Site-Specific Predictive Modeling of Peak Particle Velocity Induced by Blasting in Nepal Young Himalayas

Abstract

Drilling and blasting are widely used excavation methods due to their cost-effectiveness and adaptability in varied geological conditions. However, blasting generates ground vibrations that can affect nearby structures, typically characterized by Peak Particle Velocity (PPV). This study presents site-specific predictive modeling of PPV in the Tanahun Hydroelectric Project, Nepal, located within the young, geologically disturbed Himalayas. Vibrations were recorded using an Instantel Minimate Plus at varying distances and directions to measure transverse, vertical, and longitudinal components. The scaled distance and PPV data were statistically analyzed to establish empirical prediction equations for both open surface and underground blasts. Results showed that PPV strongly depends on the scaled distance and geological discontinuities. The derived attenuation equations were PPV = 46.95(SD)^-0.745) for underground blasts and PPV = 390.63(SD)^-1.501 for open surface blasts, with R² values of 0.51 and 0.71 respectively. Open surface blasts produced higher PPV and lower frequencies (2–25 Hz), whereas underground blasts produced lower PPV but higher frequencies (26–100 Hz). A linear–exponential relationship was observed between site constants K and β, suggesting that β decreases as K increases. Joint characteristics such as aperture, joint set number, and infilling were key controlling parameters. Comparison with the DGMS (1997) Indian Standard revealed that underground blasts are within permissible limits, while open surface blasts may exceed them, posing risks to nearby settlements and structures. The study highlights the importance of site-specific PPV models for optimizing blasting designs and ensuring structural safety in Himalayan projects.