United States Nuclear Regulatory Commission - Protecting People and the Environment

Characterizing Explosive Effects on Underground Structures (NUREG/CR-7201)

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Publication Information

Manuscript Completed: September 2013
Date Published: September 2015

Prepared by:
A. H. Chowdhury, CNWRA
T. E. Wilt, CNWRA

Center for Nuclear Waste Regulatory Analyses
Southwest Research Institute®
6220 Culebra Road
San Antonio, Texas 78238-5166

Kris Jamgochian, NRC Project Manager
Peter S. Lee, NRC Technical Monitor

NRC Job Code N4128

Office of Nuclear Security and Incident Response
U.S. Nuclear Regulatory Commission
Washington DC 20555-0001

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A literature review and finite element analyses were conducted to characterize the effects of explosions on underground structures for explosive charges located close to and on the ground surface. Explosive charge weights were selected to be consistent with Vehicle Borne Improvised Explosive Devices (VBIEDs) terrorists make mostly using chemicals and available precursor materials. The phenomena associated with air and surface explosions of VBIEDs, propagation of their dynamic waves through air, crater formation, and propagation through subsurface media are similar to those of conventional high explosive military weapons. Empirical equations for predicting these blast-induced effects and designing underground structures under explosive loads are available in the literature. These empirical equations, however, do have a specific range of applicability. Numerical analysis techniques (e.g., finite element) also require specific assumptions and idealizations. A limited finite element parametric study was used to investigate the influence of important parameters. These influences include the explosive charge weight and how the distance of a point in the subsurface soil from the location of explosion affects the explosion-generated pressure distribution in the underground soil. The blast-induced pressure wave in the soil surrounding an underground structure results in time-dependent loading (pressure or impulse force) of the underground structure. The current methodology for the designing underground structures subjected to explosive loads uses concepts and provisions of other specific codes, standards, and design manuals commonly used in designing reinforced concrete, prestressed concrete, masonry, and steel structures. An underground structure that may be subjected to both explosive and seismic loads should consider both types of loads in appropriate combinations.

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