Empirical and numerical analysis of the blast - induced structural damage in rock tunnels

One of the main hazards in rock tunneling by using the drill and blast method is the damage of the nearby pre-existing underground structures due to ground vibrations generated by the explosion. A simplified empirical approach is commonly adopted for the assessment of blast - induced structural damage, based on the peak particle velocity (PPV) and related empirical threshold values. A more sophisticated approach consists in numerical analysis of rock – sup-port interaction under the dynamic load induced by blasting. This allows evaluate ground vibrations and internal forces inside the underground structures. Both approaches are applied in the present paper for evaluating the feasibility of a drill and blast tunnel excavation in the vicinity of a pre-existing tunnel. Based on the presented results, it is possible to conclude that the simplified empirical approach significantly overestimates the risk of the blast - induced structural damage compare to the numerical stress analyses.