Modelling the effect of blast-induced vibrations on the stability of a faulted mine slope

Abstract

SYNOPSIS Blasting, which is carried out regularly in open-pit mines, causes considerable ground vibration in the vicinity of the blasting site. These vibrations may affect the stability of mine slopes, causing problems in safety and constituting a hazard to life and property. In this study, the effect of the blasting-induced vibrations on slope stability was investigated using finite element (FE) analysis. A pit slope containing a fault was examined under seismic loading caused by successive explosions with varying intensity. Some reference points were selected above/under the fault surface and their motions recorded during the FE analysis. The results show that the points above the fault surface have the greatest displacement, while below the fault surface, only minimal (negligible) motions occur. Also, the intensity of the explosion has the greatest impact on motions at the upper points, but below the fault surface, the effect of the blast intensity was minimal. Usually, each explosion causes only small displacements in the mine slopes, but the destabilizing effect of repeated weekly blasts is significant, as confirmed in the present study. A sensitivity analysis proved a direct relationship between both the shear stiffness and friction angle of the fault surface and the motions of upper reference points. Likewise, in the presence of underground water pressure, the blasting-induced movements increase sharply. Keywords: blasting, slope stability, finite element analysis, dynamic analysis.