A strength criterion for frozen moraine soils

Abstract

The strength behavior of frozen soils has been extensively investigated in frozen soils mechanics for many years. In order to study the strength properties of frozen moraine soils, a series of cryogenic tri-axial compression tests are carried out under confining pressures ranging from 0.5 MPa to 16 MPa at the temperatures of −0.5 °C, −2.0 °C and −6.0 °C, respectively. The test results show that when the mean stress is less than the consolidation yield pressure defined as a boundary stress of the strength envelope, the strength envelope is nonlinear, while when the mean stress is greater than the consolidation yield pressure, the strength envelope becomes linear approximately and can be described by the Mohr-Coulomb strength criterion. According to the test results, a new strength criterion is proposed based on the concept of binary medium model to describe the nonlinear strength behavior of frozen moraine soils. The proposed strength criterion has taken the heterogeneous characteristics of frozen moraine soils into account and can describe the nonlinear strength behavior on the hypothesis of that a representative volume element (RVE) of frozen moraine soils is a binary medium consisting of some bonded elements and frictional elements, and the bonded elements will be gradually broken and transformed into frictional elements under certain stress conditions. Finally, compared with test results, it is demonstrated that the proposed new strength criterion could well reflect the strength behavior of frozen moraine soils at the temperatures of −0.5 °C, −2.0 °C and −6.0 °C, respectively.