Research Of Frozen Soil Dielectric Characteristics And Establishment Of Ice Content Measurement Model Based On Frequency Domain Dielectric Spectrum

Seasonal frozen soil is widely distributed in China,and the changes in soil geological characteristics caused by seasonal changes have a huge impact on human daily life.The existence of frozen soil has an important impact on ecological environment,geological engineering and resource utilization.Therefore,it is of great significance to deeply understand and explore the geological conditions of frozen soil.At present,dielectric sensors have become increasingly mature in applications such as soil moisture content,salt content,and soil physicochemical properties.However,few people have explored the relationship between the dielectric properties of frozen soil and ice content.The detection of frozen soil mainly includes research on the dielectric properties of frozen soil,the dielectric model of frozen soil,and the depth of soil freezing.The dielectric properties of frozen soil refer to the response of frozen soil materials to electromagnetic waves,which is one of the important parameters for detecting frozen soil.By studying the dielectric properties of frozen soil,rapid and accurate detection of frozen soil can be achieved.The study of permafrost dielectric model refers to the establishment of a mathematical model for the interaction between permafrost and electromagnetic waves,which can help explain detection results and optimize detection methods.Soil freezing depth refers to the depth of frozen cover in the soil,which is another important parameter for detecting frozen soil.By measuring and analyzing the depth of soil freezing,we can gain a deeper understanding of the spatial and temporal characteristics of frozen soil distribution,providing scientific basis for resource utilization and environmental protection.(1)This thesis analyzes the differences in electric field response intensity of different substances at different temperatures through polarization theory,and further studies the contribution of each component to the dielectric constant of the frozen soil system.The relationship between the macroscopic dielectric performance of frozen soil and the microscopic polarization of frozen soil particles is studied,and a frozen soil dielectric mixing model is established by selecting sensitive frequency bands.(2)After the experiment,the soil was dried to calibrate the actual initial moisture content.The ice content changes of each soil under different initial conditions were simulated using Comsol 5.6 finite element simulation software.Based on the analysis of the frequency domain dielectric spectrum of frozen soil,an empirical formula for measuring ice content in frozen soil was established based on a bilinear calculation model,providing a new research method for studying the dielectric properties of frozen soil and inverting ice content.(3)The test measurement after manually setting the soil freezing depth shows that the ITDR technology based on vector network analyzer can be used to measure layered media at low temperature,and the detection results are not affected by temperature.I-TDR was used to measure the freezing front of four types of soil with different textures: silty clay loam,clay loam,silty loam,and sand.The soil freezing depths were artificially set at 0 cm,6 cm,9 cm,12 cm,15 cm,and 20 cm,and the measurement depth was fitted with the actual set depth to establish a soil freezing front measurement model.The determination coefficient R2 of the obtained model was 0.98,and the RMSE was less than 1 cm,indicating good fitting effect.By studying the dielectric properties of frozen soil,it is helpful to explore the response of soil to electrical signals under freezing conditions,which is beneficial for the application of dielectric sensors in the field of frozen soil;By establishing a permafrost dielectric mixture model,the relationship between microwave reflectance and soil physical parameters can be utilized to obtain key data,providing a new method for exploring the physical characteristics of permafrost regions;I-TDR technology based on vector network analyzer realizes accurate monitoring of soil freezing front,with measurement error less than 1cm,which provides a new idea for automatic monitoring of frozen soil areas.