Ground Shock Propagation in Spatially Random Geological Media

Abstract : Report developed under SBlR contract for topic HDTRA1-05-P-0026. The main issue being addressed is as follows: Given what is known about a rock site, what can one say about the uncertainty in the ground-shock environment that can be expected from an explosive event? To be sure, the amount of data available is directly connected with the ground-shock uncertainty. But does a quantitative, rational procedure exist that one can use to estimate the environment uncertainty associated to the degree of uncertainty on the site? We have demonstrated in this project: (1) How heterogeneity and spatial variability of rock properties at a site, as evidenced by state-of-the-art measurements taken at the demonstration site, are captured as random fields using geostatistical techniques; (2) How these fields of mostly low-stress, in-situ or laboratory properties, which are representative of the kinds of measurements being taken, could be used to infer rock-mass mechanical properties in the high-stress, high-strain-rate response regimes of interest; (3) How the rock-mass property fields were used in ground-shock simulations to generate the corresponding ground-shock fields, employing stochastic finite-element techniques; and, lastly, (4) How local variability in the simulated ground-shock environments could be readily elicited from the stochastic realizations.