Method, device and equipment for monitoring diffusion of polyurethane in porous medium and medium

Abstract

The invention relates to the technical field of porous medium monitoring, in particular to a method, device and equipment for monitoring diffusion of polyurethane in a porous medium and the medium, and the method comprises the following steps: selecting a diffusion model according to diffusion characteristics of polyurethane in the porous medium, and winding a distributed optical fiber on a sensing cage to form a spiral line structure; mapping the coordinates of each temperature measurement point on the spiral line structure into a porous medium space rectangular coordinate system; measuring an initial moisture field before polyurethane permeation in the porous medium; in the permeation process of the polyurethane, monitoring a post-permeation moisture field in a temperature transfer fluctuation stable state when the polyurethane diffuses in the porous medium; and analyzing the change of the moisture content according to the initial moisture field and the post-permeation moisture field, and identifying the polyurethane diffusion distribution field in the porous medium in combination with a diffusion model. According to the invention, a distributed optical fiber sensing technology is adopted, and the characteristic that the heat conductivity coefficient of the cured polyurethane changes is utilized, so that the diffusion condition of the polyurethane in the porous medium is comprehensively and accurately evaluated.

Description

Technical Field

[0001] The invention relates to the technical field of porous medium monitoring, and in particular to a method, device, equipment and medium for monitoring the diffusion of polyurethane in a porous medium. Background Art

[0002] Chemical grouting has long been considered the most effective means of preventing and controlling sudden water inrush in underground projects. Among them, polyurethane, as a quick-setting slurry, can significantly enhance the engineering performance of rock and soil due to its strong permeability and low expansion, when granular materials such as cement-based materials are difficult to exert their effects. However, as an underground hidden project, grouting is mainly achieved by controlling the grouting volume or grouting pressure. However, in practical applications, these methods are difficult to intuitively obtain the diffusion of slurry in porous media. Most of the current underground hidden engineering monitoring technologies use point monitoring, which is not only costly, but also prone to missed detection in actual projects, making it difficult to achieve comprehensive monitoring of the slurry diffusion process. In summary, traditional underground engineering monitoring technologies cannot obtain the diffusion of polyurethane in rock and soil over a large area and intuitively, and it is urgent to develop new monitoring technologies to improve monitoring accuracy and coverage.

[0003] In order to overcome these defects of the existing technology, the distributed temperature sensing system (DTS) has been applied in the monitoring of the moisture field of calcareous sand due to its advantages such as long distance, low maintenance cost and high precision. For example, using the heatable sensing optical cable (AHFO) at different moisture contents and seepage velocities, the difference in the rate of heat diffusion to the surrounding area is used to establish a moisture inversion function, thereby obtaining the distribution monitoring of the soil moisture field. During the slurry infiltration process, the polyurethane slurry will not only displace the moisture in the porous medium, but also react chemically with the water. In this process, the thermal conductivity of the slurry during the phase change process is different from that after curing. This phenomenon causes the heat transfer performance of the porous medium after curing to change. Therefore, the application of distributed optical fiber temperature sensing technology to monitor the diffusion of polyurethane in porous media has become an urgent problem to be solved. Summary of the invention

[0004] The purpose of the present invention is to provide a method, device, equipment and medium for monitoring the diffusion of polyurethane in porous media, which can accurately monitor the diffusion range of polyurethane by utilizing distributed optical fiber monitoring technology combined with the changing characteristics of the thermal conductivity of the porous medium after the water-reactive polyurethane is cured.

[0005] In order to solve the above technical problems, the present invention provides a method, device, equipment and medium for monitoring the diffusion of polyurethane in a porous medium.

[0006] In a first aspect, the present invention provides a method for monitoring the diffusion of polyurethane in a porous medium, the method comprising the following steps:

[0007] A diffusion model is selected according to the diffusion characteristics of polyurethane in a porous medium, and a distributed optical fiber is wound around at least one sensing cage according to predetermined helical parameters to form a helical structure;

[0008] Taking the polyurethane penetration point as the origin, a rectangular coordinate system in the porous medium space is established, and the coordinates of each temperature measurement point on the spiral structure are mapped to the rectangular coordinate system in the porous medium space;

[0009] Connecting the optical fiber to a distributed temperature sensing system, calibrating the distributed temperature sensing system for an initial value, and measuring the initial moisture field of the porous medium before polyurethane infiltration;

[0010] During the polyurethane penetration process, the distributed temperature sensing system is used to monitor the temperature transfer fluctuation along the optical fiber when the polyurethane diffuses in the porous medium, and obtain the moisture field after penetration under the stable state of temperature transfer fluctuation;

[0011] The change of moisture content is analyzed according to the initial moisture field and the moisture field after penetration, and the polyurethane diffusion distribution field in the porous medium is identified in combination with the diffusion model.

[0012] In a further embodiment, the helix parameters include the number of fiber windings, the pitch and the helix angle of the helix structure on each sensing cage, and the mathematical expressions of the number of fiber windings, the pitch and the helix angle are respectively:

[0013]

[0014]

[0015] Where N is the number of fiber windings; H is the height of the sensing cage; P is the pitch; D is the diameter of the sensing cage; L is the winding length of the optical fiber on each sensing cage; and θ is the helix angle.

[0016] In a further embodiment, when there is only a single sensing cage, the coordinates of each temperature measuring point on the spiral structure mapped to the rectangular coordinate system in the porous medium space are specifically:

[0017]

[0018] in,

[0019]

[0020] Wherein, (x, y, z) represents the coordinates of the temperature measurement point on the helical structure mapped to the rectangular coordinate system in the porous medium space; θ represents the helix angle; p0 and d are intermediate variables; l1 represents the length of the optical fiber between the starting end of the sensing cage and the demodulator; L represents the winding length of the optical fiber on each sensing cage; n represents the number of spiral turns of the point on the helical structure; D represents the diameter of the sensing cage; and P represents the pitch.

