Study on the freezing characteristics of silty clay under high loading conditions

•An apparatus was developed to study the soil freezing characteristics under high ground pressures.•Soil samples all exhibit compression under high loading conditions, consisting of 4 stages.•Under higher load the freezing front moves down faster and water migration is also observed.•At higher pseudo temperature gradient, larger strain occurs and the freezing front is closer to the cold end.

The freezing behaviour of soil in deep alluvium is one of the important issues in artificial freezing engineering. In this paper, an apparatus was developed for studying the freezing characteristics of soil under high loading conditions and the related test procedures were also suggested. Based on this apparatus, a series of one-dimensional freezing tests were also carried out on silty clay under various loading conditions and pseudo temperature gradients. The results show that all soil samples exhibit compression under high loading conditions, and it consists of four stages in which the strain rate is I) very low, II) rapidly increasing, III) decaying and IV) relatively constant. During freezing tests, the freezing front moves downward rapidly during the initial period, and it tends to be stable after 10 h. As the increase of axial load or pseudo temperature gradient, the freezing front moves downward more quickly and lies closer to the warm end at the thermostatic stage. Even under high loading conditions, there is an obvious water redistribution phenomenon, which shows that the water migrated to the frozen part and gathered at the freezing front in the soil sample under the existence of a pseudo temperature gradient.