The paper deals with the geotechnical studies carried out to know the possible reasons of 17m high coal rib failure and also the associated dragline dump failure at Jayant Project of Northern Coalfields Ltd., Singrauli, Madhya Pradesh, India. The overburden mainly consists of top one metre of soil, medium to coarse-grained sandstone, carbonaceous shale and shaly sandstone. The main working seam is Turra seam. The coal is noncoking type. The samples of dump material were tested in the soil & rock mechanics laboratory of CIMFR. The slope stability analyses were done under different geo-mining condition to understand the effect of the variability of the different parameters of dump profile on dump slope stability. The factor of safety of the dump slope with its most likely profile was 0.98. The saturation of dump base due to presence of coal rib, cross cut and dumb bell, non-existence of planned corridor width at dragline sitting level and dumping of overburden rehandled from dumb-bell by dragline over the dragline dump would have most likely caused the dump failure.
A geotechnical study was conducted to understand the possible reasons of dump failure in the west section of Jayant Project, Northern Coalfields Limited (NCL), Coal India. The slope failed on 17–1–2009 which resulted on four casualties. The Jayant opencast project is one of the largest coal mines in India in terms of total excavation. The production of coal and OB for the year 2007–2008 was 12.786 million tones and 32.97 million m3 respectively [1]. The mining is being done with 10 m3 shovels and 85 T/120 T dumpers. There are two 24/88 R dragline. The dumpers are dumping the overburden over dragline heaps at least two dragline cuts away from present one. The total length and width of the one cut, by dragline, are about 1800 m and 70 m respectively. It takes about one and half years to complete one cut. The overburden mainly consists of top one metre of soil, medium to coarse-grained sandstone, carbonaceous shale and shaly sandstone. The main working seam is Turra seam. The coal is non-coking type and the grade is of C-D-E type. The coal seam as well as dump floor is dipping at an angle of two to three degrees. The samples of dump material collected from different parts and depths of the existing dumps were tested in the soil & rock mechanics laboratory of CIMFR. The stability analysis was done with the help of software based by limit equilibrium method. The slope stability analyses were done under different geo-mining condition to understand the effect of the variability of the different parameters of dump profile on dump slope stability and in turn to understand the possible reason of failure.
The Jayant block is located in the south-central part of the Singrauli Coalfield. The rocks of Barakar formation are exposed in this block along with recent soil/ alluvium cover. Predominant rock type of Barakar formation is sandstone followed by shale.
