Resistivity static sounding in-situ test probe for evaluating unfrozen water content and ice content of frozen soil and working method of resistivity static sounding in-situ test probe

Abstract

The invention discloses a resistivity static sounding in-situ test probe for evaluating unfrozen water content and ice content of frozen soil and a working method thereof.The test probe comprises a sounding probe body and a probe rod which are vertically distributed, the sounding probe body is located at the bottom end of the probe rod, and a coaxial cable is arranged in the probe rod in a penetrating mode; a broadband signal generator, an embedded data processor, an inclinometer, an annular electrode array, a temperature sensor, a pressure measuring assembly and a friction cylinder are sequentially arranged in the probe rod from top to bottom. According to the invention, resistivity inversion calculation and temperature compensation calculation are carried out through the embedded data processor, and end resistance, friction resistance, inclination, temperature, unfrozen water content, ice content and thaw collapse coefficient are output; according to the method, mechanical parameters and electrical parameters are synchronously obtained, multi-physical field coupling analysis is combined, the frozen soil thaw collapse deformation in-situ testing method based on broadband resistivity static sounding is constructed, and the defect that the content of unfrozen water and the content of ice in a soil body cannot be detected through an existing static sounding technology in China is overcome.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering testing technology, and in particular to an in-situ resistivity static cone penetration test probe and its working method for evaluating the unfrozen water content and ice content of frozen soil. Background Technology

[0002] Frost heave and thaw settlement of permafrost can easily lead to uneven settlement of roadbeds in cold regions, posing a severe challenge to the safety of transportation infrastructure in these areas. The unfrozen water content of permafrost is a key physical parameter affecting frost heave and thaw settlement. How to accurately determine the unfrozen water content in permafrost has become one of the core scientific problems that urgently needs to be solved in cold region engineering. Currently, the field of permafrost engineering lacks effective in-situ testing methods. Existing static cone penetration testing (CPPT) techniques mainly test single mechanical parameters such as cone tip resistance and sidewall friction, only allowing for in-situ testing of permafrost mechanical parameters. However, due to temperature field changes causing dynamic changes in the unfrozen water and ice content of permafrost, this water-ice phase transition process significantly alters the soil structure through frost heave / thaw settlement effects, causing the strength of permafrost to increase / decrease under temperature influence, leading to deviations in the initial mechanical parameters obtained based on traditional static penetration testing methods. Therefore, obtaining the unfrozen water content or ice content while evaluating the mechanical properties of permafrost can correct the in-situ mechanical test results and evaluate the potential trend of permafrost strength changes.

[0003] Existing research indicates that the electrical properties of the soil skeleton, ice crystals, and unfrozen water in permafrost differ by a significant order of magnitude. This characteristic provides a theoretical basis for the identification and phase analysis of multiphase media in permafrost based on electrical principles. However, due to the high resistivity of ice crystals, broadband AC technology is required to effectively classify permafrost components: low-frequency impedance response mainly characterizes the conductivity of unfrozen water, while high-frequency impedance response reflects the dielectric properties of ice and the residual conductivity effect of unfrozen water. The thaw settlement coefficient of permafrost is then evaluated based on the identified components.

[0004] Therefore, it is necessary to develop a resistivity static cone penetration test probe and its working method for evaluating the unfrozen water content and ice content of frozen soil to solve the above problems. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a resistivity static cone penetration test probe and its working method for evaluating the unfrozen water content and ice content of frozen soil, which is used to assess the strength and thaw settlement coefficient of frozen soil. It is particularly suitable for application scenarios that require accurate assessment of soil phase change state, such as cold region engineering and frozen soil subgrade monitoring, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A resistivity static cone penetration test probe for evaluating the unfrozen water content and ice content of frozen soil includes a vertically distributed cone probe and a probe rod. The cone probe is located at the bottom end of the probe rod, and a coaxial cable is threaded through the probe rod. The probe rod contains, from top to bottom, a broadband signal generator, an embedded data processor, an inclinometer, a ring electrode array, a temperature sensor, a pressure measuring component, and a friction cylinder. The broadband signal generator and the embedded data processor are electrically connected to the coaxial cable, and the output ends of the inclinometer, the ring electrode array, the temperature sensor, the pressure measuring component, the friction cylinder, and the cone probe are electrically connected to the input end of the embedded data processor.

