| Abstrakt: |
Choosing the appropriate slope geometry for an open pit is one of the important aspects in pit mine design regarding the wider and deeper excavation by the time. The excavation generally reduces the stability of mine slope due to the changing of slope gradient of a stable natural slope. In mining site, the slope stability depends on three main factors in which are bench dimension, geotechnical parameter of slope material, and groundwater level. The groundwater level is more dynamic compared to other parameters. Therefore, the objective of this study is to determine the optimum pit slope geometry according to various groundwater conditions. This study was performed at Marandai Mine Site of PT Bukit Baiduri Energi (PT BBE). This site is composed of material stratum of coal, siltstone, claystone, and sandstone. The physical and mechanical properties of the stratum are represented with laboratory testing results of the core sample. The geotechnical parameter considered in this analysis are material unit weight, cohesion, and angle of internal friction. Slope stability analysis used Galena slope stability software by employing the limit equilibrium method. The groundwater level position is considered unsaturated, partially saturated, and fully saturated. The analysis result showed the slope stability was controlled strongly by groundwater level, and the geometry of the slope including the angle, the width, and the height of the bench. The Merandai Pit design could be optimized to the geometry configuration with an overall slope of 35°. [ABSTRACT FROM AUTHOR] |
