Soil moisture content detection method based on unsteady heat conduction and optical fiber temperature measurement

Abstract

The application provides a soil moisture content detection method based on unsteady heat conduction and optical fiber temperature measurement, comprising: heating the soil in a target measurement area based on an active heating method, and measuring the soil temperature value at each moment at different radial distances from the heating source during the heating process; substituting the soil temperature value at any moment during the heating process and the corresponding radial distance into a pre-determined soil moisture content relationship model to obtain the soil moisture content at the corresponding radial distance position from the heating source in the target measurement area at the corresponding moment; and determining the soil moisture content of the target measurement area according to the soil moisture content at each radial distance position from the heating source in the target measurement area at the corresponding moment. The application establishes the relationship between the soil moisture content and the soil temperature value, so as to realize in-situ monitoring and long-time monitoring of a large range of soil in the target measurement area through the soil temperature value obtained by the active heating method.

Description

Technical Field

[0001] This invention relates to the field of soil moisture field monitoring technology, and in particular to a method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement. Background Technology

[0002] Moisture content, as a core indicator characterizing the moisture state of soil, is crucial for the accurate measurement of soil ecological characteristics, engineering performance, and the exploration of water transport and storage mechanisms. It is the foundation for related research in fields such as geology, geotechnical engineering, and agricultural ecology.

[0003] Currently, fiber optic-based methods for measuring soil moisture content are widely used in this field due to their advantages such as strong anti-interference capabilities, distributed monitoring, and good durability. In existing technologies, the core idea of ​​using fiber optics to calculate soil moisture content is to establish a quantitative relationship between temperature characteristic values ​​(or optical signal characteristic values) and moisture content through laboratory calibration. Specifically, technicians first prepare soil samples with different moisture contents in the laboratory, embed fiber optic sensors (such as actively heated optical fibers, distributed fiber optic temperature measurement systems, etc.) into the samples, and measure characteristic values ​​such as temperature changes, optical power attenuation, or Brillouin frequency shift of the optical fiber at different moisture contents to fit a calibration formula between the characteristic values ​​and the moisture content. This formula is then applied to field soil measurements, and the moisture content is inferred from the measured characteristic values ​​obtained through fiber optics.

[0004] However, existing technologies have significant drawbacks: on the one hand, laboratory calibration is cumbersome, requiring the preparation of a large number of soil samples with different moisture contents and even different dry densities. Furthermore, the calibration operation is affected by factors such as soil sample homogeneity and ambient temperature, making it time-consuming and labor-intensive. On the other hand, the formulas established through laboratory calibration are poorly adapted to field soil conditions—the texture, pore structure, and mineral composition of field soil often differ from laboratory samples, leading to deviations in the calibration formulas during practical applications and reducing measurement accuracy. In addition, traditional methods rely excessively on laboratory calibration results and lack universally applicable simplified models, making it difficult to quickly adapt to the measurement needs of different regions and types of soil, thus limiting the widespread application of fiber optic technology in rapid moisture content monitoring. Summary of the Invention

[0005] This invention provides a method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement, which addresses the lack of universality in existing fiber optic soil moisture content measurement methods and achieves an accurate, efficient, and convenient method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement.

[0006] This invention provides a method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement, comprising:

[0007] The soil in the target survey area is heated using an active heating method, and the soil temperature is measured at different radial distances from the heating source at each moment during the heating process. The target survey area includes several soil layers.

[0008] Substituting the soil temperature value and its corresponding radial distance at any moment during the heating process into a pre-determined soil moisture content relationship model, the soil moisture content at the radial distance from the heating source in the target area at the corresponding moment is obtained. The soil moisture content relationship model is determined based on the first relationship between the thermal diffusivity coefficient and the soil temperature value, the second relationship between the moisture content and the thermal diffusivity coefficient, and the soil layer corresponding to the soil temperature value.

[0009] The soil moisture content of the target test area is determined based on the soil moisture content at each radial distance from the heating source in the target test area at the corresponding time.

[0010] According to the present invention, a method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement is provided. The first relationship is derived from the heat conduction equation in cylindrical coordinates based on the unsteady-state heat conduction model, and the second relationship is constructed based on the Hashin-Shtrikman model.

[0011] According to the present invention, a method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement is provided, wherein the soil moisture content relationship model includes:

[0012] (1);

[0013] (2);

[0014] Wherein, equation (1) represents the second relationship, Indicates the soil moisture content. express t Radial distance from heating source in the target area at any given time r Thermal diffusivity of the soil. This represents the dry soil thermal diffusivity of the soil in the target test area. This represents the thermal diffusivity of soil water in the target test area. This indicates the dry specific heat capacity of the soil in the target survey area; Equation (2) represents the specific heat capacity of soil water in the target area; Equation (2) characterizes the first relationship. This is an empirical coefficient. T w This indicates the temperature of the heating source surface. T 0 indicates the initial temperature of the soil in the target test area before heating.

[0015] According to the present invention, a method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement, prior to the step of heating the soil in the target test area using an active heating method, further includes:

[0016] Soil samples were taken from each soil layer in the target survey area to obtain soil samples from each soil layer.

[0017] Soil drying experiments were conducted on soil samples from each soil layer to obtain the dry soil thermal diffusivity and dry soil specific heat capacity of each soil layer in the target area.

[0018] Based on the dry soil thermal diffusivity and dry soil specific heat capacity of each soil layer in the target area, a soil moisture content relationship model is determined for each soil layer in the target area.

[0019] According to the present invention, a method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement includes the step of substituting the soil temperature value and its corresponding radial distance at any moment during the heating process into a pre-determined soil moisture content relationship model to obtain the soil moisture content at the corresponding radial distance from the heating source in the target area at that moment. The specific steps include:

[0020] Based on the soil layer distribution in the target test area, determine the soil layer corresponding to each measured soil temperature value;

[0021] By calling the soil moisture content relationship model corresponding to each soil layer, and substituting the temperature value of each soil layer and its corresponding radial distance into the soil moisture content relationship model of its corresponding soil layer, the soil moisture content at the location of the soil temperature value is obtained.

