Grouting roadbed water-steam-heat coupling simulation method, system, equipment and medium

Abstract

The invention relates to the technical field of road engineering, in particular to a grouting roadbed water-steam-heat coupling simulation method, system, equipment and medium, and the method comprises the following steps: constructing a roadbed water-steam-heat coupling geometric model; obtaining a partial differential equation of a roadbed water-steam-heat coupling process, and establishing a mutual relation between physical fields; setting temperature and moisture boundary conditions; performing mapping and free triangular mesh division on the roadbed water-steam-heat coupling geometric model to obtain a mesh model; initial data are selected, simulation solution is conducted on the gridding model, a water-steam-heat coupling simulation result is obtained, and the influence of the double-layer polyurethane grouting heat preservation structure on roadbed temperature distribution, freezing and thawing cycle depth and water migration is analyzed. According to the invention, through comprehensive simulation of the double-layer polyurethane grouting thermal insulation structure roadbed under the water-steam-heat coupling effect, the influence of the polyurethane thermal insulation layer on the roadbed performance is quantitatively analyzed, and a theoretical basis is provided for road engineering technology research and roadbed optimization.

Description

Technical Field

[0001] The present invention relates to the technical field of road engineering, and in particular to a method, system, equipment and medium for grouting roadbed water-steam-heat coupling simulation. Background Art

[0002] Permafrost refers to rock and soil that has been frozen for two years or more. It is formed by the long-term interaction of a complex geo-atmospheric system and is widely distributed around the world, accounting for about 24% of the world's land area. Roadbeds built on permafrost will experience frost heave and thaw deformation due to seasonal changes in the external climate, seriously threatening the structural safety and driving safety of the road. Therefore, effective thermal insulation measures are of great significance for preventing and controlling freeze-thaw diseases of roadbed projects in permafrost areas.

[0003] At present, in order to solve the freeze-thaw disease of permafrost roadbed, the existing control measures are divided into two methods: active cooling and passive insulation. The active cooling control measures include ventilation pipe roadbed, block stone ventilation roadbed, heat rod roadbed, etc. Although these methods can reduce the roadbed temperature to a certain extent, they have obvious limitations. For example, the ventilation pipe roadbed increases the heat input of the roadbed due to the flow of hot air, the block stone ventilation roadbed may have pore blockage under the action of vehicle load, and the heat rod roadbed causes uneven temperature field distribution in the roadbed due to the point cooling characteristics. These methods It also has common problems such as great disturbance and damage to the roadbed, long construction period and high cost; in terms of passive insulation measures, the high reflectivity surface roadbed can reduce the heat input of solar radiation to the roadbed, but it cannot work at night; although the sunshade can reduce solar radiation, its cooling effect is greatly affected by strong winds, roadbed orientation and terrain conditions, the use of thermal insulation materials such as EPS (expanded polystyrene) and XPS (extruded polystyrene) can effectively insulate, but in actual applications, the process of laying EPS and XPS boards on site is very time-consuming and will interfere with traffic.

[0004] In summary, the existing technology has certain limitations in the thermal insulation of roadbed projects in permafrost areas. It is urgent to provide a water-vapor-heat coupling simulation method for a double-layer polyurethane grouting insulation structure roadbed to solve the problems of frost heave and thaw settlement caused by seasonal climate change in roadbed projects in permafrost areas. Summary of the invention

[0005] The purpose of the present invention is to provide a grouting roadbed water-steam-heat coupling simulation method, system, equipment and medium, which can quantitatively analyze the influence of the polyurethane layer on the roadbed temperature profile, freeze-thaw depth and moisture distribution through simulation, so as to improve the accuracy of simulation analysis.

[0006] In order to solve the above technical problems, the present invention provides a grouting roadbed water-steam-heat coupling simulation method, system, equipment and medium.

[0007] In a first aspect, the present invention provides a grouting roadbed water-steam-heat coupling simulation method, the method comprising the following steps:

[0008] According to the physical dimensions and position parameters of the roadbed and the double-layer polyurethane grouting insulation structure, a two-dimensional axisymmetric roadbed water-vapor-heat coupling geometric model is constructed.

[0009] Obtain the partial differential equations of the water-steam-heat coupling process of the roadbed and establish the relationship between the various physical fields;

[0010] Defining material property parameters of different material layers in the roadbed water-steam-heat coupling geometric model, and setting temperature and moisture boundary conditions in the roadbed water-steam-heat coupling geometric model;

[0011] The water-vapor-heat coupling geometric model of the roadbed is meshed by using mapping and free triangle mesh, and the mesh of the polyurethane insulation layer and its surrounding area is encrypted to obtain a meshed model;

[0012] The soil temperature and unfrozen water content at different depths are selected as initial data, and the grid model is simulated and solved to obtain water-vapor-heat coupling simulation results;

[0013] According to the water-vapor-heat coupling simulation results, the influence of the double-layer polyurethane grouting insulation structure on the roadbed temperature distribution, freeze-thaw cycle depth and moisture migration was analyzed.

[0014] In a further embodiment, the partial differential equation comprises a moisture parabolic partial differential equation, and the moisture parabolic partial differential equation is specifically:

[0015]

[0016] in,

[0017]

[0018]

[0019]

[0020]

[0021]

[0022] Where, d w is the damping coefficient of the moisture coefficient partial differential equation; S is the saturation of the soil; t is the time in seconds; γ w is the conservative flux source term of the moisture coefficient partial differential equation; a is the conservative flux convection coefficient; f wis the source term of the partial differential equation of moisture coefficient type; θs is the saturated water content of the soil; θ r is the residual water content of the soil; ρ i is the density of ice; ρ l is the density of liquid water; B i (T) is the ratio of pore ice volume to unfrozen water volume; ρ v is the density of water vapor; K lh is the isothermal hydraulic conductivity derivative; is the Laplace operator; h m is the pressure head; y is the ordinate of the soil space coordinate; K lT is the non-isothermal hydraulic conductivity derivative; T is the temperature; K vh is the isothermal steam hydraulic conductivity; K vT is the non-isothermal steam hydraulic conductivity; θ i is the volume content of ice in the soil; θ l is the volume content of unfrozen water in the soil; T f is the freezing temperature; B is an empirical constant.

[0023] In a further embodiment, the partial differential equation further includes a heat conduction parabolic partial differential equation, and the heat conduction parabolic partial differential equation is specifically:

[0024]

[0025] in,

[0026]

[0027] α=C l q l +C v q v

[0028]

[0029]

[0030] Where, d h is the damping coefficient of the partial differential equation of heat transfer coefficient type; λ is the thermal conductivity of the soil; α is the absorption coefficient; γ h is the conservative flux source term of the partial differential equation of heat transfer coefficient type; f h is the source term of the partial differential equation of heat transfer coefficient type; C is the volume heat capacity of the soil; L i is the latent heat of water freezing; S is the saturation of soil; L v is the latent heat of water vaporization; C l is the volume heat capacity of liquid water; q l is the liquid water flux in the soil; C vis the volume heat capacity of steam; q v is the water vapor flux.

