Abstract
Deformation and failure of a rock mass are strongly connected with the geological discontinuities such as cracks or faults. It is very important to estimate the effects of these defects and their interactions in order to evaluate the mechanical properties of rock mass such as elastic modulus. In order to evaluate the behavior of the rock mass which contains many small cracks, we applied two dimensional displacement discontinuity method (2D-DDM) and linear fracture mechanics to homogenized multi-crack model, and estimated the effective Young's modulus. The homogenized multi-crack model is the one that all cracks are parallel and infinitely arranged at same intervals in the all directions, and that the crack arrangement around a crack is always same at any part of the model. The behavior of each crack, therefore, is always equal and analysis of an elemental region which contains one crack is enough to estimate the properties of the whole mass. We also estimated the effective Young's modulus of the homogenized multi-crack model by Self Consistent Method and Equivalent Volume Defect Method, and discussed the validity of those methods. It was found that the interaction of cracks is crucial for the reduction of effective Young's modulus. When the cracks get closer to each other in the normal direction, the value of effective Young's modulus dramatically drops and the usage of the conventional methods is limited in the narrow range in which the effect of crack interaction is relatively small.
