Infrared measurement method for temperature distribution in frozen soil fractional congelation and expansion process
By using PE boards and PVC films to reduce the impact of obstructions during the freezing and condensation process of frozen soil, and combining temperature sensors and digital imaging methods for correction, the problem of insufficient accuracy of infrared thermal imaging technology in the freezing and condensation process of frozen soil has been solved, and high-precision temperature measurement has been achieved.
Patent Information
- Application Number
- CN202511150759.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-18
- Publication Date
- 2025-11-21
AI Technical Summary
Existing infrared thermal imaging technology lacks accuracy during the freezing and condensation process of frozen soil. This is mainly due to the non-constant emissivity and the influence of soil column obstructions, resulting in large temperature measurement errors and failing to meet the temperature measurement accuracy requirements during the freezing and condensation process of frozen soil.
An infrared temperature measurement window was installed in the soil column. PE board and PVC film were used to reduce the influence of obstructions. The temperature measured by the infrared camera was corrected by a temperature sensor. Outliers were removed by digital image method and linear regression correction was performed.
It has achieved high-precision measurement of temperature during the condensation process of frozen soil, especially non-destructive measurement of key locations such as condensation cracks, with an accuracy of up to 0.1℃.
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Figure CN120992034A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of infrared thermal imaging technology, and in particular to an infrared measurement method for temperature distribution in the process of freezing and thawing of frozen soil. BACKGROUND
[0002] As a non-contact temperature measurement method, the infrared thermal imaging method does not need to destroy the water and heat transfer of the frozen soil, and can obtain the temperature distribution of the entire soil column area in real time. However, the accuracy of this method is affected by the emissivity and smoke, water vapor and the like. The accuracy of the current infrared thermal imaging technology is generally 2℃ (or 2%).
[0003] Infrared thermal imaging can non-destructively measure the temperature of the soil surface. Many scholars have expanded the application of infrared thermal imaging by establishing the relationship between surface temperature and other properties. For example, by measuring the surface temperature with an infrared camera, non-destructive real-time identification of cracks, mechanical properties and the like has been achieved.
[0004] Currently, the infrared thermal imaging method in the prior art does not consider the calibration of the emissivity. For an infrared camera, it does not directly "measure temperature", but receives infrared radiation power from an object. The radiation power can be expressed by the following formula:
[0005] W = εσT 4 (1)
[0006] Where W is the power of radiation per unit area, Wm -2 ; ε is the emissivity; σ is the Stefan-Boltzmann constant, about 5.67 x 10 -8 Wm -2 K -4 ; T is the temperature, K.
[0007] The emissivity is the core parameter of infrared temperature measurement, and the specific value depends on factors such as material type and surface condition. Whether the infrared camera can accurately back-calculate the temperature depends on whether the correct emissivity value ε is set. If the correct ε is set in the camera, the temperature can be directly back-calculated from the received radiation power using the above formula (1).
[0008] Currently, the infrared temperature measurement method in the prior art has the following disadvantages when applied to frozen soil segregation:
[0009] 1) For frozen soil of the same soil quality, the unfrozen water content, ice content and dry density are different when the temperature is different. This causes the emissivity of the surface of frozen soil at different temperatures to be different, and needs to be calibrated.
[0010] 2) Infrared camera can only receive the energy radiated from the surface of the material, that is, can only measure the temperature of the surface of the material. When the frozen soil is separated and condensed, a closed environment needs to be ensured to ensure the normal migration of heat, water and vapor. This causes the existence of other materials shielding outside the frozen soil. The shielding causes a large error between the temperature measured by infrared measurement and the actual temperature of the soil body.
[0011] The above reasons cause the precision of the infrared temperature measurement method to be significantly reduced when applied to the frozen soil, and far from reaching the temperature measurement precision requirement when the frozen soil is separated and condensed. SUMMARY
[0012] Embodiments of the present application provide an infrared measurement method for temperature distribution in the frozen soil separation and frost heaving process to effectively measure the temperature of the frozen soil.
