Borehole Blasting-Induced Fractures in Rocks

Dynamic fracture behavior of rocks under blasting loading are a major concern in civil engineering, mining, oil and gas industries. This study presented herein is on the borehole blasting-induced fractures in rocks. The paper consists of two parts: the first part gives a brief description of a constitutive model for rocks subjected to dynamic loading, which is mainly based on a recently developed model for concrete; the second part deals with numerical simulations of borehole blasting-induced fractures in rocks. The values of various parameters in the constitutive model for granite are first estimated and then employed in the numerical simulations. It is demonstrated that the numerical results in terms of peak pressures and crack patterns predicted from the present model are in good agreement with the experimental observations made both in cylindrical granite sample reported in the literature and in square granite specimens conducted in our own laboratory. Moreover, the analysis shows that the experimentally observed crack patterns are mainly caused by tensile stress, while the smaller cracks around borehole are created largely by compression/shear stress.