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 scenarios that do not necessarily reflect real life situations. At present, there is limited understanding of how, and to what extent, blast-structure interaction influences injury risk, and the suitability of injury criteria that assume idealised loading. This work employed computational fluid dynamics to investigate the influence of blast interaction effects such as shielding and channelling on blast load characteristics and predicted PBIs. The validated modelling showed that blast interaction with common urban features like walls and corners resulted in complex waveforms featuring multiple peaks and less clearly defined durations, and that these alter potential injury risk maps. For example, blast shielding due to corners reduced peak overpressures by 43%–60% at locations behind the corner. However, when the urban layout included a corner and a wall structure, higher pressures and impulse due to channelling were observed. The channelling significantly increased the injury risk at the exposed location and reduced the shielding effects behind the corner. In these cases, the application and interpretation of existing injury criteria had several limitations and reduced reliability. This demonstrates that structural-blast interaction from common urban layouts has a significant effect on PBI risk. Specific challenges and further work to develop understanding and reliability of injury prediction for urban blast scenarios are discussed.

The Effect of Scaling Building Configuration Blast Experiments on Positive Phase Blast Wave Parameters

“…Peak incident overpressure decreased with increasing distance around the corner, as expected due to the greater stand-off distances. However, an enhanced reduction was observed due to shielding from the corner structure compared to a free-field explosion without the structure, consistent with the findings of Denny et al [24]. This is similar to shielding observed from barriers used to mitigate blast effects on other buildings due to an external detonation [36,37] or clearing, which occurs on the reflected wall of a building and reduces the positive phase blast load [38].…”

“…A schematic and photograph of the field tests are shown in Figure 9. The charge mass and dimensions were also scaled using a factor of 250% when assuming a TNT equivalency of 1.2 for PE-4 [24]. The differences between the experiments herein and the field trials [11] exist:…”

“…It would seem that the person would be safer behind the corner for the positions and TNT masses concerned. Denny et al [24] performed further numerical simulations using Autodyn and concluded that the corner offered shielding effects that lowered the risk of primary blast injuries. Gajewski and Sielicki [11] also found good agreement between empirical formulae and data from experimental tests, leading to the possibility that the loading overpressure profiles in the experimental study could be used for benchmark comparisons.…”

A Review of Blast Loading in the Urban Environment

“…It is also clearly shown that numerical modelling can be utilised to provide verification at multiple stages of experimental work, further acting as a means to provide additional data in certain studies. Understanding the physical behaviours from experimental work can assist in validating numerical models; an example of this is given by the experimental work of Gajewski and Sielicki [164] being used to validate related modelling work conducted by Denny et al [165]. In this regard, the authors wish to highlight the importance of experimentalists publishing their collected data in full and in an accessible format, in order to facilitate rigorous and detailed validation of future modelling efforts.…”

Estimating Blast Exposures From The 2020 Beirut Explosion And Examining Correlation With Blast Injuries

“…In reality, blast wave interaction within Beirut's urban landscape will have modified the magnitude and distribution of loading conditions. Blast wave propagation in urban environments is complex to characterise and can both amplify and reduce loading through multiple reflections, channelling, and shadowing effects due to blast wave interactions with structures [21].…”