Effectiveness of Horizontal Drain for Slope Stability of Coal Mining, Case Study of Slope Failure in Tambang Guntur, South Kalimantan

Abstract

Slope failure occurred in Tambang Guntur PT. Borneo Indobara in Tanah Bumbu, South Kalimantan results in not only technical problems but also a financial problem. The mining operation was terminated. An investigation was conducted to determine the cause of the landslide and obtain methods to prevent further landslides. This study focused on the inquiry into the slope failure occurred in the location mentioned above. Several boreholes were performed to determine detail sub-soil layers and soil properties especially the shear strength of soils. A piezometer was installed and used to obtain the pore-water pressure data located close to the landslide. Additional data such as rainfall data and topography data is also used. A calculation using computer program was also used to model and obtain the safety factor of the slope. The result shows that the landslide occurred due to extremely high rainfall and extended period of rain. A horizontal drain was installed to reduce pore-water pressure as a method of slope stabilization. This paper presents and discusses the effectiveness of the horizontal drain in the field to stabilize the slope.