Stability analysis in 4th Gol-e-Gohar Mine with residual parameters method and strain softening approach

Today, numerous surface and underground mining and construction projects can be found worldwide, built on a rock bed and surrounded by rock. Open pit mines are considered the primary sector for mineral production in the mining industry. The issue of slope stability is crucial for the economy and safety of open pit mines. Slope stability should be based on the determination of tectonic and lithological parameters and the determination of mine boundaries. It is illogical to allocate one slope for the entire walls of the mine, which are made of different materials and have different structural conditions. The purpose of slope stability analysis is to maintain a stable slope while mining activities continue. This research was conducted on slope stability analysis in the No. 4 Gol-e-Gohar mine in Sirjan. Geotechnical characteristics and necessary information for numerical modeling were obtained through mine visits, surveys, and tests on rock samples from exploratory boreholes. Based on two-dimensional modeling using PHASE 2D software, the CSFH behavior model (cohesion softening - friction hardening) for the northern wall will enhance the overall strength of the rock mass. However, this behavior model is not suitable for medium and weak-quality rocks. For rocks with softening behavior, the CSFS behavior model (cohesion softening - friction softening) provides more realistic results. Furthermore, to investigate the effect of schistosity plates, transisotropic behavior parameters were determined based on direct cutting tests on schistosity surfaces, and stability analysis was conducted. It was concluded that the orientation of the Turq surfaces in schist layers has a significant effect on the strength of these layers, leading to larger displacement values than other models.