[0021] In a further embodiment, when there are at least two sensing cages, the coordinates of each temperature measuring point on the spiral structure mapped to the rectangular coordinate system in the porous medium space are specifically:

[0022]

[0023] in,

[0024]

[0025]

[0026] Where (x, y, z) represents the coordinates of the temperature measurement point on the spiral structure mapped to the rectangular coordinate system of the porous medium space; i represents the i-th sensing cage, where 1≤i≤m, and m represents the number of sensing cages; θ i represents the helical angle of the helical structure on the i-th sensing cage; p0′ and d′ are intermediate variables; L i represents the winding length of the internal optical fiber on the i-th sensing cage; l i represents the length of the optical fiber between the starting end of the i-th sensing cage and the demodulator; n i Indicates the number of spiral turns of the temperature measurement point on the spiral structure of the i-th sensing cage; D i represents the diameter of the i-th sensor cage; P i represents the pitch of the helical structure on the i-th sensing cage.

[0027] In a further embodiment, the step of analyzing the change in moisture content according to the initial moisture field and the moisture field after penetration, and identifying the polyurethane diffusion distribution field in the porous medium in combination with the diffusion model comprises:

[0028] Determining a moisture content reduction area according to the initial moisture field and the post-infiltration moisture field;

[0029] According to the moisture content reduction area, the thermal conductivity reduction area in the porous medium is determined by using the functional relationship between thermal conductivity and moisture content;

[0030] The polyurethane diffusion distribution field in the porous medium is identified according to the reduced thermal conductivity region in the porous medium in combination with the diffusion model.

[0031] In further embodiments, the diffusion model comprises a spherical diffusion model or a cylindrical-hemispherical diffusion model.

[0032] In a further embodiment, the step of identifying the polyurethane diffusion distribution field in the porous medium based on the region of reduced thermal conductivity in the porous medium and in combination with the diffusion model comprises:

[0033] Mapping the pre-measured sensing cage optical fiber length data to the porous medium spatial rectangular coordinate system to obtain the three-dimensional structural data of the porous medium;

[0034] Identifying pore structure data of the porous medium in a region where thermal conductivity is reduced based on the three-dimensional structure data of the porous medium, and quantifying a quantitative index of heterogeneity of the porous medium in the region where thermal conductivity is reduced using a statistical method based on the pore structure data;

[0035] Taking the quantitative index of heterogeneity of porous media as input, microscopic molecular dynamics simulation is performed in the area where thermal conductivity decreases, microscopic diffusion characteristic parameters of polyurethane in the microstructure of porous media are predicted, and the microscopic diffusion characteristic parameters are integrated into the diffusion model to obtain a polyurethane diffusion model that takes heterogeneity into account;

[0036] A chemical reaction kinetic model of polyurethane diffusion in porous media was established. The chemical reaction kinetic model was used to analyze the time delay effect of polyurethane diffusion in the thermal conductivity reduction region and extract the time delay parameters in the polyurethane diffusion process.

[0037] The time delay parameter is introduced, and the Galerkin finite element method is used to dynamically simulate the polyurethane diffusion model considering heterogeneity in order to capture the migration characteristics of polyurethane in porous media and obtain the polyurethane diffusion distribution field considering the time delay effect.

[0038] In a second aspect, the present invention provides a device for monitoring the diffusion of polyurethane in a porous medium, the device comprising:

[0039] A device establishment module is used to select a diffusion model according to the diffusion characteristics of polyurethane in a porous medium, and to wind a distributed optical fiber around at least one sensing cage according to predetermined helix parameters to form a helix structure;

[0040] A coordinate mapping module is used to establish a rectangular coordinate system in the porous medium space with the polyurethane penetration point as the origin, and map the coordinates of each temperature measurement point on the spiral structure to the rectangular coordinate system in the porous medium space;

[0041] An initial measurement module, used to connect the optical fiber to the distributed temperature sensing system, calibrate the initial value of the distributed temperature sensing system, and measure the initial moisture field of the porous medium before the polyurethane penetrates;

[0042] A diffusion monitoring module is used to monitor the temperature transfer fluctuation along the optical fiber when the polyurethane diffuses in the porous medium by using the distributed temperature sensing system during the polyurethane penetration process, and obtain the moisture field after penetration under the stable state of temperature transfer fluctuation;

[0043] The diffusion identification module is used to analyze the change of moisture content according to the initial moisture field and the moisture field after penetration, and to identify the polyurethane diffusion distribution field in the porous medium in combination with the diffusion model.

[0044] 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.

[0045] 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.

[0046] The invention provides a method, device, equipment and medium for monitoring the diffusion of polyurethane in a porous medium. The method forms a spiral structure by winding a distributed optical fiber around at least one sensing cage; a porous medium spatial rectangular coordinate system is established with a polyurethane penetration point as the origin, and the coordinates of each temperature measurement point on the spiral structure are mapped to the porous medium spatial rectangular coordinate system; the optical fiber is connected to a distributed temperature sensing system, the distributed temperature sensing system is calibrated with an initial value, and the initial moisture field of the porous medium is measured before the polyurethane penetrates; during the polyurethane penetration process, the temperature transfer fluctuation along the optical fiber is monitored by the distributed temperature sensing system when the polyurethane diffuses in the porous medium, and the post-penetration moisture field under the stable state of the temperature transfer fluctuation is obtained; the change of moisture content is analyzed according to the initial moisture field and the post-penetration moisture field, and the polyurethane diffusion distribution field in the porous medium is identified in combination with a diffusion model. Compared with the existing technology, this method uses distributed optical fiber sensing technology to monitor the temperature changes along the optical fiber in the process of polyurethane diffusion in porous media in real time, thereby realizing low-cost and high-efficiency monitoring of large areas of porous media, improving the comprehensiveness and economy of monitoring, and at the same time utilizing the physical properties of the change in thermal conductivity after polyurethane solidification. By comparing the changes in the moisture field of the porous medium before and after grouting, the diffusion of the slurry in the porous medium can be indirectly determined, which can accurately monitor the diffusion of polyurethane in porous media and provide strong technical support for engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic flow chart of a method for monitoring polyurethane diffusion in a porous medium provided by an embodiment of the present invention;

[0048] Figure 2 is a schematic diagram of the structure of a cylindrical sensor cage provided by an embodiment of the present invention;

[0049] Figure 3 is a schematic diagram of a planar expansion of a spiral structure provided by an embodiment of the present invention;

[0050] Figure 4 is a schematic diagram of the length of the portion of the helical line that does not satisfy the single-turn requirement provided by an embodiment of the present invention;

[0051] Figure 5 Schematic diagram of a polyurethane diffusion distribution field distributed temperature sensing system provided by an embodiment of the present invention;

[0052] Figure 6 Schematic diagram of a polyurethane diffusion monitoring device in a porous medium provided by an embodiment of the present invention;

[0053] Figure 7 It is a schematic diagram of the structure of a computer device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0054] 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.

