Investigation of Large Scale Slope Failure Mechanisms and Numerical Modeling for the Safe Design of Slopes in a Lignite Mine


Tutluoglu L. , KARPUZ C.

WSEAS International Conference on Engineering Mechanics, Structures, and Engineering Geology, Heraklion, Greece, 22 - 24 July 2008, pp.292-293 identifier

  • Publication Type: Conference Paper / Full Text
  • City: Heraklion
  • Country: Greece
  • Page Numbers: pp.292-293

Abstract

With about 9.3 billion tons of reserve, lignite is a major source for energy production in Turkey. Turkish Coal Enterprises (TKI) produces about 60% of the yearly lignite production capacity. Can Surface Lignite Mine which is planned to produce approximately 2.5 million tons of 3000 kcal/kg coal, will be one of the main production areas of TKI. Possibility of large scale slope failures and their negative effects on mining operations in large Can Lignite Surface Mine on the northwestern Turkey were the major concerns in developing the proper excavation and lignite production directions, and plans for further expanding the mine in new production panels in order to meet the high lignite demand of the neighboring power plant. In order to understand mechanisms of slope failures first, a large scale landslide in an old production panel which occurred following the excavation of overburden in order to expose the thick lignite seam was studied in detail. This huge slide was modeled first by a slope stability analysis program using the method of slices for a rough estimation of parameters that controlled the slide. The detailed investigations of the sliding mass geometry, and associated displacements by using a finite difference program FLAC produced more information about the failure mechanism of the massive slide. The mechanism that controlled the landslide was explained by the presence of a weak layer right under the lignite seam everywhere in the lignite field. The peak friction angle activated along this layer during the slide was found to be around 8 degrees, going down to 2 degrees in the residual state with excessive deformations for further excavation at the slope front. Considering that the lignite seam and the weak layer underneath were typically dipping with angles reaching up to 20 degrees from the edges towards the center in this basin, improvement alternatives had to be studied, and new excavation and production methodologies had to be developed with the aid of the numerical modeling.