LAUSR

Received: 17 January 2018 Accepted: 25 May 2018 This study summarizes the stress-strain relations of rocks in the conditions of conventional triaxial compression test. Combining the two mechanisms of damage and plasticity, this study explores inner mechanism of stress-strain relation and analyzes the applicability and limitation of the classical constitutive models of linear elasticity-plasticity, nonlinear elasticity and elastic damage. Based on considering the advantages and disadvantages of classical constitutive models, classical plastic statistic damage models are improved. In addition, this study puts forward the constitutive model of plastic statistic damage simultaneously considering plastic flow and damage function, deduces constitutive relational expressions in the conditions of conventional triaxial compression test and preliminarily verifies the constitutive relational expressions using the result of conventional triaxial compression test. In research result, the constitutive model improved can well and comprehensively reflect strain softening and dilatancy of rock and reflect rocks’ character of transforming from brittle to plastic flow following the increase of confining pressure.