A levee leakage identification grading method based on temperature rise eigenvalue and flow velocity inversion

Abstract

The application discloses a dike leakage identification and grading method based on temperature rise characteristic value and flow velocity inversion, and comprises the following steps: arranging an active heating type optical fiber as a leakage monitoring device in the foundation soil of a certain depth of a soil dike backwater slope or outer slope foot, acquiring a temperature rise time history curve in the dike foundation soil under a certain power heating mode; calculating the temperature rise value and the soil temperature rise characteristic value after heating stabilization, comparing the temperature rise value with a critical threshold value determined by a water injection test, and realizing qualitative identification of a soil dike leakage section; when the soil temperature rise characteristic value is lower than the critical threshold value, identifying that the corresponding section is a leakage section. On this basis, a quantitative function model of temperature rise and seepage velocity is derived based on the heat transfer mechanism of saturated soil and the relationship between the thermal conductivity coefficient and the compaction degree, the seepage velocity in the abnormal section is inverted, the leakage severity is determined according to the seepage velocity of the leakage section, and the leakage intensity grading is realized. The whole process of identification from qualitative identification of the leakage section to quantitative grading of the dike leakage intensity is realized.

Description

TECHNICAL FIELD

[0001] The application relates to a dike leakage identification grading method based on temperature rise characteristic values and flow velocity inversion, and belongs to the technical field of soil dike leakage monitoring. BACKGROUND

[0002] Dikes are important barriers for flood control safety, and the anti-seepage performance thereof is directly related to the stability of the project and the safety of people's lives and property. Once leakage occurs, piping, seepage failure and even dike instability are easily caused. At present, dike leakage monitoring mainly relies on traditional methods such as osmotic pressure gauges, pressure measuring pipes and manual patrol. These methods are mostly point-type layout, and the monitoring range is limited, so it is difficult to realize continuous monitoring of the whole line of the dike. At the same time, abnormal leakage often has concealment and suddenness, and the traditional method is difficult to identify the leakage point in time and accurately.

[0003] With the development of distributed optical fiber temperature sensing (DTS) technology, researchers try to identify leakage by laying active heating type optical fibers. The basic idea is to lay optical fibers in the dike, and to amplify the local temperature field abnormal effect caused by the seepage water flow by means of pre-electric heating of the distributed optical fiber along the surrounding soil, that is, to monitor and locate the seepage section through the temperature field abnormal phenomenon caused by seepage. However, most of the existing technologies can only preliminarily identify the seepage area according to the relative abnormality of temperature rise, and lack of unified and clear discrimination threshold and quantitative standard. As a result, in practical application, it is easy to have inconsistent judgment or result deviation, which leads to the difficulty in accurately positioning the leakage point and the difficulty in grading the leakage intensity.

[0004] The root cause of the above problems is that, on the one hand, the influence of soil thermal conductivity and seepage velocity on optical fiber temperature rise has not formed a discrimination criterion with practical application; on the other hand, there is a lack of effective indoor calibration and field combination method, which leads to the fact that the laboratory rules cannot be directly applied to the actual dike monitoring. Therefore, there is an urgent need for a complete method which can establish a clear discrimination standard and realize the qualitative identification to quantitative inversion of dike leakage, so as to provide a scientific basis and practical means for dike leakage monitoring. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a dike leakage identification grading method based on temperature rise characteristic values and flow velocity inversion, which uses soil temperature rise characteristic values to locate the seepage section, and combines the flow velocity inversion formula to realize the flow velocity determination and leakage intensity determination of the local leakage point and section.

[0006] The technical problem to be solved by the present application is to provide a dike leakage identification grading method based on temperature rise characteristic values and flow velocity inversion, which uses soil temperature rise characteristic values to locate the seepage section, and combines the flow velocity inversion formula to realize the flow velocity determination and leakage intensity determination of the local leakage point and section.

