It’s All in the Rock

The repercussions of groundshock following an explosive event can range from minor to catastrophic when considering underground facilities, structures, and infrastructure. Accurate predictions of the shockwaves, to include their speed and strength, are highly dependent on the geometry and geomechanical properties of the geology these wave(s) must pass through. Excalibur is a high-performance computing structural dynamics software package developed by the Defense Threat Reduction Agency that is optimized, verified, and validated for predicting groundshock, as it allows users to appropriately model these vital aspects of groundshock. The software allows users to define rock materials directly using fundamental properties that are determined in the laboratory as opposed to using an equation of state. Common supported properties include, but are not limited to, unconfined compressive strength, saturation, porosity, loading and unloading moduli, crush and lockup moduli, Poisson’s ratio, tensile limit, and grain density. Excalibur supports defining rocks using models with multiple loading phases in stress space, where the phases may have abrupt or smooth varying transitions during loading and exhibit hysteric unloading. Furthermore, Excalibur applies an effective stress model to capture the behavior of the shockwave based on the amount of water present in each computational cell. In this talk, we will review a parametric study of 44 Excalibur groundshock simulations to model above ground explosions while varying the layering, rock type, and geomechanical model formulations of rocks surrounding an underground tunnel. Our study shows the range of uncertainty that analysts should expect when predicting damage based on the knowledge of the rocks simulated and the models used within the simulation.

PRESENTER

Harvey, Allen
aharvey@ara.com
703-329-0200

Applied Research Associates, Inc.

CO-AUTHORS

Thomas, Michael
mthomas@ara.com

Hariprasad, Daniel
dhariprasad@ara.com

Simmons, Dexter
dexter.l.simmons3.civ@mail.mil

Arnold, Ivan
nicholas.i.arnold.ctr@mail.mil

Kasza, Stephanie
Stephanie.Kasza@dodiis.mil

Elmore, Royal
royal.elmore@dodiis.mil

CATEGORY

Computational Structural Mechanics (CSM)

SYSTEMS USED

Raider

SECRET

No