on the cross-section, there is a compacted slurry diffusion behavior, which appears as a cavity in the slice. The spatial point cloud data of the cavity morphology is obtained by three-dimensional scanning technology, and the point cloud coordinates of the cavity position are clustered. Class analysis is used to extract and fit discontinuities. The coordinates of the marked position of the slice where the cavity is located are matched to the three-dimensional model of the stone body to determine the location and range of the compaction grouting. The final diffusion morphology of the compaction grouting portion is determined by comparing the cavity morphology with the simulated morphology and the corresponding slurry penetration time. If cracks are present on the cross-section, a three-dimensional scan of the crack and the corresponding slice is performed, and cluster analysis of the point cloud coordinates at the crack is performed to extract and fit discontinuities. The spatial coordinates of the crack located in the stone body are extracted to determine the diffusion morphology of the splitting grouting. Through the above steps, the multi-modal diffusion of slurry in porous medium formations is accurately captured. Based on the obtained visualization, the diffusion results and data are used to effectively analyze the factors affecting compaction grouting and the splitting pressure demarcation point and influencing factors of porous medium grouting. The splitting pressure value, the splitting and compaction consolidation body morphology, and the splitting and compaction grouting laws under the action of different factors are obtained.

[0086] Those skilled in the art will appreciate that the modules or steps of the present invention described above can be implemented using a general-purpose computer device. Alternatively, they can be implemented using program code executable by a computing device, which can then be stored in a storage device and executed by the computing device. Alternatively, they can be fabricated into separate integrated circuit modules, or multiple modules or steps can be fabricated into a single integrated circuit module for implementation. The present invention is not limited to any specific combination of hardware and software.

[0087] Although the above describes the specific embodiments 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 any creative work are still within the scope of protection of the present invention.

Claims

1. A porous medium grouting test system considering temperature effect, characterized in that: include: Porous medium formation simulation model, grouting system, water level regulation system, formation temperature control system, data acquisition system and data analysis system; The porous medium formation simulation model comprises a test box filled with porous medium; The grouting system is connected to the grouting port pipeline of the porous medium formation simulation model, and provides a grouting method with controllable grouting rate and grouting pressure for the porous medium formation simulation model; The water level regulating system is connected to the pipeline of the porous medium formation simulation model to provide a water injection method with adjustable water volume and controllable water temperature for the porous medium formation simulation model; The formation temperature control system comprises a heating device and a temperature monitoring sensor, wherein the temperature monitoring sensor is arranged inside the porous medium formation simulation model, and the heating device is used to heat the inside of the porous medium formation simulation model to simulate different ground temperatures; The data acquisition system includes a plurality of temperature sensors and pressure sensors, and the temperature sensors and pressure sensors are respectively arranged at different positions in the porous medium formation simulation model; The data analysis system is connected to the data acquisition system signal, and is used to compare the different time series data collected by the temperature sensor and the pressure sensor with the temperature data and pressure data solved by coupling the heat transfer equation and the momentum equation, so as to verify and analyze the grouting diffusion path, specifically: According to the test model, the fluid domain grid is constructed and the initial boundary conditions are set. The initial boundary conditions include grouting speed, grouting pressure, slurry temperature and slurry viscosity. The momentum prediction equation is constructed according to the grouting speed, grouting pressure, phase fraction and slurry viscosity, and the grouting speed is predicted by solving the momentum. The momentum equation is: Where ρ is density, p is 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; The predicted grouting velocity is solved by the discretized momentum prediction equation: Among them, 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 area vector of the control volume surface, p 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, Δt is the time step; The continuity equation of slurry water is: Where v is the fluid velocity vector, The discrete continuity equation is coupled with the momentum equation to realize the repeated solution and iteration of the slurry pressure and grouting speed. After reaching the number of iterations, the obtained grouting pressure and grouting speed are the grouting pressure and grouting speed v of the current time step. The slurry water heat transfer equation is established according to the grouting velocity v of the current time step: Q=-ΔH rxn r Where T is temperature, c p is the specific heat capacity of the fluid, k is the thermal conductivity of the porous medium, Q represents the heat generated and released during the solidification phase change of the slurry, ΔH rxn is the heat released per mole of reaction, which can be an empirical value, r is the rate of chemical reaction, which can be an empirical value, and v is the fluid velocity vector; The predicted slurry temperature is solved by the discretized prediction equation: Among them, T new With T old are the temperatures of the old and new time steps, Δt is the time step, V CV is the volume of the control volume, S face is the area vector of the control volume face, perpendicular to the face and pointing outward; The discretized heat transfer equation is coupled with the momentum equation to realize the repeated solution and iteration of the slurry temperature and grouting speed until the slurry temperature and grouting speed v are obtained after reaching the number of iterations; 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: Among them, α represents the volume proportion occupied by a certain phase in a given volume; According to the repeated iterations of the above equations, the visualization of the slurry diffusion path is finally achieved through the phase fraction equation; After the simulation is completed, the temperature field data and grouting pressure data of the current time step are compared with the actual test data. If the temperature field data, grouting pressure and velocity data are consistent with the test data, the accurate simulation of the slurry diffusion morphology and the capture of the slurry diffusion path in the porous medium are achieved.

