In this study, numerical simulation of rock blocks with nonpersistent open joints under uniaxial compression was undertaken using the particle flow modeling method. First, the micromechanical parameter values of intact material were calibrated through a trial-and-error process using macromechanical laboratory test results. Then, a back-analysis procedure was used to calibrate the joint gap and joint micromechanical parameter values using laboratory test results conducted on jointed rock blocks. Afterward, the effects of joint dip angle, joint persistency, and joint gap on the mechanical behavior of block models having nonpersistent open joints was investigated using the calibrated micromechanical parameter values. The joint dip angle and joint persistency were found to play significant roles in the failure mode, strength, and stress–strain relationship of jointed blocks. The joint gap played a significant to negligible role in the mechanical behavior of jointed block models gradually when the joint dip angle was increased from 0 to 90°. The contact and interaction of joint surfaces were found to have a significant influence on the mechanical behavior of jointed blocks.

Transversely isotropic rocks are commonly encountered in rock engineering practices, and their strength and failure behavior is often governed by the property of anisotropy. The particle flow modeling method was utilized to investigate the failure mechanism of transversely isotropic rocks subject to uniaxial compressive loading. The details for establishing transversely isotropic rock models were first presented, and then a parametric study was carried out to look into the effect of interface properties on the failure mode and strength of transversely isotropic rock models by varying the interface dip angle. The smooth joint model was incorporated to create interfaces for the completeness of establishing transversely isotropic rock models with the particle flow modeling method. Accordingly, three failure modes observed in transversely isotropic rock models with varying dip angles were tensile failure across interfaces, shear failure along interfaces, and tensile failure along interfaces. Furthermore, the interface mechanical parameters were found to differently influence the failure behavior of transversely isotropic rock models. The bonded joint cohesion and bonded joint friction angle that contribute to the shear strength of interfaces have considerable influence on the uniaxial compressive strength (UCS) values, while the joint coefficient of friction and joint tensile strength have a slight influence on the UCS values. The findings in this paper indicated the importance of interfaces in estimating failure behavior of transversely isotropic rocks.