[0007] A dike leakage identification grading method based on temperature rise characteristic values and flow velocity inversion, comprising the following steps:

[0008] Step 1, the heating type optical fiber is arranged in the foundation soil of the embankment backwater slope or outer slope foot corresponding to the depth of the to-be-identified leakage section, and the temperature change data of the soil around the optical fiber during the heating process are obtained by heating the optical fiber;

[0009] Step 2, the optical fiber is regarded as an ideal linear heat source, and a relationship between the soil temperature rise value and the heating time after the optical fiber is powered and heated is established based on the soil temperature change data and the linear heat source theory, and the coefficient in the relationship is defined as a soil temperature rise characteristic value;

[0010] Step 3, the easy-to-leak position of the to-be-identified leakage section is selected, water injection test is carried out in the easy-to-leak position to simulate embankment leakage, the optical fiber is heated again, the soil temperature rise value at different time in the easy-to-leak position is calculated, and the upper and lower limits of the soil temperature rise characteristic value are obtained by fitting according to the relationship established in step 2, and the upper limit of the soil temperature rise characteristic value is taken as a critical threshold value for judging leakage;

[0011] Step 4, the optical fiber is heated again, the temperature change data of the soil around the optical fiber during the heating process are obtained, the soil temperature rise value after being powered and heated is calculated, the soil temperature rise characteristic value is calculated according to the relationship established in step 2, and compared with the critical threshold value, so as to determine the leakage position of the embankment;

[0012] Step 5, based on the heat transfer principle of saturated soil under seepage action, and based on the linear relationship between the thermal conductivity coefficient and the compaction degree, a functional relationship between the seepage velocity and the soil temperature rise and the compaction degree is constructed;

[0013] Step 6, indoor test of flow velocity is carried out, the coefficients of the functional relationship between the seepage velocity and the soil temperature rise and the compaction degree are fitted according to the least square method, so as to obtain a flow velocity inversion formula;

[0014] Step 7, the seepage velocity of the leakage position of the embankment is calculated according to the flow velocity inversion formula, compared with the leakage intensity determination criterion, and the leakage grading determination is realized.

[0015] Compared with the prior art, the above technical scheme has the following technical effects:

[0016] 1. The present application realizes the whole process of qualitative identification of the leakage section to quantitative grading of the embankment leakage intensity, has the advantages of large continuous monitoring range, high positioning accuracy, objective and quantitative grading results, and significantly makes up for the lack of leakage monitoring and leakage grade evaluation system of embankment and similar anti-seepage engineering.

[0017] 2. The present application establishes a discrimination criterion based on a critical threshold value, avoids fuzzy identification, and makes the discrimination criterion clear.

[0018] 3. The heating type distributed optical fiber can realize continuous monitoring of key parts of the whole embankment anti-seepage, and has wide coverage.

[0019] 4. The method of the present invention can not only qualitatively determine whether leakage has occurred, but also quantitatively calculate the seepage rate to form a judgment on the intensity of leakage. Attached Figure Description

[0020] Figure 1 This is a flowchart of a method for identifying and classifying levee seepage based on temperature rise characteristic values ​​and flow velocity inversion according to the present invention.

[0021] Figure 2 It is a fitting graph showing the temperature rise over time at specific locations along the fiber optic cable installation route in practical applications.

[0022] Figure 3 These are the characteristic values ​​of soil temperature rise along the fiber optic cable laying route in practical applications.

[0023] Figure 4 It is a flow velocity diagram at various locations along the fiber optic cable installation route in practical applications. Detailed Implementation

[0024] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0025] like Figure 1 As shown, this invention provides a method for identifying and classifying dike seepage based on temperature rise characteristic values ​​and flow velocity inversion. The specific steps are as follows:

[0026] S1. Acquisition of distributed continuous temperature and temperature rise value in the foundation of earthen embankment: A circular heating type optical fiber is laid in the foundation soil at a certain depth on the back slope or outer slope of the earthen embankment. The optical fiber is heated with a certain power and the monitoring data is obtained from the distributed temperature demodulator.

[0027] A circularly heated distributed optical fiber is buried in a vertical S-shape in a certain depth in the foundation soil at a high-risk leakage location (such as the embankment toe, the embankment foundation interface, or the seepage interlayer on the water-facing slope) of an earthen embankment. The fiber is heated for 15 minutes using a voltage regulator to achieve the optimal power of 18.6A, and then allowed to cool naturally. Soil temperature change data is then read from a distributed temperature demodulator. Figure 2 As shown.