2. A porous medium grouting test system considering temperature effect as described in claim 1, characterized in that: A slurry-permeable partition is arranged in the test box, a porous medium is filled in the test box and below the slurry-permeable partition, and a pebble cushion is filled in the test box and above the slurry-permeable partition.

3. A porous medium grouting test system considering temperature effect as claimed in claim 1, characterized in that: The grouting system includes a slurry storage tank, a screw, a piston and an air pressure regulating valve. The slurry storage tank is used to store slurry. The screw is arranged on a screw platform and is located in the slurry storage tank. The piston is arranged below the screw. An air pressure regulating channel is arranged between the screw platform and the piston, and an air pressure valve is arranged on the piston.

4. A porous medium grouting test system considering temperature effect as claimed in claim 1, characterized in that: The water level regulation system includes a water level sensor, a water tank and a water level controller; the water level sensor is arranged in the test box, and the water tank is connected with the pipeline of the porous medium formation simulation model; the water level controller controls the start and stop of the water tank to inject water into the porous medium formation simulation model according to the water level in the test box detected by the water level sensor.

5. A porous medium grouting test system considering temperature effect as claimed in claim 1, characterized in that: The data acquisition system also includes a soil pressure sensor and a seepage pressure sensor. The soil pressure sensor is arranged around the inside of the test box and at the slurry outlet to monitor the pressure changes during the grouting process; the seepage pressure sensor is arranged inside the porous medium to monitor the pore water pressure inside the porous medium.

6. A porous medium grouting test system considering temperature effect as claimed in claim 5, characterized in that: The data analysis system is also used to analyze the pressure data of the grouting process monitored by the soil pressure sensor to obtain a pressure range suitable for grouting and plugging of porous media under the influence of temperature effect and water richness; the heating device adopts an external circulation water bath temperature control method to provide the required constant temperature environment for the pore model.

7. A porous medium grouting test system considering temperature effect as claimed in claim 1, characterized in that: It also includes a waste liquid treatment system, which is connected to the porous medium formation simulation model pipeline and is used for solid-liquid separation of slurry-water on the waste liquid flowing out of the porous medium formation simulation model.

