Blast Displacement in Field Fortifications

Abstract : The objectives of this project were (1) to determine the displacement-time histories of dummies inside 3 ft x 6 ft fighting bunkers and inside a 14 ft x 14 ft underground personnel shelter and (2) to use these data to confirm a method for predicting whole-body translation of personnel in open structures. Background airblast-displacement effects on personnel inside field fortifications have received little attention. Because of the lack of information in this area, blast-casualty criteria have been based solely on damage to the structure, and safety and risk criteria have been linked to damage to the fortification or to direct-overpressure effects (Reference 1). Results from a previous field test (Reference 2) have suggested that impact injury associated with whole-body displacement induced by the entering jet flow can occur at overpressure well below those required for injury from direct-overpressure effects or structural collapse. Laboratory studies of jet phenomena in scale models of field fortifications in a shock tube have resulted in the development of a method for predicting whole-body translation of personnel in open structures. It was desirable to confirm this method using full-scale structures on the Dice-Throw field test.