Microseismic frequency-spectrum evolutionary rule of rockburst triggered by roof fall

Strong rockburst disaster in deep coal mines is easily triggered by the higher static stress of mining coal seam and the dynamic stress wave disturbance generated by hard and thick roof fall. Revealing the frequency spectrum evolutionary rule of microseismic (MS) signals before and after roof fall is a very important issue for evaluating and forecasting rockburst danger. By experimental tests for combined coal and rock samples rockburst failure and in-situ measurements in a strong rockburst coal mine. the frequency-spectrum evolutionary rule and precursory characters were analyzed in detail. The following conclusions were drawn: (1) Precursory MS signals show the elevated energy and events, lower frequency and trend of spectrum moving to low frequency band; (2) rnainshock signals of rockburst are characterized by maximum amplitude (vibration velocity), wider spectrum, and higher predominant frequency; and (3) aftershock signals are characterized by he sudden decreasing amplitude, highest predominant frequency, and trend of spectrum moving to high-frequency band. (C) 2013 Elsevier Ltd. All rights reserved.