[0031] In a further embodiment, the material property parameters include hydrothermal physical parameters of the roadbed and soil layer and thermophysical parameters of the polyurethane;

[0032] The hydrothermal physical parameters of the roadbed and soil layer include dry density, specific heat capacity of thawed soil, specific heat capacity of frozen soil, thermal conductivity of thawed soil, thermal conductivity of frozen soil, porosity, saturated water content and residual water content;

[0033] The thermophysical parameters of the polyurethane include dry density of the polyurethane, thermal conductivity of the polyurethane and specific heat capacity of the polyurethane.

[0034] In a further embodiment, the temperature and moisture boundary conditions include the top temperature boundary conditions, the bottom heat flow boundary conditions, the side adiabatic boundary conditions, and the surrounding zero flux moisture boundary conditions of the roadbed water-steam-heat coupling geometric model; wherein the top temperature boundary conditions include the thermal boundary conditions of the roadbed top surface, the slope and the natural surface;

[0035] The top temperature boundary condition adopts a sinusoidal function form, specifically:

[0036]

[0037] Where R is the temperature that changes with the sinusoidal function; T a is the annual average temperature of shallow soil; k is the annual warming rate; t a is the time in days; A is the annual amplitude of shallow soil temperature; is the initial phase of the soil.

[0038] In a further embodiment, the step of meshing the water-vapor-heat coupling geometric model of the roadbed using mapping and free triangle meshes, and meshing the polyurethane insulation layer and its surrounding area to obtain a meshed model comprises:

[0039] By minimizing the global mesh error of the roadbed water-steam-heat coupling geometric model as the goal, the global mesh of the roadbed water-steam-heat coupling geometric model is iteratively refined multiple times to obtain a global optimized mesh;

[0040] According to the spatial distribution data of the subgrade moisture state of the subgrade water-steam-heat coupling geometric model, an integral based on the subgrade moisture state along the subgrade boundary is defined as a moisture state boundary error index;

[0041] According to the geometric characteristics of the roadbed water-steam-heat coupling geometric model and the temperature and moisture boundary conditions, the moisture state boundary error index is used to identify the key characteristic areas of water-steam-heat coupling from the global optimization grid;

[0042] The physical field coupling effect in the grid is quantified based on the water migration and heat exchange on the boundary of the key characteristic area of ​​water-steam-heat coupling, and the multi-physical field coupling effect evaluation matrix is ​​constructed using Gaussian integral.

[0043] According to the multi-physics field coupling effect evaluation matrix, the global optimization grid is locally adaptively meshed using the moisture state boundary error index to obtain a local optimization grid;

[0044] A mapping method is used to map the local optimized grid to different material layers of the roadbed water-steam-heat coupling geometric model, and a free triangle meshing method is used to refine the grids of different material layers according to the physical properties of the different material layers in the roadbed water-steam-heat coupling geometric model to obtain a layered grid model; the material layer includes a double-layer polyurethane insulation layer and a roadbed material layer;

[0045] According to the predetermined scaling ratio, the key characteristic areas of water-steam-heat coupling in the hierarchical grid model are meshed and encrypted to obtain a gridded model.

[0046] In a further embodiment, a transient solver is used to perform water-steam-heat coupling simulation on the gridded model.

[0047] In a second aspect, the present invention provides a grouting roadbed water-steam-heat coupling simulation system, the system comprising:

[0048] The geometric model building module is used to build a two-dimensional axisymmetric water-steam-heat coupling geometric model of the roadbed according to the physical size and position parameters of the roadbed and the double-layer polyurethane grouting insulation structure;

[0049] Model coupling analysis module, used to obtain the partial differential equations of the water-steam-heat coupling process of the roadbed and establish the relationship between various physical fields;

[0050] A model condition determination module, used to define material property parameters of different material layers in the roadbed water-steam-heat coupling geometric model, and to set temperature and moisture boundary conditions in the roadbed water-steam-heat coupling geometric model;

[0051] A model meshing module, used for meshing the water-vapor-heat coupling geometric model of the roadbed by using mapping and free triangle meshes, and meshing the polyurethane insulation layer and its surrounding area to obtain a meshed model;

[0052] A model coupling simulation module is used to select soil temperature and unfrozen water content at different depths as initial data, simulate and solve the grid model, and obtain water-vapor-heat coupling simulation results;

[0053] The subgrade characteristic analysis module is used to analyze the influence of the double-layer polyurethane grouting insulation structure on the subgrade temperature distribution, freeze-thaw cycle depth and moisture migration based on the water-vapor-heat coupling simulation results.

[0054] In a third aspect, the present invention further provides a computer device, comprising a processor and a memory, wherein the processor is connected to the memory, the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory so that the computer device performs the steps of implementing the above method.

[0055] In a fourth aspect, the present invention further provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program implements the steps of the above method when executed by a processor.

[0056] The invention provides a grouting roadbed water-vapor-heat coupling simulation method, system, equipment and medium. The method comprises the following steps: constructing a two-dimensional axisymmetric roadbed water-vapor-heat coupling geometric model according to the physical dimensions and position parameters of the roadbed and a double-layer polyurethane grouting insulation structure; obtaining a partial differential equation of the roadbed water-vapor-heat coupling process, and establishing the relationship between various physical fields; defining material property parameters of different material layers in the roadbed water-vapor-heat coupling geometric model, and setting temperature and moisture boundary conditions in the roadbed water-vapor-heat coupling geometric model; meshing the roadbed water-vapor-heat coupling geometric model by using mapping and free triangular meshes, and meshing the polyurethane insulation layer and its surrounding area to obtain a meshed model; selecting soil temperature and unfrozen water content at different depths as initial data, simulating and solving the meshed model, and obtaining a water-vapor-heat coupling simulation result; and analyzing the influence of the double-layer polyurethane grouting insulation structure on the roadbed temperature distribution, freeze-thaw cycle depth and moisture migration according to the water-vapor-heat coupling simulation result. Compared with the existing technology, this method comprehensively considers factors such as temperature changes, moisture migration and insulation layer performance in roadbed projects in high-altitude cold areas, simulates and quantitatively analyzes the impact of the polyurethane layer on the roadbed temperature profile, freeze-thaw depth and moisture distribution, providing a scientific basis and technical support for the insulation design of roadbed projects in permafrost areas, and improving the stability and durability of roadbed projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic flow chart of a grouting roadbed water-steam-heat coupling simulation method provided by an embodiment of the present invention;

[0058] Figure 2 It is a schematic diagram of mesh division of a roadbed water-steam-heat coupling geometric model provided by an embodiment of the present invention;

[0059] Figure 3It is a schematic diagram of the winter roadbed temperature contour lines of the grouting roadbed provided by an embodiment of the present invention;

[0060] Figure 4 It is a schematic diagram of the temperature contour lines of a natural roadbed in winter provided by an embodiment of the present invention;

[0061] Figure 5 It is a schematic diagram of the summer roadbed temperature contour lines of the grouting roadbed provided by an embodiment of the present invention;

