Numerical study of the effect of orientation and infilling material of joint on the strength and deformation behavior of jointed rock

 This paper investigates the influence of two key properties of rock joints, namely orientation and infilling material, on the strength and deformation behavior of jointed rock. To achieve this objective, numerical experiments were conducted using the UDEC code based on the discrete element method (DEM). The simulations involved uniaxial compression tests on a limestone rock specimen with a single joint. Twelve models of jointed rock were created, incorporating three different types of infilling materials (F1, F2, and F3) and four joint orientation angles (0°, 45°, 60°, and 90°). A novel technique based on the equilibrium principle of the models during loading was employed to mimic realistic static loading conditions, ensuring controlled application of axial loads and preventing sudden catastrophic failure. Two-dimensional (2D) models were used to evaluate the computational models' uniaxial compressive strength (UCS) and stress-strain behavior. The results indicate that the combination of joint orientation angle and infilling material significantly influences jointed rock's strength and deformation behavior. Under pressure, the jointed rock models exhibit orientation and infilling material-dependent behaviors, leading to varying UCS values. The UCS of jointed rocks decreased as the orientation angles increased from 0 to 60 degrees, ranging from 25 MPa for the strongest infilling material (F1) at a joint orientation angle of 0° to 0.63 MPa for the weakest infilling material (F2) at a joint orientation angle of 60°. The maximum UCS values of jointed rock were observed at a joint orientation angle of 90°: 26.3 MPa for F1, 22.1 MPa for F2, and 24.1 MPa for F3 infilling materials. The deformation behaviors of the jointed rock are nonlinear and ductile, irrespective of the orientation and infilling materials of the rock joint. These findings highlight the importance of considering the combined effect of joint properties to reduce uncertainty in the strength and deformation parameters of jointed rock.