A numerical investigation of blast-structure interaction effects on primary blast injury risk and the suitability of existing injury prediction methods

Abstract

Explosions increasingly occur in densely populated, urban locations. Primary blast injuries (PBIs), caused by exposure to blast wave overpressure, can be predicted using injury criteria, although many are based on idealised loading inputs. At present, no studies have analysed in detail how, and to what extent blast-structure interaction influences injury risk, and the suitability of injury criteria that assume ideal loading inputs. Computational fluid dynamics (CFD) was used to investigate shielding and channelling blast interaction effects involving a rigid corner and a wall, in comparison to the free-field scenario. Models examined the effects of structural-blast interaction on loading parameters at certain locations, the effect this has on expected PBIs, and the suitability and limitations of using available injury criteria. Blast wave interaction with the corner resulted in shielding that reduced peak overpressures by 43%-60% at locations behind the corner in comparison to the free-field scenario. Blast wave interaction with the corner and wall structure resulted in higher pressures and impulse due to channelling that significantly increased injury risk at the exposed location and reduced shielding behind the corner, in comparison to the corner alone. Blast interaction with the structures resulted in complex waveforms featuring multiple peaks and less clearly defined durations. In these cases, the application and interpretation of existing injury criteria had several limitations and reduced reliability. This numerical study demonstrates that structural-blast interaction has significant effect on PBI risk. Specific challenges and further work to develop understanding and reliability of injury prediction for urban blast scenarios are discussed.