[0028] The heating type optical fiber comprises a four-core optical fiber and a metal loose tube, a cable layer, an inner insulation layer, an armored stress relief device auxiliary component and an outer protective layer which are sequentially covered outside the four-core optical fiber; the four-core optical fiber comprises a 1-core 50 / 125 multimode optical fiber, a 1-core 62.5 / 125 multimode optical fiber and two-core single-mode optical fibers; the two-core single-mode optical fibers comprise tight-buffered optical fibers and loose-buffered optical fibers; the loose-buffered optical fibers are in a spiral shape, the loose-buffered optical fibers have a loose-buffered plastic structure, and corresponding single-mode optical fibers can freely move in the loose-buffered optical fibers; the tight-buffered optical fibers have a tight-buffered plastic structure, and corresponding single-mode optical fibers cannot freely move in the tight-buffered optical fibers; the four-core optical fibers are all double-layered acrylate optical fibers with a coating layer, and the coating layer can improve micro-bending performance. The cable layer comprises a heating cable, a low-voltage cable and a plurality of core wires; the plurality of core wires are uniformly arranged around the outer circumferential side of the metal loose tube; and the core wires are metal alloy wires with a positive temperature coefficient of resistance.

[0029] S2, construction of the soil temperature rise characteristic value based on the line heat source theory: the temperature measuring optical fiber is regarded as an ideal linear heat source, and a quantitative index, the soil temperature rise characteristic value, can be obtained according to the relationship between the heating time and the temperature rise;

[0030] The temperature change of the optical fiber in the soil can be simplified as the following differential equation:

[0031] ,

[0032] In the formula, is the thermal conductivity of the optical fiber ;

[0033]

[0034] The above formula is solved as follows:

[0035] ,

[0036] In the formula, is the temperature rise of the optical fiber at the moment , is the heat flow rate per unit length of the optical fiber , is the thermal conductivity of the soil .

[0037] Let , then , and the following can be obtained:

[0038] ,

[0039] When is small, the following is obtained:

[0040] , ​

[0041] when When they were very young, that is The value is very small or If the value is very large, it can be simplified to:

[0042] ,

[0043] Selected at the distance of fiber optic cable At a certain location, respectively recorded in and Temperature rise at time t , Then we have:

[0044] ,

[0045] The relationship between the temperature rise of the optical cable after it is energized and heated and the change over time is as follows:

[0046] ,

[0047] In the formula, For temperature rise value, The initial temperature, The time coefficient related to the contact surface between the optical fiber and the surrounding soil; defined It is a characteristic value of soil temperature rise, which reflects the magnitude of temperature change and provides a theoretical basis for quantifying temperature change;

[0048] The temperature rise value after the optical cable is heated With heating time The mathematical relationship is as follows:

[0049]

[0050] During the experiment, the optical cable was heated in different soil types and with different moisture contents. Based on the data fitting analysis of the above formula, the actual measurement showed that when the heating time... The time interval is 0 min, and the temperature rise of the optical cable is 0 ℃. To better fit the fitting curve, we take... As shown in the following formula:

[0051] .

[0052] S3, Critical Threshold Acquisition: Water injection tests were conducted at locations prone to leakage within the monitoring section, and the critical threshold was determined using the actual values ​​of the soil in that section of the embankment after heating the optical fiber. ;

[0053] Water was injected into the PVC pipe near the leak-prone point, and then the optical fiber was heated according to step S1. The temperature rise at different times was calculated. Obtain the temperature rise curves over time in different sections, and then apply the formula... The fitted soil temperature rise characteristic value The soil temperature rise characteristic value corresponding to the water injection position about 1.62~1.95, given the critical threshold As a standard for determining leakage anomalies, that is, When, determine that leakage occurs.

[0054] S4, positioning of the leakage section: calculate the soil temperature rise characteristic value with the optimal power heating, and compare it with the critical threshold to determine the leakage position;

[0055] Draw the temperature rise value of the optical fiber along the line along the optical fiber layout direction And the distribution curve of the soil temperature rise characteristic value When , it indicates that there is a phenomenon of heat carried away by seepage at this place, according to Figure 3 The curve gives the corresponding section of 32m~33m, 38m~40m, 77m~78m and 85m~86m, and the embankment has water accumulation or abnormal seepage, which is determined as an abnormal section.

