Disposal slope design based on low-plasticity rock’s shear strength in coal mining activities.

Slope stability is the primary factor in designing a stable slope. The strength of the disposal slope relies on the characteristic of the dump materials. The rock shear strength denotes the rock's ability to withstand the burden, both constant and dynamic load. The weakest material used as a reference in designing the disposal slope is siltstone in Pulaubalang formation (location-04). The safety value in locations 04 and 02 tend to drop quickly as the inclination increase, while the safety in locations 01 and 03 tend to fall slowly. This indicates that rocks with a lower plasticity index tend to be stronger in steeper slope conditions. The slope geometry was designed to be 10, 15, 20, and 25 m high with a slope angle of 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, and 60° . The slope geometry is considered stable and safe. However, this study suggests that the most effective slope design is the slope with 25 m high, an overall slope of 25.3° ; a single slope of 35° ; a berm width of 4.66 m, bench height of 5 m, with a safety factor value of 4.30 (SF= 4.30). [ABSTRACT FROM AUTHOR]