[0013] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions.
[0014] An infrared measurement method for temperature distribution in the frozen soil separation and frost heaving process, comprising:
[0015] The frozen soil is placed in the soil column barrel, a temperature sensor is arranged at the position of the frozen soil, an infrared camera is arranged outside the soil column barrel, an infrared temperature measurement window is opened at a certain height in the soil column barrel, a polyethylene thin PE plate is fixedly installed at the position of the infrared temperature measurement window, a layer of polyvinyl chloride PVC film is pasted on the inner side of the polyethylene thin plate PE, the infrared rays emitted by the infrared camera pass through the PE plate and the PVC film to irradiate on the frozen soil, the infrared camera receives the reflected rays reflected back by the frozen soil, and the temperature of the frozen soil is measured according to the reflected rays.
[0016] The temperature of some sections of the frozen soil is measured by the temperature sensor, and the temperature of the frozen soil measured by the infrared camera is corrected by the temperature measured by the temperature sensor.
[0017] Preferably, the infrared camera receives the reflected rays reflected back by the frozen soil, and the temperature of the frozen soil is measured according to the reflected rays, comprising:
[0018] The temperature T measured by the infrared camera is calculated according to the total energy received by the infrared camera in ,
[0019]
[0020] T in is the temperature measured by the infrared camera; W soil is the energy absorbed by the infrared camera after the energy radiated by the soil body is transmitted through the PE thin plate, ε pvc is the emissivity of PVC, ε pvc = 0.95; τ is the transmittance of the PE thin plate, T soil is the soil temperature measured by the temperature sensor, and W peEnergy radiated to the PE sheet, ε pe Emissivity of PE; pe Temperature of PE; re Energy reflected by the PE sheet, W air Energy radiated to the air.
[0021] Preferably, the temperature sensor is used to measure the temperature of some cross sections of the frozen soil, and the temperature measured by the temperature sensor is used to correct the temperature of the frozen soil measured by the infrared camera, including:
[0022] T pe affected by the temperature T soil of the soil inside the PE sheet:
[0023] T pe = δT soil (3)
[0024] Where δ is the influence factor, when the temperature T soil at this position is less than the ambient temperature, δ>1, otherwise δ<1;
[0025] Substitute equation (3) into equation (2) to get:
[0026]
[0027] From the above equation, and there is a linear relationship, the slope k=τ+ε pe δ 4 / ε pvc , the intercept μ=(W re +W air ) / ε pvc σ, k and μ reflect the influence of the transmittance and emissivity of the shield.
[0028] Preferably, the temperature sensor is used to measure the temperature of some cross sections of the frozen soil, and the temperature measured by the temperature sensor is used to correct the temperature of the frozen soil measured by the infrared camera, further including:
[0029] The temperature T s of the frozen soil at a certain height is measured by a temperature sensor, the temperature data of the infrared thermal imaging of the frozen soil at this height is obtained, the mean and standard deviation of all the temperature data of the infrared thermal imaging of the frozen soil at this height is calculated, the temperature value that is more than 3 times the standard deviation from the mean is considered as an outlier, all the temperature values of the outliers are removed, and the average of the remaining temperature values is taken as the temperature T in of the frozen soil at this height measured by the infrared camera.
[0030] According to t s , Tin The correction is performed to obtain a corrected temperature T c1 :
[0031] T c1 = α1×T in + β1 (5)
[0032] Wherein, α1, β1 are fitting parameters.
[0033] According to multiple sets of (T in , T s ) data, fitting is performed to obtain the values of fitting parameters α1, β1.
[0034] Preferably, the emissivity of the infrared camera is set to the PVC emissivity, which is 0.95.
[0035] As can be seen from the technical solutions provided by the above embodiments of the present application, the embodiments of the present application use a limited number of temperature sensors and a digital image method to correct infrared images, thereby achieving high-precision temperature measurement of the full cross section of the soil column, especially the key positions such as the split fracture.