[0056] S5, establishment of soil heat flow coupling flow rate inversion function: based on the basic principle of heat transfer of saturated soil under seepage action, and based on the linear relationship between thermal conductivity and compaction degree, the functional relationship between seepage velocity, optical fiber temperature rise and compaction degree is derived;

[0057] (1) Compaction degree Relationship with soil thermal conductivity

[0058] ,

[0059] The maximum dry density of the soil is a fixed value, and the compaction degree is proportional to the dry density , so the thermal conductivity of the soil is determined by the dry density of the soil, and the relationship between the two needs to be established. The established thermal conductivity model is mostly based on saturation , natural density , porosity , etc. as direct parameters, and the above parameters are related to the dry density :

[0060] ,

[0061] ,

[0062] In the formula, is the specific gravity of the soil, is the density of water , The mass moisture content is.

[0063] The thermal conductivity of soil is related to the volume, distribution and arrangement of each phase. The soil is regarded as a mixture of solid particles, water and air, and the parallel function model assumes that the heat flux of different components is the same, which is one of the basic models for calculating the thermal conductivity of soil:

[0064] ,

[0065] In the formula, The thermal conductivity of soil only considering compaction is, and The thermal conductivity of solid phase, liquid phase and gas phase is , which are constants.

[0066] Solve the above equations simultaneously, and determine that the soil in the fiber laying area of the leakage section is saturated soil:

[0067] ,

[0068] In the formula, is a fixed value, so and the compaction degree is a linear relationship:

[0069] ,

[0070] where, The compaction degree is, , , which are constants .

[0071] (2) The relationship between the heat convection coefficient and the flow rate

[0072] Considering the heat convection in seepage, the approximate model suitable for slow seepage (Darcy flow) is:

[0073] ,

[0074] In the formula, is a constant , The flow rate is , then the thermal conductivity of soil can be expressed as:

[0075] ,

[0076] Select a unit length of optical fiber. According to Ohm's law, the heat generated by the unit length of copper resistance wire of the optical fiber in unit time is:

[0077] ​ ,

[0078] where, is the heat generated by the copper resistance wire per unit length of the optical fiber per unit time , is the voltage applied to the resistance wire per unit length of the optical fiber , is the resistance per unit length of the optical fiber According to Fourier's law of heat conduction, the heat dissipated per unit length of the optical fiber per unit time is:

[0079] ,

[0080] where, is the heat dissipated per unit length of the optical fiber per unit time , is the final thermal conductivity is a scalar related to the properties of the soil itself. is the temperature gradient, according to the law of conservation of energy, the heat received by the optical fiber per unit time is:

[0081] ,

[0082] where, is the actual heat received by the optical fiber , is the specific heat capacity of the optical fiber , is the measured temperature of the soil after the optical fiber is powered and heated T0 is the initial temperature of the soil before the optical fiber is powered and heated , is the current flowing through the resistance wire of the optical fiber By combining the above equations, we get:

[0083] ,

[0084] When the temperature field is stable, the temperature gradient is a constant due to the isotropy and uniformity of the soil to be measured. Therefore, the above equation can be simplified as:

[0085] ,

[0086] where, , are all constants.

[0087] Further derivation and arrangement give:

[0088] , ​

[0089] ,

[0090] wherein, , , ; and are constants.

[0091] S6, determining the flow velocity inversion formula: the flow velocity determination chamber indoor test is fitted according to the least square method and ;

[0092] The indoor model test is carried out, the field clay in the saturated state under different compactness is prepared, and the seepage passage is buried to simulate the seepage state, the water level height of the water supply tank is controlled to control different seepage velocities, the optical fiber is heated using a certain heating power, the temperature rising process of the optical fiber under different seepage velocities is obtained, and finally the coefficients in the above relationship are fitted to obtain the inversion formula .

