The small-strain stiffness of frozen clay soils at different temperatures and initial water contents: Experimental study and predicted model

The small-strain stiffness of frozen soils is important for the constructions of geotechnical structures in cold regions and artificial ground freezing engineering. The variation in the small-strain shear modulus Gmax of frozen soils with decreasing temperature T was studied in detail through temperature-controlled bender element tests, and the effect of initial water content w0 on the changes was detected. A double-upscaling mechanism, involving the compaction of pore ice and bonded contact of solid particles, is proposed to interpret the changes in Gmax and then a predicted model of Gmax is proposed. In this model, the void ratio e and cryogenic suction ψ in frozen soils are the indictors of the double-upscaling mechanism, which can be determined for frozen soils with any T and initial water content w0 with the assistance of SFCC and the Clapeyron equation. The void ratio function and suction function on Gmax incorporated in this model are borrowed or slightly revised from the models for unsaturated soils reported in several relevant literature sources. The good performance of model is found via our own tests and two independent experimental datasets on two frozen clays, and the comparison results show that the predicted results are in reasonable agreement with the measured data.