Abstract:
This paper investigates whether a micromechanical model developed to investigate the relation between the basic failure processes at grain-scale and the macroscopic failure pattern can be applied to model the fracturing around large-scale excavations. The simulated fracture pattern around a vertical shaft is compared to the fracturing around a shaft at a depth of 3400 m. The simulations suggest that wedge-shaped zones, called dog-ears, are formed by a progressive splitting-like failure of the rock. The fractures forming these slabs nucleate in the zones subjected to the highest compressive stresses. Both shear and tensile mechanisms are responsible for the fracturing. The dog-ears deepen and widen as spalling continues.
