Department of Defense (DoD) installations increasingly are encountering complaints and damage claims alleging that military activities are producing bothersome ground vibrations. Although some civilian regulations address ground vibration, DoD has not formally adopted any methods to regulate vibrations or assess these complaints. The current procedure used to assess damage claims attributed to ground motion from military activities uses empirical equations formulated by the mining industry. These equations estimate the peak level of ground vibration caused by the military activity. Mining industry blasting, however, significantly differs from military activities, especially in the use of large explosive charges spread over a relatively large area. As such, the empirical equations currently used may not be accurate when applied to military activities.
The objective of this project was to develop a simple, accurate procedure for estimating the peak ground vibration produced by military training and demilitarization activities.
This project analyzed existing measurements for typical military activities, including small explosive detonations, artillery firing, and demilitarization. A simple model was developed to provide predictions of peak ground vibration from military noise sources for a variety of soil and ground conditions. To ensure a full understanding of the process of acoustically induced ground motion and its dependence on relevant factors, acoustic pressure and associated ground motion also were calculated using a high-fidelity frequency-domain propagation code. The code predictions were validated against existing waveform data for acoustic-to-seismic coupling and used to refine the values of the coupling coefficients used in the simple model and to explore their dependence on ground conditions. No frequency dependence of the coefficients was indicated.
The new procedure developed by this project provides a simple method to predict ground vibrations induced by military noise sources with more accuracy than the currently used method. This new method enables complaints and damage claims attributed to ground vibrations caused by military activities to be accurately assessed. (Project Completed - 2006)