(Special session/Open call for public) YARO15: Research activities on rock engineering during the COVID-19 pandemic

[3K0101-08-07] Brittle creep failure as the rockburst mechanism at Mufulira Mine, Copperbelt Province, Zambia

○Pardon Sinkala¹, Yoshiaki Fujii¹, Jun-ichi Kodama¹, Daisuke Fukuda¹, Ellan Chanda² (1. Hokkaido University, 2. Mopani Copper Mines Plc)

Chairman:Atsushi SAINOKI (Kumamoto University)

Keywords:Rockburst, Brittle creep failure, Damage rate, DDM

In order to understand the behavior of the rock mass and its failure mechanism associated with rockburst at Mufulira mine, 3-D mine-wide stress analysis by Displacement Discontinuity Method (DDM) was carried out, followed by 2-D FEM analysis in order to obtain precise stress distribution around the mining drives on rockburst sections. DDM showed significant as well as gradual stress increase around the mining drives with face advance. 2-D FEM indicated a slight increase in stress severity for sections where DDM predicted a significant stress increase with face advance and almost no increase in stress severity for sections where gradual stress increase was observed. The former rockburst can be explained as an instantaneous failure of the intact rock mass due to stress increase by mining. This explanation cannot be used for the latter rockburst. Instead, a concept of brittle creep failure as a possible mechanism for the latter rockburst was proposed. Therefore, this study aims to propose brittle creep failure as a possible mechanism of the latter rockburst. A damage rate is assumed to have a positive correlation with normal stress. The damage is calculated based on DDM results, and the calculation is made only for the edge elements, where the stress state is almost uniaxial. Edge elements were regarded as fractured when the damage reaches a critical value. The fracturing of the elements can be considered as a rockburst.