Phenomenological model for rock with time-dependent strength

Abstract

Abstract Modelling of material behaviour constitutes a major part of the engineering design and construction process. Time-dependent deformation and failure mechanisms must often be considered, particularly in situations where the rock mass is stressed to relatively high stress levels. Under these conditions, it is necessary to model the time-dependent near failure and post-peak strength behaviour. A phenomenological model describing time-dependent failure process in strain-weakening rock has been presented, described and tested qualitatively on published test results from creep test, relaxation tests and variable strain rate tests. The model postulates that rock basically consists of a time-dependent and a time-independent resistance to deformation. Various parameter distribution functions are required to model different types of rocks or rock masses in detail, but it is shown that the proposed model describes essentially all observed time-dependent rock failure data.