[0008] The penetrometer has a built-in static penetrometer mechanical measurement unit and a broadband resistivity testing module. The inclinometer, annular electrode array, temperature sensor, pressure measuring component, friction cylinder and penetrometer are all connected in parallel with a coaxial cable. The cone tip resistance, sidewall friction resistance, inclination and soil temperature signal at the target test depth of the penetrometer and probe are collected and fed back to the embedded data processor. The resistivity is used to test the unfrozen water content and ice content of the soil.

[0009] Preferably, the probe is cone-shaped with a cone angle of 60° and a cone base cross-sectional area of ​​10 cm². 2 .

[0010] Preferably, the probe and the probe rod are detachably connected, and the diameter of the cone bottom of the probe is the same as the outer diameter of the probe rod.

[0011] Preferably, the pressure measuring assembly is installed at the connection between the probe and the probe rod, and the pressure measuring assembly includes a sleeve pressure measuring element and a cone tip pressure measuring element, wherein the sleeve pressure measuring element is attached to the inner wall of the probe rod, and the cone tip pressure measuring element is attached to the probe.

[0012] Preferably, the number of the annular electrode arrays is set to four, and the four annular electrode arrays are arranged in a vertically stacked manner.

[0013] Preferably, the outer surface of the annular electrode array is covered with a nano-alumina wear-resistant material, and the electrodes of the annular electrode array are made of platinum-graphene composite material. The electrode surface is laser-etched with a micron-level groove structure, and the middle layer of the electrode is made of insulating material.

[0014] Preferably, the outer surface of the friction cylinder is covered with a nano-alumina wear-resistant material, and the surface area of ​​the friction cylinder is set to 150 cm². 2 .

[0015] Preferably, the wideband signal generator is used to transmit a wideband excitation signal, and the frequency of the transmitted excitation signal is 0.1Hz-10MHz.

[0016] Preferably, the embedded data processor has a built-in temperature compensation algorithm for establishing a mapping relationship between broadband resistivity and unfrozen water content and ice content.

[0017] This application also discloses a working method for an in-situ resistivity static cone penetration test probe used to evaluate the unfrozen water content and ice content of frozen soil, comprising the following steps:

[0018] S1. Assemble the test probe and calibrate the resistivity measurement system: Transport the broadband thermo-electric coupling CPT probe, which integrates a temperature sensor, a broadband resistivity test module and a static penetration mechanical measurement unit, to the test site, calibrate the resistivity measurement system of the CPT probe, set the low-frequency test mode and the high-frequency test mode, and record the resistivity reference value at the corresponding calibration temperature Tref.

[0019] S2. Install the test probe: Insert the probe to the target test depth at the specified rate, while keeping the surrounding soil in its original position.

[0020] S3, Resistivity Inversion Calculation: By adjusting the frequency of the resistivity probe, current is released into the frozen soil at low and high frequencies respectively;

[0021] When operating in low-frequency testing mode: the main response is the unfrozen water phase in the soil pores, and the low-frequency water phase resistivity ρ is measured. w ;

[0022] When operating in high-frequency testing mode: it primarily responds to the ice phase in the soil pores, and measures the high-frequency ice phase resistivity ρ. i ;

[0023]

[0024] Where, ρ cal For the equivalent resistivity of the soil at the target test depth, θ i To determine the ice content of the soil at the target test depth, θ w To determine the water content of the soil at the target test depth;

[0025] S4. Temperature Compensation Calculation: Considering the influence of temperature changes on the conductivity of unfrozen water, the calculation is based on the measured temperature T and its effect on the low-frequency water phase resistivity ρ. w The compensation and correction are performed, and the compensation algorithm is as follows:

[0026] ρ w,corr =ρ w [1+α(TT ref )]

[0027] Where, ρ w,corr For unfrozen water, the conductivity law is used, with the coefficient α set to 0.02 by default. T is the current temperature. ref For calibration temperature;

[0028] S5. Calculate the ice content θ of frozen soil based on the broadband resistivity mixing model. i and water content θ w ;

[0029] The formula for calculating ice content is as follows:

[0030]

[0031] The formula for calculating moisture content is as follows:

[0032]

[0033] Among them, among them, ρ is the porosity of the soil. eff,100MHz The equivalent resistivity was measured at a high frequency of 100MHz.

