Rough crack shear fracture mechanics in rocks.

Rock joint dilation is roughness dependant which plays an important role in rock engineering. This phenomenon is widely utilized in many practical projects such as hydraulic conductivity that impose a decisive impact in exploitation of unconventional oil and gas reservoirs. Realizing the importance of rough joint shear response, numerous studies have been conducted, but still remain many ambiguities especially on rough crack shear fracture. Effect of crack surface roughness and internal fluid pressure on crack tip stress intensity factor together with growth path of the propagated cracks is of immense importance needed to be considered for a thorough research investigation. Extended finite element method (XFEM) based on linear elastic fracture mechanics (LEFM) was used to conduct a computational model to investigate the effect of crack surface roughness on crack tip stress intensity factor (SIF) in shear mode (mode H) and induced SIF in mode I. Furthermore, shear direction effect on crack tip SIF in shear mode was attempted and hence a new expression was proposed based on Tatone and Grasselli's roughness quantification method. The details of the investigations associated with rough crack initiation angle, propagation path and the influence of uniform fluid pressure inside contact surface of rough crack and on the crack tip SIF of mode II are presented. [ABSTRACT FROM AUTHOR]