[0055] refer to Figure 1 The embodiment of the present invention provides a method for monitoring the diffusion of polyurethane in a porous medium, such as Figure 1 As shown, the method comprises the following steps:

[0056] S1. A diffusion model is selected according to the diffusion characteristics of polyurethane in a porous medium, and a distributed optical fiber is wound around at least one sensing cage according to predetermined helix parameters to form a helix structure.

[0057] S2. Taking the polyurethane penetration point as the origin, a rectangular coordinate system of the porous medium space is established, and the coordinates of each temperature measurement point on the spiral structure are mapped to the rectangular coordinate system of the porous medium space.

[0058] When monitoring the diffusion of slurry during the grouting process of porous media, this embodiment can select a diffusion model based on the diffusion characteristics of polyurethane in porous media. The diffusion model can adopt a spherical diffusion model or a column-hemispherical diffusion model. Its diffusion mode can be determined according to the number of grouting holes and the permeability of the foundation. In order to realize polyurethane diffusion monitoring, this embodiment can use epoxy resin material to wind the distributed optical fiber on the sensor cage during the optical fiber laying stage to form a spiral structure on the sensor cage. For the convenience of explanation, as shown in FIG. Figure 2 As shown, this embodiment will be described in detail by taking the structure of the sensing cage as a cylinder as an example. At this time, the optical fiber wound on the sensing cage is equivalent to a spiral line wound on the cylinder. Those skilled in the art can set the shape of the sensing cage according to the specific implementation situation, which is not limited to the embodiment of the present invention. In three-dimensional space, the spiral line is a curve that rotates along a certain axis (such as the axis of the cylinder) and extends along the axis at the same time. When the spiral line structure is unfolded on a two-dimensional plane, as shown in FIG. Figure 3 , Figure 4 As shown, the helical parameters of the distributed optical fiber when it is wound on the sensor cage include the number of optical fiber windings, the pitch and the helical angle of the helical structure on each sensor cage. The mathematical expressions of the number of optical fiber windings, the pitch and the helical angle are respectively:

[0059]

[0060] The relationship between the pitch P and the helix angle θ is expressed as:

[0061]

[0062] Where N is the number of fiber windings; H is the height of the sensing cage; P is the pitch; D is the diameter of the sensing cage; L is the winding length of the optical fiber inside each sensing cage; and θ is the helix angle.

[0063] In the actual process of laying distributed optical fibers, the length L of the optical fiber wound around each sensing cage is a fixed value. In this embodiment, the pitch P is determined according to the diameter and height of the sensing cage, and one end of the optical fiber is connected to the distributed temperature sensing system DTS through a jumper. The distributed temperature sensing system can capture and transmit the temperature changes of each temperature measuring point along the optical fiber to the terminal device in real time. The position where the temperature change occurs is the specific position where the polyurethane spreads on the temperature measuring optical fiber. This position is the marking point where the polyurethane diffuses to the optical fiber, thereby realizing the monitoring of the diffusion range of the polyurethane in the porous medium.

[0064] In order to accurately describe this diffusion process, this embodiment takes the polyurethane penetration point as the origin and the direction perpendicular to the porous medium as the z-axis to establish a porous medium space rectangular coordinate system, and maps the coordinates of each temperature measurement point on the spiral structure to the porous medium space rectangular coordinate system, so that each corresponding target position length L on the optical fiber corresponds to the coordinate in the porous medium space rectangular coordinate system, thereby quantifying the diffusion of polyurethane in the porous medium according to the corresponding coordinate changes of the initial moisture field and the moisture field after penetration after temperature stabilization in the porous medium space rectangular coordinate system. This embodiment can use MATLAB software to Real-time data is processed to visualize the diffusion process. Specifically, this embodiment uses MATLAB software combined with the Kd-Tree neighbor point search algorithm to select an arbitrary coordinate point, and screens out the coordinate point closest to it on the adjacent sensor cage as the point on the slurry diffusion path in a certain direction, and traverses all the coordinate points on the sensor cage to ensure that each coordinate point has a corresponding point; then, this embodiment performs three-dimensional interpolation on the adjacent spatial coordinate points to determine the specific diffusion path of the slurry in this direction; finally, this embodiment obtains the diffusion situation of the slurry at any time through visualization processing, and derives the slurry diffusion distribution field.

[0065] In view of the specific situation of optical fiber deployment, this embodiment is discussed in the following two situations: a single sensor cage and multiple sensor cages:

[0066] Single sensing cage: When there is only one sensing cage, this embodiment can determine that the temperature measurement point is located on the nth circle of the sensing cage according to the winding length L of the optical fiber inside each sensing cage, the diameter D of the sensing cage, the height H of the sensing cage, and the length l1 of the starting end connected to the distributed temperature sensing system. The specific calculation formula for the number of winding circles n of the temperature measurement point on the sensing cage is:

[0067]

[0068] Then we have:

[0069]

[0070] From this, the coordinates of each temperature measuring point on the spiral line are further derived. In this embodiment, the coordinates of each temperature measuring point on the spiral line structure mapped to the rectangular coordinate system in the porous medium space are specifically:

[0071]

[0072] Wherein, (x, y, z) represents the coordinates of the temperature measurement point on the helical structure mapped to the rectangular coordinate system in the porous medium space; θ represents the helix angle; L represents the winding length of the optical fiber inside each sensing cage; n represents the number of spiral turns of the point on the helical structure; D represents the diameter of the sensing cage; P represents the pitch; l1 represents the length of the optical fiber between the starting end of the sensing cage and the demodulator; p0 represents the length of the part that does not exceed the pitch length; d represents the diameter corresponding to the part that does not exceed the length of a single spiral turn.

