Analysis of scour around a group of vertical piles in the field

A study of the scour around a group of piles in the field exposed to oscill atory waves was carried out. The main purpose was to derive simple predicti ve formulas for the geometric properties of the scour hole in terms of nond imensional parameters describing the flow, sediment, and pile characteristi cs. A comprehensive data set from the Pacific coast of Japan was employed w here the beach profile along a pier experiencing scour around its piles was surveyed every week. Detailed wave measurements were available, and only t he outer piles exposed to nonbreaking (oscillatory) waves were investigated . The maximum scour depth showed a distinct correlation with the Keulegan-C arpenter number, and an empirical relationship was derived that agreed with some earlier laboratory experiments, if an equivalent diameter was defined for the pile groups. The width of the scour hole displayed little correlat ion with the Keulegan-Carpenter or other nondimensional numbers employed, a lthough it should be noted thar only one pile configuration was investigate d in the present study.