Back Analysis of 1135_1065mRL Slope Failure in Shaba Open PIT

This study is about stability analysis of the Shaba open-pit, the back-analysis of the slope failure on the Eastern wall that ripped the main ramp away. The aimis replicate the factor of safety and deduct the geotechnical properties before failure in order to estimate appropriate parameters while taking into account the influence of water on the rock mass as well as that of other others parameters for the normal and safe continuation of mining activities below the unstable zone.The failure of the Eastern wall slope (1135-1065 mRL) has been caused by many factors. The presence of cracks along the contact zone between many friable lithologies. The failure is associated to the combination of many factors leading to gradual reduction of the rock mass properties and finally to the slope failure.The cumulative effects of surface and underground water as well as the blast vibrations around the failure zone accelerated slope failure.Stability analyses were conducted with Slide and other ancillary softwares GEM4D, Trimble 4D, etc? in order to make the best choice possible of geotechnical parameters for the better continuation of mining activities.The back-analysis results have shown that water had a significant impact on the ground stability even in case of buttress. And that in case of dry slope, buttress would increase the factor of safety with the same parameters. Buttress should be built with good quality rock and always ensure that this is correctly compacted to reduce the permeability in order to increase the shear strength. In case of wet slope, drain-holes should be considered for depressurization.