Rock mechanics model capable of representing initial heterogeneities and full set of 3D failure mechanisms

In this work we present a full 3D model capable of representing cracks propagating through rock mass until complete localized failure. The model is based upon the discrete lattice of Timoshenko beams that can capture failure modes by using the embedded strong discontinuities. The model can also capture the pre-existing cracks and induced rock mass initial heterogeneities with corresponding variability of model parameters. The main advantage of the proposed failure model is in successful representation of full set of 3D failure modes, along with progressive development starting from micro-crack initiation to their coalescence into larger macro-cracks. The complete set of 3D failure modes is included with: mode I of tensile crack-mouth opening, mode II of in-plane shear sliding and mode III of out-of-plane shear sliding, along with the mixed-mode fracture propagation that is often the dominant mechanism in rock failure. Several numerical examples are provided to illustrate the proposed model performance showing the influence of pre-existing cracks and other defects upon the final failure mechanism. It is interesting to note that the distribution of material heterogeneities also contributes to making the computational iterative procedure more robust. The comparison against experimental results is provided for complete model validation.