[0093] S7, determination of seepage intensity: the seepage velocity of the seepage section is calculated according to the flow velocity inversion formula, and is compared with the seepage intensity determination standard to carry out grading identification;

[0094] The present application is based on the soil particle starting flow velocity The seepage intensity determination criterion is constructed. The starting flow velocity refers to the minimum water flow velocity at which the soil or gravel particles start to loosen, roll or migrate under the action of seepage or local flow velocity disturbance, that is, the critical flow velocity that can overcome the particle self-weight and friction. The parameter is usually related to particle size, surface structure, compactness, hydraulic slope and pore structure and other factors, is a key index reflecting whether the embankment is damaged, and can be generally calculated by the Shamo experience formula.

[0095] 1) Micro seepage (flow velocity )

[0096] The seepage is not enough to cause the surface particles to loosen, and only shows that the water content increases or local slow seepage, and there is no structural damage risk;

[0097] 2) Mild seepage (flow velocity )

[0098] The seepage velocity is close to the particle starting condition, local particles may appear reversible loosening or micro disturbance, the surface structure integrity is reduced, and there is a potential risk of continuous development;

[0099] 3) Moderate seepage (flow velocity )

[0100] When the seepage velocity exceeds the critical value of the incipient velocity of the surface particles, the surface particles may migrate, fall off or be locally scoured, and the leakage channel tends to spontaneously expand, which is an important precursor to embankment slope failure or piping.

[0101] 4) Severe leakage (4) )

[0102] The seepage velocity is much greater than the critical value of the incipient velocity of the surface particles. Severe and rapid scouring occurs, which easily leads to structural damage such as embankment slope collapse and foot trench emptying.

[0103] According to the measured temperature rise of the optical fiber, the inversion formula is substituted The seepage velocity distribution along the embankment is calculated, and according to Figure 4 It is shown that at the positions of 32m~33m, 38m~40m, 77m~78m and 85m~86m of the optical fiber, It is significantly lower than the average value, and the flow rate value appears an obvious abnormal protrusion, which is 1.61×10 -5 m / s, 1.76×10 -5 m / s, 1.99×10 -5 m / s and 2.444×10 -5 m / s, respectively, which are all medium leakage sections.

[0104] This embodiment verifies the application effect of the discrimination method based on the characteristic value of the soil temperature rise in the embankment leakage monitoring. Through the discrimination of the critical characteristic value of the soil temperature rise, the normal and leakage areas can be effectively distinguished, and the qualitative identification of the leakage section is realized. Compared with the traditional point-type seepage pressure monitoring, this method has the advantages of strong continuity and accurate positioning. Through the whole process method of "indoor calibration-site application", the relationship between is determined by the indoor flow rate determination test, and the accurate identification of the leakage section and the point is realized in the field application. Compared with simply relying on the characteristic value of the soil temperature rise, the combination of the flow rate inversion can quantify the leakage intensity, and the scientificity and early warning accuracy of the embankment leakage monitoring are improved.

[0105] Based on the same inventive concept, the embodiments of the present application provide a computer device, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the aforementioned embankment leakage identification and grading method based on the characteristic value of the temperature rise and the flow rate inversion when executing the computer program.

[0106] Based on the same inventive concept, the embodiments of the present application provide a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the steps of the aforementioned embankment leakage identification and grading method based on the characteristic value of the temperature rise and the flow rate inversion.

[0107] Those skilled in the art will appreciate that embodiments of the present application can be readily used as software, hardware, or a combination of software and hardware. In a software embodiment, the methods can be tangibly embodied in a machine-readable storage medium having stored thereon instructions that can be used to program a computer to perform any of the methods. The software implementation can be initialized by loading and executing a set of instructions arranged to perform one of the methods into the computer's memory. Alternatively, hard-wired circuitry can be used in place of, or in combination with, software instructions. Thus, the

[0108] The present application is described in reference to the flowchart and / or block diagrams of the methods, apparatus (systems) and computer program products according to embodiments of the present application. It will be understood that each block of the flowchart and / or block diagrams, and combinations of blocks in the flowchart and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processing device, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in one or more of the flowchart and / or block diagram block or blocks. Figure 1 means for performing one or more functions specified in one or more of the flowchart and / or block diagram block or blocks.

