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The seasonal freeze-thaw cycle of frozen soil regulates soil hydrothermal processes and serves as a crucial indicator of climate change in high-latitude cold regions. Monitoring the dynamic evolution of frozen soil structure and composition is essential for infrastructure development, soil conservation and carbon storage regulation. Compared to in-situ borehole measurements and remote sensing, near-surface geophysical methods offer spatially resolved insights into freeze-thaw processes at different depths. In this study, we applied electrical resistivity tomography and ambient noise seismic monitoring to investigate seasonal freeze-thaw cycles at a frozen soil test site in Northeast China. Geophysical data collected over a complete freeze-thaw cycle reveal the coupling between soil structure and hydrothermal properties, with strong consistency observed between physical parameters and hydrological information. Resistivity variations correlate with temperature, water content, and solute concentration across different freeze-thaw stages. Seismic relative velocity changes (dv/v) and surface wave phase velocity changes (dc/c) were negatively correlated with accumulated temperature and groundwater levels, reflecting soil pore freezing and the hydrothermal state of the deep subsurface environment. Meanwhile, the measured data verify that dc/c offers higher spatiotemporal resolution than dv/v. Sensitivity analysis indicate that resistivity is more responsive to shallow thermal exchange, while seismic velocity changes are more sensitive to deep hydrological variations. Integrating pore geometry and water-ice phase mechanisms, we construct a freeze-thaw evolution model for seasonally frozen soil based on combined hydrological and geophysical data. The results validate the effectiveness of geophysical methods for detecting and monitoring frozen soil, and provide technical support for quantifying phase transition mechanisms in freeze-thaw processes.

来源平台：CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION