Sawmliana, C. and Hembram, Panchanan and Singh, Rakesh Kumar and Banerjee, S. and Singh, P. K. and Roy, P. Pal (2020) An Investigation to Assess the Cause of Accident due to Flyrockin an Opencast Coal Mine: A Case Study. Journal of The Institution of Engineers (India): Series D, 105. pp. 15-26. ISSN 2250-2122

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Abstract The paper deals with the investigation carried out to find out the possible reason of the fly rock incident causing fatality of one person at Bhurkunda ‘A´’ Colliery of Central Coalfields Limited (CCL). The flying fragment travelled up to 280 m from the blasting source causing the accidental death. The blasts were conducted in over burden rock strata consisting of medium grained sandstone and shale. The blast hole diameter used in the blast was160 mm, and the average hole depth was 6.0 m. Site mixed emulsion (SME) explosive was used in the blast, and explosive charge per hole was 50.00 kg. Non-electric initiation systems were used for in-hole explosive and surface hole-to-hole initiations. The design parameters used in the blast were thoroughly analyzed using blast simulation software to check any anomaly in the blast design viz. sequence of hole firing, success rate of burden movement, maximum charge per delay fired within 8ms windows, etc. The different fly rock fragments prediction models were used to assess the maximum possible travel distance of the flying in the blast. A synonymous blast was also conducted in the mines to replicate the blast where fly rock accident occurred. All the blasting events were recorded and monitored using a digital video camera. The simulation results of the blast showed the success rate of burden relief more than 80% with sufficient delay intervals for the rock movement during the blast. The maximum possible travel distance of flying fragments based on different fly rock prediction models was 227 m. In the synonymous blast only vertical throws of the flying fragments up to 70 m(approximate) height were observed. It was difficult to find out the exact cause of fly rock incident. However, based on the detailed investigation, it was concluded that the possible cause of flying fragments travelling up to a distance of280 m could be due to the presence of a weak zone in the rock strata

Item Type: Article
Uncontrolled Keywords: Blasting Flyrock Prediction model Explosive Safety
Subjects: Blasting
Depositing User: Mr. B. R. Panduranga
Date Deposited: 28 Dec 2020 09:04
Last Modified: 28 Dec 2020 09:04

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