[0022] According to the present invention, a method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement is provided. The step of heating the soil in the target test area based on the active heating method specifically includes:

[0023] One active heating fiber and several temperature measuring fibers are deployed in the target measurement area. The several temperature measuring fibers are used to measure the temperature of several measurement segments that are parallel to each other and spaced at different radial distances from the active heating fiber.

[0024] The active heating optical fiber is heated to a preset surface temperature, and the soil temperature in the target area reaches a steady state.

[0025] This invention also provides a soil moisture content detection system based on unsteady-state heat conduction and fiber optic temperature measurement, comprising:

[0026] The acquisition module is used to obtain the soil temperature value at each moment under different radial distances from the heating source during the heating process, wherein the heating process is a process of heating the soil in the target test area based on the active heating method, and the target test area includes several soil layers;

[0027] The calculation module is used to substitute the soil temperature value and its corresponding radial distance at any moment during the heating process into a pre-determined soil moisture content relationship model to obtain the soil moisture content at the radial distance position from the heating source in the target area at the corresponding moment. The soil moisture content relationship model is determined based on the first relationship between the thermal diffusivity coefficient and the soil temperature value, the second relationship between the moisture content and the thermal diffusivity coefficient, and the soil layer corresponding to the soil temperature value.

[0028] The determination module is used to determine the soil moisture content of the target test area based on the soil moisture content at each radial distance from the heating source in the target test area at the corresponding time.

[0029] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement as described above.

[0030] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the soil moisture content detection method based on unsteady heat conduction and fiber optic temperature measurement as described above.

[0031] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement as described above.

[0032] The soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement provided by this invention establishes the relationship between soil moisture content and soil temperature value. It enables in-situ and long-term monitoring of a large area of ​​soil in the target test area by using soil temperature value obtained through active heating method. Moreover, the detection process does not require a lot of complicated laboratory operations, thus improving the efficiency of soil moisture content detection in large areas. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a flowchart illustrating the method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement provided by the present invention.

[0035] Figure 2This is a graph showing the relationship between temperature and time and distance fitted by the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement provided by the present invention.

[0036] Figure 3 This is a comparison diagram of the numerical solution and the engineering approximate solution in the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement provided by the present invention.

[0037] Figure 4 This is a schematic diagram illustrating the influence of empirical coefficients on the engineering approximate solution in the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement provided by this invention.

[0038] Figure 5 This is a graph showing the relationship between temperature and distance and time in the verification of the soil moisture content detection method based on unsteady heat conduction and fiber optic temperature measurement provided by the present invention.

[0039] Figure 6 This is a graph showing the relationship between the thermal diffusivity coefficient and radial distance fitted during the verification of the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement provided by this invention.

[0040] Figure 7 This is a graph showing the relationship between moisture content and radial distance obtained during the verification of the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement provided by this invention.

[0041] Figure 8 This is a schematic diagram of the soil moisture content detection system based on unsteady-state heat conduction and fiber optic temperature measurement provided by the present invention.

[0042] Figure 9 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0044] The following is combined Figures 1 to 7 This invention introduces a method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement, such as... Figure 1 As shown, it includes:

[0045] Step 101: The soil in the target survey area is heated based on the active heating method, and the soil temperature value at each moment is measured at different radial distances from the heating source during the heating process. The target survey area includes several soil layers.

[0046] Active heating method (AHFO) is an in-situ monitoring technology based on the principle of heat conduction. It analyzes the temperature response characteristics of the soil after heating to invert the water content by placing heating probes and measuring probes in parallel in the soil. The heating probes are used to heat the soil in the surrounding area, and the measuring probes are used to measure the temperature of the soil after heating. The temperature measurement values ​​of different depths of the soil are obtained based on the readings of the measuring probes at different locations.

[0047] In this embodiment, the target test area is the three-dimensional region corresponding to the target area defined in the plane of the target test field at a preset measurement depth. The number of soil layers included in the target test area varies depending on the preset measurement depth. Based on the target test field and the preset measurement depth, the determined target test area includes one or more soil layers.

[0048] Optionally, a borehole of a predetermined measurement depth is drilled at the center of the target area, and a heating probe is embedded therein. Then, based on the size of the target area and the number of measuring probes, boreholes are drilled at different radial distances from the heating probes, ensuring that the number of boreholes is the same as the number of measuring probes, and that multiple boreholes cover different locations within the target area as much as possible. A temperature measuring probe is embedded in each borehole, thereby obtaining the soil temperature values ​​at different radial distances from the heating source during the heating process based on the readings of the temperature measuring probes at each moment after heating to a steady state.

[0049] Step 102: Substitute the soil temperature value and its corresponding radial distance at any moment during the heating process into a pre-determined soil moisture content relationship model to obtain the soil moisture content at the radial distance from the heating source in the target area at the corresponding moment. The soil moisture content relationship model is determined based on the first relationship between the thermal diffusivity coefficient and the soil temperature value, the second relationship between the moisture content and the thermal diffusivity coefficient, and the soil layer corresponding to the soil temperature value.

[0050] The soil moisture content relationship model consists of a first relationship and a second relationship. The second relationship represents the relationship between soil moisture content and thermal diffusivity, while the first relationship represents the relationship between thermal diffusivity and soil temperature. Thus, after substitution with thermal diffusivity, the soil moisture content relationship model represents the relationship between soil moisture content and soil temperature.

[0051] Based on this, by determining the soil temperature values ​​obtained at different radial distances, the soil moisture content relationship model can be substituted into the soil temperature value to calculate the soil moisture content at the corresponding location.

