A discussion on numerical modeling of fault for large open pit mines

The interaction of lithology and different geological units (e.g., joints, beds, faults, and alteration) and their impacts on rock slope stability can impose significant challenges for a mining operation. Numerical modeling is a powerful tool for simulating fault response. This paper attempts to highlight the challenges in simulating faults in numerical modeling using FLAC3D software and ways to overcome these problems. A case history for a fault slip was used to assess the performance of present methods (weak zone, ubiquitous-joint, and interface) for fault modeling. Strength reduction method was used to evaluate the stability of the slope. A sensitivity analysis was conducted to investigate the impact of fault geometry and thickness on the overall stability of the slope. It is found that the fault responds differently using each method. The lowest FOS value were observed in weak zone method, whereas the ubiquitous-joint technic showed the highest FOS value. Furthermore, the mechanism of slope failure was slightly different using each simulation method. The reason for this is whether the fault is modeled, so tight that has no reaction to mining or alternatively, is moving in an uncontrolled manner. Therefore, it is important to calibrate the model for correct fault movements.