Preshot, In situ Site Investigation Vibratory and Seismic Techniques, Pre-Gondola II, Fort Peck, Montana.
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MISS
Pagination or Media Count:
An in situ site investigation consisting of vibratory and refraction seismic tests was conducted prior to the Pre-Gondola II cratering event near Fort Peck, Montana. The refraction seismic tests indicated existence of two subsurface zones. The near-surface soil exhibited a compression wave velocity range of 1100 to 1670 fps and extended from the ground surface to depths varying from 9 to 28 ft. The second zone encountered, shale bedrock, exhibited a velocity range of 5700 to 6000 fps and extended to an undetermined depth. Numerous irregularities were detected in the surface of the bedrock layer. The vibratory tests indicated initial shear wave velocities to increase uniformly with depth, from 250 fps at a depth of about 2.5 ft to 1140 fps at approximately 74 ft. Author
- Soil Mechanics