[0036] Additional aspects and advantages of the present application will be described in part in the description that follows, and will become apparent from the description that follows, or will be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS
[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.
[0038] Figure 1 A schematic diagram of the principle of infrared thermal imaging in a soil column system is provided for the embodiments of the present application.
[0039] Figure 2 A schematic diagram of data processing of an infrared image (taking three cross sections at h=1, 5, 9 cm as an example) is provided for the embodiments of the present application.
[0040] Figure 3 A schematic diagram of real-time correction of infrared temperature is provided for the embodiments of the present application.
[0041] Figure 4 A calibration diagram of a temperature sensor is provided for the embodiments of the present application.
[0042] Figure 5 A schematic diagram of a freezing test system is provided for the embodiments of the present application, wherein (a) is a side view of the system, and (b) is a plan view of the system.
[0043] Figure 6 A correction diagram for infrared temperature provided by an embodiment of the present application: (a) variation trend of two fitting parameters; (b) fitting effect of three stages. DETAILED DESCRIPTION
[0044] Embodiments of the present application are described in detail below with reference to several specific embodiments, examples of which are illustrated in the accompanying drawings, wherein the same or similar numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be interpreted as a limitation on the present application.
[0045] Those skilled in the art can understand that, unless specifically stated, the singular forms "a", "an" and "the" used herein also include the plural forms. It should be further understood that the use of the phrase "comprising" in the specification of the present application means that the features, integers, steps, operations, elements and / or components exist, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there can be intermediate elements. In addition, "connected" or "coupled" used herein can include wireless connection or coupling. The phrase "and / or" used herein includes any one of the associated listed items and all combinations thereof.
[0046] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as that generally understood by those skilled in the art to which the present application belongs. It should also be understood that terms such as those defined in a general dictionary should be understood to have meanings consistent with those in the context of the prior art, and should not be interpreted with idealized or overly formal meanings unless defined as such.
[0047] In order to facilitate the understanding of the embodiments of the present application, the following will be further explained and described with several specific embodiments as examples in conjunction with the accompanying drawings, and each embodiment does not constitute a limitation on the embodiments of the present application.
[0048] The segregation frost heaving of frozen soil refers to the phenomenon that water in the pores of frozen soil migrates to the low temperature area due to the action of temperature gradient and freezes in the area, thereby causing cracking of the soil body. At present, there is no non-destructive measurement method for the temperature of the upper and lower edges of the cracks caused by the segregation frost heaving of frozen soil. The indoor study of the segregation frost heaving of frozen soil generally needs to carry out one-dimensional freezing experiment. The experiment needs to use a soil column barrel to ensure the closed environment of frozen soil. Figure 1This is a schematic diagram illustrating the infrared thermal imaging principle of a soil column system according to an embodiment of the present invention. It includes: a soil column, a polyvinyl chloride (PVC) film, a polyethylene (PE) sheet, and an infrared camera. Frozen soil is placed inside the soil column, and a temperature sensor is installed at the location of the frozen soil. To address the issues of inconsistent emissivity and obstruction by the soil column, a 2cm wide infrared temperature measurement window is cut at a certain height inside the soil column. A PE sheet is fixedly installed at the infrared temperature measurement window, and a layer of black PVC film is tightly attached to the inside of the PE sheet. Infrared rays emitted by the infrared camera pass through the PE sheet and PVC film sequentially to illuminate the frozen soil. The infrared camera receives the reflected rays from the frozen soil and measures the temperature of the frozen soil based on the reflected rays.
[0049] This invention replaces the acrylic glass at the window position with a 2mm thick PE sheet. The PE sheet has higher infrared transmittance, allowing the infrared camera to better reflect the temperature of the permafrost. Furthermore, the PE sheet has a low thermal conductivity, providing excellent insulation.
