Safety of engineered structures against blast vibrations: A case study

TLDR

Blasting for rock excavation generates ground vibrations that can damage nearby structures, with damage depending on ground motion, structural dynamics, and geology, making safety of surrounding buildings a major concern. This paper demonstrates a systematic rock‑blasting approach designed to protect an 85‑year‑old masonry dam and adjacent green concrete during a 30,000 m³ hard‑rock excavation. The authors implemented safe vibration thresholds, site‑specific attenuation relations, charge calculations for various distances, blast‑pattern design, and real‑time vibration monitoring to safeguard the structures. The approach allowed the excavation to finish on schedule while the dam’s safety was maintained through continuous vibration monitoring.

Abstract

Blasting used for rock excavation is associated with ground vibrations having potential damage to surrounding structures. The extent of damage produced in a structure depends largely on ground motion characteristics, dynamic characteristics of structure and the type of geological strata on which it is founded. The safety of surrounding structures against blast vibrations is a cause of concern. However, use of a systematic approach to rock blasting helps to complete the excavation safely in time without endangering the safety of surrounding structures. Various steps are commonly adopted at construction sites to ensure safety of engineered structures against blast vibrations, e.g. adopting a suitable safe vibration level, developing site-specific attenuation relation, estimating safe charges for different distances, designing blasting pattern, and monitoring vibrations during actual blasting. The paper describes the details of studies conducted for ensuring safety of an 85 years old masonry dam and green concrete of varying ages during excavation of about 30,000 m3 of hard rock in Maharashtra, India. The studies helped to complete the rock excavation safely in time and the safety of the dam was ensured by monitoring blast vibrations during actual rock excavation.