Abstract
Experiments were designed to investigate near field damages caused by blasting in a rock cavern. Six blast holes were detonated with well-designed blast parameters and drilled cores, oriented normal to the blast surface, were obtained sequentially from a retained wall. Covered rocks were removed so as to enable observation of the damage zone. Both the pre-existing cracks and the blast-induced cracks on the wall were observed visually.
Primary waves propagated normal to drilled core axes were measured in order to evaluate blast-induced cracks. It has been found that surrounding region within 30cm from the blast hole was seriously fractured into small pieces and the region within 50cm was damaged and resulted in numerous small cracks. Primary wave recovery was found beyond these regions although a few radial cracks were detected up to 1m from the blast holes. No blast-induced damage was found beyond this region.
