Abstract: Temperature, water content and pressure strongly influence the deformation and strength behaviors of frozen soil. In order to study the effect of initial water state on deformation and strength behaviors of frozen silty clay, a series of triaxial compression tests has been conducted under initial water contents varying from 12.5% to 20% at ?6 ℃. The results show that the frozen silty clay presents strain softening and strain hardening successively under low initial water content with increasing the confining pressure, but the frozen silty clay mainly exhibits strain softening when the initial water content is more than 16%. With increasing the initial water content, the relationship between initial tangent modulus and confining pressure changes from linear increase to parabola form. Meanwhile, in order to describe the nonlinearity between strength and confining pressure of frozen silty clay under the initial water contents of 12.5%, 14% and 16%, a nonlinear Mohr-Coulomb strength criterion is built based on the envelope theory. The linear Mohr-Coulomb strength criterion can describe the strength development with confining pressure of frozen silty clay under the initial water contents of 18% and 20%.

Key words: frozen silty clay, deformation law, strength characteristic, initial water content, strength criterion