A new strength criterion for frozen soils considering the influence of temperature and coarse-grained contents

Strength of frozen soils is a hot topic, which has been being extensively investigated in frozen soil mechanics. In order to describe the effects of temperature and coarse-grained contents on the strength properties of frozen soils, a series of cryogenic triaxial compression tests for frozen soils are analyzed at different temperatures, and different coarse-grained contents at − 6 °C. A new strength criterion is proposed based upon the modified slope method of downward CSL (critical state line) curve in the meridian plane, in which the various parameters as well as their physical meanings are analyzed and discussed in detail, with their variations expressed by temperature and coarse-grained contents. In addition, on the basis of envelope theorem, the internal frictional angle is investigated and introduced to Lade-Duncan model in the deviatoric plane. Compared with test results, it is demonstrated that the proposed new strength criterion could well reflect the strength varying rules at different confining pressures ranging from lower to higher pressures for frozen soils. For frozen mixed soils with different coarse-grained contents, the strength decreases first and then increases with increasing coarse-grained content, which can also be predicted by the proposed strength criterion well.