Analysing the influence of woody debris on debris-flow impact forces on bridge superstructures

Debris flows can cause large damages to infrastructure-especially bridges. In this study, we investigate the influence of wood on debris-flow impact forces on bridge superstructures by means of miniaturized laboratory experiments. We show that woody debris flows transfer different and larger forces to bridge superstructures than debris flows without wood. Especially the horizontal impact forces are significantly larger with woody debris flows: the maximum horizontal impact force is up to twice as high as for woody debris flows. Uplift forces occur during woody debris flow impact that could not be observed with normal debris flow impact in our experiments.