[0052] Since the soil moisture content relationship in this embodiment includes the relationship between the thermal diffusivity coefficient and the soil temperature, that is, the law of heat diffusion in the soil, it can be understood that different soil layers will have different corresponding first relationships, that is, the parameter values ​​in the soil moisture content relationship model will also be different.

[0053] Therefore, for each measured soil temperature value, the soil layer to which it belongs is first determined based on its measurement location, and the parameter values ​​of the soil moisture content relationship model corresponding to that soil layer are determined. Then, the soil moisture content of the soil at its location is calculated by substituting it into the determined soil moisture content relationship model.

[0054] Step 103: Determine the soil moisture content of the target test area based on the soil moisture content at each radial distance from the heating source in the target test area at the corresponding time.

[0055] For any given moment, the soil temperature values ​​acquired by all temperature measuring elements at different radial distances are used to determine the soil moisture content corresponding to each temperature value using the method described above. By integrating the soil moisture contents corresponding to each soil temperature value location, the soil moisture content of the target measurement area can be obtained.

[0056] By taking all soil temperature values ​​acquired at any given time as a set and integrating multiple soil temperature value sets across the entire time series, the soil moisture content of the target measurement area that changes over time can also be obtained. Thus, temperature monitoring enables the overall measurement and long-term monitoring of soil moisture content in a large area.

[0057] This invention establishes a relationship between soil moisture content and soil temperature, enabling in-situ and long-term monitoring of a large area of ​​soil in the target area using soil temperature values ​​obtained through active heating. Furthermore, the detection process does not require extensive and complex laboratory operations, thus improving the efficiency of soil moisture content detection in large areas.

[0058] In the soil moisture content detection method based on unsteady heat conduction and fiber optic temperature measurement of the present invention, the first relationship is derived from the heat conduction equation in cylindrical coordinates based on the unsteady heat conduction model, and the second relationship is constructed based on the Hashin-Shtrikman model.

[0059] For unsteady temperature changes, the temperature changes over time. To control the number of variables, a thermal diffusivity is introduced: The system monitors only the temperature change of the optical fiber itself, assuming perfect contact between the fiber and the soil, with the only gaps being the soil's pores and no excess air. The soil's thermal diffusivity varies with moisture content. According to Fourier's law, a higher thermal conductivity corresponds to a higher heat flux. The cable radius is negligible relative to the soil. During cable heating, temperature rapidly diffuses into the soil, where the soil's thermal diffusivity becomes crucial. The soil's moisture content determines the magnitude of this thermal diffusivity. Within the same soil type and moisture content area, the temperature change monitored by the optical fiber is consistent, meaning the temperature rise is the same under the same heating power. same.

[0060] In this embodiment, in order to establish the relationship between soil moisture content and soil temperature, the thermal diffusivity is used as an intermediate quantity to derive the first relationship between the thermal diffusivity and soil temperature and the second relationship between soil moisture content and thermal diffusivity.

[0061] The derivation of the first relation is as follows:

[0062] In unsteady-state heat conduction, the temperature at each point within an object is a function of time and space. Using a cylindrical coordinate system for analysis, the heat conduction differential equation with a heat source is determined. Since the heating fiber / cable, acting as the heat source, is a linear heat source within the soil in the active heating method, axial heat conduction is neglected, and the heat conduction differential equation can be simplified to a one-dimensional unsteady-state equation.

[0063] Based on this, let heating be defined as follows: given an initial temperature, heat diffuses into the soil and is then captured by a thermometric fiber optic cable; that is, let the heating fiber optic cable be cylindrical with a radius of... Buried in the soil, the surface temperature of the heated optical fiber is kept constant. T w The differential equation for heat conduction in unsteady-state thermal conductivity, taken in cylindrical coordinates, can be simplified to:

[0064] ;

[0065] In the above equation, the left half represents the change of temperature with time, and the right half represents the unsteady one-dimensional cylindrical coordinate heat conduction relationship simplified to only contain radially varying heat conduction without internal heat sources.

[0066] in, Indicates the radial distance of the soil. r ,time t The temperature below, This is the soil thermal diffusivity.

[0067] Furthermore, we define initial conditions and boundary conditions to solve the above equation, where the initial conditions characterize the state of the soil before heating, and the boundary conditions characterize the state of the soil after it has been heated to a steady state using the active heating method.

[0068] Optionally, the initial conditions defined in this embodiment ( t =0): T 0: T ( r ,0)= T 0 ( );in, This represents the radius of the active heating optical fiber that acts as the heating source. T 0 represents the initial temperature of the soil before heating.

[0069] Optionally, the boundary conditions defined in this embodiment are:

[0070] : T ( r ,0)= T w ( t >0);

[0071] : ( t ≥0);

[0072] The simplified heat conduction differential equation is solved using the above initial and boundary conditions to determine the relationship between soil temperature and distance and time.

[0073] As a preferred embodiment, to reduce the number of variables, this implementation defines dimensionless parameters for dimensionless processing of initial and boundary conditions, specifically including:

[0074] Dimensionless temperature: ;in, , Corresponding to the surface temperature of the heating cable, The temperature at an infinity distance from the heating cable.

[0075] Dimensionless radius: ; , Corresponding to the position on the surface of the heating cable.

[0076] Dimensionless time: Used to characterize the degree of thermal diffusion.

[0077] Based on this, the dimensionless governing equations are obtained as follows:

[0078] ;

[0079] The corresponding dimensionless initial conditions and dimensionless boundary conditions are:

[0080] , ;

[0081] , ;

[0082] , .

[0083] Due to the complexity of calculating the governing equations, this implementation uses the finite difference method to discretize the equations and solve them through programming. The resulting temperature change curve is shown below. Figure 2 As shown.