[0073] Overlapping of multiple sensor cages: When there are at least two sensor cages (m sensor cages with overlapping central axes), this embodiment uses the diameter D of each sensor cage as i , height H i , the number of windings in each sensor cage n i , pitch p i 、Helix angle θ i And the optical fiber length l between each sensor cage i , where the value range of i is 1≤i≤m. It can be determined that each temperature measurement point is located on the nth circle of the tth sensing cage. The specific calculation formula for the number of winding circles n of the temperature measurement point on the sensing cage is:

[0074]

[0075]

[0076] Then we have:

[0077]

[0078] From this, the coordinates of each temperature measurement point on the spiral line are further derived. The coordinates of each temperature measurement point on the spiral line structure mapped to the rectangular coordinate system in the porous medium space are specifically:

[0079]

[0080] Where (x, y, z) represents the coordinates of the temperature measurement point on the spiral structure mapped to the rectangular coordinate system of the porous medium space; i represents the i-th sensing cage, where 1≤i≤m, and m represents the number of sensing cages; θ i represents the helical angle of the helical structure on the i-th sensing cage; L i represents the winding length of the optical fiber inside the i-th sensing cage; n i Indicates the number of spiral turns of the temperature measurement point on the spiral structure of the i-th sensing cage; D i represents the diameter of the i-th sensor cage; P irepresents the pitch of the helical structure on the i-th sensing cage; l represents the length of the optical fiber from the starting part of the first sensing cage to the input port of the distributed temperature sensing system; p0′ represents the length of the part that does not exceed the pitch length; d′ represents the diameter corresponding to the part that does not exceed the length of a single turn of the helix; l i represents the length of the optical fiber between the starting end of the i-th sensing cage and the demodulator; n i Indicates the number of spiral turns of the temperature measurement point on the spiral structure of the i-th sensing cage; D i represents the diameter of the i-th sensor cage; P i represents the pitch of the helical structure on the i-th sensing cage.

[0081] S3. Connecting the optical fiber to the distributed temperature sensing system, calibrating the distributed temperature sensing system for initial values, and measuring the initial moisture field of the porous medium before the polyurethane penetrates.

[0082] S4. During the polyurethane penetration process, the distributed temperature sensing system is used to monitor the temperature transfer fluctuation along the optical fiber when the polyurethane diffuses in the porous medium, and obtain the post-penetration moisture field under the stable state of temperature transfer fluctuation.

[0083] S5. Analyze the change of moisture content according to the initial moisture field and the moisture field after penetration, and identify the polyurethane diffusion distribution field in the porous medium in combination with the diffusion model.

[0084] In this embodiment, the step of analyzing the change of moisture content according to the initial moisture field and the moisture field after penetration, and identifying the polyurethane diffusion distribution field in the porous medium in combination with the diffusion model includes:

[0085] Determining a moisture content reduction area according to the initial moisture field and the post-infiltration moisture field;

[0086] According to the moisture content reduction area, the thermal conductivity reduction area in the porous medium is determined by using the functional relationship between thermal conductivity and moisture content;

[0087] The polyurethane diffusion distribution field in the porous medium is identified according to the reduced thermal conductivity region in the porous medium in combination with the diffusion model.

[0088] In this embodiment, the step of identifying the polyurethane diffusion distribution field in the porous medium according to the region with reduced thermal conductivity in the porous medium and in combination with the diffusion model includes:

[0089] Mapping the pre-measured sensing cage optical fiber length data to the porous medium spatial rectangular coordinate system to obtain the three-dimensional structural data of the porous medium; wherein the sensing cage optical fiber length data includes the winding length of the optical fiber on each sensing cage, the optical fiber length connecting adjacent sensing cages, and the optical fiber length from the starting part of the first sensing cage to the input port of the distributed temperature sensing system;

[0090] Identifying pore structure data of the porous medium in a region where thermal conductivity is reduced based on the three-dimensional structure data of the porous medium, and quantifying a quantitative index of heterogeneity of the porous medium in the region where thermal conductivity is reduced using a statistical method based on the pore structure data;

[0091] Taking the quantitative index of heterogeneity of porous media as input, microscopic molecular dynamics simulation is performed in the area where thermal conductivity decreases, microscopic diffusion characteristic parameters of polyurethane in the microstructure of porous media are predicted, and the microscopic diffusion characteristic parameters are integrated into the diffusion model to obtain a polyurethane diffusion model that takes heterogeneity into account;

[0092] A chemical reaction kinetic model of polyurethane diffusion in porous media was established. The chemical reaction kinetic model was used to analyze the time delay effect of polyurethane diffusion in the thermal conductivity reduction region and extract the time delay parameters in the polyurethane diffusion process.

[0093] The time delay parameter is introduced, and the Galerkin finite element method is used to dynamically simulate the polyurethane diffusion model considering heterogeneity in order to capture the migration characteristics of polyurethane in porous media and obtain the polyurethane diffusion distribution field considering the time delay effect.

[0094] Specifically, this embodiment calculates the moisture content change at each position according to the initial moisture field and the moisture field after infiltration, determines the moisture content reduction area, and determines the area with reduced thermal conductivity in the porous medium according to the moisture content reduction area by using the functional relationship between thermal conductivity and moisture content, thereby converting the moisture content reduction area into the thermal conductivity reduction area, obtaining the three-dimensional structure data of the porous medium, identifying the pore structure data of the porous medium in the thermal conductivity reduction area according to the three-dimensional structure data of the porous medium, for example, the pore structure data may include structure data such as pore distribution, size and shape, and then Then, according to the pore structure data, a quantitative index of the heterogeneity of the porous medium in the area where the thermal conductivity coefficient decreases is quantified by using a statistical method. For example, the quantitative index of the heterogeneity of the porous medium may include permeability distribution, etc. This embodiment is based on the physicochemical properties of polyurethane and porous media, performs microscopic molecular dynamics simulation in the area where the thermal conductivity coefficient decreases, and introduces the quantitative index of the heterogeneity of the porous medium in the simulation process to predict the microscopic diffusion characteristic parameters of polyurethane in the microstructure of the porous medium, convert the microscopic diffusion characteristic parameters to the macroscopic scale, and integrate them into the macroscopic diffusion model to obtain the thermal conductivity of the porous medium. The microscopic diffusion characteristic parameters adjust the parameters of the diffusion model (such as diffusion coefficient, boundary conditions, etc.), thereby reflecting the influence of the heterogeneity of the porous medium on the diffusion of polyurethane, and obtaining a polyurethane diffusion model considering the heterogeneity. Next, this embodiment establishes a chemical reaction kinetic model of the diffusion of polyurethane in porous media, while considering the physical adsorption, chemical reaction and other processes between polyurethane and the medium. The chemical reaction kinetic model is used to analyze the time delay effect of the diffusion process of polyurethane in the thermal conductivity reduction region, and the time delay parameters in the polyurethane diffusion process, such as reaction rate constant, adsorption equilibrium time, etc., are extracted to quantitatively describe the non-instantaneous characteristics of the diffusion of polyurethane in porous media. Finally, this embodiment uses the Galerkin finite element method to establish a dynamic simulation of the polyurethane diffusion model considering heterogeneity, and introduces the time delay parameter in the simulation process to capture the migration characteristics of polyurethane in porous media, and obtain the polyurethane diffusion distribution field considering the time delay effect. By introducing the heterogeneity of the porous medium and considering the time delay effect, this embodiment can more accurately predict the diffusion behavior of polyurethane in porous media and obtain the polyurethane diffusion distribution field.

[0095] It should be noted that the porous medium heterogeneity introduced in this embodiment mainly refers to the inhomogeneity of the physical, chemical or structural properties of the porous medium, such as the inhomogeneity of the pore distribution and connectivity of the porous medium. In this embodiment, the corresponding porous medium geometric characteristics can be extracted through pore structure data, etc., and the corresponding porous medium geometric characteristics are quantified by statistical methods to obtain a quantitative index of the heterogeneity of the porous medium. Those skilled in the art can use other methods to calculate the quantitative index of the heterogeneity of the porous medium, which is not limited to the embodiment of the present invention. By introducing the quantitative index of heterogeneity through the porous medium, the complex diffusion behavior in the porous medium can be more effectively described; and the time delay effect mainly refers to the occurrence of a process or phenomenon with a significant lag time relative to its triggering factor or starting condition. In the diffusion process of polyurethane in the porous medium, the time delay effect causes a time delay in the diffusion process due to multiple factors such as the chemical reaction time of the polyurethane and the complexity of the medium structure, which increases the resistance and time of the diffusion. In this embodiment, the time delay effect is introduced into the polyurethane diffusion model, which can more accurately describe and predict the non-instantaneous characteristics of the actual diffusion process.

[0096] In summary, in this embodiment, the distributed optical fiber is connected to the distributed temperature sensing system (DTS) through a jumper. The DTS can capture and transmit the temperature change of each position of the optical fiber in real time, so as to display the temperature change in real time. Then, the distributed temperature sensing system is calibrated, the spatial resolution, time resolution and heating power of the distributed temperature sensing system are set, and the initial value of the distributed temperature sensing system is calibrated. The distributed temperature sensing system is started and the moisture is measured to obtain the initial moisture field M1. During the polyurethane penetration process, the distributed temperature sensing system is used to monitor the temperature change of the distributed optical fiber in the polyurethane diffusion process in real time, and after the temperature is basically stable, the moisture field is measured again to obtain the post-penetration moisture field M2 under the temperature stable state. According to the functional relationship between the thermal conductivity and the moisture content, the areas where the moisture content of M1 and M2 is reduced are compared, that is, the areas where the thermal conductivity is reduced, and then the diffusion of polyurethane in the porous medium is obtained. In this embodiment, the polyurethane diffusion behavior includes but is not limited to the diffusion path, range and morphology of polyurethane in the porous medium. For the sake of clarity, the heat source theory and the polyurethane diffusion distribution field monitoring principle in the polyurethane diffusion distribution field theory are specifically described below:

[0097] (1) Heat source theory

[0098] In a homogeneous, isotropic porous medium with uniform initial temperature, the heat transfer can be described by Fourier's law:

[0099]

[0100] For a heat pulse generated by an infinitely long heat source, if the influence of radial dimensions and cable material is ignored, the process of heat diffusion to the surrounding during heating can be expressed as:

[0101]

[0102] In the formula, c represents specific heat capacity (unit: J / (kg·℃)); T represents temperature; t represents time; They represent the partial derivatives of temperature in different directions of the x-axis, y-axis and z-axis respectively; t0 represents the heating time; λ represents the thermal conductivity (in W / (m·℃)); P represents the heating power per unit length of the linear heat source (in J / (m·s)); S is the distance from the test point to the heat source (in m); and b represents a constant.

[0103] When the radius of the heat source is considered, the heat diffusion during the heating process can be expressed as:

[0104]

[0105] Where R and γ are the interface impedance (in m 2 ℃ / W) and Euler constant, which are fitted by the least square method; r is the heat source radius (in m), which is obtained by numerical simulation.

[0106] (2) Principle of polyurethane diffusion distribution field monitoring

[0107] Before grouting, the porous medium contains a moisture field. First, the active heated fiber optic method (AHFO) is used to calibrate the initial moisture field M1 in the porous medium. At this time, the soil is composed of air, soil particles and water. The thermal conductivity of the gas is relatively small and can be ignored. This embodiment uses The soil thermal conductivity prediction model established by Konrad (hereinafter referred to as the CK model) establishes the relationship between the thermal conductivity of soil and the saturation. The change of saturation directly affects the value of thermal conductivity. In porous media, the increase or decrease of moisture will directly affect the saturation of the soil, that is, the change of water content directly reflects the change of saturation. Therefore, through the above two relationships, this embodiment indirectly associates the thermal conductivity with the water content. The change of water content leads to the change of saturation, which in turn affects the value of thermal conductivity. The relationship between water content and saturation is the prior art and will not be repeated here. The calculation formula of the thermal conductivity of the rock and soil before grouting is:

[0108] λ1=(λ sat -λ dry )K e1 +λ dry

[0109]

[0110] Where λ1 represents the thermal conductivity of rock and soil; λ sat Indicates the thermal conductivity of saturated soil; λ dry Indicates the thermal conductivity of dry soil; K e1 represents the normalized thermal conductivity before grouting; λ dry represents; a represents the weight coefficient, which is a parameter related to the composition, structure and temperature of the soil; S r1 Indicates the soil saturation before grouting (%).

