Centrifuge modeling of surface blast effects on underground structures

The effects of surface blasts on underground structures were studied through centrifuge model tests. Centrifuge scaling relationships make it possible to model the effects of large explosions, using a relatively small quantity of explosives under a high g-level. Centrifuge tests, conducted at 70 g, using 2.6 mg of TNT equivalent of explosives, resulted in explosions equivalent to those using 8.7 kN (0.9 tons) of TNT equivalent under normal (1 g) gravity. Strains induced at different locations of the model structure due to the explosion were measured using strain gages. Results indicated that the strains depend on the thickness and nature of the intervening medium. The presence of a polyurethane geofoam compressible inclusion barrier appeared to mitigate the impact of the explosion. Centrifuge model testing is useful in determining the effectiveness of different design alternatives, in studying the mitigating effects of different barrier systems, and in verifying and calibrating results of numerical models related to explosions and underground structures. Copyright © 2007 by ASTM International.