[0062] Figure 6 It is a schematic diagram of the summer roadbed temperature contour lines of a natural roadbed provided by an embodiment of the present invention;

[0063] Figure 7 It is a schematic diagram of the moisture content contour of the grouting roadbed in winter provided by an embodiment of the present invention;

[0064] Figure 8 It is a schematic diagram of the water content contour of the grouting roadbed in summer provided by an embodiment of the present invention;

[0065] Fig. 9 is a schematic diagram of the effect of temperature on water vapor migration and liquid water flow provided by an embodiment of the present invention;

[0066] Fig.10 It is a block diagram of a grouting roadbed water-steam-heat coupling simulation system provided by an embodiment of the present invention;

[0067] Fig.11 It is a schematic diagram of the structure of a computer device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0068] The following specifically illustrates the implementation mode of the present invention in conjunction with the accompanying drawings. The embodiments are provided for illustrative purposes only and cannot be understood as limiting the present invention. The accompanying drawings are provided for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0069] refer to Figure 1 , the embodiment of the present invention provides a grouting roadbed water-steam-heat coupling simulation method, such as Figure 1 As shown, the method comprises the following steps:

[0070] S1. According to the physical size and position parameters of the roadbed and the double-layer polyurethane grouting insulation structure, a two-dimensional axisymmetric roadbed water-vapor-heat coupling geometric model is constructed.

[0071] This embodiment analyzes the overall process of water and heat changes by analyzing the vertical section of the roadbed, and constructs the roadbed structure into a two-dimensional axisymmetric roadbed water-steam-heat coupling geometric model according to the physical size and position parameters of the roadbed and the double-layer polyurethane grouting insulation structure, so as to observe and analyze the water and heat change process. Specifically, the roadbed water-steam-heat coupling geometric model mainly includes the roadbed, slope, soil layer and polyurethane insulation layer, with a 2.5-meter-thick roadbed at the top, which is mainly filled with crushed stone and gravel, and is designed with two levels of slopes, wherein the first level slope has a slope of 1:1 and a height of 1.5 meters, and the second level slope has a slope of 1:0.8 and a height of 1m; the middle part is a 5.5-meter-thick gravel layer; at the top of the roadbed, this embodiment designs a roadbed top surface width of 3 meters, and the roadbed bottom width is designed to be 7.3 meters to ensure stability.

[0072] In order to improve the insulation effect, a double-layer polyurethane insulation layer with a rectangular geometry is drawn at 0.75 meters and 1.5 meters from the top of the roadbed, and on the two-level slopes of the roadbed. The thickness of each layer is 0.01 meters. These insulation layers can effectively reduce heat loss and keep the temperature of the roadbed stable. In the deeper strata, the interval from -5.5 meters to 0 meters is divided into gravel layers, while the interval from -10 meters to -5.5 meters is composed of strongly weathered mudstone layers. The total width of these two areas reaches 17.3 meters. Such a layered design helps to simulate and analyze the influence of different strata on the stability of the roadbed, and provides important reference data for actual projects.

[0073] S2. Obtain the partial differential equations of the water-steam-heat coupling process of the roadbed and establish the relationship between the various physical fields.

[0074] The partial differential equation used in this embodiment realizes the direct coupling simulation of the moisture, water vapor and heat energy transfer process, and converts the volumetric moisture content θ in the traditional moisture parabolic partial differential equation into l (liquid water), volumetric ice contentθ i (solid ice) and the volume content of vapor water θ v The three key variables are integrated into a single variable, namely, soil saturation S. This simplified strategy not only improves the convergence of the numerical model and ensures the stability and efficiency of the calculation process, but also enriches the model's ability to capture actual physical phenomena. Specifically, this embodiment uses a single variable, soil saturation S, which can comprehensively and continuously simulate the dynamic changes in the moisture field inside the roadbed driven by water vapor migration (including evaporation, condensation, diffusion, etc.). This feature is extremely important for predicting the evolution of the physical state of roadbed materials, the attenuation of thermal insulation performance, and potential water damage risks under different climatic conditions and road usage conditions.

[0075] Specifically, this embodiment uses a partial differential equation module (PDE) in the simulation software to simulate physical processes such as heat conduction, moisture migration and vapor diffusion, and defines the required partial differential equations and the interaction relationship between the physical fields to simulate the multi-field coupling effect in the roadbed and the double-layer polyurethane insulation structure. In this embodiment, the partial differential equation includes a moisture parabolic partial differential equation and a heat conduction parabolic partial differential equation, and the moisture parabolic partial differential equation is specifically:

[0076]

[0077] in,

[0078]

[0079]

[0080]

[0081]

[0082]

[0083] Where, d w is the damping coefficient of the moisture coefficient partial differential equation; S is the saturation of the soil; t is the time in seconds; γ w is the conservative flux source term of the moisture coefficient partial differential equation; a is the conservative flux convection coefficient; f w is the source term of the moisture coefficient partial differential equation; θ s is the saturated water content of the soil; θ r is the residual water content of the soil; ρ i is the density of ice; ρ l is the density of liquid water; B i (T) is the ratio of pore ice volume to unfrozen water volume; ρ v is the density of water vapor; K lh is the isothermal hydraulic conductivity derivative; is the Laplace operator, defined as h m is the pressure head; x is the horizontal coordinate of the soil space coordinate; y is the vertical coordinate of the soil space coordinate; K lT is the non-isothermal hydraulic conductivity derivative; T is the temperature; K vh is the isothermal steam hydraulic conductivity; K vT is the non-isothermal steam hydraulic conductivity; θ i is the volume content of ice in the soil; θ l is the volume content of unfrozen water in the soil; T fis the freezing temperature; B is an empirical constant, which is 0.61 for sand, 0.47 for silt, and 0.56 for clay.

[0084] At the same time, the heat conduction parabolic partial differential equation is specifically:

[0085]

[0086] in,

[0087]

[0088] α=C l q l +C v q v

[0089]

[0090]

[0091] Where, d h is the damping coefficient of the partial differential equation of heat transfer coefficient type; λ is the thermal conductivity of the soil, in W·m -1 ·K -1 ; α is the absorption coefficient; γ h is the conservative flux source term of the partial differential equation of heat transfer coefficient type; f h is the source term of the partial differential equation of heat transfer coefficient type; C is the volume heat capacity of the soil, in J·m -3 ·K -1 ; L i is the latent heat of water freezing, in kJ·kg -1 ; S is the saturation of soil; L v is the latent heat of water vaporization, in kJ·kg -1 ; C l is the volume heat capacity of liquid water, in J·m -3 ·K -1 ;q l is the liquid water flux in the soil; C v is the volume heat capacity of steam, in J·m -3 ·K -1 ;q v is the water vapor flux, in m·s -1 .

