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Coastal Engineering: Theory and Practice
Problem V
A caisson of height 6.5 m from the top of a mound in a water depth of 6 m
is exposed to waves with H3 = 1 m or Hmax = 1.8 m and I\/3 =4 sec
Calculate the forces on the caisson using the formula of Goda (2010) and
Miche-Rundgren (1958).
Solution
From dispersion relation —> L = 20.9 m, k = 0.301 m-1 at Hs = 4 m
Assume non-breaking waves:
(a) Miche-Rundgren (1958)
ho
7T x 1.82
20.9
coth(0.301 x 4) = 0.58 m
pi =
1 x 1.8
2 Lc°sh.(0.301 x 4)
= 0.99 t/m2
Re
_ (4 + 1.8 + 0.58)(l x 4 + 0.99)
1 x 42
= 7.9 t/m
2
2
(b) Goda (2010)
p* = 0.75(1 + cos0)1.8 = 2.7 m
from dispersion relation
k = 0.272 m-1 at d = 6 m
hc = 2.5 m < rj*
assume hb = d = 6 m
hw = 6.5 + (4.5 -4) = 7 m
Coastal Engineering: Theory and Practice
Problem V
A caisson of height 6.5 m from the top of a mound in a water depth of 6 m
is exposed to waves with H3 = 1 m or Hmax = 1.8 m and I\/3 =4 sec
Calculate the forces on the caisson using the formula of Goda (2010) and
Miche-Rundgren (1958).
Solution
From dispersion relation —> L = 20.9 m, k = 0.301 m-1 at Hs = 4 m
Assume non-breaking waves:
(a) Miche-Rundgren (1958)
ho
7T x 1.82
20.9
coth(0.301 x 4) = 0.58 m
pi =
1 x 1.8
2 Lc°sh.(0.301 x 4)
= 0.99 t/m2
Re
_ (4 + 1.8 + 0.58)(l x 4 + 0.99)
1 x 42
= 7.9 t/m
2
2
(b) Goda (2010)
p* = 0.75(1 + cos0)1.8 = 2.7 m
from dispersion relation
k = 0.272 m-1 at d = 6 m
hc = 2.5 m < rj*
assume hb = d = 6 m
hw = 6.5 + (4.5 -4) = 7 m