abstract

A source characterization of bermed surface bursts utilizing vertical and horizontal point sources has been developed. The equivalence of this formulation with a radial force couple and vertical point force is shown. This representation is formulated so that with analytic propagation path models and observational data, inverse techniques can be applied and the source estimated. The inverse procedure is applied to the Pre-HYBRID GUST I-04, 05, and 06 data sets (13.6 kg for 04, 13.6 kg for 05, and 39 kg for 06 of sand bermed C-4). The method is able to model the observational data explaining the R−1.6 decay of the radial velocity as near-field body waves and the R−0.5 decay of the vertical velocity as Rayleigh waves. The radial source function is a factor of 2 larger than the vertical for all tests, indicating the dominance of the radial force in cratering. Source rise time correlates well with the time the sand berm contains the explosive products while pulse width may be driven by nonlinear processes, such as spall. The sources appear to cube root yield scale. Stresses predicted using the determined source functions indicate large vertical stresses can develop from the Rayleigh wave.

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