Modeling of Mixed Cracks in Rock-Like Brittle Materials Under Compressive Stresses by a Double-Phase-Field Method

A new double-phase-field model is proposed in this paper for modeling cracking processes in rock-like brittle materials under compression-dominating stresses. For this purpose, two crack-phase fields are used to describe tensile and shear cracks respectively. Compared with previous works, a stress-based new criterion is proposed to more physically capture the evolution of shear cracks in rock-like materials. The effects of mean stress and internal friction are taken into account. The proposed model is implemented in the finite element framework. It is applied to investigating cracking processes in a rock sample containing two initial flaws and subjected to uniaxial and biaxial compression. Both the tensile wing and shear cracks as well as crack coalescence observed in laboratory tests are successfully reproduced by the proposed method. Highlights A new phase-field model is developed for modeling complex cracking in rock-like materialsunder compressive loads. Two damage fields are introduced in order to describe tensile and shear cracks. A new criterion is proposed for the description of shear crack under multi-axial compression. The new model is able to well reproduce complex cracking processes observed in laboratorytests