DID YOU KNOW? DTIC has over 3.5 million final reports on DoD funded research, development, test, and evaluation activities available to our registered users. Click
HERE to register or log in.
Accession Number:
ADA278477
Title:
Basic Research in Nuclear Test Monitoring: Explosions in Non-Spherical Cavities: Investigations of Enhanced Backscattering
Corporate Author:
MASSACHUSETTS INST OF TECH CAMBRIDGE EARTH RESOURCES LAB
Report Date:
1994-01-01
Abstract:
We report on two studies. The first is a theoretical study of the seismic radiation from explosions detonated in finite cylindrical tunnels embedded in a homogeneous, isotropic, elastic medium. We developed a frequency domain boundary elementdiscrete wave number algorithm to model the seismic wavefields from such sources, and applied the algorithm to study two specific cases of explosion sources-nuclear and non-nuclear. Our calculations show different source radiation patterns between the two types of explosions, especially when the explosion is located off-center in the tunnel in which case the non-nuclear explosion radiation displays strong directivity effects. Both types of explosions radiate significant shear wave energy outside the cavity. The second study is on enhanced seismic backscattering from rough interfaces. We experimentally and numerically investigate the scattering of an acoustic P wave incident on a highly irregular, random acoustic-elastic interface to determine whether enhanced backscattering occurs. The experiments involve ultrasonic waves reflected from a glass surface etched to produce a highly irregular 3-D surface. We find that 2-D numerical results predict the 3-D experimental results well at small incident angles. Both numerical and experimental results strongly support the presence of enhanced backscattering. Explosion seismology, Non-spherical cavities, Seismic scattering, Enhanced backscattering.
Descriptive Note:
Annual technical rept. 1 Aug 1992-31 Jul 1993
Pages:
0103
Distribution Statement:
Approved for public release; distribution is unlimited.
Contract Number:
F49620-92-J-0413
File Size:
3.42MB
