Influence of freeze–thaw cycles on the compressibility of the clay of core-wall soil materials

Diurnal freeze–thaw process occurs in the Lianghekou area in winter, which will affect the construction progress and quality of the project. In this paper, the compressibility of clay experiencing the freeze–thaw (F-T) cycles under different impacting factors was investigated. A series of unidirectional F-T tests were carried out in a closed system, and the compressibility tests were carried out for the same specimens underwent F-T cycles to study the compressibility along the specimen height. The experimental results demonstrate that the initial moisture content of specimens, the cooling temperature, and the number of F-T cycles affect the compressibility of specimens. As the cooling temperature decreases, the initial moisture content or the number of F-T cycles increases, the compressive strain of the affected zone of specimens increases under the same vertical pressure, while the confined compressive modulus decreases. The variation of the compressibility for the unaffected zone is different from that for the affected zone. For the same impacting factor, the compressive strain of the affected zone is greater than that of the unaffected zone, while the confined compressive modulus of the former is less than that of the latter. The change of compressibility is mainly affected by the characteristics of cryostructure and moisture migration of the specimen after F-T. This research may provide some guidance for the engineering construction process in winter in the seasonally frozen ground region.