Rockburst characteristics and mechanisms during steeply inclined thin veins mining : a case study in Zhazixi Antimony Mine, China

Abstract

With the increase of mining depth, rockbursts have become important safety problems in Zhazixi Antimony Mine, where overlying strata exceed 560 m. Due to the small spacing between the steeply inclined veins, mining activities have great influences on rockbursts of adjacent veins. In order to study rockburst characteristics and mechanisms in Zhazixi Antimony Mine, in situ measurement, field geological survey, uniaxial compression tests, and numerical simulation are conducted to analyze rockburst proneness and simulate the elastic strain energy accumulation characteristics. Consequently, rockburst proneness criteria are established on the basis of experimental results to propose the necessary lithologic conditions for rockburst aiming to Zhazixi Antimony Mine. Rockburst dangerous districts are defined based on high stress concentration and elastic strain energy distribution characteristics in mining process obtained by theory analysis and numerical simulation. Accordingly, it is suggested that thrown-Type rockbursts mainly occur in massive stibnite of ventilation shafts and stopes where the elastic strain energy exceeds 300 kJ·m-3, spalling-Type rockbursts generally appear in slate of roadways where the elastic strain energy exceeds 100 kJ·m-3, and ejection-Type rockbursts arise in different rock masses under a certain condition. Last but not the least, prediction results are basically consistent with statistics data of rockburst events after comparative analysis.