[0050] The PVC film has a thickness of 0.15 mm. Since the PVC film is in close contact with the frozen soil, it can be assumed that the PVC film and the frozen soil are in temperature equilibrium. Therefore, the monitoring of the frozen soil surface temperature is improved to monitoring the temperature of the PVC film. Because the composition of the PVC film is constant and does not change with temperature, the emissivity of the infrared camera is set to the PVC emissivity, i.e., 0.95. Emissivity is an inherent property of the material, and the emissivity of PVC is constant, with a value of 0.95.
[0051] The above settings significantly reduce the effects of inconsistent emissivity and obstruction from the soil column. However, the energy radiated by the PE board itself can affect the temperature measurement results of the infrared camera. To further reduce the influence of the PE board and ambient temperature, it is necessary to correct the infrared image by incorporating the measurement results from the temperature sensor.
[0052] exist Figure 1 In the experimental system shown, the energy of the reflected light received by the infrared camera at a certain location includes the energy radiated by materials such as frozen soil, PE, and air, as well as the energy reflected by the PE board. Based on the working principle of the infrared camera,
[0053]
[0054] In equation (2), the right side represents all the energy received by the infrared camera. The temperature T measured by the infrared camera can be calculated based on the total energy received by the infrared camera. in .
[0055] Among them, T in Temperature measured by an infrared camera; W soil This refers to the energy radiated from the soil, transmitted through a PE sheet, and absorbed by an infrared camera. ε pvcε is the emissivity of the PVC pvc = 0.95; τ is the transmissivity of the PE sheet soil T is the soil temperature, measured by the temperature sensor pe W is the energy radiated by the PE sheet ε pe is the emissivity of the PE pe T is the temperature of the PE re W is the energy reflected by the PE sheet air W is the energy radiated by the air
[0056] From equation (2), if the emissivity is set correctly, the main factors causing the error between the infrared temperature and the actual temperature of the soil are: the energy radiated by the shelter W PE , the energy reflected by the shelter from the outside world W re , and the energy radiated by the air W air . This results in the infrared temperature T in being different from the actual temperature of the soil T soil . Therefore, the infrared temperature at different soil temperatures needs to be corrected.
[0057] At this position, W PE characterizes the average temperature T pe of the PE sheet. T pe is mainly affected by the temperature T soil of the soil inside the PE sheet:
[0058] T pe = δT soil (3)
[0059] where δ is an influence factor. When this position T soil is less than the ambient temperature, δ > 1, otherwise δ < 1. T pe is between the ambient temperature and T soil .
[0060] Substituting equation (3) into equation (2), we get:
[0061]
[0062] From the above equation, there is a linear relationship between T and T . The slope k = τ + ε pe δ 4 / ε pvc . k mainly reflects the influence of the transmissivity and emissivity of the shelter. If the PE is replaced by other materials, the slope will be different. The intercept μ = (W re + W air ) / ε pvc σ, K 4μ primarily reflects the influence of the environment, namely the energy reflected by obstructions and the energy radiated from the air. Due to the influence of the surrounding enclosure, the energy reflected by obstructions varies at different locations on the soil column.
[0063] The embodiments of this invention conduct a one-dimensional freezing experiment, where theoretically, the cross-sectional temperature of soil columns at the same height should be completely equal. However, due to factors such as angle, distance, and air temperature, the initial thermal images captured by the infrared camera may contain outliers, and the temperatures at the same height are not completely equal, exhibiting slight differences. Figure 2 This is a schematic diagram of infrared image data processing (taking three cross-sections at h = 1, 5, and 9 cm as examples) provided by an embodiment of the present invention. The embodiment of the present invention obtains T from infrared images. in (h,t j The 3sigma principle is used to correct for temperatures at the same altitude.
[0064] Based on the working principle of infrared cameras, different colors in infrared images represent different temperatures and different energies. Temperature can be directly exported from infrared images using the camera's built-in software.
