A novel fracture criterion for elastic-brittle cracked body under compression and shear conditions

When the elastic-brittle cracked body is subjected to compressive-shear loading, not only does the phenomenon of wing crack initiation and propagation occur, but there is also a notable incidence of secondary crack initiation and propagation due to shear stress. Moreover, the shear fracture toughness (KIIc) predicted by the fracture criterion in the framework of classical fracture mechanics is usually smaller than the tensile fracture toughness (KIc), which is inconsistent with the actual observations. Therefore, this research firstly establishes a mechanical model of an elastic-brittle cracked body under biaxial compression considering three kinds of crack parameters and materials' mechanical properties. Then, the stress field characteristics at the crack tip are analyzed. Next, a compression-shear mixed fracture criterion is proposed. Finally, the effects of the lateral pressure coefficient (lambda), critical plastic zone size (rc), friction coefficient (f), and deformation parameters of the crack surface on the failure modes at the crack tip are investigated. A distinction is made between the failure and loading modes of the cracked rock mass. The stress field at the crack tip under compression and shear conditions is analyzed. A compression-shear fracture criterion related to KIc and KIIc of materials is proposed. Conditions for the occurrence of shear failure at the crack tip are discussed.