2D back analysis of slopes of a lignite open pit using Finite Element Method (FEM): A case study

All mining activities such as, extraction of mineral, overburden excavation, transport, waste management are carried out by creating slopes in open pit mines. In these type of mines, a possible slope failure may harm to structures, people and equipment which are close to the slope and also may lead to interruption of the production and increment in the cost of mining. Aim of this study is to analyze instabilities that have developed in the permanent east slopes of the Orhaneli open cast. In addition to this, while mass movement is continuing, it is targeted for determining the direction and failing model of mass movement. In this context, totally five sections, were prepared to understand the geometry of the instabilities and Two-Dimensional (2D) Back Analyses of the failing model have been carried out by using Finite Elements Method (FEM). As a result of the analysis, it was found that the slope failure examined in this study will not continue at the time after the last excavation. However, it was predicted that instability of benches in front of the slope (inside the pit) would increase as long as the excavation continues for coal production.