Geomaterials, 2011, 1, 1-13 doi:10.4236/gm.2011.11001 Published Online April 2011 (http://www.SciRP.org/journal/gm) Copyright © 2011 SciRes. GM A Coal Mine Dump Stability Analysis —A Case Study Ashutosh Kainthola*, Dhananjai Verma, S. S. Gupte, T. N.Singh Department of Earth Sciences, Indian Institute of Technology Bombay, Mumbai, India E-mail: ashuddn@live.com Received April 12, 2011; revised April 14, 2011; accepted April 18, 2011 Abstract The present paper mainly deals with a case study of failed dump slope in western coalfield limited, Nagpur, India. A huge mass of debris flow had happened during the routine the activity of mining. The failed dump had a height of 75 m with 43 ˚ slope angle which had slipped forward by 18m. Representative loose dump material samples were collected from the site and tested to determine the physico-mechanical properties of dump material. The dump material consisted of loose fragments and lumps of friable sandstone, shale, clay and carbonaceous shale. To evaluate the condition of failure, a well known, shear strength reduction tech- nique has been applied to achieve the desired factor of safety using two dimensional finite element code. Fi- nally, a economical, sustainable and stable dump angle and height has been suggested for smooth and safe disposal of the dump. Keywords: Dump Stability, Factor of Safety, Shear Strength Reduction, Wardha Valley 1. Introduction With the increasing size of opencast mines and the large stripping ratio associated with these mines, the amount of overburden removal will also increase substantially. Only Coal India Limited (CIL) has removed overburden 21, 160, 462 and 695 million cubic metres during 1976, 1986 - 87, 1999 - 2000 and 2009 - 2010 respectively. Considering the major opencast projects XII Five Year plan, the amount of overburden to be handled in near future will be more than 20 000 million cubic metres for these projects alone. The maximum overburden disposal from an individual mine in the coal sector is likely to be 50 million cubic metres per year (WCL). Overburden dumps can be external dumps created at a site away from the coal bearing area or it can be internal- dumps created by in-pit dumping (IPD) concurrent to the creation of voids by extraction of coal. Practice of dumping overburden in the external dumps have some serious problems [1] foremost amongst them are re- quirement of additional land, involves very high trans- port and rehandling cost which will increase the cost of coal production substantially, stability and reclamation at the site. It is not possible to eliminate the option of the external dumps concept completely, even if we adopt IPD practice. The internal dump concept is very well utilized by various local producing countries like Austra- lia, Canada and USA, then there is no fear to adopt this technique to avoid further requirement of land for dumping and aggravate various associated problems. However, the combination of external dumps and inter- nal dumps shall substantially reduce the required land. As a result, it shall reduce the surface land requirement significantly which is very difficult task to arrange in any area due to growth of population forest cover and associ- ated problem. In this decade few destabilization of inter- nal dumps have taken place in coal mines. It is necessary to study such cases and find out the cause of destabiliza- tion. 2. Destabilization of Internal Dumps Failure of internal dumps is a complex problem. In addi- tion to environmental considerations, it directly affects the resource recovery, mine safety and mining cost. Overburden has been traditionally disposed off in the most economical way throughout the world. However, some massive spoil pile failures around the world attract the attention of geo-scientists and engineers to this prob- lem [2-4]. The stability of dump is now recognized to be an important aspect of designing large open pit mines. The majority of slope stability analyses performed in