Calculations of the FLAX events with comparisons to particle velocity data recorded at low stress
Year: 1993
Type: conference-paper
Abstract: The FLAX event, fired in 1972, produced two particle velocity data sets from two devices in the same hole, U2dj. The data are of interest because they contain verification of focusing of a shock wave above the water table. The FLAX data show the peak velocity attenuation from the device buried in saturated tuff are different from those emanating from the upper device buried in porous alluvium. The attenuations of the peaks are different in regions traversed by both waves traveling at the same sound speed and measured by the same particle velocity gages. The attenuation rate from the lower device is due to 2-D effects attributed to wave focusing above the water table and is a feature that should be captured by 2-D calculations. LLNL`s KDYNA calculations used for containment analyses have utilized a material model initially developed by Butkovich, which estimates strength and compressibility based on gas porosity, total porosity, and water content determined from geophysical measurements. Unfortunately, the material model estimates do not correctly model the more important details of strength and compressibility used for matching the velocity data. The velocity gage data contain information that can be related to the strength properties of the medium, provided that there are more than two gages recording in the stress region of plastic deformation of the material. A modification to Butkovich`s model incorporated approximate strengths derived from the data. The mechanisms of focusing will be discussed and will incorporate additional information from the TYBO event.
Author: J.T. Rambo
Language: English
Subfield: Mechanics of Materials
Field: Engineering
Domain: Physical Sciences
Open Access status: green
Awards: G1702950523, G660437508
OpenAlex ID: W43032299