Cowboy Trails. Analysis of Gauge Records for Peak Velocity and Wavespeed

摘要

Ten explosive events in a salt dome near Grand Saline, Texas, comprise the core of the Cowboy Trails program. Seven were driven by single spheres of pelletized TNT weighing from 672 to 850 N, and three by two such spheres detonated simultaneously. The resulting ground-motion records have been analyzed to obtain the time of the first-signal arrival, and peak material velocity, as functions of slant-range, r. Though noise and baseline problems affected 491 of the 514 velocity records obtained, and as-built shot layouts proved difficult to determine, 117 records from single-charge events appeared (with simple corrections) to give credible peak velocities; 368 gave times-of-arrival. Inconsistencies among the records reduced these numbers to 73 and 292, respectively. Further study of the velocity gauge to determine the cause of baseline problems and correct for them, plus the application of digital processing procedures, should allow recovery of useful data from the bulk of the flawed records. Independent measurement of displacement (attempted in one of the events considered here) would provide a direct test of correction accuracy.