Resultant axial stresses in instrumented rockbolts induced by dynamic effects occurred due to multi-face blasting in the working areas

Abstract Multi-face blasting is one of the most frequently used active rockburst prevention methods in the Polish copper mines. Simultaneous firing of a group of faces generates vibrations which, propagating in the form of para-seismic waves, affect the condition of the rock mass structure and allow to trigger high-energy tremors during the production process. However, the simultaneous firing of explosives in several mining faces may have the negative impact on the condition of the rockbolt support system in the roof strata and stability of the roof rocks located in the vicinity of the mining front. Therefore, this impact under the conditions of selected mining panels of the Lubin mine was examined by measuring the axial stresses in instrumented rockbolts. The statistical correlation between the measured axial stresses and the estimated para-seismic peak particle velocity has been analysed to determine the potential dependence between these quantities. The obtained results have shown that in the geologic and mining conditions of the analysed mining panels, simultaneous firing of explosives in a number of mining faces did not induce significant permanent changes in values of the measured axial stresses within the instrumented resin anchored rockbolts. In result, further development of multi-face blasting in terms of seismic wave amplification may be proceeded without risk of significant damaging of the immediate roof strata.