[0034] S6. Continue to penetrate the CPT probe to the next predetermined depth, repeat S2–S5, until the full-section ice content and water content distribution test within the target survey depth range is completed.

[0035] S7. Plot the ice and water content results at different depths obtained from the calculation into a profile diagram, and combine the mechanical parameters including cone tip resistance, sidewall friction and pore pressure to comprehensively evaluate the permafrost structural characteristics, ice-water spatial distribution law and thermoelectric response characteristics.

[0036] The present invention has the following beneficial effects:

[0037] By using broadband current scanning, resistivity data at multiple frequencies and soil temperature monitored in real time by a high-precision temperature sensor are acquired. An embedded data processor is used for resistivity inversion calculation and temperature compensation calculation, outputting end resistance, friction, tilt, temperature, unfrozen water content, ice content, and thaw settlement coefficient. Broadband resistivity static cone penetration testing (BCPT) technology enables the simultaneous acquisition of mechanical and electrical parameters. Combined with multiphysics coupling analysis, a method for in-situ testing of frozen soil thaw settlement deformation based on broadband resistivity BCPT is finally constructed. This method can effectively evaluate the stability of foundation soil, achieve simultaneous detection of water and ice phases, and solve the deficiency of existing domestic static cone penetration testing techniques in detecting unfrozen water content and ice content in soil. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1This is a schematic diagram of the overall structure of the test probe provided by the present invention.

[0040] Among them are:

[0041] Coaxial cable-1; Wideband signal generator-2; Embedded data processor-3; Inclinometer-4; Ring electrode array-5; Temperature sensor-6; Pressure measuring assembly-7; Friction cylinder-8; Penetration probe-9; Probe rod-10. Detailed Implementation

[0042] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0043] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0044] Secondly, the present invention will be described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure will be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0045] Furthermore, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that mutually excludes other embodiments.

[0046] like Figure 1 The resistivity static cone penetration test probe shown is used to evaluate the unfrozen water content and ice content of frozen soil. It includes a vertically distributed cone probe 9 and a probe rod 10. The cone probe 9 is located at the bottom end of the probe rod 10, and a coaxial cable 1 runs through the probe rod 10. The probe rod 10 is arranged from top to bottom as follows: a broadband signal generator 2, an embedded data processor 3, an inclinometer 4, a ring electrode array 5, a temperature sensor 6, a pressure measuring component 7, and a friction cylinder 8. The broadband signal generator 2 and the embedded data processor 3 are electrically connected to the coaxial cable 1, and the output terminals of the inclinometer 4, the ring electrode array 5, the temperature sensor 6, the pressure measuring component 7, the friction cylinder 8, and the cone probe 9 are electrically connected to the input terminal of the embedded data processor 3.

[0047] The penetrometer 9 incorporates a static penetrometry mechanical measurement unit and a broadband resistivity testing module. The inclinometer 4, annular electrode array 5, temperature sensor 6, pressure measuring component 7, friction cylinder 8, and penetrometer 9 are all connected in parallel with the coaxial cable 1. This collects the cone tip resistance, sidewall friction resistance, inclination, and soil temperature signals at the target test depth from the penetrometer 9 and probe rod 10, and feeds these signals back to the embedded data processor 3. Resistivity is then used to test the unfrozen water content and ice content of the soil. Based on existing technology, this embodiment further expands the multifunctional static penetrometry technology. During measurement, the probe device needs to be vertically inserted into the soil to be tested, and a broadband current scan is performed when it reaches the specified depth. Specifically, the device is remotely started from the control terminal, and the broadband scanning mode is selected. Resistivity data at various frequencies and the soil temperature monitored in real time by the temperature sensor 6 are collected according to the actual situation. The embedded data processor 3 performs resistivity inversion calculation and temperature compensation calculation, and finally outputs the terminal resistance, friction resistance, inclination, temperature, unfrozen water content, ice content, and melt-settlement coefficient.

[0048] In this embodiment, temperature sensor 6 is a high-precision temperature sensor, which is used to acquire the temperature information of the soil at the target test depth. Its temperature measurement range is -50℃ to 10℃; its accuracy reaches ±0.1℃; and its resolution is 0.01℃.

[0049] In this embodiment, an inclinometer 4 is used to obtain the inclination of the probe 9 and the probe rod 10. When the inclinometer 4 is working, the apex angle measurement range is 0°-15°; the accuracy reaches ±0.1°; and the apex angle resolution is 0.01°.