[0092] In order to facilitate the understanding of the partial differential equation of the water-vapor-heat coupling process of the roadbed, this embodiment will explain in detail the implementation process of the partial differential equation of the water-vapor-heat coupling process of the roadbed. First, it is necessary to define the partial differential equation that describes the water-vapor-heat coupling behavior in the unsaturated soil. This embodiment constructs the water-vapor-heat coupling control equation in the unsaturated soil based on the defined water mass conservation equation of liquid water migration, gaseous water migration and ice content in the unsaturated soil, and the heat transfer equation considering the phase change effect of ice-water-vapor during the freezing and thawing process of the soil, to simulate the complex physical process of the roadbed under the action of water-vapor-heat coupling, wherein the water mass conservation equation of liquid water migration, gaseous water migration and ice content in the unsaturated soil is:

[0093]

[0094] In the formula, θ l is the volume content of liquid water; t is time, in seconds; T is temperature, in degrees Celsius; ρ v is the density of water vapor; ρ l is the density of liquid water; θ v is the volume content of water vapor, in m 3 ·m -3 ρ i is the density of ice, in kg·m -3 θ i is the volume content of ice, in m 3 ·m -3 ; K lh is the isothermal hydraulic conductivity derivative, in m·s -1 ; K lT is the non-isothermal hydraulic conductivity derivative, in m 2 ·K -1 ·s -1 ; K vh is the isothermal steam hydraulic conductivity, in m·s -1 ; K vT is the non-isothermal steam hydraulic conductivity, in m 2 ·K -1 ·s -1 .

[0095] When Fourier's law and the law of conservation of energy are used to consider the phase change effect of ice-water-vapor during the freezing and thawing process of soil, the corresponding heat transfer equation can be expressed as follows:

[0096]

[0097] Then, the above-mentioned moisture mass conservation equation and heat transfer equation are converted into the standard coefficient partial differential equation form in the simulation software to meet the requirements of the PDE (partial differential equation) solver of the mathematical module in the simulation software. In this embodiment, according to the needs of the physical model and the actual problem, the coefficients in the converted coefficient type partial differential equation are assigned values, and partial differential equations with various properties can be obtained. These coefficients include mass coefficient, damping coefficient, diffusion coefficient, absorption coefficient, convection coefficient, conserved flux convection coefficient, conserved flux source term and source term, etc. The values ​​of these coefficients depend on the physical properties of the material and the characteristics of the process. After assigning values ​​to the coefficients of the equation, a numerical solution method is set. In this embodiment, the implicit Euler backward difference method can be used to discretize the time term in the equation, and the nonlinear iterative modified damped Newton method is used to solve the equation. The standard coefficient partial differential equation form is:

[0098]

[0099] In the formula, u is the variable to be solved; e a is the quality coefficient; d a is the damping coefficient; c is the diffusion coefficient; α is the absorption coefficient; β is the convection coefficient; a is the conservative flux convection coefficient; γ is the conservative flux source term; and f is the source term.

[0100] It should be noted that, for the conversion process of converting the water-vapor-heat coupling control equation in unsaturated soil into a parabolic partial differential equation with temperature and relative saturation as variables, this embodiment will be described in detail through a series of derivation processes. The process of transforming the water-vapor-heat coupling control equation in unsaturated soil into the standard coefficient partial differential equation form in the simulation software through term transfer transformation is as follows:

[0101] This embodiment defines effective saturation, and derives a relationship function between unfrozen water content and temperature based on soil freezing temperature, initial water content and empirical constants. When freeze-thaw action is considered, the water in frozen soil includes ice, liquid water and vapor water. The volume water content of frozen soil can be expressed as:

[0102]

[0103] θ l +θ i +θ v =n

[0104] Where, θ is the volumetric water content of frozen soil; n is the porosity; θ l is the volume content of liquid water; θ v is the volume content of water vapor; θ i is the volume content of ice.

[0105] To facilitate the following mathematical derivation process, the effective saturation of frozen soil can be defined as:

[0106]

[0107] In the formula, θ r is the residual water content of the soil; θ s is the saturated water content of the soil; S e is the effective saturation of frozen soil.

[0108] During the freezing process of soil, the relationship function between unfrozen water content and temperature is as follows:

[0109]

[0110] T<T f

[0111] Where w0 is the initial soil moisture content (%); w l is the moisture content of unfrozen water at negative temperature T (%); T f is the freezing temperature of soil (℃); B is an empirical constant, generally speaking, it is 0.61 for sandy soil, 0.47 for silt soil, and 0.56 for clay.

[0112] In this embodiment, the ratio of the pore ice volume to the unfrozen water volume is derived based on the relationship function between the unfrozen water content and the temperature, and the ratio of the pore ice volume to the unfrozen water volume is defined as the solid-liquid ratio, and the following formula is derived:

[0113]

[0114] In the formula, B i is the solid-to-liquid ratio; the coefficient 1.1 is the ratio of the density of water to the density of ice.

[0115] It can be seen that the solid-liquid ratio is a single-valued function of temperature. Therefore, this embodiment uses the solid-liquid ratio and effective saturation to derive the connection equation between pore ice, unfrozen water and temperature in frozen soil. The connection equation between pore ice, unfrozen water and temperature in frozen soil is:

[0116] θ i =B i (T)·θ l

[0117] The time derivative of the relationship equation between pore ice, unfrozen water and temperature in frozen soil can be used to obtain the change rate of pore ice and unfrozen water with time, from which the first equation can be obtained:

[0118]

[0119] Based on the calculation formula of effective saturation of frozen soil, the second equation can be obtained:

[0120] θ l =S(θ s -θ r )+θ r

[0121] The second equation can be derived with respect to time, which gives the third equation:

[0122]

[0123] Based on the first and third equations, we can get the fourth equation:

[0124]

[0125] Similarly, based on the third equation and the fourth equation, the fifth equation can be obtained:

[0126]

[0127] Substitute the fourth and fifth equations into the water mass conservation equations for liquid water migration, gaseous water migration and ice content in unsaturated soil, use the relative saturation as a field function for mathematical calculation, and construct a parabolic partial differential equation with relative saturation as a variable:

[0128]

[0129] Substitute the fourth and fifth equations into the heat transfer equation that considers the phase change effect of ice-water-vapor during the freezing and thawing process of soil, use temperature as a field function for mathematical calculation, and construct a parabolic partial differential equation with temperature as a variable:

[0130]

[0131] This embodiment uses the implicit Euler backward difference method to discretize the time term, and uses the nonlinear iterative modified damped Newton method to solve and construct a parabolic partial differential equation with temperature and relative saturation as variables to simulate the water-vapor-heat coupling process in unsaturated soil, so that the simulation results can fully reflect the changes in temperature, humidity and ice content of the roadbed under different seasons and climatic conditions.

[0132] S3. Define material property parameters of different material layers in the roadbed water-steam-heat coupling geometric model, and set temperature and moisture boundary conditions in the roadbed water-steam-heat coupling geometric model.

[0133] In this embodiment, the temperature and moisture boundary conditions both adopt Dirichlet boundary conditions, and their partial differential equations are:

[0134]

[0135] in, represents the Laplace operator, the domain The Dirichlet boundary conditions take the form:

[0136]

[0137] The Dirichlet boundary condition is used in numerical software to set boundary conditions more flexibly and freely, and can meet boundary conditions that are consistent with actual conditions.

