A new discrete method for modeling hydraulic fracturing in cohesive porous materials

A new 2D hydromechanical rigid block spring method is developed for studying hydraulic fracturing in cohesive porous materials. The continuum medium is discretized into an assembly of discrete rigid blocks. Macroscopic deformation and failure are related to local properties of interfaces between blocks. Fluid flow in porous continuum is described by an equivalent discrete fracture network model. Biot's theory is extended to discrete porous interfaces for studying interactions between fluid flow and mechanical behavior. Further, the hydraulic conductivity evolution due to fracture propagation is taken into account through the change of aperture of interfaces. The proposed discrete hydromechanical model is first verified through the response of an elastic isotropic thick-walled cylinder subjected to an inner pressure under the steady state flow condition. The obtained numerical results agree well with the corresponding analytical solutions. Further, the numerical model is applied to studying the hydraulic fracturing of the thick-walled cylinder. The effect of transient flow on fracturing pressure is highlighted. The effect of materials strength anisotropy on fracturing process is also studied. It is shown that the proposed discrete model provides an efficient tool for modeling hydraulic fracturing in cohesive rock-like materials.