Statistical Features of the Dam-Break-Induced Surge Impact Pressure

In this study, a series of dam-break laboratory experiments were carried out to investigate the statistical characteristics of the surge-induced impact pressure on a downstream vertical wall and its foundation. In the surge impact process, both the initial impact of the incoming flow and the falling strike of the recurved water mass after the surge run-up along the wall could result in significant increase in the impact pressure, as well as its variability. Accordingly, statistical analysis of the two representative surge impact parameters, i.e., the peak pressure and its rise time, was conducted. The peak surge impact pressure near the wall toe (both on the wall and bed) is non-deterministic while it occurs at a relatively specified time instant, whereas the peak surge impact pressure away from the wall toe is generally quantitatively uniform while its rise time becomes non-deterministic. Three types of statistical models, i.e., the Weibull, the log-normal and the Gumbel, were then used to fit the probability distribution of the measured surge-induced peak impact pressure, and variation features of the corresponding parameters were also specified. With respect to the RMSE, all three model simulations generally perform well, especially for the impact pressure measured near the wall toe.