[0065] like Figure 2 As shown, based on the 3 sigma principle (three standard deviations), the infrared thermal imaging temperature data for the j-th hour is extracted, and the mean and standard deviation of all temperatures at a certain altitude are calculated. Temperature values exceeding three standard deviations from the mean are considered outliers and discarded. The remaining temperature data are then averaged again to obtain the infrared measurement temperature T at that altitude. in .
[0066] Figure 3 This is a schematic diagram illustrating real-time corrected infrared temperature according to an embodiment of the present invention. Figure 3 As shown, due to the occlusion and atmospheric errors mentioned in equation (4), the IRT (Infrared Thermography) T in Nominal temperature and temperature sensor T s There is a significant difference between the measured values, with the latter having an error of approximately 0.1℃, which can be considered the accurate temperature of the soil surface. Therefore, correction is needed to reduce IRTT. in The nominal temperature error is determined using the following method:
[0067] Due to deformation caused by frost heave, the position of the temperature sensor changes in real time. Therefore, a method based on Digital Image Correlation (DIC) is used to measure soil deformation. A layer of black and white quartz sand is applied to the frozen soil surface; the sand will move upwards along with the soil deformation. A camera is used to capture real-time images of the quartz sand, and the images are analyzed using GeoPIV-RG software to calculate the soil displacement in real time. This allows for the calculation of the sensor's real-time position. Determining the temperature sensor's position based on the measured displacement field and performing real-time IRT calibration is crucial.
[0068] DIC requires a DSLR camera to calculate soil displacement and further determine the location of the temperature sensor; IRT requires an infrared camera to measure temperature at different heights. The infrared temperature at the same height position of the sensor is extracted and corrected using the sensor's temperature reading.
[0069] like Figure 3 As shown, when considering the effects of frost heave, the new position of the temperature sensor differs from its initial height. The displacement field caused by frost heave is calculated using DIC, and the position of the temperature sensor is updated accordingly. The temperature (T) measured by the temperature sensor at the updated position on the IRT is... s ) and the temperature measured by the infrared camera (T) in ) was extracted.
[0070] Should be in T in and T s Linear regression was performed between them. Then, the correction temperature (T) of the IRT was... c1 It can be calculated as follows:
[0071] T c1 =α1×T in +β1 (5)
[0072] Where α1 and β1 are fitting parameters, which need to be determined based on 3 to 5 sets (T in ,T s The data was fitted. c1 The infrared temperature is adjusted to account for frost heave deformation.
[0073] The temperature (T) measured by the temperature sensor at the temperature sensor update location on the IRT. s ) and the temperature measured by the infrared camera (T) in The temperature sensor is extracted. If there are 3 to 5 temperature sensors, then these 3 to 5 sets (T) are used. in ,T s) data to obtain two fitting parameters, a1 and b1. Then, because the infrared camera can obtain the infrared temperature at all heights of the soil column, the two fitting parameters are used to obtain the corrected infrared temperature at any height based on equation (5).
[0074] Due to the characteristics of the material itself and the manufacturing process, the temperature sensor may have a small measurement error when it is shipped. Therefore, the temperature sensor needs to be calibrated before use. The temperature sensor and the calibrated mercury thermometer (first-class standard, 0.05℃ precision) are placed in a cold bath. The reading of the mercury temperature is taken as the actual temperature. Five points are selected in the range of -20-0℃, and the cold bath is allowed to balance at each temperature point for 2 hours. The readings of the temperature sensor (T s ) and the mercury thermometer (T r ) at different temperatures of the cold bath are extracted, and five sets of T r and T s data are linearly fitted. Then the actual temperature can be calculated from the sensor reading. Figure 4 A calibration diagram of a temperature sensor is provided for an embodiment of the present application.
[0075] Application example
[0076] This example carries out a one-dimensional freezing experiment of silty clay under water replenishment conditions, and the temperature field during the freezing process of the frozen soil is monitored by using an infrared camera and a temperature sensor. The deformation is monitored by using a digital image method.
