Ground Vibration Attenuation Relationship for Underground Blast: A Case Study

For a particular important infrastructure project, a deep open excavation was necessary although a few sensitive structures were located near the excavation site. For the existing structures, low values of safe peak particle velocities resulting from blasts were stipulated: 3 mm/s, 10 mm/s and 20 mm/s. Site-specific relationship was developed by exploring different models in addition to the popular power model. Alongside, different exponents were used for evaluating the best-fit scaled distance formula in addition to the generally adopted value of ‘0.5’. Reciprocal model with an exponent of 0.667 was identified as the best suited for the site under consideration. The safe charge weights during blasting corresponding to the stipulated safe PPVs were evaluated for varying distances and were provided in graphical form for ready reference. The site-specific study helped to arrive at practical and efficient blasting design. The guidelines in IS codes for measurement and monitoring during the controlled blasting operation were also discussed. This case study would serve as a reference for practicing engineers towards planning and implementation of similar blasting activities in a more efficient manner. © 2019, The Institution of Engineers (India).