Modified Statistical Damage Constitutive Model for Frozen Sand Based on Nonlinear Strength Criterion

Abstract

The strength of frozen soil is a crucial criterion to judge the excavation of cross-passages or tunnels during artificial ground freezing. To better understand the combined influence of the temperature and confining pressure on the strength of frozen soil during freezing, typically triaxial compression tests were carried out on Harbin frozen sand under various temperatures and confining pressures. A nonlinear strength criterion considering the coupled experiment conditions was established according to the results obtained from the triaxial compression tests. Based on continuum damage mechanics, a modified statistical damage constitutive model was derived, in which the Weibull distribution was employed to describe the development of microcracks and defects, and the element strength was considered a random variable. The undetermined parameters in the model were solved using the nonlinear programming method. The effectiveness of the proposed model was verified by comparing the calculated and experimental results. The results indicate that the proposed model can reflect the nonlinear characteristics of the soil strength and accurately predict the stress—strain relationship of frozen sand, especially the phenomenon of pressure melting caused by high confining pressure.