[0084] In practical applications, it is necessary to achieve rapid estimation, trend analysis, and real-time monitoring of engineering processes. Therefore, by combining the logarithmic decay characteristics of thermal conduction in cylindrical coordinates, a characterization method is obtained. Figure 2 Simplified analytical expression for the common trend of multiple curves:

[0085] (3);

[0086] In the formula, This is an empirical coefficient. .

[0087] Specifically, in the process of finding the approximate solution to the above engineering problem, similarity variables are introduced: In the formula, This represents the ratio of the radial distance increment to the characteristic diffusion length. It is thermal disturbance over time t The diffusion distance within.

[0088] Based on this, the exact solution of the dimensionless governing equation after introducing the above variables is obtained as follows:

[0089] ;

[0090] in, The complementary error function has the following form: .

[0091] By analyzing the asymptotic properties of the error function, when hour, (Asymptotic expansion), its trend of change is similar to that of the exponential function. The attenuation characteristics are consistent, which can be further simplified in engineering by ignoring the coefficient differences and directly using an exponential function to fit the attenuation trend of the error function, that is:

[0092] ;

[0093] In the formula, Let be the empirical coefficient, then regarding the deviation between the correction exponential function and the error function.

[0094] The exact solution then becomes: , as an exponential approximation.

[0095] Substituting similar variables and exponential approximations into the excessive temperature... From the definition, we get the above equation (3).

[0096] The engineering approximate solution derived above is verified, such as... Figure 3 and Figure 4 As shown:

[0097] when hour, ,but The surface temperature conditions are met.

[0098] when hour, ,but T → T 0 satisfies the far-field condition.

[0099] Based on this, the first relationship between the thermal diffusivity and the soil temperature is derived from equation (1):

[0100] (2).

[0101] The derivation of the second relation is as follows:

[0102] The thermal diffusivity of soil is determined by the thermophysical properties of its components (dry soil and water) and its structural characteristics (such as porosity and saturation). The mass water content of natural soil ( The ratio of the mass of water in the soil to the mass of dry soil can be expressed as:

[0103] ;

[0104] In the formula, Indicates the density of soil water. This indicates the porosity of natural soil. Indicates the saturation level of natural soil. This indicates the dry soil density.

[0105] Combined with the expression for thermal diffusivity The porosity and saturation of natural soil are incorporated into a volume-weighted average model to estimate the thermal conductivity of the natural soil composite medium. The influence of gas on solids and liquids is negligible; therefore, air is not considered in subsequent calculations. The volume percentages of dry soil and water are: ;in, and These represent the volumes of dry soil and soil water, respectively.

[0106] but:

[0107] ;

[0108] ;

[0109] The derivation yields: .

[0110] Furthermore, thermal conductivity k The heat conductivity of natural soil can be estimated using the Hashin-Shtrikman model framework, taking into account both dry soil and water materials and their coupling effects, while neglecting the influence of air.

[0111] ;

[0112] In the formula, k It is the thermal conductivity coefficient of natural soil. These are the thermal conductivity coefficients of dry soil, water, and air, respectively. These are the volume fractions of dry soil, water, and air, respectively.

[0113] After simplification, we get:

[0114] ;

[0115] ;

[0116] Substituting this into the expression for the thermal diffusivity, we get: .

[0117] Right now: .

[0118] Substituting this into the expression for soil moisture content, we derive the second relationship:

[0119] .

[0120] Based on this, the soil moisture content relationship model constructed according to the derived first and second relationships includes:

[0121] (1);

[0122] (2);

[0123] Wherein, equation (1) represents the second relationship, Indicates the soil moisture content. express t Radial distance from heating source in the target area at any given time r Thermal diffusivity of the soil. This represents the dry soil thermal diffusivity of the soil in the target test area. This represents the thermal diffusivity of soil water in the target test area. This indicates the dry specific heat capacity of the soil in the target survey area; Equation (2) represents the specific heat capacity of soil water in the target area; Equation (2) characterizes the first relationship. This is an empirical coefficient. T w This indicates the temperature of the heating source surface. T 0 indicates the initial temperature of the soil in the target test area before heating.

[0124] In one specific implementation method T The measured soil temperature value, T W The target heating temperature is determined based on the heating cable used in the active heating method. t Determined based on the actual heating time corresponding to the soil temperature value obtained. Measurements were taken before the soil in the target test area was heated. r Determined based on the location corresponding to the soil temperature value. k The thermal conductivity was measured after sampling the soil in the target test area using a thermal conductivity meter before heating the soil.

[0125] The thermal diffusivity of soil water can be found in a table using the thermal diffusivity of natural water.

[0126] The thermal diffusivity of dry soil can be obtained by collecting soil samples on-site and obtaining dry soil samples through soil drying experiments, and then directly measuring the dry soil samples using a thermal conductivity meter.

[0127] The specific heat capacity of soil water can be obtained by referring to a table using the specific heat capacity of natural water.

[0128] The specific heat capacity of dry soil can be calculated using a formula. Specifically, the volume and mass of a dry soil sample are measured to calculate the density of the dry soil, and then the specific heat capacity of the dry soil is calculated by combining this with the thermal diffusivity of the dry soil.

[0129] Using the above method, based on the soil layer distribution in the target survey area, the dry soil thermal diffusivity and dry soil specific heat capacity of each soil layer are sampled and determined in advance, thereby determining the parameter values ​​of the soil moisture content relationship model corresponding to each soil layer. Then, by substituting the measured soil temperature value into the soil moisture content relationship model corresponding to the soil layer at the measurement location, the soil moisture content at the measurement location can be directly calculated.