[0138] In this embodiment, the material property parameters of different material layers in the roadbed water-steam-heat coupling geometric model can be determined according to the coefficients that need to be assigned. The material property parameters include the hydrothermal physical parameters of the roadbed and the soil layer and the thermophysical parameters of the polyurethane. As shown in Table 1, the hydrothermal physical parameters of the roadbed and the soil layer include the dry density ρ d , specific heat capacity of molten soil C u Specific heat capacity of frozen soil C f , thermal conductivity of molten soil λ u , thermal conductivity of frozen soil λ f , porosity n, saturated water content θ s and residual moisture content θ r It should be noted that Table 1 is an exemplary value of the hydrothermal physical parameters of the roadbed and soil layer:

[0139] Table 1

[0140]

[0141] The thermophysical parameters of the polyurethane include the dry density of the polyurethane Polyurethane thermal conductivity λ p and polyurethane specific heat capacity C p ; Table 2 shows the thermophysical parameters of the polyurethane of the example:

[0142] Table 2

[0143]

[0144] Next, this embodiment selects the Dirichlet boundary condition to define the temperature boundary condition, wherein the temperature boundary condition includes the top temperature boundary condition of the roadbed top surface, slope and natural surface, the bottom heat flow boundary condition, the side adiabatic boundary condition, and the zero flux moisture boundary condition on all sides, wherein the heat flux of the bottom thermal boundary condition is 0.06W·m -2 At the same time, this embodiment defines the temperature boundary condition as a sine function, ignoring the difference in temperature boundary conditions between the yin and yang slopes. The annual amplitude of the shallow soil temperature on the top surface of the roadbed, the slope and the natural surface and the initial phase of the soil are obtained by fitting. The temperature boundary condition in the form of a sine function is expressed as follows:

[0145]

[0146] Where R is the temperature that changes with the sinusoidal function; T a is the annual average temperature of shallow soil; k is the annual warming rate; t a is the time in days (d); A is the annual amplitude of shallow soil temperature; is the initial phase of the soil.

[0147] S4. The water-vapor-heat coupling geometric model of the roadbed is meshed by using mapping and free triangular meshes, and the mesh of the polyurethane insulation layer and its surrounding area is encrypted to obtain a meshed model.

[0148] In this embodiment, the steps of meshing the roadbed water-vapor-heat coupling geometric model using mapping and free triangle meshes, and meshing the polyurethane insulation layer and its surrounding area to obtain a meshed model include:

[0149] By minimizing the global mesh error of the roadbed water-steam-heat coupling geometric model as the goal, the global mesh of the roadbed water-steam-heat coupling geometric model is iteratively refined multiple times to obtain a global optimized mesh;

[0150] According to the spatial distribution data of the subgrade moisture state of the subgrade water-steam-heat coupling geometric model, an integral based on the subgrade moisture state along the subgrade boundary is defined as a moisture state boundary error index;

[0151] According to the geometric characteristics of the roadbed water-steam-heat coupling geometric model and the temperature and moisture boundary conditions, the moisture state boundary error index is used to identify the key characteristic areas of water-steam-heat coupling from the global optimization grid;

[0152] The physical field coupling effect in the grid is quantified based on the water migration and heat exchange on the boundary of the key characteristic area of ​​water-steam-heat coupling, and the multi-physical field coupling effect evaluation matrix is ​​constructed using Gaussian integral.

[0153] According to the multi-physics field coupling effect evaluation matrix, the global optimization grid is locally adaptively meshed using the moisture state boundary error index to obtain a local optimization grid;

[0154] According to the geometric features of the roadbed water-steam-heat coupling geometric model and the physical properties of the material layer, a mapping method is used to map the local optimized grid to different material layers of the roadbed water-steam-heat coupling geometric model, and according to the physical properties of different material layers in the roadbed water-steam-heat coupling geometric model, a free triangle meshing method is used to refine the grids of different material layers to obtain a layered grid model; the material layer includes a double-layer polyurethane insulation layer and a roadbed material layer;

[0155] According to a predetermined scaling ratio, mesh encryption processing is performed on the key characteristic areas of water-vapor-heat coupling in the layered grid model to obtain a grid model; the key characteristic areas of water-vapor-heat coupling include a double-layer polyurethane insulation layer and its surrounding areas, as well as areas with high moisture content or drastic heat changes.

[0156] Specifically, in the present embodiment, the global mesh of the roadbed water-steam-heat coupling geometric model is refined in the initial stage to ensure that the error is effectively controlled within the entire model range. For example, the global mesh of the roadbed water-steam-heat coupling geometric model is refined multiple times by calculating the L2 norm error estimate between the model nodule mesh solutions, thereby refining the area where small cells are required and coarsening the area where fine meshes are not required, and coarsening the mesh in the area with lower error requirements to balance the error distribution in the roadbed water-steam-heat coupling geometric model. In this process, the present embodiment can perform four iterative refinements to gradually improve the accuracy of the model, and each iteration is Based on the previous results, the grid division is further optimized. Then, in order to further improve the simulation accuracy, especially for the complex area of ​​water-vapor-heat coupling in the double-layer polyurethane grouting insulation structure roadbed, on the basis of global grid refinement, this embodiment further adopts local adaptive grid division technology. In this process, since the moisture state in the roadbed has an important influence on the water-vapor-heat coupling process, this embodiment selects the roadbed moisture state (such as volumetric moisture content) as the model variable. The trapezoidal method or Simpson method can be used to calculate the integral value of the model variable along the roadbed boundary to form a moisture state boundary error index to guide the grid in the water-vapor-heat coupling process. Refinement of key feature areas. The moisture state boundary error index can quantify the moisture distribution on the boundary and is used to evaluate the mesh refinement requirements of different areas. This embodiment evaluates the errors of each mesh area of ​​the model according to the moisture state boundary error index, and can automatically identify areas that have a significant impact on water-steam-heat coupling, such as areas with moisture accumulation, steam penetration or active heat exchange, or points where moisture flows in and out, and places where temperature changes drastically. This embodiment quantifies the coupling effect of moisture migration and heat exchange on the boundary on the physical field in the grid based on the volumetric moisture content distribution of each point on the boundary of the key feature area of ​​water-steam-heat coupling and the temperature and moisture boundary conditions. The Gaussian The multi-physical field coupling effect evaluation matrix is ​​integrally constructed and used to guide the local refinement of the grid. In the process of local adaptive grid division, the moisture state boundary error index is used to evaluate the error of each region of the model (such as areas with high moisture content or drastic heat changes), so as to achieve gradual optimization of grid division from global to local. At the same time, combined with the physical properties such as thermal conductivity and moisture migration characteristics of different material layers and the key characteristic areas in the water-steam-heat coupling process, a comprehensive grid encryption division of the complex water-steam-heat coupling process in the double-layer polyurethane grouting insulation structure roadbed is achieved, providing strong technical support for engineering design and optimization.