[0050] Specifically, in the above technical solution, the probe 9 is cone-shaped, with a cone angle of 60° and a cone base cross-sectional area of ​​10 cm². 2 .

[0051] Specifically, in the above technical solution, the probe 9 and the probe rod 10 are detachably connected, and the diameter of the cone bottom of the probe 9 is the same as the outer diameter of the probe rod 10.

[0052] Specifically, in the above technical solution, the pressure measuring component 7 is installed at the connection between the probe 9 and the probe rod 10, and the pressure measuring component 7 includes a sleeve pressure measuring element and a cone tip pressure measuring element, wherein the sleeve pressure measuring element is attached to the inner wall of the probe rod 10, and the cone tip pressure measuring element is attached to the probe 9.

[0053] Specifically, in the above technical solution, the number of annular electrode arrays 5 is set to four, and the four annular electrode arrays 5 are arranged in a vertically stacked manner.

[0054] Specifically, in the above technical solution, the outer surface of the annular electrode array 5 is covered with a nano-alumina wear-resistant material, and the electrodes of the annular electrode array 5 are made of platinum-graphene composite material. The electrode surface has a micron-level groove structure laser-etched, and the middle layer of the electrode is made of insulating material. The electrode diameter is set to 6 mm.

[0055] Specifically, in the above technical solution, the outer surface of the friction cylinder 8 is covered with a nano-alumina wear-resistant material, and the surface area of ​​the friction cylinder 8 is set to 150 cm². 2 .

[0056] Specifically, in the above technical solution, the wideband signal generator 2 is used to transmit wideband excitation signals, and the frequency of the transmitted excitation signals is 0.1Hz-10MHz.

[0057] Specifically, in the above technical solution, the embedded data processor 3 has a built-in temperature compensation algorithm to establish a mapping relationship between broadband resistivity and unfrozen water content and ice content.

[0058] This application also discloses a working method for an in-situ resistivity static cone penetration test probe used to evaluate the unfrozen water content and ice content of frozen soil, comprising the following steps:

[0059] S1. Assemble the test probe and calibrate the resistivity measurement system: Transport the broadband thermo-electric coupling CPT probe, which integrates a temperature sensor 6, a broadband resistivity test module, and a static penetration test mechanical measurement unit, to the test site. Calibrate the resistivity measurement system of the CPT probe, set the low-frequency test mode and the high-frequency test mode, and record the resistivity reference value at the corresponding calibration temperature Tref. The working frequency of the low-frequency test mode and the high-frequency test mode is set manually, such as 10Hz for low frequency and 10MHz for high frequency.

[0060] S2. Install the test probe: Insert the probe into the target test depth at the specified rate (set manually, such as 1 cm / s) while keeping the surrounding soil in its original position.

[0061] S3, Resistivity Inversion Calculation: By adjusting the frequency of the resistivity probe, current is released into the frozen soil at low and high frequencies respectively;

[0062] When operating in low-frequency testing mode: the main response is the unfrozen water phase in the soil pores, and the low-frequency water phase resistivity ρ is measured. w ;

[0063] When operating in high-frequency testing mode: it primarily responds to the ice phase in the soil pores, and measures the high-frequency ice phase resistivity ρ. i ;

[0064]

[0065] Where, ρ cal For the equivalent resistivity of the soil at the target test depth, θ i To determine the ice content of the soil at the target test depth, θ w To determine the water content of the soil at the target test depth;

[0066] S4. Temperature Compensation Calculation: The influence of temperature changes on the conductivity of unfrozen water is considered. Since the conductivity of unfrozen water is significantly affected by temperature changes, specifically approximately 2% / ℃, the calculation is based on the measured temperature T and its impact on the low-frequency water phase resistivity ρ. w The compensation and correction are performed, and the compensation algorithm is as follows:

[0067] ρ w,corr =ρ w [1+α(TT ref )]

[0068] Where, ρ w,corr For unfrozen water, the conductivity law is used, with the coefficient α set to 0.02 by default. T is the current temperature. ref For calibration temperature;

[0069] S5. Calculate the ice content θ of frozen soil based on the broadband resistivity mixing model. i and water content θ w ;

[0070] The formula for calculating ice content is as follows:

[0071]

[0072] The formula for calculating moisture content is as follows:

[0073]

[0074] Among them, among them, ρ is the porosity of the soil. eff,100MHz The equivalent resistivity was measured at a high frequency of 100MHz.

