Ice Gathering Feature in the Soil Freezing Process and its Influence on Soil Local Deformation

Abstract

The variation in frozen soil’s ice content is the main cause of engineering diseases in cold regions. However, currently, there is a lack of experimental data on the coupling of frozen local temperature, ice content, and local deformation. This paper focused on the frost heave process in unsaturated soil and utilized a self-developed multi-field coupled frost heave test device. In the soil column frost heave test, the temporal and spatial variations of local temperature, pore volume ice content, and local strain were synchronously collected, and the decoupling of multi-source data in a single test was realized. Based on the test data, the following conclusions were drawn: 1. In unsaturated silty clay, a critical frost segregation temperature exists. When the local temperature is between the freezing point and the critical temperature, both the deformation and ice content of the soil continue to increase. For non-bottom frost segregation cracks that meet this condition, their width can also increase continuously and slowly. When the local temperature falls below the critical frost segregation temperature, the rate of local deformation and ice content variation gradually slows down. 2. The critical temperature can be approximated from the turning point of the soil’s SFCC. 3. Segregation cracks in unsaturated frozen soil can form partially frozen cracks with a maximum ice saturation of less than 60%. The mechanism behind their formation may be related to water film thickness and freezing rate. The findings of this study contribute to the improvement of the theoretical framework of frozen soil mechanics.

Keywords: Unsaturated frozen soil, Segregation frost heave, Volumetric Ice content, Local strain, Ice saturation