[0109] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in one or more of the flowchart and / or block diagram block or blocks. Figure 1 means for performing one or more functions specified in one or more of the flowchart and / or block diagram block or blocks.

[0110] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in one or more of the flowchart and / or block diagram block or blocks. Figure 1 means for performing one or more functions specified in one or more of the flowchart and / or block diagram block or blocks.

[0111] The above embodiments are merely illustrative of the technical idea of the present application and cannot limit the scope of protection of the present application. Any modification made according to the technical idea of the present application on the basis of the technical solution falls within the scope of protection of the present application.

Claims

1. A method for identifying and classifying seepage of embankment based on temperature rise eigenvalue and flow velocity inversion, characterized in that, The method comprises the following steps: Step 1, heating the optical fiber and laying it in the foundation soil of the embankment backwater slope or outer slope foot to be identified in the corresponding depth of the leakage section, obtaining the temperature change data of the soil around the optical fiber during the heating process by heating the optical fiber; Step 2, regarding the optical fiber as an ideal linear heat source, establishing a relationship between the soil temperature rise value and the heating time after the optical fiber is powered and heated based on the soil temperature change data and the linear heat source theory, and defining the coefficient in the relationship as the soil temperature rise characteristic value; Step 3, selecting a position prone to leakage in the leakage section to be identified, performing a water injection test to simulate embankment leakage at the position prone to leakage, heating the optical fiber again, calculating the soil temperature rise value at different times at the position prone to leakage, and fitting the upper and lower limits of the soil temperature rise characteristic value according to the relationship established in step 2, taking the upper limit of the soil temperature rise characteristic value as a critical threshold for determining leakage; Step 4, heating the optical fiber again, obtaining the temperature change data of the soil around the optical fiber during the heating process, calculating the soil temperature rise value after the optical fiber is powered and heated, calculating the soil temperature rise characteristic value according to the relationship established in step 2, and comparing it with the critical threshold to determine the embankment leakage position; Step 5, based on the heat transfer principle of saturated soil under seepage action, and based on the linear relationship between the thermal conductivity coefficient and the compaction degree, a functional relationship between the seepage velocity and the soil temperature rise and the compaction degree is constructed; the specific process is as follows: Step 5.1, degree of compaction Relationship with thermal conductivity of soil The thermal conductivity of soil is only considered by compaction degree if the soil is regarded as a mixture of solid particles, water and air is represented as: ， ， ， wherein, and are the thermal conductivities of solid, liquid and gas phases, respectively, is the porosity, is the saturation degree, is the dry density of the soil, is the specific weight of the soil, is the density of water, is the mass water content; By combining the above formula and determining that the soil in the optical fiber embedding area of the leakage section is saturated soil, the following formula can be obtained: ， In the formula, is the compaction degree, , is the maximum dry density of soil, is a fixed value, then and the compaction degree is a linear relationship: ， In the formulae, , ; Step 5.2, functional relationship between seepage velocity and soil temperature rise and compaction degree Considering the convective heat transfer in seepage, the approximate model suitable for slow seepage is: ， wherein is the heat convection coefficient, is the constant coefficient, is the flow rate; the soil thermal conductivity is expressed as: ， According to the law of conservation of energy, the heat received by the optical fiber per unit time is represented as: ， ， ， wherein, Q is the actual heat received by the optical fiber, Q is the heat generated by the resistance wire per unit length of the optical fiber per unit time, Q is the heat dissipated per unit length of the optical fiber per unit time, C is the specific heat capacity of the optical fiber, T is the actual measured temperature of the soil after the optical fiber is powered on and heated, T is the initial temperature of the soil before the optical fiber is powered on and heated, V is the voltage applied to both ends of the resistance wire per unit length of the optical fiber, R is the resistance per unit length of the optical fiber, is the temperature gradient; Further: ， wherein is the current flowing through the fiber optic resistance wire; i.e. , , , ; Further derivation gives: ， That is , , , ; and are constants; Step 6, indoor test of flow velocity is carried out, the coefficient of the functional relationship between the seepage velocity and the soil temperature rise and the compaction degree is fitted according to the least square method, and thus the flow velocity inversion formula is obtained; Step 7, the seepage velocity of the embankment leakage position is calculated according to the flow velocity inversion formula, compared with the leakage intensity determination criterion, and the leakage classification determination is realized.

