Moisture migration and pressure-melting of artificially frozen soft soil based on low-temperature triaxial seepage MRI

Using the self-developed and designed low-temperature triaxial multiphase seepage magnetic resonance imaging (MRI) test analysis system, the moisture migration and pressure-melting tests on the artificially frozen clay and sandy silt under seepage conditions are systematically carried out. The development of seepage channels and the change of unfrozen water content in soft soil under the coupling of freezing and seepage are analyzed, and the information of ice evolution during pressure-melting process is obtained. The test results show that the seepage action leads to the existence of non-uniform seepage channels concentrated in the seepage outlets of frozen clay, while the sandy silt forms more uniform seepage channels. Under the coupling of freezing and seepage, the unfrozen water content inside the soil body gradually decreases, and the contents of unfrozen water of the clay and the sandy silt at -30℃ are reduced by 40% and 93%, respectively, compared to those at the room temperature. The pressure melting results in the gradual conversion of ice to water and an increasing unfrozen water content within the clay. This study promotes the development of frozen soil testing technology and provides a scientific theoretical basis for the construction of infrastructure in frozen soil areas or artificial freezing projects.