[0111] Under non-freezing conditions, the thermal conductivity of saturated sand is sat for:

[0112]

[0113] In the formula, λ w Represents the thermal conductivity of water; λ s represents the thermal conductivity of sand particles; n represents the porosity of the soil (%).

[0114]

[0115] In the formula, represents the thermal conductivity of each mineral component; x j It indicates the volume fraction (%) of each mineral component.

[0116] The thermal conductivity of dry soil is:

[0117] λ dry =10 -ηn χ

[0118] Where χ and η are material parameters.

[0119] Thermal conductivity λ of polyurethane during phase change p1 Before grouting, the probe method is used to mix polyurethane and water in a preset ratio, and then the probe can be inserted to start measuring λ p1 The test time is about 10 minutes. Since the initial mixing of polyurethane and water will release a lot of heat, causing the temperature to rise and affecting the accuracy of the data, the probe is heated 3 minutes after mixing and the test is completed at about 13 minutes to measure the thermal conductivity λ of polyurethane during the phase change process. p1 .

[0120] When grouting begins, polyurethane slowly penetrates into the porous medium and reacts with water to start phase change, causing the thermal conductivity of the porous medium to change. During the grouting process, the water in the porous medium is constantly displaced and reacts, and the water field changes. It is difficult to accurately obtain the saturation of the porous medium during the phase change process. Therefore, it is assumed that during the phase change process, the saturation of the porous medium is the saturation after the reaction S r2 Since the infiltration grouting does not cause much disturbance to the porous medium itself, it can be considered that the porous medium does not produce displacement during the polyurethane penetration, displacement and curing process. Therefore, during the phase change process, the thermal conductivity λ2 in the porous medium can be calculated using the CK model and can be expressed as:

[0121] λ2=(λ sat -λ dry )K e2 +λ dry +λ p1

[0122]

[0123] In the formula, K e2 represents the normalized thermal conductivity during the grouting process and after the slurry solidifies; λ p1 Represents the thermal conductivity of polyurethane during phase change; S r2 Indicates the soil saturation during the grouting process (%).

[0124] At this time, the DTS is started synchronously to monitor the temperature field changes in the porous medium in real time, so that the slurry diffusion can be monitored in real time.

[0125] After the slurry solidifies, part of the volume occupied by the pores in the porous medium is replaced by polyurethane, the water and air are displaced by polyurethane, and the water field is redistributed. At this time, the thermal conductivity λ3 of the stone body can be expressed as:

[0126] λ3=(λ sat -λ dry )K e2 +λ dry +λ p2

[0127] In the formula, λ p2 It indicates the thermal conductivity of the cured polyurethane and can be tested by a Hot Disk thermal constant analyzer or a corundum tube thermal probe method.

[0128] At this time, AHFO is used again to monitor the reconstructed moisture field to obtain the post-infiltration moisture field M2. AHFO is used to monitor before infiltration and after curing, and by comparing the initial moisture field M1 and the post-infiltration moisture field M2, the area where the moisture content is reduced can be determined. Specifically, the initial moisture field M1 and the post-infiltration moisture field M2 measured by AHFO before and after grouting are used to calculate the moisture content change of each monitoring point, thereby identifying the area where the moisture content is significantly reduced. Then, by analyzing the change in thermal conductivity, the diffusion of polyurethane can be inferred. When λ3<λ1, it is the diffusion distribution field of polyurethane.

[0129] (II) Design and calibration of distributed optical fiber sensing system for polyurethane diffusion distribution field

[0130] like Figure 5 As shown, the distributed temperature sensing system of polyurethane diffusion distribution field consists of a distributed temperature sensing system 1, a host computer 2, a data transmission line 3, a data processor 4, a time-controlled switch 5, a DC power supply 6, a copper conductor 7, a porous medium 8, an optical fiber 9 and a sensing cage 10, wherein a heating module composed of a DC power supply and a time-controlled switch is used to heat the optical fiber, wherein the time-controlled switch is used to accurately control the heating time, and its accuracy must reach 1 second; a distributed temperature sensing system is used to monitor temperature changes; a demodulation module of the distributed temperature sensing system is used to convert the measured Raman optical signal into temperature information; the data transmission line uses a mobile 5G network to send data to a terminal; the data processor has two major functions: one is the control function to ensure the coordinated work between the modules; the other is the data post-processing function, which converts the temperature fluctuation information into an analysis of the moisture content change, and infers the diffusion distribution field of the polyurethane based on this.

[0131] In terms of system calibration, the active heating fiber method AHFO is used to calibrate the initial moisture field of the porous medium to obtain the initial moisture field. During the infiltration process, DTS is started synchronously to monitor the temperature changes in real time and record the temperature changes caused by the reaction and diffusion of polyurethane, thereby realizing real-time monitoring of the diffusion of slurry in the porous medium. In the post-processing stage, after the grouting is completed, the reconstructed post-infiltration moisture field M2 is measured again. According to the functional relationship between thermal conductivity and water content, the area with reduced thermal conductivity is determined by comparing the area with reduced water content, that is, the diffusion distribution field of polyurethane is identified.

[0132] The traditional technology for analyzing grouting engineering based on optical fiber sensing technology mainly substitutes the temperature data monitored by optical fiber sensing technology into MATLAB to obtain the slurry temperature field cloud map or directly uses the temperature data as the basis for judgment to intuitively display the range of slurry diffusion. However, this traditional method is easily affected by various factors such as the external environment temperature, the thermal conductivity of the medium and the temperature loss during the grouting process, which will cause the temperature field to deviate from the actual slurry diffusion range, resulting in serious deviations in the final measurement results. The flow of polyurethane in porous media is a relatively complex physical process involving fluid mechanics, thermodynamics and the physical properties of porous media. Considering the thermal effect characteristics during the curing process of polyurethane, directly determining the diffusion range of the slurry by temperature changes will make it difficult for temperature data to accurately reflect the diffusion situation. Therefore, the polyurethane diffusion monitoring method in porous media provided in this embodiment is to monitor the moisture field changes of porous media, combined with the relationship between thermal conductivity and water content, to more accurately analyze the diffusion behavior of slurry in porous media. This method is based on physical principles and can more accurately reflect the changes in the internal state of porous media, providing a scientific basis for the design and construction of grouting engineering.

