Coal mining under difficult geological conditions: The Can lignite open pit (Canakkale, Turkey)

This paper describes the slope instability problems in the Can (Canakkale — northwestern Turkey) coal mine. Slope instabilities have been one of the major problems in the pit mine since the beginning of mining activities. In particular, the West and East Sector panels in front of the TKI (Turkish Coal Enterprises) buildings and the Seramic factory located in the vicinity of the pit mine have been suffering from slope instability problems. To assess the instabilities, field data collection from boreholes, surface sampling and monitoring studies were performed. Deterministic stability analyses such as limit equilibrium, sensitivity and back analyses were applied. Based on the results, the active–passive wedge type of failure was determined as the most dominant instability type. Based on the back analysis results, mean values of residual shear strength parameters were determined as c = 42 kPa, Ø = 8°. The results also indicate that the excessive excavation of the toe along the huge lignite open pit was the main cause of the instability. The weak contacts between the lithological units were also an important factor. Taking into consideration the results of the analyses, some remedial measures were also suggested for the coal mine such as decreasing the inclination of the toe, safe benching and effective drainage of surface water and groundwater.

► Energy is one of the fundamental requirements for daily life and industry.
► Coal is still one of the main energy sources.
► The study aims to solve the slope problems of an open pit mine.
► After applying the necessary methods, safe design is suggested.