[0077] Figure 5 A freezing test system diagram is provided for an embodiment of the present application, (a) is a side view of the system; (b) is a plane diagram of the system, including: a temperature control system, a sensor system, a data acquisition system and a soil column cylinder are needed.
[0078] Temperature measurement: the temperature distribution of the entire soil column is measured by using an infrared thermal imager. The infrared camera can monitor the temperature above -20℃, and the resolution can reach 256*192. The pt100 temperature sensor is used to measure the temperature of some sections of the soil column, and the infrared thermal imaging picture is corrected.
[0079] Deformation measurement: the frost heaving deformation is measured by using a digital image method. Black and white quartz sand is used as a tracer particle, and the movement of the tracer particle is analyzed by real-time shooting and a digital single-lens reflex camera (resolution 5184*3456 pixel) and a software package, which can realize timed shooting and real-time photo transmission. The data acquisition frequency is 10 minutes. The quartz sand area in the picture is extracted, median filter denoising is performed, and it is converted into a binary image. The binary image is analyzed by using the GeoPIV-RG program to calculate the displacement field and the strain field.
[0080] Temperature control: A freeze-thaw test chamber was used to provide a stable ambient temperature, and a constant-temperature water bath was connected to the upper and lower ends to provide stable upper and lower end temperatures.
[0081] All sensors were connected to a computer through a Data Taker 85 data acquisition instrument. The collection frequency of the temperature and ice content was 5 min. A Mariotte bottle was used to supply water at the bottom of the soil column at 0 kPa. The soil column mold was a cylindrical barrel made of transparent organic glass with a wall thickness of 1.0 cm and an inner diameter of 14 cm. In the infrared observation area, a 2 cm wide window was opened.
[0082] Figure 6 A correction diagram for infrared temperature provided by the embodiment of the present application is shown in (a) the change trend of two fitting parameters; and (b) the fitting effect of three stages, as shown in Figure 6 The evolution trend of alpha and beta, two fitting parameters, can be divided into three stages. The first stage is 0-78 h, alpha and beta increase significantly, and the frequency of correction needs to be increased. The second stage is 78-368 h, alpha is basically stable, and beta increases slowly. The frequency of correction can be reduced in this stage. The third stage is after 368 h, alpha and beta do not change basically. Figure 6 The fitting effect at different times for the three stages is shown in (a) and (b), and R 2 is greater than 0.98.
[0083] The two parameters should be corrected according to the development trend of temperature and deformation. When the temperature is in a transient state, it is recommended to increase the correction frequency, and correction is needed once about 1 h. When the temperature does not change and the segregation crack develops slowly, the correction frequency can be reduced, and correction is needed once about 30-50 h. When the temperature and the segregation crack do not change, no correction is needed. The temperature field of frozen soil during segregation can be measured in real time, especially the non-destructive measurement of key positions such as segregation cracks, and the accuracy can reach 0.1 DEG C.
[0084] In summary, the embodiment of the present application uses a limited number of temperature sensors and a digital image method to correct infrared images, and realizes high-precision temperature measurement of the full cross-section of the soil column, especially the key positions such as the segregation crack. The embodiment of the present application can measure the temperature field of frozen soil during segregation in real time, especially the non-destructive temperature measurement of key positions such as the segregation crack, and the accuracy can reach 0.1 DEG C.
[0085] Those skilled in the art can understand that the drawings are only schematic diagrams of an embodiment, and the modules or flows in the drawings are not necessarily necessary for implementing the present application.
[0086] Those skilled in the art can clearly understand the present application by the description of the above embodiments. Based on such an understanding, the technical solutions of the present application can be embodied in the form of a software product, and the computer software product can be stored in a storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, and the like, and includes a plurality of instructions to cause a computer device (which can be a personal computer, a server, or a network device, and the like) to execute the methods described in the various embodiments or some parts of the embodiments.
