Analysis of a Disaster and Determination of Capacity of Powered Roof Supports for a Single Pass Thick Seam Longwall Face Under Massive Roof Condition—A Case Study

摘要

A disaster took place in the year 1997 in a mechanized longwall panel [located in the R-Ⅲ/Ⅱ seam (Samla Seam)]of a mine belonging to the Raniganj Coalfields of India causing 3 fatal accidents, 1 serious bodily injury,10 minor injuries and total damage of 62 number of powered roof supports. The disaster was due to the sudden caving of massive sandstone roof over a number of two legged shield supports (each capacity 2 x 476 t) installed in the longwall face of 120 m length. The details regarding the investigation, examination and analysis of the behavior of the roof strata and the powered supports of the longwall panel are highlighted in this paper. From detailed analysis and investigation it was found that the powered supports were much under-rated under the envelope of massive roof condition of the said mine. The calculation of the optimum capacity of the powered support was done based on the formula developed by the author and the formula was developed based on the realistic strata mechanics concepts. Under the thick seam and massive roof conditions, the horizontal force used to come from goaf to the face side. Under such conditions 4 legged compact chock-shield powered roof supports with legs inclined towards the goaf would have been the best proposition. The optimum capacity of the powered supports (chock-shield supports), to be used in the R-Ⅲ/Ⅱ seam (Samla Seam) of the said mine, should have been 808t (for support spacing 1.8m).