Figure A6.
Submerged breakwater nomenclature
Hs
Ns =
(A2)
∆Dn50
where ∆ = relative mass density (ρs/ρ -1), Dn50 = nominal diameter of rock =
(M50/ρs)1/3, and M50 median stone mass.
Ahrens (1987, 1989) also introduced the spectral stability number to account
for the observation that longer period waves cause more displacement of
material:
2
1
H
3L 3
p
*
Ns =
(A3)
∆Dn50
the toe of the structure.
For dynamically stable reef breakwaters (i.e., breakwaters of low crest
elevation which will undergo significant reshaping during wave attack),
van der Meer and Pilarczyk (1990) suggest the following equation to predict the
At
()
hc =
(A4)
*
exp aN s
A8
Appendix A
Stability Analysis of a Submerged Spur, North Jetty, Grays Harbor, WA
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