[0133] An embodiment of the present invention provides a method for monitoring the diffusion of polyurethane in a porous medium. The method forms a spiral structure by winding a distributed optical fiber around at least one sensing cage; a porous medium spatial rectangular coordinate system is established with a polyurethane penetration point as the origin, and the coordinates of each temperature measurement point on the spiral structure are mapped to the porous medium spatial rectangular coordinate system; the optical fiber is connected to a distributed temperature sensing system, the distributed temperature sensing system is calibrated with an initial value, and the initial moisture field of the porous medium is measured before the polyurethane penetrates; during the polyurethane penetration process, the temperature transfer fluctuation along the optical fiber is monitored by the distributed temperature sensing system when the polyurethane diffuses in the porous medium, and the post-penetration moisture field under the stable state of the temperature transfer fluctuation is obtained; the change of moisture content is analyzed according to the initial moisture field and the post-penetration moisture field, and the polyurethane diffusion distribution field in the porous medium is identified in combination with a diffusion model. Compared with the prior art, the method provided in the embodiment of the present invention utilizes a distributed temperature sensing system to monitor in real time the temperature changes of the distributed optical fiber during the diffusion process of the polyurethane, and combines the functional relationship between the thermal conductivity and the moisture content to analyze the moisture field changes in the porous medium to achieve a comprehensive and accurate evaluation of the diffusion of the polyurethane in the porous medium. This not only improves the comprehensiveness and economy of the monitoring, but also avoids the serious errors caused by directly using the temperature to measure the diffusion range, thereby improving the accuracy of the monitoring and having broad application prospects.

[0134] 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.

[0135] In one embodiment, Figure 6 As shown, an embodiment of the present invention provides a device for monitoring the diffusion of polyurethane in a porous medium, the device comprising:

[0136] The device establishment module 101 is used to select a diffusion model according to the diffusion characteristics of polyurethane in a porous medium, and to wind the distributed optical fiber on at least one sensing cage according to predetermined helical parameters to form a helical structure;

[0137] A coordinate mapping module 102 is used to establish a rectangular coordinate system in the porous medium space with the polyurethane penetration point as the origin, and map the coordinates of each temperature measurement point on the spiral structure to the rectangular coordinate system in the porous medium space;

[0138] An initial measurement module 103 is used to connect the optical fiber to the distributed temperature sensing system, calibrate the initial value of the distributed temperature sensing system, and measure the initial moisture field of the porous medium before the polyurethane penetrates;

[0139] The diffusion monitoring module 104 is used to monitor the temperature transfer fluctuation along the optical fiber when the polyurethane diffuses in the porous medium by using the distributed temperature sensing system during the polyurethane penetration process, and obtain the moisture field after penetration under the stable state of temperature transfer fluctuation;

[0140] The diffusion identification module 105 is used to analyze the change of moisture content according to the initial moisture field and the moisture field after penetration, and identify the polyurethane diffusion distribution field in the porous medium in combination with the diffusion model.

[0141] For the specific definition of a polyurethane diffusion monitoring device in a porous medium, please refer to the above-mentioned definition of a polyurethane diffusion monitoring method in a porous medium, which will not be repeated here. A person 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.

[0142] The embodiment of the present invention provides a device for monitoring the diffusion of polyurethane in a porous medium. The device winds a distributed optical fiber around at least one sensing cage to form a spiral structure through a device establishment module; a coordinate mapping module takes the polyurethane penetration point as the origin to establish a rectangular coordinate system in the porous medium space, and maps the coordinates of each temperature measurement point on the spiral structure to the rectangular coordinate system in the porous medium space; an initial measurement module connects the optical fiber to a distributed temperature sensing system, performs initial value calibration on the distributed temperature sensing system, and measures the initial moisture field of the porous medium before the polyurethane penetrates; during the polyurethane penetration process, the diffusion monitoring module uses the distributed temperature sensing system to monitor the temperature transfer fluctuation along the optical fiber when the polyurethane diffuses in the porous medium, and obtains the post-penetration moisture field under the stable state of the temperature transfer fluctuation; the diffusion identification module analyzes the change of moisture content according to the initial moisture field and the post-penetration moisture field, and identifies the polyurethane diffusion distribution field in the porous medium in combination with the diffusion model. Compared with the prior art, the device provided in the embodiment of the present invention utilizes a distributed temperature sensing system to monitor in real time the temperature changes of the distributed optical fiber during the polyurethane diffusion process, and combines the functional relationship between thermal conductivity and moisture content to achieve a comprehensive and accurate evaluation of the diffusion of polyurethane in porous media, which has broad application prospects.

[0143] Figure 7 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.

[0144] 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.

[0145] Additionally, the memory may be a physically separate unit or may be integrated with the processor.

[0146] It can be understood by those skilled in the art that Figure 7 The 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.

[0147] 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.

[0148] The embodiments of the present invention provide a method, device, equipment and medium for monitoring the diffusion of polyurethane in a porous medium. The method for monitoring the diffusion of polyurethane in a porous medium combines optical fiber technology with the characteristics of the change in thermal conductivity of polyurethane after curing to achieve high-precision, real-time and comprehensive monitoring of the diffusion of polyurethane in the porous medium, which not only achieves low-cost and high-efficiency monitoring, but also improves the accuracy and comprehensiveness of monitoring.

[0149] 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.

[0150] 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.

[0151] 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 method for monitoring the diffusion of polyurethane in porous media, characterized in that: The following steps are involved: A diffusion model is selected according to the diffusion characteristics of polyurethane in a porous medium, and a distributed optical fiber is wound around at least one sensing cage according to predetermined helical parameters to form a helical structure; Taking the polyurethane penetration point as the origin, a rectangular coordinate system in the porous medium space is established, and the coordinates of each temperature measurement point on the spiral structure are mapped to the rectangular coordinate system in the porous medium space; Connecting the optical fiber to a distributed temperature sensing system, calibrating the distributed temperature sensing system for an initial value, and measuring the initial moisture field of the porous medium before polyurethane infiltration; During the polyurethane penetration process, the distributed temperature sensing system is used to monitor the temperature transfer fluctuation along the optical fiber when the polyurethane diffuses in the porous medium, and obtain the moisture field after penetration under the stable state of temperature transfer fluctuation; The change of moisture content is analyzed according to the initial moisture field and the moisture field after penetration, and the polyurethane diffusion distribution field in the porous medium is identified in combination with the diffusion model.