[0075] S6. Continue to penetrate the CPT probe to the next predetermined depth, repeat S2–S5, until the full-section ice content and water content distribution test within the target survey depth range is completed.

[0076] S7. The calculated ice and water content at different depths are plotted as profile diagrams. Combined with mechanical parameters including cone tip resistance, sidewall friction, and pore pressure, the structural characteristics, spatial distribution of ice and water, and thermoelectric response of the permafrost are comprehensively evaluated. This provides a scientific basis for engineering design and stability assessment in permafrost regions. Furthermore, using this method for in-situ permafrost testing, simultaneously evaluating permafrost strength and thaw settlement coefficient, is particularly suitable for applications requiring precise assessment of soil phase change states, such as cold-region engineering and permafrost subgrade monitoring, providing rapid and effective engineering parameters for foundation stability evaluation in cold-region engineering.

[0077] The above solution addresses the shortcomings of existing domestic static testing techniques in detecting unfrozen water content and ice content in soil, effectively evaluating the stability of foundation soil. Specifically, it enables simultaneous detection of water and ice phases, with a water content resolution of ±1.5% and an ice content detection error of <±2%; a temperature compensation algorithm improves testing accuracy by 80% at -50℃; the wear-resistant electrode structure exhibits a contact impedance change of <5% after 100 freeze-thaw cycles; single-hole testing time is reduced to 1 / 20th of traditional methods, and costs are reduced by 60%; it can continuously acquire soil phase distribution profiles within a depth range of 0-30m.

[0078] It is important to note that the constructions and arrangements of this application shown in several different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible (e.g., changes in the size, dimensions, structure, shape, and proportions of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in this application). For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of elements may be inverted or otherwise altered, and the nature or number or position of discrete elements may be changed or altered. Therefore, all such modifications are intended to be included within the scope of the invention. The order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and not only structurally equivalent but also equivalent in structure. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of the invention. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0079] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments (i.e., those features that are not relevant to the best mode of carrying out the invention as currently considered, or those features that are not relevant to implementing the invention) may be omitted.

[0080] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.

[0081] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A resistivity static cone penetration test probe for evaluating the unfrozen water content and ice content of frozen soil, comprising vertically distributed cone probes (9) and probe rods (10), wherein the cone probes (9) are located at the bottom end of the probe rods (10), and a coaxial cable (1) is threaded through the probe rods (10), characterized in that: The probe rod (10) is equipped with, from top to bottom, a broadband signal generator (2), an embedded data processor (3), an inclinometer (4), a ring electrode array (5), a temperature sensor (6), a pressure measuring component (7), and a friction cylinder (8). The broadband signal generator (2) and the embedded data processor (3) are electrically connected to the coaxial cable (1). The output terminals of the inclinometer (4), the ring electrode array (5), the temperature sensor (6), the pressure measuring component (7), the friction cylinder (8), and the probe (9) are electrically connected to the input terminal of the embedded data processor (3). The penetrometer (9) has a built-in static penetrometer mechanical measurement unit and a broadband resistivity test module. The inclinometer (4), the ring electrode array (5), the temperature sensor (6), the pressure measuring component (7), the friction cylinder (8) and the penetrometer (9) are all connected in parallel with the coaxial cable (1). The cone tip resistance, side wall friction resistance, inclination and soil temperature signal at the target test depth of the penetrometer (9) and the probe rod (10) are collected and fed back to the embedded data processor (3). The resistivity is used to test the unfrozen water content and ice content of the soil.

2. The resistivity static cone penetration test probe for evaluating the unfrozen water content and ice content of frozen soil according to claim 1, characterized in that: The probe (9) is cone-shaped with a cone angle of 60° and a cone base cross-sectional area of ​​10 cm². 2 .

3. The resistivity static cone penetration test probe for evaluating the unfrozen water content and ice content of frozen soil according to claim 2, characterized in that: The probe (9) is detachably connected to the probe rod (10), and the diameter of the cone bottom of the probe (9) is the same as the outer diameter of the probe rod (10).