[0157] Specifically, this embodiment uses mapping and free triangle meshing to mesh the roadbed water-vapor-heat coupling geometric model, and sets the number and proportion of units in different areas to ensure the mesh density and calculation accuracy of key areas (such as the polyurethane insulation layer and the junction of different soil layers). Figure 2As shown, in this embodiment, the strongly weathered mudstone and gravel area is mapped and meshed, the vertical boundary of the strongly weathered mudstone area is set to 18 units, and the horizontal boundary is set to 100 units. Then, the polyurethane insulation layer and the gravel and gravel area are free triangular meshed according to the geometric shape and calculation requirements. Figure 2 The blue area is the grid division of the insulation layer. The vertical boundary of the gravel area is set to 22 units, and the horizontal boundary is set to 100 units. The scaling ratio is adjusted to adapt to different areas. For example, in this embodiment, the area corresponding to the polyurethane insulation layer can be selected, the horizontal ratio in the scaling geometry is set to 1, and the vertical ratio is set to 1. At the same time, the areas corresponding to the gravel and sand of the free triangle grid are selected, the horizontal ratio in the scaling geometry is set to 6, and the vertical ratio is set to 6.

[0158] S5. Select soil temperature and unfrozen water content at different depths as initial data, simulate and solve the grid model, and obtain water-vapor-heat coupling simulation results.

[0159] In this embodiment, the soil temperature and unfrozen water content at different depths measured on site can be used as initial data. The initial data include the initial soil temperature and the initial unfrozen water content. The use of measured data can ensure that the initial state of the simulation is consistent with the actual conditions, thereby improving the reliability of the simulation results. In this embodiment, the soil temperature and unfrozen water content at different depths measured on site or theoretically estimated are used as initial data. In combination with partial differential equations, the relationship between various physical fields, temperature and moisture boundary conditions, and material property parameters of different material layers, this embodiment uses a transient solver to calculate the grid model, simulates the moisture migration, heat transfer and phase change process inside the roadbed, and analyzes the influence of the polyurethane insulation layer on the roadbed performance. In this embodiment, the calculation step length of the simulation solution can be set to 4 hours, and the total calculation time is 1 year.

[0160] S6. Based on the water-vapor-heat coupling simulation results, the influence of the double-layer polyurethane grouting insulation structure on the roadbed temperature distribution, freeze-thaw cycle depth and moisture migration was analyzed.

[0161] This embodiment can perform data visualization processing on the water-vapor-heat coupling simulation results, analyze the influence of the polyurethane insulation layer on the water-vapor-heat coupling process of the roadbed, and thus quantitatively analyze the influence of the polyurethane layer on the temperature profile, freeze-thaw depth and moisture distribution of the roadbed, and evaluate its insulation effect and its effect on improving the stability of the roadbed.

[0162] Figure 3 and Figure 4 The temperature contour lines of the grouting roadbed and the natural roadbed in winter are shown. Figure 3The yellow line represents the polyurethane layer. The temperature change of the grouting roadbed with the polyurethane layer is discontinuous. The soil temperature difference between the shallow polyurethane plate and the deep polyurethane plate of the grouting roadbed is 6°C and 2°C respectively. The temperature change of the natural roadbed without the polyurethane layer is continuous. In addition, the depth of the 0°C isotherm indicates the freezing depth. The freezing depth at the center of the grouting roadbed is 0.65m shallower than that at the center of the natural roadbed, indicating that the polyurethane layer reduces the freezing depth and thus reduces frost damage.

[0163] Figure 5 and Figure 6 The temperature contours of the grouting roadbed and the natural roadbed in summer are shown. The soil temperature difference between the shallow polyurethane layer and the deep polyurethane layer of the grouting roadbed is 7°C and 2°C respectively. The shallow polyurethane layer intercepts most of the heat and plays a major role in heat insulation. Figure 5 and Figure 6 It can be seen that the melting depth at the center of the grouting roadbed is 1.65m shallower than the daily melting depth at the center of the natural roadbed, indicating that the polyurethane layer can reduce the melting settlement of the roadbed.

[0164] Depend on Figure 7 It can be seen that the volumetric water content of the soil above the shallow polyurethane layer is 0.1, and 45.9% of the liquid water is frozen. Below the polyurethane layer, the volumetric water content is 0.16, and only 13.5% of the liquid water is converted into solid ice. The shallow polyurethane layer reduces the freezing of liquid water by 32.4%. Figure 8 It can be seen that the water content between the polyurethane layers is significantly higher than that in other areas. This is attributed to the fact that the evaporation migration of water vapor is hindered and condensed into liquid water under the polyurethane layer and accumulated there. The polyurethane layer affects the moisture distribution by hindering the evaporation and drainage process.

[0165] Fig. 9 The effects of temperature on water vapor migration and liquid water flow were revealed. Specifically, Fig. 9 (a) and Fig. 9 Figure 9(b) shows the temperature change curves when only the heat transfer process is considered and when the water-steam-heat interaction process is considered. The comparative analysis shows that there are significant differences in temperature distribution in the early stage of thawing (from May 20 to June 20), which indicates that the convection movement of water has a significant impact on the temperature distribution. Further observations show that Fig. 9 The upper depth of permafrost in (b) is Fig. 9 (a) in Fig. 1 is reduced by 0.6 m, which further confirms the significant influence of mass transfer process on temperature distribution. Fig. 9(c) in the figure reveals that a large amount of liquid water accumulates between the polyurethane (PU) layers. This phenomenon occurs because water vapor migrates to the PU layer and condenses into liquid water there, while being hindered from condensing into liquid water by the polyurethane layer. The accumulation of liquid water not only affects the heat transfer efficiency, but also leads to a decrease in local temperature.

[0166] In this embodiment, a water-vapor-heat coupling geometric model of the roadbed of the double-layer polyurethane grouting insulation structure is established based on COMSOL Multiphysics, and the direct coupling of multiple physical fields is realized. At the same time, secondary development is carried out through the partial differential equation module (PDE) in the simulation software, and the actual situation of the temperature profile, freeze-thaw depth and moisture distribution in the frozen soil roadbed is obtained by using numerical calculation software, which proves that the polyurethane polymer has excellent thermal insulation ability and can reduce the disturbance depth of air temperature. The freezing and melting depths of the roadbed can be reduced by 0.65m and 1.65m respectively. During freezing, the upper PU layer produces a temperature difference of 6°C between the surface and deep layers of the roadbed, thereby preventing 32.4% of the liquid water from turning into ice. Similarly, during melting, the upper PU layer causes a temperature difference of up to 7°C between the surface and deep layers. At the same time, analysis shows that the double-layer polyurethane structure uses the upper polyurethane layer as the main barrier to prevent heat transfer between the surface and deep layers of the roadbed, while the lower polyurethane layer further strengthens the thermal insulation performance.

