A fast calculation method for internal blast shock wave in confined structures

Internal explosions are more complicated and destructive than external explosions. It is hard to give accurate predictions of the internal blast load by existing simplified models. In the present work, a fast calculation method for the shock wave of internal blast within a confined space was developed. Firstly, the theoretical bases of this method, the reflection addition rules and the image burst theory, were introduced and validated. Then, the concept of the influence region of image burst for internal blast calculation was proposed, and the detailed calculation method for internal blast load was presented. In addition, the internal blast loads inside a typical cubic structure and a tunnel model were calculated using this developed method, respectively. Moreover, comparison studies between the calculated results and experimental data as well as numerical simulation results were conducted. It was found that the results of the fast calculation model are in good agreement with those of the blast experiment and fine numerical simulation, but the fast calculation takes only less than 2 min. Finally, the advantages and defects of the present method were discussed and further study advices were suggested to improve the accuracy.