Small-Scale Airblast Testing for the Assessment of Multiple Perimeter Wall Barriers on Shock Wave Propagation

Assessment of the impact of structural systems on blast wave propagation has traditionally been explored using experimental, analytical, and/or numerical methods. Though numerical modeling techniques have grown in popularity because of their lower cost and high accuracy, experimental testing remains necessary for verifying these models. Issues of scale, equipment capacity, and the availability of research funding continue to limit full-scale testing of subassemblies or complete structures under blast loads. In addition, full-scale blast testing can be time-consuming, allowing only a handful of tests to be conducted. Small-scale airblast experiments offer an economic alternative to full-scale testing, in terms of material and labor requirements. Additionally, these small-scale experiments can be performed rapidly with repeatable results. The use of a novel reusable tabletop small-scale airblast experiment framework is presented for repeatable, cost-effective, quick turnaround testing of airblast scenarios. This novel setup also allows for reflective surfaces to be included as part of the investigation of the behavior of the shockwave-interaction with structures. The goal is to understand the behavior of the blast shockwave interacting with multiple barriers and the effect of pressure due to those barriers; therefore, the scaled structure remains rigid in the experimental and numerical analysis. Three different wall configurations were used to investigate how the presence of multiple barriers affects the shockwave and subsequent observed pressures around and behind the barriers. The explosives used were hemispherical and elevated spherical C4 charges. Pressure gauges were used to read pressures in front of, between, and behind the barriers on the tabletop. The airblast effects such as pressure and impulse, from the scaled experiments are presented and compared to the analytical predictions using a hydrocode model. It was found that multiple walls are measurably effective in reducing the pressure shockwave compared to no walls. The use of single and double walls reduced the pressure by 50% and 25%, respectively, compared to having no walls at the same scaled distance. The hydrocode model results were generally in agreement with the experimental data. The results can allow engineers and decision makers to understand the impact that properly distanced multiple barriers can have on protection from blast events.