Comparative Evaluation of Peak Particle Velocity and Dominant Frequency in Open-Cast and Underground Blasting of Gneissic Rock for Structural Safety Assessment

Abstract

Blasting remains the most widely employed technique for rock excavation in both open-cast and underground mining operations. Despite technological advances in mechanical excavation methods, drilling and blasting continue to dominate due to their adaptability to diverse geological formations, cost-effectiveness, and operational flexibility (Chakraborty, 1994) . However, blasting generates seismic waves that propagate through the surrounding rock mass, resulting in ground vibrations characterized by Peak Particle Velocity (PPV), a key parameter for assessing blast-induced impacts. Excessive PPV values can lead to structural damage, rock mass instability, and safety concerns, necessitating precise prediction and control. The magnitude of PPV depends on several factors, including explosive charge per delay, burden, spacing, initiation system, and site-specific geological conditions. Numerous empirical relationships have been developed to correlate PPV with scaled distance; however, their accuracy varies with rock type and blasting environment. In open-cast operations, the presence of a free surface enhances wave propagation and reflection, typically leading to higher vibration levels. Conversely, in underground settings, energy dissipation within confined rock masses often results in reduced PPV magnitudes. The present study aims to conduct a comparative evaluation of PPV characteristics in open-cast and underground blasting within gneissic rock formations. Field measurements were carried out to analyze vibration behavior under varying charge and distance conditions. The findings provide insights into the influence of confinement and geological factors on vibration attenuation, contributing to improved blast design and vibration management strategies for sustainable mining operations.