[0130] Compared to existing active heating methods that calibrate the relationship between temperature characteristics and soil moisture content based on laboratory-prepared samples with different moisture contents, the method in this embodiment only requires simple operation to calculate the correlation coefficient of dry soil after sampling at the target test area, determine the parameter values ​​of the soil moisture content relationship model, and then use the active heating method to measure the soil temperature values ​​at different radial spacings, thereby directly calculating the corresponding soil moisture content, which improves measurement efficiency.

[0131] This invention combines in-situ field testing with limited laboratory data to construct a simplified model based on physical mechanisms. It derives the moisture content calculation formula using the response relationship between temperature and fiber optic signals, reducing reliance on complex calibration processes. Simultaneously, it incorporates readily available soil parameters, such as density and particle size distribution, to locally modify the model, thereby improving its applicability under different geological conditions. Furthermore, it allows for the development of supporting data processing algorithms to achieve automatic moisture content calculation and real-time feedback, enhancing measurement efficiency and intelligence.

[0132] In the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement of the present invention, before the step of heating the soil in the target test area based on the active heating method, the method further includes:

[0133] Soil samples were taken from each soil layer in the target survey area to obtain soil samples from each soil layer.

[0134] Pre-sampling is used to determine the distribution of soil layers in the target survey area. If the target survey area includes multiple soil layers, samples are taken from each soil layer to obtain soil samples from each soil layer.

[0135] Soil drying experiments were conducted on soil samples from each soil layer to obtain the dry soil thermal diffusivity and dry soil specific heat capacity of each soil layer in the target area.

[0136] Since the soil moisture content relationship model requires the determination of the dry soil thermal diffusivity and dry soil specific heat capacity of the soil in the target test area, the dry soil thermal diffusivity and dry soil specific heat capacity of each soil layer are determined by conducting soil drying experiments on soil samples from each soil layer.

[0137] Specifically, for each soil layer, a soil sample is taken using a ring cutter, and the volume of the ring cutter is determined as the soil sample volume. The soil sample taken by the ring cutter is dried, and the dry soil mass is obtained by weighing it using a balance. Based on the soil sample volume and the dry soil mass, the dry soil density is calculated using the density formula.

[0138] Based on this, the thermal diffusivity of the dried soil sample was directly measured using a thermal conductivity meter to obtain the thermal diffusivity of the dry soil.

[0139] The specific heat capacity of dry soil is then calculated using the formula for the thermal diffusivity.

[0140] Based on the dry soil thermal diffusivity and dry soil specific heat capacity of each soil layer in the target area, a soil moisture content relationship model is determined for each soil layer in the target area.

[0141] Based on the calculated dry soil thermal diffusivity and dry soil specific heat capacity of each soil layer in the target area, the parameter values ​​of the soil moisture content relationship model corresponding to each soil layer in the target area are determined, thereby determining the soil moisture content relationship model corresponding to each soil layer.

[0142] Based on this, when using it, once the soil temperature measurement point belongs to the soil layer, the corresponding soil moisture content relationship model can be called to calculate the soil moisture content at that location.

[0143] In the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement of this invention, the step of substituting the soil temperature value and its corresponding radial distance at any moment during the heating process into a pre-determined soil moisture content relationship model to obtain the soil moisture content at the corresponding radial distance from the heating source in the target area at that moment specifically includes:

[0144] Based on the soil layer distribution in the target test area, determine the soil layer corresponding to each measured soil temperature value;

[0145] By calling the soil moisture content relationship model corresponding to each soil layer, and substituting the temperature value of each soil layer and its corresponding radial distance into the soil moisture content relationship model of its corresponding soil layer, the soil moisture content at the location of the soil temperature value is obtained.

[0146] Determine the soil layer distribution in the target survey area, specifically including the soil layer type and the depth range corresponding to each soil layer.

[0147] Based on the temperature measuring element used to measure the soil temperature, the depth value of each measuring point on the temperature measuring element is determined after the element is deployed, and the soil layer to which each measuring point belongs is identified based on the depth value.

[0148] By determining the measuring point to which each soil temperature value belongs, the corresponding soil layer can be identified.

[0149] For each measured soil temperature value, the soil moisture content relationship model corresponding to its soil layer is called to obtain the soil moisture content at the measuring point location corresponding to that soil temperature value.

[0150] In the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement of this invention, the step of heating the soil in the target test area based on the active heating method specifically includes:

[0151] One active heating fiber and several temperature measuring fibers are deployed in the target measurement area. The several temperature measuring fibers are used to measure the temperature of several measurement segments that are parallel to each other and spaced at different radial distances from the active heating fiber.

[0152] The active heating optical fiber is heated to a preset surface temperature, and the soil temperature in the target area reaches a steady state.

[0153] In this embodiment, an active heating optical fiber is selected as the heating source for the active heating method, and a temperature measuring optical fiber is used as the temperature measuring element for the active heating method.

[0154] Optionally, the number of temperature-sensing optical fibers used can be determined according to the size of the target measurement area. If the target measurement area has a large planar range or a deep depth, more temperature-sensing optical fibers are required. If the target measurement area is small, only one temperature-sensing optical fiber can be used to measure the soil temperature at different radial distances.

[0155] Taking the active heating fiber as an example, several temperature measuring fibers are laid at radial distances of 7cm, 14cm and 21cm from the center of the target measurement area.

[0156] When the depth is sufficient, three temperature-sensing optical fibers are used to measure the soil temperature at three radially spaced locations. All three fibers are connected to a DTS thermometer to obtain the readings at each measuring point on the fiber, thus obtaining the soil temperature value. When the target measurement area is shallow, one temperature-sensing optical fiber is used for measurement. The fiber is installed in a U-shape in the borehole corresponding to each radial spacing, so that one fiber is deployed at three borehole locations with different radial spacings, thereby achieving the measurement of soil temperature values ​​at different radial spacings.

[0157] Optionally, the U-shaped layout allows for two measurement segments at a radial distance, and the data from either measurement segment can be used as the soil temperature value at that radial distance.