4. The resistivity static cone penetration test probe for evaluating the unfrozen water content and ice content of frozen soil according to claim 1, characterized in that: The pressure measuring component (7) is installed at the connection between the probe (9) and the probe rod (10), and the pressure measuring component (7) includes a sleeve pressure measuring element and a cone tip pressure measuring element, wherein the sleeve pressure measuring element is attached to the inner wall of the probe rod (10), and the cone tip pressure measuring element is attached to the probe (9).

5. The resistivity static cone penetration test probe for evaluating the unfrozen water content and ice content of frozen soil according to claim 1, characterized in that: The number of the annular electrode arrays (5) is set to four, and the four annular electrode arrays (5) are arranged in a vertical stacked distribution.

6. The resistivity static cone penetration test probe for evaluating the unfrozen water content and ice content of frozen soil according to claim 1, characterized in that: The outer surface of the annular electrode array (5) is covered with nano-alumina wear-resistant material, and the electrodes of the annular electrode array (5) are made of platinum-graphene composite material. The electrode surface is laser-etched with micron-level groove structure, and the middle layer of the electrode is made of insulating material.

7. The resistivity static cone penetration test probe for evaluating the unfrozen water content and ice content of frozen soil according to claim 1, characterized in that: The outer surface of the friction cylinder (8) is covered with nano-alumina wear-resistant material, and the surface area of ​​the friction cylinder (8) is set to 150 cm². 2 .

8. The resistivity static cone penetration test probe for evaluating the unfrozen water content and ice content of frozen soil according to claim 1, characterized in that: The wideband signal generator (2) is used to transmit wideband excitation signals, and the frequency of the transmitted excitation signals is 0.1Hz-10MHz.

9. The resistivity static cone penetration test probe for evaluating the unfrozen water content and ice content of frozen soil according to claim 1, characterized in that: The embedded data processor (3) has a built-in temperature compensation algorithm to establish a mapping relationship between broadband resistivity and unfrozen water content and ice content.

10. The working method of an in-situ resistivity static cone penetration test probe for evaluating the unfrozen water content and ice content of frozen soil as described in any one of claims 1-9, characterized in that: Includes the following steps: S1. Assemble the test probe and calibrate the resistivity measurement system: Transport the broadband thermo-electric coupling CPT probe, which integrates a temperature sensor (6), a broadband resistivity test module and a static penetration mechanical measurement unit, to the test site, calibrate the resistivity measurement system of the CPT probe, set the low-frequency test mode and the high-frequency test mode, and record the resistivity reference value at the corresponding calibration temperature Tref. S2. Install the test probe: Insert the probe to the target test depth at the specified rate, while keeping the surrounding soil in its original position. S3, Resistivity Inversion Calculation: By adjusting the frequency of the resistivity probe, current is released into the frozen soil at low and high frequencies respectively; When operating in low-frequency testing mode: the main response is the unfrozen water phase in the soil pores, and the low-frequency water phase resistivity ρ is measured. w ; When operating in high-frequency testing mode: it primarily responds to the ice phase in the soil pores, and measures the high-frequency ice phase resistivity ρ. i ; Where, ρ cal For the equivalent resistivity of the soil at the target test depth, θ i To determine the ice content of the soil at the target test depth, θ w To determine the water content of the soil at the target test depth; S4. Temperature Compensation Calculation: Considering the influence of temperature changes on the conductivity of unfrozen water, the calculation is based on the measured temperature T and its effect on the low-frequency water phase resistivity ρ. w The compensation and correction are performed, and the compensation algorithm is as follows: r w,corr =ρ w [1+α(TT ref )] Where, ρ w,corr For unfrozen water, the conductivity law is used, with the coefficient α set to 0.02 by default. T is the current temperature. ref For calibration temperature; S5. Calculate the ice content θ of frozen soil based on the broadband resistivity mixing model. i and water content θ w ; The formula for calculating ice content is as follows: The formula for calculating moisture content is as follows: in, ρ is the porosity of the soil. eff,100MHz The equivalent resistivity was measured at a high frequency of 100MHz. S6. Continue to penetrate the CPT probe to the next predetermined depth, repeat S2–S5, until the full-section ice content and water content distribution test within the target survey depth range is completed. S7. Plot the ice and water content results at different depths obtained from the calculation into a profile diagram, and combine the mechanical parameters including cone tip resistance, sidewall friction and pore pressure to comprehensively evaluate the permafrost structural characteristics, ice-water spatial distribution law and thermoelectric response characteristics.

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