On crack propagation in weak geomaterials: Revisiting the superdislocation model in the context of hydraulic fracture

In this paper the problem of hydraulic fracture in elasto-plastic pressure sensitive material is analyzed. The superdislocation model is used to approximate the plastic deformations in the crack tip area. This model is employed to derive a new crack propagation condition based on the concept of effective fracture toughness. A parametric analysis supported by FEM simulations is conducted to verify the underlying assumptions of the superdislocation model and the resulting crack propagation condition. The results, obtained with the new crack propagation condition for the HF problem, are compared with those produced by a commercial geomechanical FEM package Elfen. The comparison proves the validity of the new crack propagation condition and the proposed modeling approach.