Experiments on the impact process of dry and saturated mixtures against obstacles of various shapes

The purposes of this work are to experimentally analyze the impact of dry and saturated granular flows on obstacles of various shapes and to compare the maximum forces measured in the experiments with the ones predictable with analytical formulae available in the literature. Effects of interstitial fluid, mixture composition, obstacle size, shape and orientation were examined. Experimental results do not show a particular relevance of grain size composition, whereas obstacle orientation and height clearly affect the maximum force value. Measurements of the impact process against high dams show that saturated mixtures, like clear water, form vertical jets with instantaneous overshoots one order of magnitude greater than the force corresponding to the hydrostatic front pressure. Immediately after the impulse, measured forces exerted by both dry and saturated mixtures are very similar, accounting for the different mixture densities, and are well approximated by analytical literature equations.