270
Coastal Engineering: Theory and Practice
is 2.8 m and for 10 sec is 3.2 m. Find the maximum pressure, horizontal
force, and overtopping moment about the toe of the wall for the given slope.
Solution
For T = 6 sec, d = 2.5 m
= 0.04448 =
Lq
56.2
- = 0.08826, Ld = 28.3 m.
L
D = ds + (Ld) x 0.05 = 3.9 m.
= 0.0694,
= 0.1134, Ld =
= 34.4 m.
Lq
Ljj
0.1134
i.e. Ld — 35 m
From Eq. (8.15),
pm = 1017^. ^-(D + ds)
L,d y
pm = 331 kN/m2
A similar analysis for T = 10 sec gives, pm — 182 kN/m2
The above values can be obtained more rapidly by using Fig. 8.12.
To use the figure.
ds _
2.5
~gTï ~ 9.81 x 62
= 0.0071
With m — 0.05 read pm/^Hb corresponding to ds/gT2 — 0.0071 (Fig. 8.12)
.'. pm = 12 x 10 x 2.8 = 336 kN/m2
Similarly for T = 10 sec, pm = 176 kN/m2
The force can be evaluated as
r->
PmHb
331 x 2.8
.
= —x— =----- ------ = 309 kN/m
O
O
Mm = Rmds =
kN-m/m
O
Similarly for T = 10 sec, the force and moment are calculated as Rm -
194 kN/m, Mm = 485 kN-m/m.