[0087] Each of the embodiments in the specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other. Each of the embodiments mainly describes the difference from other embodiments. In particular, for the device or system embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the related parts can be referred to the part of the method embodiments. The above-described device and system embodiments are merely illustrative, and the units described as separate components can be or can not be physically separated, and the components displayed as units can be or can not be physical units, that is, they can be located in one place, or can be distributed on multiple network units. Part or all of the modules can be selected to achieve the purpose of the embodiments according to the actual needs. Those skilled in the art can understand and implement it without creative labor.
[0088] The above describes only the preferred embodiments of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims
1. A method for infrared measurement of temperature distribution in the process of freezing soil segregation frost heaving, characterized in that, The application relates to a method for measuring the temperature of frozen soil, which comprises the following steps: placing frozen soil in a soil column barrel, arranging a temperature sensor at the position of the frozen soil, arranging an infrared camera outside the soil column barrel, opening an infrared temperature measuring window at a certain height in the soil column barrel, fixing a polyethylene thin PE plate at the position of the infrared temperature measuring window, sticking a layer of polyvinyl chloride PVC film on the inner side of the polyethylene thin PE plate, and irradiating the frozen soil with infrared rays emitted by the infrared camera through the PE plate and the PVC film, wherein the infrared camera receives the reflected rays reflected by the frozen soil, and the temperature of the frozen soil is measured according to the reflected rays. The temperature of some sections of the frozen soil is measured by using a temperature sensor, and the temperature of the frozen soil measured by the infrared camera is corrected by using the temperature measured by the temperature sensor. The infrared camera receives the reflected rays reflected by the frozen soil, and the temperature of the frozen soil is measured according to the reflected rays.
2. The method of claim 1, wherein, The temperature of some sections of the frozen soil is measured by using a temperature sensor, and the temperature of the frozen soil measured by the infrared camera is corrected by using the temperature measured by the temperature sensor. The temperature T measured by the infrared camera is calculated from the sum of the energies received by the infrared camera in , T in Temperature measured by the infrared camera; W soil Energy emitted by the soil and transmitted through the PE sheet and absorbed by the infrared camera, ε pvc Emissivity of the PVC, ε pvc = 0.95; T is the transmittance of the PE sheet, T soil Temperature of the soil measured by the temperature sensor, W pe Energy emitted by the PE sheet, ε pe Emissivity of the PE; T pe Temperature of the PE; W re Energy reflected by the PE sheet, W air Energy emitted by the air.
3. The method of claim 2, wherein, The formula (3) is brought into the formula (2), and the following formula (4) is obtained: T pe The PE plate is affected by the temperature T soil of the soil on the inner side of the PE plate. T pe = δT soil (3) where δ is an influence factor, δ > 1 when the location T soil is less than ambient temperature, otherwise δ < 1; The temperature of some sections of the frozen soil is measured by using a temperature sensor, and the temperature of the frozen soil measured by the infrared camera is corrected by using the temperature measured by the temperature sensor. From the above equation, With There is a linear relationship, the slope k = τ + ε pe δ 4 / ε pvc , the intercept μ = (W re +W air ) / ε pvc σ, k and μ reflect the influence of the transmittance, emissivity of the shield.
4. The method of claim 1, wherein, Wherein, alpha1 and beta1 are fitting parameters. A temperature sensor is used to measure the temperature T of the frozen soil at a certain height s , the temperature data of the infrared thermal imaging of the frozen soil at the height is obtained, the mean and standard deviation of all the temperature data of the infrared thermal imaging of the frozen soil at the height are calculated, the temperature value that is more than 3 times the standard deviation away from the mean is considered as an abnormal value, all the abnormal temperature values are removed, and the mean of the remaining temperature values is taken as the temperature T of the frozen soil at the height measured by the infrared camera in . According to T s in corrected temperature T c1 : T c1 = a1 x T in + b1 (5) The emissivity of the infrared camera is set as the PVC emissivity, and the emissivity is 0.
95. According to the multiple sets (T in ,T s ) data, the fitting parameters α1, β1 are obtained.
5. The method according to any one of claims 1 to 4, characterized in that,