Heat transfer characteristics of gravelly soils with different compactness during unidirectional freezing process

Abstract

During the construction of clay core rockfill dam in cold regions in winter, the heat transfer characteristics of gravelly soil are important to the anti-freezing control of the core. Laboratory experiment and field test data showed that the frost depth of gravelly soil in unconsolidated state was deeper than that in compacted state at the early period of soil freezing. With the increase of the freezing time, however, the frost depth of compacted soil is deeper than that of unconsolidated soil. Further study showed that this phenomenon was main caused by the change of thermophysical parameters between unconsolidated and compacted soil. Under the same soil temperature, the thermal conductivity of compacted soil was approximately 2.6 times of that of unconsolidated soil, and the volume heat capacity and phase change latent heat of compacted soil was approximately 1.7 times of that of unconsolidated soil. The different thermophysical parameters caused the differences of the heat transfer rate, temperature distribution and heat release by cooling between compacted soil and unconsolidated soil. This study provides a theoretical guidance for freezing process of soil with different compactness and anti-freezing technology of clay core rockfill dam in cold regions.