[0158] Optionally, the active heating method requires determining the temperature of the active heating fiber surface. If the active heating fiber itself includes a temperature-sensing fiber, its reading can be used to characterize the temperature measurement value of the active heating fiber surface. If the active heating fiber does not include a temperature-sensing fiber, an additional temperature-sensing fiber can be used and attached to the active heating fiber to determine the temperature of the active heating fiber surface. T w .

[0159] In other words, the measurement method of the present invention, after determining the temperature of the surface of the active heating optical fiber, deploys at least one measuring optical fiber at a preset radial distance from the active heating optical fiber to obtain the soil temperature value at the preset radial distance. Based on the soil temperature value and the temperature of the surface of the active heating optical fiber, the soil moisture content at the preset radial distance can be calculated.

[0160] When using the active heating method to heat the soil in the target survey area, monitoring is performed... T w To determine whether the surface temperature of the active heating optical fiber has reached the target value, which is 40°C in this embodiment, the readings of each temperature-measuring optical fiber are monitored, and the thermal conductivity of the soil in the target area is measured using a thermal conductivity meter during the heating process. Based on the change in thermal conductivity, it is determined whether the soil in the target area has been heated to a steady state. After the soil in the target area has been heated to a steady state, the measured value of the temperature-measuring optical fiber at a certain moment or time period is read as the soil temperature value at that moment or time period, and the soil moisture content of the target area at that moment or the change in soil moisture content of the target area over a period of time is calculated accordingly.

[0161] In one specific implementation, in order to verify the soil moisture content relationship model proposed in this implementation, a field environment was simulated in the laboratory and tests were conducted.

[0162] Specifically, a standard experimental model box with dimensions of 4m in length, 50cm in width, and 49cm in depth was selected. The test medium (fine river sand was used in this experiment) was laid evenly inside the box with a uniform thickness of 40cm. The medium was also homogenized beforehand to ensure the consistency of the initial moisture content.

[0163] Heating optical cables are laid inside the model box, and a transformer is used to regulate the heating power, keeping the voltage constant at 75V and the heating power at 128W. During the heating process, temperature changes are monitored in real time through temperature-sensing optical fibers arranged at equal intervals inside the box. The temperature is kept constant at 40℃, and heating ends once the temperature inside the model box reaches a steady state.

[0164] The entire experiment lasted 8 hours, with 3 hours dedicated to media pretreatment and fiber optic cable deployment, and the remaining 5 hours to formal monitoring, including data acquisition and analysis.

[0165] By laying optical fibers at equal intervals of 0.07m on the same horizontal plane of the medium under test, the monitoring range can cover the entire temperature influence radius of the heating cable. Only one deployment is required to achieve synchronous detection and monitoring of the moisture content of the entire area using DTS temperature monitoring instruments. During the 5 hours of formal testing, temperature data of the area is automatically collected every minute (time is adjustable), and the moisture content result is then derived from the temperature data.

[0166] Using a common drying method as a comparison, measurement points were selected around the fiber optic cable of the model box according to the principle of uniform distribution (5 measurement points were taken along the direction of each fiber optic cable). At each measurement point, a medium sample with a depth of 10 cm was collected using a sampler. The samples were placed in a drying oven at 105℃ and dried to constant weight (12 hours). The moisture content of each measurement point was calculated by weighing, and the average value of the moisture content data of all measurement points was taken to obtain the approximate result of the moisture content of the experimental area at that time.

[0167] As can be seen, compared with the traditional drying method, firstly, for measuring the overall moisture content of a region, the method of the present invention can easily measure the moisture content of a larger area and clarify the variation law of the regional moisture content without the need for a large number of samples; secondly, for monitoring the change of moisture content, after the installation of heating cables and temperature measuring optical fibers is completed, the method of the present invention only requires temperature monitoring to monitor the change of regional moisture content, without the need for repeated sampling and measurement.

[0168] Furthermore, under the aforementioned laboratory conditions, the fitted temperature variation with time and radial direction is as follows: Figure 5 As shown; Figure 6 As shown, the thermal diffusivity calculated using the central optical fiber as a cylindrical model for radial diffusion (recorded every two minutes) is uniformly distributed within a range of 4 × 10⁻⁶. -7 The error is within ±0.5×10 -7 Between these parameters, the thermal diffusivity can be obtained within a reasonable range, thereby verifying the accuracy of the thermal diffusivity formula (first relationship) obtained from the engineering approximation solution of this invention.

[0169] like Figure 7 As shown, the moisture content is recorded every two minutes. The calculated moisture content is compared with that of the drying method. The mean error is also around 0.001, indicating that the results are close and can be used for rough estimation over a large area, realizing time-domain moisture content measurement.

[0170] The soil moisture content detection system based on unsteady-state heat conduction and fiber optic temperature measurement provided by the present invention is described below. The soil moisture content detection system based on unsteady-state heat conduction and fiber optic temperature measurement described below can be referred to in correspondence with the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement described above.

[0171] like Figure 8 As shown, the soil moisture content detection system based on unsteady heat conduction and fiber optic temperature measurement includes an acquisition module 801, a calculation module 802, and a determination module 803.

[0172] The acquisition module 801 is used to obtain the soil temperature value at each moment under different radial distances from the heating source during the heating process. The heating process is a process of heating the soil in the target test area based on the active heating method. The target test area includes several soil layers.

[0173] Active heating method (AHFO) is an in-situ monitoring technology based on the principle of heat conduction. It analyzes the temperature response characteristics of the soil after heating to invert the water content by placing heating probes and measuring probes in parallel in the soil. The heating probes are used to heat the soil in the surrounding area, and the measuring probes are used to measure the temperature of the soil after heating. The temperature measurement values ​​of different depths of the soil are obtained based on the readings of the measuring probes at different locations.