[0167] The embodiment of the present invention provides a grouting roadbed water-vapor-heat coupling simulation method, the method comprising constructing a two-dimensional axisymmetric roadbed water-vapor-heat coupling geometric model; obtaining partial differential equations of the roadbed water-vapor-heat coupling process, and establishing the relationship between various physical fields; defining material property parameters of different material layers in the roadbed water-vapor-heat coupling geometric model, and setting temperature and moisture boundary conditions in the roadbed water-vapor-heat coupling geometric model; meshing the roadbed water-vapor-heat coupling geometric model using mapping and free triangular meshes, and meshing a polyurethane insulation layer and its surrounding area to obtain a meshed model; selecting soil temperature and unfrozen water content at different depths as initial data, simulating and solving the meshed model, and obtaining water-vapor-heat coupling simulation results; and analyzing the influence of a double-layer polyurethane grouting insulation structure on the roadbed temperature distribution, freeze-thaw cycle depth, and moisture migration based on the water-vapor-heat coupling simulation results. Compared with the prior art, the method proposed in this embodiment uses a numerical simulation method to simulate the moisture migration, heat transfer and phase change process inside the roadbed to evaluate the influence of the polyurethane insulation layer on the water-vapor-heat coupling process of the roadbed, and analyze the influence of the polyurethane insulation layer on the stability and durability of the roadbed. It realizes the simulation study of the double-layer polyurethane grouting insulation structure roadbed under the action of water-vapor-heat coupling, and provides a theoretical basis for optimizing the insulation design and improving the stability and durability of the roadbed.

[0168] It should be noted that the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0169] In one embodiment, Fig.10 As shown, an embodiment of the present invention provides a grouting roadbed water-steam-heat coupling simulation system, the system comprising:

[0170] The geometric model building module 101 is used to build a two-dimensional axisymmetric water-steam-heat coupling geometric model of the roadbed according to the physical size and position parameters of the roadbed and the double-layer polyurethane grouting insulation structure;

[0171] The model coupling analysis module 102 is used to obtain the partial differential equation of the water-steam-heat coupling process of the roadbed and establish the relationship between various physical fields;

[0172] A model condition determination module 103, used to define material property parameters of different material layers in the roadbed water-steam-heat coupling geometric model, and to set temperature and moisture boundary conditions in the roadbed water-steam-heat coupling geometric model;

[0173] A model meshing module 104 is used to mesh the water-vapor-heat coupling geometric model of the roadbed by using mapping and free triangle meshes, and to mesh the polyurethane insulation layer and its surrounding area to obtain a meshed model;

[0174] The model coupling simulation module 105 is used to select soil temperature and unfrozen water content at different depths as initial data, simulate and solve the grid model, and obtain water-vapor-heat coupling simulation results;

[0175] The roadbed characteristic analysis module 106 is used to analyze the influence of the double-layer polyurethane grouting insulation structure on the roadbed temperature distribution, freeze-thaw cycle depth and moisture migration according to the water-steam-heat coupling simulation results.

[0176] For the specific definition of a grouting roadbed water-steam-heat coupling simulation system, please refer to the above-mentioned definition of a grouting roadbed water-steam-heat coupling simulation method, which will not be repeated here. Those of ordinary skill in the art will appreciate that the various modules and steps described in conjunction with the embodiments disclosed in this application can be implemented in hardware, software, or a combination of both. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0177] The embodiment of the present invention provides a grouting roadbed water-steam-heat coupling simulation system, wherein the system constructs a two-dimensional axisymmetric roadbed water-steam-heat coupling geometric model through a geometric model construction module; obtains the partial differential equation of the roadbed water-steam-heat coupling process through a model coupling analysis module, and establishes the relationship between various physical fields; defines the material property parameters of different material layers in the roadbed water-steam-heat coupling geometric model through a model condition determination module, and sets temperature and moisture boundary conditions in the roadbed water-steam-heat coupling geometric model; meshes the roadbed water-steam-heat coupling geometric model through a model meshing module, and meshes a polyurethane insulation layer and its surrounding area to obtain a meshed model; selects soil temperature and unfrozen water content at different depths as initial data through a model coupling simulation module, simulates and solves the meshed model, and obtains a water-steam-heat coupling simulation result; and analyzes the influence of a double-layer polyurethane grouting insulation structure on the roadbed temperature distribution, freeze-thaw cycle depth, and moisture migration through a roadbed characteristic analysis module. Compared with the prior art, the system proposed in this embodiment uses a numerical simulation method to simulate the moisture migration, heat transfer and phase change process inside the roadbed to evaluate the influence of the polyurethane insulation layer on the water-vapor-heat coupling process of the roadbed, and analyze the influence of the polyurethane insulation layer on the stability and durability of the roadbed. It realizes the simulation study of the double-layer polyurethane grouting insulation structure roadbed under the action of water-vapor-heat coupling, and provides a theoretical basis for optimizing the insulation design and improving the stability and durability of the roadbed.

[0178] Fig.11 A computer device provided by an embodiment of the present invention includes a memory, a processor and a transceiver, which are connected via a bus; the memory is used to store a set of computer program instructions and data, and can transmit the stored data to the processor, and the processor can execute the program instructions stored in the memory to perform the steps of the above method.

[0179] The memory may include a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories; the processor may be a central processing unit, a microprocessor, an application-specific integrated circuit, a programmable logic device, or a combination thereof. By way of example but not limitation, the programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic, or any combination thereof.

[0180] Additionally, the memory may be a physically separate unit or may be integrated with the processor.

[0181] It can be understood by those skilled in the art that Fig.11The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have the same component arrangement.

[0182] In one embodiment, the present invention provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the above method are implemented.

[0183] The embodiments of the present invention provide a grouting roadbed water-steam-heat coupling simulation method, system, equipment and medium. The grouting roadbed water-steam-heat coupling simulation method realizes the simulation research of the double-layer polyurethane grouting insulation structure roadbed under the water-steam-heat coupling effect, which not only improves the accuracy of the model and the reliability of the simulation results, but also comprehensively simulates the physical process of the roadbed in a complex environment. Through the visualization and analysis of the results, the positive impact of the polyurethane insulation layer on the stability and durability of the roadbed is evaluated, providing a scientific and quantitative theoretical basis for the roadbed engineering.

[0184] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, computer, server or data center to another website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) mode. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integrated. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., an SSD), etc.

[0185] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing related hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods.

[0186] The above-mentioned embodiments only express several preferred implementation modes of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in the technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be regarded as the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be based on the protection scope of the claims.

Claims

1. A grouting roadbed water-steam-heat coupling simulation method, characterized in that: The following steps are involved: According to the physical dimensions and position parameters of the roadbed and the double-layer polyurethane grouting insulation structure, a two-dimensional axisymmetric roadbed water-vapor-heat coupling geometric model is constructed. Obtain the partial differential equations of the water-steam-heat coupling process of the roadbed and establish the relationship between the various physical fields; Defining material property parameters of different material layers in the roadbed water-steam-heat coupling geometric model, and setting temperature and moisture boundary conditions in the roadbed water-steam-heat coupling geometric model; The water-vapor-heat coupling geometric model of the roadbed is meshed by using mapping and free triangle mesh, and the mesh of the polyurethane insulation layer and its surrounding area is encrypted to obtain a meshed model; The soil temperature and unfrozen water content at different depths are selected as initial data, and the grid model is simulated and solved to obtain water-vapor-heat coupling simulation results; According to the water-vapor-heat coupling simulation results, the influence of the double-layer polyurethane grouting insulation structure on the subgrade temperature distribution, freeze-thaw cycle depth and moisture migration was analyzed.

