A micromechanical analysis of the fracture properties of saturated porous media

A two-dimensional single edge crack problem is employed to investigate the fracture behavior of saturated poroelastic media. The media are mimicked by a micromechanical model consisting of elastic matrix and square arrays of voids with prescribed uniform pore pressure. Finite element method is used to simulate the fracture responses of the model subject to remote stress and pore pressure loading. The stress extrapolation method is extended for the porous media to calculate the nominal stress intensity factor (SIF) from the crack tip stress field. By adopting the tensile strength criterion and assuming either brittle or ductile failure of the constituent solid skeleton of the porous media, lower and upper bounds of the fracture toughness are obtained. Theoretical expressions for the stress intensity factor and the toughness are derived, agreeing well with numerical results. The effects of the arrangement of pores and the non-uniform pore pressure on the cracking of porous media are discussed and are found to only have moderate effects on the obtained results.