Influence of Duration at the Entrance on Distribution of Blast Loadings in Corrugated Steel–Lined Tunnels

Abstract

Corrugated steel structures have been found to have outstanding blast resistance and enable rapid attenuation of blast waves in tunnels. The propagation of blast waves is influenced by the structural parameters and duration of blast waves at the entrance in tunnels, forming various blast loadings. To investigate the effect of duration at the entrance in corrugated steel–lined tunnels, trinitrotoluene (TNT) and aluminized explosives were used to obtain various durations of blast waves at the entrance in testing. A series of simulations was designed and verified, in which the effect of duration at the entrance was analyzed under the same scaled distance. The variation caused by duration and linings on loading curves was analyzed, and the influence mechanisms of the duration at the entrance and the linings on blast waves were discussed using pressure nephograms. Meanwhile, the distribution of blast loadings under different conditions was obtained. A prediction model for the distribution of peak blast loading in corrugated steel–lined tunnels (CSLTs) was established, considering the duration at the entrance. The results showed that corrugated steel linings destroyed the reflection conditions on a flat wall surface, resulting in longer periods of loading fluctuations. A longer duration of blast waves at the entrance extended the distribution of blast loadings and even resulted in a significantly higher peak loading appearing after the first peak near the entrance, altering the characteristics of loadings.