Microseismic monitoring of longwall strata to provide real time instability indications to mine management at Rajendra coalmine in India

Abstract

Rooffalls are the most common problems encountered during various stages of longwall mine operation resulting in loss of production and machinery. A real time microseismic monitoring system was installed at Rajendra underground coal mine and acquired rock fracturing information from different roof layers. These data were analysed and obtained stress concentration zones, which ultimately resulted in rooffalls. Based on the microseismic event release rate advanced strata instability information was provided to mine management through daily reports. This information has helped in carrying out effective and optimized blasting operations to distress the high stress zone. The microseismic data also helped in mapping real time fracture process to get the extent of fractures in roof strata. The significant and reliable precursor found was microseismic event release rate (ERR) for rooffalls. Daily reports were submitted to mine management regarding stress concentration zones and rockfall information, which were confirmed from underground observations. The details of the microseismic technique and its application to longwall mine problems are discussed in this paper. � 2008, ARMA, American Rock Mechanics Association.