Numerical Investigation of Effect of Rock Bolt Angle on Shear Behavior of Rock Bridges

In this work, the effect of rock bolt angle on the shear behavior of Rock Bridges is investigated using the particle flow code in two dimensions (PFC۲D) for three different Rock Bridge lengths. Firstly, the calibration of PF۲D is performed to reproduce the gypsum sample. Then the numerical models with the dimensions of ۱۰۰ mm * ۱۰۰ mm are prepared. The Rock Bridge is created in the middle of the model by removal of the narrow bands of discs from it. The uniaxial compressive strength of the Rock Bridge is ۷.۴ MPa. The Rock Bridge lengths are ۳۰ mm, ۵۰ mm, and ۷۰ mm. The rock bolt is calibrated by a parallel bond. The tensile strength of the simulated rock bolt is ۳۶۰ MPa.One rock bolt is implemented in the Rock Bridge. The rock bolt angles related to the horizontal axis are the changes from ۰ to ۷۵ degrees. Totally, ۱۸ models are prepared. The shear test condition is added to the models. The normal stress is fixed at ۲ MPa, and the shear load is added to the model till failure occurs. The results obtained show that in a fixed rock bolt angle, the tensile crack initiates from the joint tip and propagates parallel to the shear loading axis till coalescence to rock bolt. In a constant Rock Bridge length, the shear strength decreases with increase in the rock bolt angle. The highest shear strength occurs when the rock bolt angle is ۰°.

کلیدواژه ها:

rock bridge ، rock bolt ، PFC۲D