Modeling of unstable creep failure of spatial variable rocks subjected to sustained loading

Abstract

The unstable creep failure of rock materials is detrimental to underground tunnels and mines. Influenced by the inherent spatial variability of rock properties, creep failure intensity shows large fluctuations among samples, even under the same conditions, which is an important concern in the evaluation of long-term structural reliability. In this study, a stochastic analysis procedure is presented to model the unstable creep failure behavior that accounts for the material spatial variability and time-dependent behavior of rock, based on the Abaqus-Matlab co-simulation. The effects of sustained load levels and material spatial variability on creep failure intensity were systematically analyzed. The numerical results show that the lifetime randomness of rock specimens is much larger than the variation in material strength properties, which can be attributed to the unstable damage evolution under sustained loading. This randomness of the failure time increases significantly with sustained load levels. The larger the spatial variability of the rock, the lower the mean failure time. Furthermore, the failure time of the specimen approximately follows a normal distribution, as the input strength parameters are normally distributed.