Behavior of Model Rocks Containing Obliquely Oriented Double Flaws in True Triaxial Conditions
摘要
The strength, deformation, and cracking characteristics of flawed rocks are significant concerns in rock mechanics and engineering. In the field, rock masses are subjected to a three-dimensional state of stress, where the intermediate principal stress plays a significant role in the behavior of rock masses. In this study, true triaxial compression tests have been conducted on model rock specimens consisting of double flaws oriented obliquely and dipping towards each other at various angles. The induced stress anisotropy owing to the varying direction of the intermediate principal stress relative to the orientation of flaws was investigated. The rate of increase in peak strength with respect to the intermediate principal stress is higher when σ2 is oriented perpendicular compared to when it is oriented parallel to the flaws. Model rock specimens with obliquely oriented flaws under true triaxial compression mainly fail due to cracks initiating at the flaw tips. The crack initiation angle varies with the flaw dip angle and confining conditions. The applicability of the Mogi–Coulomb criterion for predicting the strength of flawed rock masses under true triaxial stress conditions is demonstrated. The criterion parameters depend on the flaw angle and the orientation of the intermediate principal stress relative to the flaws. The experimental results enhance the understanding of rock mass mechanics by accounting for anisotropy arising from the coexistence of two obliquely oriented flaws under a three-dimensional state of stress.