2. The embankment leakage identification grading method based on temperature rise characteristic value and flow velocity inversion according to claim 1, characterized in that, The specific process of step 1 is as follows: The heating type optical fiber is embedded in the foundation soil of the embankment backwater slope or outer slope foot to be identified in the corresponding depth of the leakage section in a vertical S-shaped manner, the optical fiber is heated by adjusting the voltage regulator to make the current form an optimal power of 18.6A for 15 minutes, and the temperature change data of the soil around the optical fiber during the heating process is obtained by using a distributed temperature measurement demodulator.

3. The embankment leakage identification and classification method based on temperature rise eigenvalue and flow velocity inversion according to claim 1, characterized in that, The specific process of step 2 is as follows: The optical fiber is powered and heated, The time interval from the optical fiber The soil temperature at the optical fiber Is expressed as: ， wherein is the heat flow rate per unit length of the optical fiber, is the thermal conductivity of the soil, is the thermal conductivity of the optical fiber; Then the relationship between the soil temperature rise after the optical fiber is powered and heated and the time is: ， In the formula, is the temperature rise of the soil, is the measured temperature of the soil after the optical fiber is powered on and heated, and T0 is the initial temperature of the soil before the optical fiber is powered on and heated, is a time coefficient related to the contact surface between the optical fiber and the surrounding soil. Definitions is the characteristic value of the temperature rise of the soil, then the temperature rise of the soil is given by the mathematical relationship with the heating time ， Take Then .

4. The embankment leakage identification and classification method based on temperature rise eigenvalue and flow velocity inversion according to claim 1, characterized in that, In step 4, the soil temperature rise value along the fiber layout direction is drawn to obtain a distribution curve of the soil temperature rise characteristic value and the soil temperature rise characteristic value When the soil temperature rise characteristic value at a certain position is less than a critical threshold value, it indicates that the position has a phenomenon of heat carried away by seepage, i.e. it is determined that seepage occurs at the position.

5. The embankment leakage identification and classification method based on temperature rise eigenvalue and flow rate inversion according to claim 1, characterized in that, The specific process of step 7 is as follows: The compaction degree and the temperature rise of the soil are substituted into the flow velocity inversion formula to calculate the seepage velocity at the leakage position of the embankment; and the incipient velocity of the soil particles is calculated based on the particle size distribution of the soil A leakage intensity determination criterion is constructed, and the specific process is as follows: When the seepage velocity is less than , the leakage level is determined to be slight leakage, and the seepage effect is not enough to cause the surface layer particles to loosen, only showing an increase in water content or local slow seepage, and there is no risk of structural damage to the embankment. When the seepage velocity is greater than or equal to and less than , it is determined that the leakage level is slight leakage, the seepage velocity is close to the critical value of the particle starting flow rate, local particles appear reversible loosening or slight disturbance, the surface structure integrity decreases, and there is a potential risk of continuous development; When the seepage velocity is greater than or equal to and less than , the leakage level is determined to be medium leakage, the seepage velocity exceeds the critical value of the particle starting flow rate, the surface layer particles migrate, fall off or are locally scoured, and the leakage channel tends to spontaneously expand, which is a precursor to embankment slope damage or piping. When the seepage velocity greater than or equal to is heavy leakage, the seepage velocity is much greater than the critical value of the particle starting flow rate, and the dike occurs structural damage.

6. A computer device comprising a memory, a processor, and a computer program stored in the memory and capable of running on the processor, characterized in that, The processor executes the computer program to realize the steps of the embankment leakage identification classification method based on the temperature rise characteristic value and the flow velocity inversion according to any one of claims 1 to 5.

7. A computer-readable storage medium storing a computer program, wherein the computer program comprises the following steps of: receiving a request for a resource from a client; determining whether the client is authorized to access the resource; and if the client is authorized to access the resource, providing the resource to the client. The computer program is executed by the processor to realize the steps of the embankment leakage identification classification method based on the temperature rise characteristic value and the flow velocity inversion according to any one of claims 1 to 5.

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