Bm. Sumer et J. Fredsoe, WAVE SCOUR AROUND GROUP OF VERTICAL PILES, Journal of waterway, port, coastal, and ocean engineering, 124(5), 1998, pp. 248-256
The paper presents the results of an experimental investigation on sco
ur around pile groups with different configurations exposed to waves.
Two kinds of tests were carried out: the actual scour experiments, and
bed shear stress measurements. Seven kinds of pile-group arrangements
were tested, including the side-by-side arrangements of piles, tandem
arrangements of piles, and triangular and square group arrangements w
ith two-, three-, and four-pile groups, The variations with the pile s
pacing as well as the Keulegan-Carpenter number, KC, were investigated
. The scour depth can increase with respect to its single-pile value b
y as much as a factor of 3 for moderate KC numbers [such as O(10)] for
most of the pile-group configurations for small pile spacings. For sm
all KC numbers, this increase can be even higher, by as much as a fact
or of 10 or more. For a given pile spacing, the scour depth is mainly
governed by the KC number. In agreement with the single-pile case, the
larger the KC number, the larger the scour depth. The bed was live in
all the tests except a few cases.