A constitutive model and associated testing for soft rock

Abstract

A general yet simplified constitutive model is proposed to characterize stress-deformation behaviour of rocks. It is based on the theory of elasto-plasticity and allows for factors such as hardening, volume changes, stress paths, cohesive and tensile strengths and variation of yield behaviour with mean pressure. It is applied to characterize behaviour of a soft rock, soapstone. The constants for the model are determined from a comprehensive series of laboratory tests under different initial confinements and stress paths by using a multiaxial testing device. The model is verified with respect to laboratory tests used for finding the constants and complex stress path tests not used for finding the constants. Overall, the proposed model involves less or equal number of constants compared to available models of similar capabilities and is easier to implement in (numerical) solution procedures.