Evaluation of rock slope using q-slope, limit equilibrium and failure probability at andesite mine of Sidomulyo Village

Abstract

For an open pit mine, the rock slope stability is one of the major significant challenges at every stage in the operation. It became a concern from the planning until the mining closure. Mining activities in the research location have entered the mining closure phase and produced the final slope that consists of 4 single slopes with an overall slope height of 65m and an angle of 62° that its stability is not yet known. The actual overall slope has discontinuities which affect the potential for failure. Most of the methods used in geotechnical practice for estimating slope stability are based on the traditional limit equilibrium methods. On the other side, very few empirical techniques exist to assess the slope stability. The empirical method of the Q-Slope is a relatively new methodology for assessing the slope stability in terrains built from rock masses. This method was developed over the last decade by Barton and Bar (2015), with modifications to the original Q-System for application in rock slope stability through the parameter of RQD, Jn, Jr, Ja, O-Factor, Jwice, SRFa, SRFb and SRFc. The stability analysis by Q-Slope method has resulted the slope in stable condition because the value of βQ-Slope > βSlope. The factor of safety limit equilibrium method and probability of failure used the actual geometry and Q-Slope geometry is known in stable condition because it fulfils acceptance criteria with FoS ≥ 1.1 and PoF ≤ 37,5% according to the regulation Ministry of Energy and Mineral Resources Decree 1827/K/30/MEM/2018.