8. A porous medium grouting test method considering temperature effect, characterized in that: include: Injecting water with a preset water-richness and a preset water temperature into the porous medium formation simulation model through a water level adjustment system; wherein the porous medium formation simulation model is filled with porous medium; The interior of the porous medium formation simulation model is heated to a preset ground temperature by a formation temperature control system; Grouting is performed into the porous medium stratum simulation model through a grouting system from a grouting port arranged below the porous medium stratum simulation model; The temperature data and pressure data during the grouting process are collected through the data acquisition system and transmitted to the data analysis system; The data analysis system compares the temperature data and pressure data collected by the temperature sensor and pressure sensor at different time series with the temperature data and pressure data solved by coupling the heat transfer equation with the momentum equation to verify and analyze the grouting diffusion path. Specifically: According to the test model, the fluid domain grid is constructed and the initial boundary conditions are set. The initial boundary conditions include grouting speed, grouting pressure, slurry temperature and slurry viscosity. The momentum prediction equation is constructed according to the grouting speed, grouting pressure, phase fraction and slurry viscosity, and the grouting speed is predicted by solving the momentum. The momentum equation is: Where ρ is density, p is 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; The predicted grouting velocity is solved by the discretized momentum prediction equation: Among them, 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 area vector of the control volume surface, p 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, Δt is the time step; The continuity equation of slurry water is: Where v is the fluid velocity vector, The discrete continuity equation is coupled with the momentum equation to realize the repeated solution and iteration of the slurry pressure and grouting speed. After reaching the number of iterations, the obtained grouting pressure and grouting speed are the grouting pressure and grouting speed v of the current time step. The slurry water heat transfer equation is established according to the grouting velocity v of the current time step: Q=-ΔH rxn r Where T is temperature, c p is the specific heat capacity of the fluid, k is the thermal conductivity of the porous medium, Q represents the heat generated and released during the solidification phase change of the slurry, ΔH rxn is the heat released per mole of reaction, which can be an empirical value, r is the rate of chemical reaction, which can be an empirical value, and v is the fluid velocity vector; The predicted slurry temperature is solved by the discretized prediction equation: Among them, T new With T old are the temperatures of the old and new time steps, Δt is the time step, V CV is the volume of the control volume, S face is the area vector of the control volume face, perpendicular to the face and pointing outward; The discretized heat transfer equation is coupled with the momentum equation to realize the repeated solution and iteration of the slurry temperature and grouting speed until the slurry temperature and grouting speed v are obtained after reaching the number of iterations; 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: Among them, α represents the volume proportion occupied by a certain phase in a given volume; According to the repeated iterations of the above equations, the visualization of the slurry diffusion path is finally achieved through the phase fraction equation; After the simulation is completed, the temperature field data and grouting pressure data of the current time step are compared with the actual test data. If the temperature field data, grouting pressure and velocity data are consistent with the test data, the accurate simulation of the slurry diffusion morphology and the capture of the slurry diffusion path in the porous medium are achieved.

9. A porous medium grouting test method considering temperature effect as claimed in claim 8, characterized in that: The temperature, grouting velocity and slurry diffusion path are solved by coupling the heat transfer equation with the momentum equation, specifically: The fluid domain grid is constructed and initialized according to the porous medium grouting test model; A momentum prediction equation is constructed according to the grouting speed, grouting pressure, phase fraction and slurry viscosity, and the grouting speed of the current time step is predicted according to the momentum prediction equation; A slurry water heat transfer prediction equation is established according to the predicted grouting speed of the current time step, and the slurry temperature and grouting speed of the current time step are predicted according to the slurry water heat transfer prediction equation; The slurry-water two-phase fraction equation is constructed according to the grouting velocity of the current time step, and the iterative calculation is performed until the number of iterations is reached to realize the slurry diffusion path analysis.

10. A porous medium grouting test method considering temperature effect as claimed in claim 9, characterized in that: Also includes: The temperature and pressure data of the current time step are obtained and compared with the measured temperature and pressure data, and the accuracy of the slurry diffusion simulation is determined based on the comparison results; the stone body inside the simulation test is obtained, and the slurry diffusion path image of the stone body slice is analyzed, and the slurry diffusion morphology is verified and captured based on the manifestation of slurry penetration in the slurry diffusion path image, as well as the morphology of voids and cracks.

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