The Key Factors Controlling the Mechanisms of Consecutive Failures in the Collolar Open Pit in the Afsin-Elbistan Lignite (AEL) Basin in Southeast Türkiye

Abstract Mass movements pose a great threat to the safe operation of open pit mines and seriously affect the mining economy, human health and environmental safety. In cases of insufficient dewatering or excessive groundwater withdrawal, different types of stability problems may arise especially in weak and saturated geological settings. In engineering practice, back analyses by finite element method (FEM) is a valuable tool for the evaluation of such cases and revealing their causes. In this study, mechanisms of consecutive failures occurred in an open pit slopes in the Afşin Elbistan Lignite (AEL) basin, southeast of Türkiye, were assessed based on intensive data obtained from the field and laboratory investigations. As a result of back analyses carried out through 2D FEM analyses, it was concluded that the high plasticity clay layers within the geological formation and the hydraulic interaction of two aquifers with different characteristics at the edge of the basin are two key factors controlling mining activities in the AEL basin.