Effects of confining pressure and temperature on strength and deformation behavior of frozen saline silty clay

Abstract

Buildings are always affected by frost heave and thaw settlement in cold regions, even where saline soil is present. This paper describes the triaxial testing results of frozen silty clay with high salt content and examines the influence of confining pressure and temperature on its mechanical characteristics. Conventional triaxial compression tests were conducted under different confining pressures (0.5–7.0 MPa) and temperatures (−6 °C, −8 °C, −10 °C, and −12 °C). The test results show that when the confining pressure is less than 1 MPa, the frozen saline silty clay is dominated by brittle behavior with the X-shaped dilatancy failure mode. As the confining pressure increases, the sample gradually transitions from brittle to plastic behavior. The strength of frozen saline silty clay rises first and then decreases with increasing confining pressure. The improved Duncan-Chang hyperbolic model can describe the stress-strain relationship of frozen saline silty clay. And the parabolic strength criterion can be used to describe the strength evolution of frozen saline silty clay. The function relation of strength parameters with temperature is obtained by fitting, and the results of the parabolic strength criterion are in good agreement with the experimental results, especially when confining pressure is less than 5 MPa. Therefore, the study has important guiding significance for design and construction when considering high salinity soil as an engineering material in cold regions.