Simulation of the Crack Propagation in Rocks Using Fracture Mechanics Approach

Abstract

Crack propagation in brittle rock was simulated under different conditions to describe fracturing behavior of rocks due to the applied stress e.g., water pressure. It is assumed that pre-existing cracks initiate and propagate from the edges of the borehole. The two-dimensional finite element fracture code Franc2D with the non-cohesive method was used for computing the stress intensity factor (SIF), energy-release rates (G), and crack propagation and fracturing time. Static tensile and normal-distributed stresses were used within Franc2D to describe the fracture creation and propagation. Therefore, the pressure inside the bore hole was distributed as a tensile load along with the crack faces. Different scenarios were simulated by changing the boundary conditions, crack initiation, and propagation paths. The SIF determines the amount of tensile failure that is required to create a fracture. Then, the injection rate and pressure can be determined. The direction of fracturing is perpendicular to the maximum applied stresses. The crack propagation direction was compared with experimental observations taken from the literature. The predefined SIF solutions were modified according to the Franc2D solutions. Hence, the ability to use Franc2D for fracture simulation in brittle rock was demonstrated.