STUDY OF WAVEFORM CHARACTERISTICS FOR USE IN THE ANALYSIS OF SHOCK ISOLATION SYSTEMS FOR UNDERGROUND PROTECTIVE STRUCTURES
Abstract
A recent review of nuclear groundshock test data revealed oscillatory motions of undetermined origin, but of sufficient magnitude to be of concern in the design of shock isolation systems for underground protective structures. Response spectra of the oscillations exhibited amplification ratios far exceeding those employed in most groundshock prediction methods, the ratios being functions of the number of oscillations, and the amplitude and period of each cycle. As the source of the oscillations was not identified, there was no rational basis for relating these waveform parameters to such basic site and weapon conditions as yield, range, geologic structure and properties of the medium. In this investigation, two possible sources of the oscillatory motion are examined. First, the propagation of waves in a stratified site are studied and their directions and phase relationships estimated by use of wavefront diagrams and time-distance curves. Second, the form and strength of Rayleigh waves in an elastic, homogeneous half-space which result from surface pressure distributions similar to those generated by nuclear bursts were calculated. In both cases, oscillatory phenomena can be predicted and certain features related to the observed oscillations. However, the simple approaches employed in this analysis will not yield realistic wave strengths and thus, the composite waveform at a point in the half-space cannot be determined quantitatively.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1967
- Accession Number
- AD0805746
Entities
People
- C. C. Chao
- H. R. Saffell
- R. T. Frankian