Slope stability analysis at Namekara vermiculite open pit mine

Abstract

Vermiculite mining is being carried out in Bugobero sub county at Namekara mining company in Manafa district and it is the leading producer of vermiculite ore in Uganda, East Africa and it’s also among the leading producers in the whole world. The method of mining used in the ore extraction is a surface open pit mining method. However, this forms benches of a bout 20m and slopes which may become unstable with time so there was need to analyze the stability of slopes at the mine to assess the major critically unstable failure zones and modes of slope failures, the possible geometric design parameters and to obtain the factor of safety for an optimal stable slope. The purpose of slope stability analysis by Roc science slide 6 and Flac3D software is not only to assess the overall stability of the slopes in the mine, but also including obtaining the possible geometric design parameters and optimal factor of safety for an open pit mine of Namekara mining company so as to reduce on chances of slope failure to avail safe working conditions to workers and also increase on the daily productivity. Based on parametric studies it can be concluded that, slope angle plays a major role on slope stability, factor of safety varied from o.8 to 1.53 for varying slope angle of 35 degrees to 75 degrees but also increasing the height of the slope, decreased the factor of safety indicating less stability. Therefore, it is recommended to maintain the slope angle not steeper than 45 degrees for an open pit mine and F.O.S was evaluated by varying the slope angle and height of dump. This was observed that as the angle and height of the slope increases, F.O.S decreases.