Crack Response to Weather Effects, Blasting, and Construction Vibrations

Autonomous Crack Measurement (ACM) facilitates simultaneous measurement of crack response to environmental changes and vibrations produced by various construction activities. Dual-purpose crack displacement sensors measure crack response, while the vibration environment is defined by standard seismological transducers and the weather environment is defined as changes in temperature and humidity. This investigation involved an ACM study to examine the effects of rock blasting at the Stiles Road Quarry site in Southbury, Connecticut and vibrations produced by heavy construction equipment at the West Ann Road site in Las Vegas, Nevada. The study also allowed for the examination of blast design effects on crack displacement and a comparison of crack response from typical blasting and construction activities with that produced by weather changes. Measurements and analysis show that (i) long-term weather-induced crack displacement is 30 to 150 times greater than the crack displacement produced by the largest blasting event (≈0.35 ips) at the Connecticut site and the largest construction event (≈0.45 ips) at the Las Vegas site, (ii) ground vibration frequency and stemming length have the largest effect on crack displacement of the four blast design controls studied, (iii) appropriate triggering mechanisms and on-site observation greatly facilitate vibration monitoring, and (iv) rock blasting at distances of approximately 2500 feet produced homogenous crack response, while localized construction activity in soils at distances less than 50 feet produced time varying, localized crack response.