A NUMERICAL MODEL FOR PROGRESSIVE TIME-DEPENDENT DEFORMATION AND FRACTURING OF LAYERED ROCK

A better understanding of progressive time-dependent deformation and fracturing of anisotropic rock is essential for determining appropriate measures to ensure the long-term integrity of layered rock masses surrounding engineering structures such as underground mining, subway and nuclear waste repository. In the present paper, a three-dimensional numerical model based on the microplane model is proposed to investigate the progressive time-dependent deformation and fracturing of layered rock. The subcritical crack growth and time-independent damage evolution constitutive on the microplanes are incorporated into the model. Furthermore, material heterogeneity and structure of layered rock are also considered in the anisotropic model. Cooperative interaction between strain and damage evolution on microplanes leads to the degeneration in local material with respect to time. This model can also characterize the temporal and spatial acoustic emissions or microcracking in the rock sample during time-dependent deformation and fracturing of layered rock. The numerical simulations reproduce the phenomenon observed in layered rock fracturing experiments that the stress levels and layered angle have influence on the rupture time and type. It also shows that microscale interaction of cracks (microplanes) can describe the complex macroscopic time dependent behavior of rock, and it is possible to predict the time-to-failure and the rupture patterns with the calibrated model in laboratory tests. The proposed numerical model can be further extended to identify the excavated damage zone and predict long-term stability of the surrounding rock mass around underground workings and rock slopes.