Underground coal extractions lead to continuous stress and pressure redistribution around mine openings which, in some cases, may lead to coal and gas outburst and rock bursts. This paper presents seismic monitoring research, which aimed at characterising the dynamic behaviour of the coal seam in response to gateroad development and longwall top coal caving mining at Coal Mine Velenje. The early campaigns involved time-lapse active seismic tomography and microseismic monitoring at the two selected longwall panels. Based on the findings of this early work, a more comprehensive microseismic monitoring programme was set up. Seismic monitoring data were processed and used for model development and rock burst/gas outburst risk assessment purposes, which also led to the development of measures to mitigate against seismic hazards.

1 Introduction

Underground coal extractions lead to continuous stress and pressure redistribution around mine openings. Rock bursts are generally triggered in conditions where a slight change in stress equilibrium can lead to an instantaneous release of a large amount of stored strain energy ejecting rock and/or coal particles in the mine opening. Rock bursts have been extensively studied in hard rock mines, and less so in coal mines (Ortlepp and Stacey, 1994; Wang and Park, 2001; Haramy and McDonnell, 1988, Zhao and Jiang, 2009, Calleja and Nemcik, 2016).

Numerous experimental investigations have been carried out to elucidate the burst process (Kidybinski, 1981; Huang et al., 2001; He et al., 2010; Ohta and Aydan, 2010). Zubelewicz and Mroz (1983) applied a dynamic failure approach to numerically study the process of rock bursts. A finite element method was proposed by Sharan (2007) to predict the occurrence of rock bursts in underground openings. Numerical models simulating fracture initiation and propagation were used in the modelling of pillar rock bursts (Wang et al., 2006) and rock bursts induced by dynamic disturbance (Zhu et al., 2010).

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