ABSTRACT
Mining in deep underground mines continues to face the challenges of rockburst caused by high mining-induced stresses during excavation. Destress blasting technique has been reported in many practices as an active rockburst mitigation measure with various degrees of success. Rockburst is becoming significant in the Kiirunavaara Mine, Sweden when it continues to reach deeper deposits. Based on the in-situ stress situation in a footwall drift of the Kiirunavaara Mine, a destress blasting pattern was proposed, and the numerical modelling was conducted to evaluate the effectiveness of the proposed destress blasting pattern. The entire modelling process including applying in-situ stresses, excavating drift, drilling blastholes, and blasting was carried out with the LS-DYNA code. Blast-induced damage was evaluated. The principal stress redistribution with and without destress blasting was compared to evaluate the performance of the destress blasting. Numerical modelling results indicate that destress blasting with emulsion explosives induces more damage to the rock mass compared to ANFO explosive; moreover, the principal stress redistribution after destress blasting is more complex compared to the case without destress blasting but stress reduction around the blastholes is observed.