[0174] In this embodiment, the target test area is the three-dimensional region corresponding to the target area defined in the plane of the target test field at a preset measurement depth. The number of soil layers included in the target test area varies depending on the preset measurement depth. Based on the target test field and the preset measurement depth, the determined target test area includes one or more soil layers.

[0175] Optionally, a borehole of a predetermined measurement depth is drilled at the center of the target area, and a heating probe is embedded therein. Then, based on the size of the target area and the number of measuring probes, boreholes are drilled at different radial distances from the heating probes, ensuring that the number of boreholes is the same as the number of measuring probes, and that multiple boreholes cover different locations within the target area as much as possible. A temperature measuring probe is embedded in each borehole, thereby obtaining the soil temperature values ​​at different radial distances from the heating source during the heating process based on the readings of the temperature measuring probes at each moment after heating to a steady state.

[0176] The calculation module 802 is used to substitute the soil temperature value and its corresponding radial distance at any moment during the heating process into a pre-determined soil moisture content relationship model to obtain the soil moisture content at the radial distance position from the heating source in the target area at the corresponding moment. The soil moisture content relationship model is determined based on the first relationship between the thermal diffusivity coefficient and the soil temperature value, the second relationship between the moisture content and the thermal diffusivity coefficient, and the soil layer corresponding to the soil temperature value.

[0177] The soil moisture content relationship model consists of a first relationship and a second relationship. The second relationship represents the relationship between soil moisture content and thermal diffusivity, while the first relationship represents the relationship between thermal diffusivity and soil temperature. Thus, after substitution with thermal diffusivity, the soil moisture content relationship model represents the relationship between soil moisture content and soil temperature.

[0178] Based on this, by determining the soil temperature values ​​obtained at different radial distances, the soil moisture content relationship model can be substituted into the soil temperature value to calculate the soil moisture content at the corresponding location.

[0179] Since the soil moisture content relationship in this embodiment includes the relationship between the thermal diffusivity coefficient and the soil temperature, that is, the law of heat diffusion in the soil, it can be understood that different soil layers will have different corresponding first relationships, that is, the parameter values ​​in the soil moisture content relationship model will also be different.

[0180] Therefore, for each measured soil temperature value, the soil layer to which it belongs is first determined based on its measurement location, and the parameter values ​​of the soil moisture content relationship model corresponding to that soil layer are determined. Then, the soil moisture content of the soil at its location is calculated by substituting it into the determined soil moisture content relationship model.

[0181] The determination module 803 is used to determine the soil moisture content of the target test area based on the soil moisture content at each radial distance from the heating source in the target test area at the corresponding time.

[0182] For any given moment, the soil temperature values ​​acquired by all temperature measuring elements at different radial distances are used to determine the soil moisture content corresponding to each temperature value using the method described above. By integrating the soil moisture contents corresponding to each soil temperature value location, the soil moisture content of the target measurement area can be obtained.

[0183] By taking all soil temperature values ​​acquired at any given time as a set and integrating multiple soil temperature value sets across the entire time series, the soil moisture content of the target measurement area that changes over time can also be obtained. Thus, temperature monitoring enables the overall measurement and long-term monitoring of soil moisture content in a large area.

[0184] This invention establishes a relationship between soil moisture content and soil temperature, enabling in-situ and long-term monitoring of a large area of ​​soil in the target area using soil temperature values ​​obtained through active heating. Furthermore, the detection process does not require extensive and complex laboratory operations, thus improving the efficiency of soil moisture content detection in large areas.

[0185] Figure 9 An example is a schematic diagram of the physical structure of an electronic device, such as... Figure 9As shown, the electronic device may include: a processor 910, a communication interface 920, a memory 930, and a communication bus 940, wherein the processor 910, the communication interface 920, and the memory 930 communicate with each other through the communication bus 940. The processor 910 can call logic instructions in the memory 930 to execute a soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement. This method includes: heating the soil in a target area using an active heating method and measuring the soil temperature at different radial distances from the heating source at each moment during the heating process, wherein the target area comprises several soil layers; substituting the soil temperature value and its corresponding radial distance at any moment during the heating process into a pre-determined soil moisture content relationship model to obtain the soil moisture content at the corresponding radial distance from the heating source in the target area at that moment, wherein the soil moisture content relationship model is determined based on a first relationship between the thermal diffusivity coefficient and the soil temperature value, a second relationship between moisture content and the thermal diffusivity coefficient, and the soil layer corresponding to the soil temperature value; and determining the soil moisture content of the target area based on the soil moisture content at each radial distance from the heating source in the target area at the corresponding moment.

[0186] Furthermore, the logical instructions in the aforementioned memory 930 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0187] On the other hand, the present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the soil moisture content detection method based on unsteady heat conduction and fiber optic temperature measurement provided by the above methods. The method includes: heating the soil in the target test area based on an active heating method and measuring the soil temperature value at each moment at different radial distances from the heating source during the heating process, wherein the target test area includes several soil layers; substituting the soil temperature value and its corresponding radial distance at any moment during the heating process into a pre-determined soil moisture content relationship model to obtain the soil moisture content at the corresponding radial distance position from the heating source in the target test area at the corresponding moment, wherein the soil moisture content relationship model is determined based on a first relationship between the thermal diffusivity coefficient and the soil temperature value, a second relationship between moisture content and the thermal diffusivity coefficient, and the soil layer corresponding to the soil temperature value; and determining the soil moisture content of the target test area based on the soil moisture content at each radial distance position from the heating source in the target test area at the corresponding moment.

