Experimental and numerical study on strength and deformation behaviors of sandstone with intersecting flaws

The distribution pattern of flaws has a significant impact on the mechanical behavior of the rock. To understand the cracking mechanism of the rock with intersecting flaws, the cracking behavior of sandstone containing two intersecting flaws under uniaxial compression was investigated through laboratory tests and particle flow code (PFC2D). The strength and failure characteristics of sandstone with intersecting flaws were studied. Subsequently, the evolution of the stress fields and displacement fields were analyzed, and the cracking mechanism of intersecting flaws was discussed. The results showed that the peak stress and average modulus decrease with increasing intersecting angle alpha of intersecting flaws in both experiments and numerical simulation. The experimental peak stress shows an increasing tendency, while the experimental average modulus first increases and then decreases with increasing direction angle beta, which is slightly different from simulation results. The cracking mode of the intersecting flaws was determined by angles alpha and beta. Specifically, when alpha and beta were small, the main fracture surfaces formed at the inner and outer tips of one flaw. When alpha and beta were large, the main fracture surfaces formed at the outer tips of the two flaws. The variation in the high tensile stress zone with alpha and beta is the essential reason for the change in cracking modes with alpha and beta. In addition, a new type of displacement field (defined as DF_IV) related to crack initiation was found. In this type of displacement field, the displacement difference is the main cause of cracking.