Beyond Perret & Bass: Data Analysis and Simulation of DAG-1 & DAG-2 Chemical Explosions

Date: 4/24/2019

Time: 11:45 AM

Room: Cascade I

The Source Physics Experiment (SPE) is an ongoing effort to improve explosion monitoring by conducting a series of chemical explosions at the Nevada National Security Site (NNSS) and using the resulting observations to improve and validate physics-based simulations of explosion phenomena. Four chemical explosions are being conducted in dry alluvium geology (DAG) as part of SPE Phase II. Two first explosions, DAG-1 & DAG-2 have been successfully executed in 2018. Perret & Bass in 1975 compiled free-field triplet peak accelerations, velocities and displacements of several historical nuclear shots. Using regressions, Perret & Bass inferred different regimes and correlations of the peak responses as a function of the scaled depth of burial. Peak responses of alluvium is characterized by two regimes: an initial non-linear regime followed by a linear one. The linear-regime onset in alluvium is at ~110 m kt^-1/3 and the largest scaled depth data point is ~350 m kt^-1/3. It is worth noting that beyond 350 m kt^-1/3 field designers are left at the mercy of the extrapolations of the suggested inferred regressions based on very limited data beyond the linear regime onset. Here, we will, first, address the pos and cons of Perret & Bass analyses and we will highlight inconsistencies. Second, Perret & Bass regressions are used for surface accelerometer emplacements using scaled slant distances and doubling the peak triplets to account for the effect of free surface. This has been proving successful for strong material, such as granite. It has, however, data collected during DAG-1 and DAG-2 have proved that the latter approach is non-reliable in alluvium. Using physics-based coupled numerical codes, Geodyn-L for non-linear regime and WPP for the linear regime, we develop a new sets of surface peak accelerations, velocities and displacements attenuation curves and their functional correlation forms to be used for the subsequent DAG-3 and DAG-4 experiments. Third, we assess the statistical differences and significances of the newly developed correlations versus Perret and Bass.

Presenting Author: Souheil M. Ezzedine

Authors