Microseismic Roof Fall Warning System.
Farstad-AJ; Kalvels-D; Kehrman-RF; Et Al
NTIS: PB/262-868 Available for Reference At Bureau Libraries :154 pages
Acoustic emission techniques show promise for the prediction of roof falls in coal mines. Of the two types of data obtained on this program (that is, acoustic threshold exceedance time and microseismic event count), the former is more indicative of the onset of a potential roof fall. In most cases, the acoustic threshold exceedance time increased gradually with increasing stress buildup in the roof and suddenly decreased sharply just prior to a roof fall. The main uncertainty that remains in attempting to analyze the data thus obtained is how long a time period should elapse between the sudden drop in acoustic emission activity and the associated impending roof fall. Obviously, this time duration will be a function of the strength of the roof and its associated mechanical properties. A statistical analysis of the data obtained should aid in identifying correlating factors between roof type and size, acoustic emission activity, and roof fall behaivor.
CP; Final Contract Report;
NTIS Accession No.
NTIS: PB/262-868 Available for Reference At Bureau Libraries
Westinghouse Electric Corp.