Numerical Modeling of Rock Blocks with Nonpersistent Rough Joints Subjected to Uniaxial Compressive and Shear Loadings

Characterizing the mechanical behavior of jointed rocks is important to understand the behavior of structures in rock masses. Jointed rocks can be composed of persistent and nonpersistent joints where the impact of nonpersistent joints requires careful consideration for an accurate rock mass mechanical characterization. Most previous investigations into nonpersistent jointed rocks focused on joints with smooth surfaces, and a few experimental studies focused on nonpersistent rough joints and nothing specific has been reported numerically. Therefore, this study investigated several synthetic jointed rocks with nonpersistent rough joints numerically under uniaxial compressive and shear loadings. The PFC2D-based synthetic rock mass (SRM) approach was adopted to assess the impact of bridge angle (& gamma;) and length (L), joint roughness coefficient (JRC), and normal stress (& sigma;(n)) on the shear strength (& tau;(n)) and cracking in jointed rocks with nonpersistent rough joints. In addition, the impacts of & gamma;, L, JRC, and joint inclination (& theta;) on the uniaxial compressive strength (UCS or & sigma;(cm)), elastic modulus (E-m), and failure pattern in the jointed blocks were examined numerically. First, several numerical models were developed and verified by the laboratory data, followed by an extensive parametric study to assess the effects of the defined parameters further. The effects of JRC and & sigma;(n) on & tau;(n) were more pronounced than & gamma; and L due to the formation of interlocking cracks, which could cause significant shear resistance during shear loading. In addition, the numerical results under axial loading revealed that an increase in & theta; could reduce the deformation modulus and the value of the other parameters, in particular the JRC, could lead to an increase in the strength of jointed samples.

Automated summary

This study investigated the mechanical behavior of synthetic jointed rocks with nonpersistent rough joints under uniaxial compressive and shear loadings. The effects of bridge angle, length, joint roughness coefficient, and normal stress on shear strength and cracking behavior were examined numerically. The results showed that the joint roughness coefficient and normal stress had a more significant impact on shear strength, while the bridge angle and length had a smaller effect. Additionally, an increase in joint inclination reduced the deformation modulus, and a higher joint roughness coefficient increased the strength of jointed samples.