Slope Stability Analysis of the Highwall in Coal Mine Pit X, Balangan Regency, South Kalimantan

Abstract

Coal mining is generally carried out using the open-pit method, which results in the formation of surrounding
slopes. Slope stability analysis is essential to determine the safety factor value and prevent potential landslides. This study
aims to identify the rock formations and determine the safety factor of the highwall slope in pit “X.” Administratively, the
study area is located in Balangan Regency, South Kalimantan Province. The research methodology includes field
mapping to obtain primary data on lithology types and orientations, as well as the scanline method on the rock slope to
determine the Geological Strength Index (GSI). Secondary data obtained from the company include slope design data,
current topography, laboratory test results of rock samples, and groundwater level data. Slope stability analysis was
conducted on six cross-sections, from section A–A’ to section F–F’, along the highwall using the Limit Equilibrium
Method (LEM) with the Morgenstern-Price approach and the Generalized Hoek-Brown failure criterion. The analysis
was performed under both static and dynamic conditions with a horizontal seismic coefficient of 0.05. The results show
that all six slope sections have safety factor values greater than 1.3 under static conditions and greater than 1.1 under
dynamic conditions, indicating that the slopes are classified as stable.