The strength criterion and elastoplastic constitutive model of frozen soil under high confining pressures

A series of triaxial compressive tests of frozen soil has been conducted at a temperature of − 6 °C under high confining pressures. The results verify that the strength of frozen soil increases to a peak value with increasing confining pressure, but with a further increase in confining pressure, the strength decreases for crushing and pressure melting phenomena under high confining pressures. In order to meet the needs of the engineering activities in underground works, where the frozen soil is under high confining pressures, a new failure criterion is proposed based on the experimental results. To analyze the deformation of frozen soil under high confining pressures, an elastoplastic constitutive model has to be established. In this study, the yield condition is proposed by employing an elliptical yield surface. The plastic potential surface depends on the same arguments, but a nonassociated flow rule is used. All parameters of the model are identified by tests. The validity of the model is verified by comparing its modeling results with the corresponding experimental results.