2. A method for monitoring polyurethane diffusion in porous media according to claim 1, characterized in that: The helix parameters include the number of fiber windings, the pitch and the helix angle of the helix structure on each sensing cage. The mathematical expressions of the number of fiber windings, the pitch and the helix angle are respectively: Where N is the number of fiber windings; H is the height of the sensing cage; P is the pitch; D is the diameter of the sensing cage; L is the winding length of the optical fiber inside each sensing cage; and θ is the helix angle.

3. A method for monitoring polyurethane diffusion in porous media according to claim 1, characterized in that: When there is only a single sensing cage, the coordinates of each temperature measurement point on the spiral structure mapped to the rectangular coordinate system in the porous medium space are specifically: in, Wherein, (x, y, z) represents the coordinates of the temperature measurement point on the helical structure mapped to the rectangular coordinate system in the porous medium space; θ represents the helix angle; p0 and d are intermediate variables; l1 represents the length of the optical fiber between the starting end of the sensing cage and the demodulator; L represents the winding length of the optical fiber on each sensing cage; n represents the number of spiral turns of the point on the helical structure; D represents the diameter of the sensing cage; and P represents the pitch.

4. A method for monitoring polyurethane diffusion in porous media according to claim 1, characterized in that: When there are at least two sensing cages, the coordinates of each temperature measurement point on the spiral structure mapped to the rectangular coordinate system in the porous medium space are specifically: in, Where (x, y, z) represents the coordinates of the temperature measurement point on the spiral structure mapped to the rectangular coordinate system of the porous medium space; i represents the i-th sensing cage, where 1≤i≤m, and m represents the number of sensing cages; θ i represents the helical angle of the helical structure on the i-th sensing cage; p0 ′ and d ′ is the intermediate variable; L i represents the winding length of the internal optical fiber on the i-th sensing cage; l i represents the length of the optical fiber between the starting end of the i-th sensing cage and the demodulator; n i Indicates the number of spiral turns of the temperature measurement point on the spiral structure of the i-th sensing cage; D i represents the diameter of the i-th sensor cage; P i represents the pitch of the helical structure on the i-th sensing cage.

5. The method for monitoring the diffusion of polyurethane in porous media according to claim 1, characterized in that: The step of analyzing the change of moisture content according to the initial moisture field and the moisture field after penetration, and identifying the polyurethane diffusion distribution field in the porous medium in combination with the diffusion model comprises: Determining a moisture content reduction area according to the initial moisture field and the post-infiltration moisture field; According to the moisture content reduction area, the thermal conductivity reduction area in the porous medium is determined by using the functional relationship between thermal conductivity and moisture content; The polyurethane diffusion distribution field in the porous medium is identified according to the reduced thermal conductivity region in the porous medium in combination with the diffusion model.

6. A method for monitoring the diffusion of polyurethane in a porous medium as claimed in claim 5, characterized in that: The diffusion model includes a spherical diffusion model or a cylindrical-hemispherical diffusion model.

7. A method for monitoring the diffusion of polyurethane in a porous medium as claimed in claim 5, characterized in that: The step of identifying the polyurethane diffusion distribution field in the porous medium according to the area with reduced thermal conductivity in the porous medium and in combination with the diffusion model comprises: Mapping the pre-measured sensing cage optical fiber length data to the porous medium spatial rectangular coordinate system to obtain the three-dimensional structural data of the porous medium; Identifying pore structure data of the porous medium in a region where thermal conductivity is reduced based on the three-dimensional structure data of the porous medium, and quantifying a quantitative index of heterogeneity of the porous medium in the region where thermal conductivity is reduced using a statistical method based on the pore structure data; Taking the quantitative index of heterogeneity of porous media as input, microscopic molecular dynamics simulation is performed in the area where thermal conductivity decreases, microscopic diffusion characteristic parameters of polyurethane in the microstructure of porous media are predicted, and the microscopic diffusion characteristic parameters are integrated into the diffusion model to obtain a polyurethane diffusion model that takes heterogeneity into account; A chemical reaction kinetic model of polyurethane diffusion in porous media was established. The chemical reaction kinetic model was used to analyze the time delay effect of polyurethane diffusion in the thermal conductivity reduction region and extract the time delay parameters in the polyurethane diffusion process. The time delay parameter is introduced, and the Galerkin finite element method is used to dynamically simulate the polyurethane diffusion model considering heterogeneity in order to capture the migration characteristics of polyurethane in porous media and obtain the polyurethane diffusion distribution field considering the time delay effect.

8. A polyurethane diffusion monitoring device in a porous medium, characterized in that: The device comprises: A device establishment module is used to select a diffusion model according to the diffusion characteristics of polyurethane in a porous medium, and to wind a distributed optical fiber around at least one sensing cage according to predetermined helix parameters to form a helix structure; A coordinate mapping module is used to establish a rectangular coordinate system in the porous medium space with the polyurethane penetration point as the origin, and map the coordinates of each temperature measurement point on the spiral structure to the rectangular coordinate system in the porous medium space; An initial measurement module, used to connect the optical fiber to the distributed temperature sensing system, calibrate the initial value of the distributed temperature sensing system, and measure the initial moisture field of the porous medium before the polyurethane penetrates; A diffusion monitoring module is used to monitor the temperature transfer fluctuation along the optical fiber when the polyurethane diffuses in the porous medium by using the distributed temperature sensing system during the polyurethane penetration process, and obtain the moisture field after penetration under the stable state of temperature transfer fluctuation; The diffusion identification module is used to analyze the change of moisture content according to the initial moisture field and the moisture field after penetration, and to identify the polyurethane diffusion distribution field in the porous medium in combination with the diffusion model.

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.

Images