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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 G max of frozen soils with decreasing temperature T was studied in detail through temperature-controlled bender element tests, and the effect of initial water content w 0 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 G max and then a predicted model of G max 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 w 0 with the assistance of SFCC and the Clapeyron equation. The void ratio function and suction function on G max 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. • Bender element tests were conducted to investigate the frozen fine-grained soils. • The effect of initial water content and temperature on soil's stiffness are analyzed. • Proposing a dual upscaling mechanism: pore ice compaction, solid particles bonded. • A predicted model is proposed to estimate frozen soil's small-strain shear modulus. [ABSTRACT FROM AUTHOR]

Observation of the cyclic behavior of compacted soils in a frozen state is required for assessing the dynamic stability of subgrades or embankments induced by earthquakes or traffic in cold regions, in which the compacted frozen soils have often experienced deviator stress history before applying cyclic stress. Therefore, strain-controlled monotonic triaxial tests followed by stress-controlled cyclic triaxial tests were carried out on compacted frozen soils to investigate the influence of deviator stress history on the cyclic behavior of such soils. The results shows that nonlinear and accumulated behaviors are represented in the stress-strain response of frozen soils regardless the amounts of residual strain induced by stress history. Although the volume fluctuations along with the general path are observed in the cyclic loading sequence, the general path seems consistent with volume changes during the monotonic loading stage, which potentially indicates that the plastic flow characteristics of this frozen soil are independent of the axial loading models (monotonic or cyclic loading). Moreover, an increase in the residual strains induced by stress history led to a decrease in the axial strain accumulation rate and to an increase in cyclic stiffness due to strain hardening induced by preloading. A previously proposed model for predicting the changes in the accumulated strain with the cyclic loading process was found to be applicable to compacted frozen soils regardless of the amounts of residual strain induced by stress history. • Monotonic loading followed by cyclic loading in triaxial tests were conducted. • Deviator stress history led to a decrease in the accumulation rate of frozen soils. • Deviator stress history led to an increase in cyclic stiffness of frozen soils. • An accumulation model of frozen soils with deviator stress history are proposed. [ABSTRACT FROM AUTHOR]