[0188] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing a computer program thereon. When executed by a processor, the computer program implements the soil moisture content detection method based on unsteady heat conduction and fiber optic temperature measurement provided by the above methods. The method includes: heating the soil in a target test area based on an active heating method and measuring the soil temperature value at each moment at different radial distances from the heating source during the heating process, wherein the target test area contains several soil layers; substituting the soil temperature value and its corresponding radial distance at any moment during the heating process into a pre-determined soil moisture content relationship model to obtain the soil moisture content at the corresponding radial distance position from the heating source in the target test area at the corresponding moment, wherein the soil moisture content relationship model is determined based on a first relationship between the thermal diffusivity coefficient and the soil temperature value, a second relationship between the moisture content and the thermal diffusivity coefficient, and the soil layer corresponding to the soil temperature value; and determining the soil moisture content of the target test area based on the soil moisture content at each radial distance position from the heating source in the target test area at the corresponding moment.

[0189] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0190] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0191] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement, characterized in that, include: The soil in the target survey area is heated using an active heating method, and the soil temperature is measured at different radial distances from the heating source at each moment during the heating process. The target survey area includes several soil layers. Substituting the soil temperature value and its corresponding radial distance at any moment during the heating process into a pre-determined soil moisture content relationship model, the soil moisture content at the radial distance from the heating source in the target area at the corresponding moment is obtained. The soil moisture content relationship model is determined based on the first relationship between the thermal diffusivity coefficient and the soil temperature value, the second relationship between the moisture content and the thermal diffusivity coefficient, and the soil layer corresponding to the soil temperature value. The soil moisture content of the target test area is determined based on the soil moisture content at each radial distance from the heating source in the target test area at the corresponding time. The soil moisture content relationship model includes: （1）； （2）； Wherein, equation (1) represents the second relationship, Indicates the soil moisture content. express t Radial distance from heating source in the target area at any given time r Thermal diffusivity of the soil. This represents the dry soil thermal diffusivity of the soil in the target test area. This represents the thermal diffusivity of soil water in the target test area. This indicates the dry specific heat capacity of the soil in the target survey area; Equation (2) represents the specific heat capacity of soil water in the target area; Equation (2) characterizes the first relationship. This is an empirical coefficient. T The measured soil temperature value, T w This indicates the temperature of the heating source surface. T 0 indicates the initial temperature of the soil in the target test area before heating.

2. The method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement according to claim 1, characterized in that, The first relationship is derived from the heat conduction equation in cylindrical coordinates based on the unsteady heat conduction model, and the second relationship is constructed based on the Hashin-Shtrikman model.

3. The method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement according to claim 1, characterized in that, Before the step of heating the soil in the target survey area based on the active heating method, the method further includes: Soil samples were taken from each soil layer in the target survey area to obtain soil samples from each soil layer. Soil drying experiments were conducted on soil samples from each soil layer to obtain the dry soil thermal diffusivity and dry soil specific heat capacity of each soil layer in the target area. Based on the dry soil thermal diffusivity and dry soil specific heat capacity of each soil layer in the target area, a soil moisture content relationship model is determined for each soil layer in the target area.

4. The method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement according to claim 3, characterized in that, The step of substituting the soil temperature value and its corresponding radial distance at any moment during the heating process into a pre-determined soil moisture content relationship model to obtain the soil moisture content at the corresponding radial distance from the heating source in the target area at that moment specifically includes: Based on the soil layer distribution in the target test area, determine the soil layer corresponding to each measured soil temperature value; By calling the soil moisture content relationship model corresponding to each soil layer, and substituting the temperature value of each soil layer and its corresponding radial distance into the soil moisture content relationship model of its corresponding soil layer, the soil moisture content at the location of the soil temperature value is obtained.

5. The method for detecting soil moisture content based on unsteady-state heat conduction and fiber optic temperature measurement according to any one of claims 1-3, characterized in that, The steps for heating the soil in the target survey area based on the active heating method specifically include: One active heating fiber and several temperature measuring fibers are deployed in the target measurement area. The several temperature measuring fibers are used to measure the temperature of several measurement segments that are parallel to each other and spaced at different radial distances from the active heating fiber. The active heating optical fiber is heated to a preset surface temperature, and the soil temperature in the target area reaches a steady state.

6. A soil moisture content detection system based on unsteady-state heat conduction and fiber optic temperature measurement, characterized in that, include: The acquisition module is used to obtain the soil temperature value at each moment under different radial distances from the heating source during the heating process, wherein the heating process is a process of heating the soil in the target test area based on the active heating method, and the target test area includes several soil layers; The calculation module is used to substitute the soil temperature value and its corresponding radial distance at any moment during the heating process into a pre-determined soil moisture content relationship model to obtain the soil moisture content at the radial distance position from the heating source in the target area at the corresponding moment. The soil moisture content relationship model is determined based on the first relationship between the thermal diffusivity coefficient and the soil temperature value, the second relationship between the moisture content and the thermal diffusivity coefficient, and the soil layer corresponding to the soil temperature value. The determination module is used to determine the soil moisture content of the target test area based on the soil moisture content at each radial distance from the heating source in the target test area at the corresponding time. The soil moisture content relationship model includes: （1）； （2）； Wherein, equation (1) represents the second relationship, Indicates the soil moisture content. express t Radial distance from heating source in the target area at any given time r Thermal diffusivity of the soil. This represents the dry soil thermal diffusivity of the soil in the target test area. This represents the thermal diffusivity of soil water in the target test area. This indicates the dry specific heat capacity of the soil in the target survey area; Equation (2) represents the specific heat capacity of soil water in the target area; Equation (2) characterizes the first relationship. This is an empirical coefficient. T The measured soil temperature value, T w This indicates the temperature of the heating source surface. T 0 indicates the initial temperature of the soil in the target test area before heating.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement as described in any one of claims 1 to 5.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement as described in any one of claims 1 to 5.

9. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the soil moisture content detection method based on unsteady-state heat conduction and fiber optic temperature measurement as described in any one of claims 1 to 5.

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