2. A grouting roadbed water-steam-heat coupling simulation method as claimed in claim 1, characterized in that: The partial differential equation includes a moisture parabolic partial differential equation, and the moisture parabolic partial differential equation is specifically: in, Where, d w is the damping coefficient of the partial differential equation of moisture coefficient type; S is the saturation of soil; t is the time in seconds; γ w is the conservative flux source term of the moisture coefficient partial differential equation; a is the conservative flux convection coefficient; f w is the source term of the moisture coefficient partial differential equation; θ s is the saturated water content of the soil; θ r is the residual water content of the soil; ρ i is the density of ice; ρ l is the density of liquid water; B i (T) is the ratio of pore ice volume to unfrozen water volume; ρ v is the density of water vapor; K lh is the isothermal hydraulic conductivity derivative; is the Laplace operator; h m is the pressure head; y is the ordinate of the soil space coordinate; K lT is the non-isothermal hydraulic conductivity derivative; T is the temperature; K vh is the isothermal steam hydraulic conductivity; K vT is the non-isothermal steam hydraulic conductivity; θ i is the volume content of ice in the soil; θ l is the volume content of unfrozen water in the soil; T f is the freezing temperature; B is an empirical constant.

3. A grouting roadbed water-steam-heat coupling simulation method as claimed in claim 2, characterized in that: The partial differential equation also includes a heat conduction parabolic partial differential equation, and the heat conduction parabolic partial differential equation is specifically: in, α=C l what l +C v what v Where, d h is the damping coefficient of the partial differential equation of heat transfer coefficient type; λ is the thermal conductivity of the soil; α is the absorption coefficient; γ h is the conservative flux source term of the partial differential equation of heat transfer coefficient type; f h is the source term of the partial differential equation of heat transfer coefficient type; C is the volume heat capacity of the soil; L i is the latent heat of water freezing; S is the saturation of soil; L v is the latent heat of water vaporization; C l is the volume heat capacity of liquid water; q l is the liquid water flux in the soil; C v is the volume heat capacity of steam; q v is the water vapor flux.

4. A grouting roadbed water-steam-heat coupling simulation method as claimed in claim 1, characterized in that: The material property parameters include hydrothermal physical parameters of the roadbed and soil layer and thermophysical parameters of the polyurethane; The hydrothermal physical parameters of the roadbed and soil layer include dry density, specific heat capacity of thawed soil, specific heat capacity of frozen soil, thermal conductivity of thawed soil, thermal conductivity of frozen soil, porosity, saturated water content and residual water content; The thermophysical parameters of the polyurethane include dry density of the polyurethane, thermal conductivity of the polyurethane and specific heat capacity of the polyurethane.

5. A grouting roadbed water-steam-heat coupling simulation method as claimed in claim 1, characterized in that: The temperature and moisture boundary conditions include the top temperature boundary conditions, bottom heat flow boundary conditions, side adiabatic boundary conditions, and zero flux moisture boundary conditions on all sides of the roadbed water-steam-heat coupling geometric model; wherein the top temperature boundary conditions include the thermal boundary conditions of the roadbed top surface, slope and natural surface; The top temperature boundary condition adopts a sinusoidal function form, specifically: Where R is the temperature of the sinusoidal function; T a is the annual average temperature of shallow soil; k is the annual warming rate; t a is the time in days; A is the annual amplitude of shallow soil temperature; is the initial phase of the soil.

6. A grouting roadbed water-steam-heat coupling simulation method as claimed in claim 1, characterized in that: The steps of meshing the water-steam-heat coupling geometric model of the roadbed by using mapping and free triangle meshes, and meshing the polyurethane insulation layer and its surrounding area to obtain a meshed model include: By minimizing the global mesh error of the roadbed water-steam-heat coupling geometric model as the goal, the global mesh of the roadbed water-steam-heat coupling geometric model is iteratively refined multiple times to obtain a global optimized mesh; According to the spatial distribution data of the subgrade moisture state of the subgrade water-steam-heat coupling geometric model, an integral based on the subgrade moisture state along the subgrade boundary is defined as a moisture state boundary error index; According to the geometric characteristics of the roadbed water-steam-heat coupling geometric model and the temperature and moisture boundary conditions, the moisture state boundary error index is used to identify the key characteristic areas of water-steam-heat coupling from the global optimization grid; The physical field coupling effect in the grid is quantified based on the water migration and heat exchange on the boundary of the key characteristic area of ​​water-steam-heat coupling, and the multi-physical field coupling effect evaluation matrix is ​​constructed using Gaussian integral. According to the multi-physics field coupling effect evaluation matrix, the global optimization grid is locally adaptively meshed using the moisture state boundary error index to obtain a local optimization grid; A mapping method is used to map the local optimized grid to different material layers of the roadbed water-steam-heat coupling geometric model, and a free triangle meshing method is used to refine the grids of different material layers according to the physical properties of the different material layers in the roadbed water-steam-heat coupling geometric model to obtain a layered grid model; the material layer includes a double-layer polyurethane insulation layer and a roadbed material layer; According to the predetermined scaling ratio, the key characteristic areas of water-steam-heat coupling in the hierarchical grid model are meshed and encrypted to obtain a gridded model.

7. A grouting roadbed water-steam-heat coupling simulation method as claimed in claim 1, characterized in that: The gridded model is solved by water-steam-heat coupling simulation using a transient solver.

8. A grouting roadbed water-steam-heat coupling simulation system, characterized in that: The system comprises: The geometric model building module is used to build a two-dimensional axisymmetric water-steam-heat coupling geometric model of the roadbed according to the physical size and position parameters of the roadbed and the double-layer polyurethane grouting insulation structure; Model coupling analysis module, used to obtain the partial differential equations of the water-steam-heat coupling process of the roadbed and establish the relationship between various physical fields; A model condition determination module, used to define material property parameters of different material layers in the roadbed water-steam-heat coupling geometric model, and to set temperature and moisture boundary conditions in the roadbed water-steam-heat coupling geometric model; A model meshing module, used for meshing the water-vapor-heat coupling geometric model of the roadbed by using mapping and free triangle meshes, and meshing the polyurethane insulation layer and its surrounding area to obtain a meshed model; A model coupling simulation module is used to select soil temperature and unfrozen water content at different depths as initial data, simulate and solve the grid model, and obtain water-vapor-heat coupling simulation results; The subgrade characteristic analysis module is used to analyze the influence of the double-layer polyurethane grouting insulation structure on the subgrade temperature distribution, freeze-thaw cycle depth and moisture migration based on the water-vapor-heat coupling simulation results.

9. A computer device, characterized in that: The computer device comprises a processor and a memory, wherein the processor is connected to the memory, the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the computer device executes the method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed, the method according to any one of claims 1 to 7 is implemented.

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