Hussein, M., Ibrahim, A., Imbaby, S. (2013). APPLICATION OF THE ROCK MASS CLASSIFICATION SYSTEMS TO PILLAR DESIGN IN LONGWALL MINING FOR ABU-TARTUR LONGWALL PHOSPHATE MINING CONDITIONS. JES. Journal of Engineering Sciences, 41(No 5), 2012-2020. doi: 10.21608/jesaun.2013.114931
M. A. Hussein; A. R. Ibrahim; S.S. Imbaby. "APPLICATION OF THE ROCK MASS CLASSIFICATION SYSTEMS TO PILLAR DESIGN IN LONGWALL MINING FOR ABU-TARTUR LONGWALL PHOSPHATE MINING CONDITIONS". JES. Journal of Engineering Sciences, 41, No 5, 2013, 2012-2020. doi: 10.21608/jesaun.2013.114931
Hussein, M., Ibrahim, A., Imbaby, S. (2013). 'APPLICATION OF THE ROCK MASS CLASSIFICATION SYSTEMS TO PILLAR DESIGN IN LONGWALL MINING FOR ABU-TARTUR LONGWALL PHOSPHATE MINING CONDITIONS', JES. Journal of Engineering Sciences, 41(No 5), pp. 2012-2020. doi: 10.21608/jesaun.2013.114931
Hussein, M., Ibrahim, A., Imbaby, S. APPLICATION OF THE ROCK MASS CLASSIFICATION SYSTEMS TO PILLAR DESIGN IN LONGWALL MINING FOR ABU-TARTUR LONGWALL PHOSPHATE MINING CONDITIONS. JES. Journal of Engineering Sciences, 2013; 41(No 5): 2012-2020. doi: 10.21608/jesaun.2013.114931
APPLICATION OF THE ROCK MASS CLASSIFICATION SYSTEMS TO PILLAR DESIGN IN LONGWALL MINING FOR ABU-TARTUR LONGWALL PHOSPHATE MINING CONDITIONS
Mining and Metallurgical Eng. Depart. Faculty of Engineering, Assiut University, Egypt
Abstract
Pillars are designed to ensure regional stability or local support in stopes and along drifts, or to yield under a measure of control. In all cases, the strength of the material and the variations in strength must be known both for the pillar and for the roof and floor. The stability in longwall faces depends mainly on the interaction between the roof strata, face support, roadway support and dimensions of pillars. The main aim of this paper is to apply rock mass classification systems to longwall pillar design at Abu-Tartur mining area. The pillar load is estimated taking into account the physical and mechanical properties of phosphate deposit and roof rock, panel width, mining height, depth below surface. Two methods from classification systems are used in calculation pillars stress and strength to pillars design namely Geological Strength Index (GSI) and Rock Mass Rating (RMR) systems. GSI values for immediate, main roof rocks and phosphate ores are determined from geological conditions, as lithology, structure of the interlocking of rock blocks and the conditions of the surfaces between these blocks. RMR value can be determined by correlation it with GSI system. The pillar widths calculated by applying rock mass classifications (GSI& RMR) are 49m and 64m at a factor of safety 2 and panel width 100m with extraction ratios of 70 and 64 % respectively. The data used in calculations are collected from geological reports of the company and from laboratory tests of phosphate ores and shale rocks in the roof.
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