Hydraulic Structures: Fourth Edition

The horizontal part at 8.0 m OD is assumed to be 6 m, which is

greater than the crest width given by equation (15.35). The thickness of

the cover layer (equation (15.33)) is

t 1  2 1.0

1/3

1.83 m.

The area of the cover layer per unit width of sea wall, A

[12^2 (3^2  12 )]1/238 m^2. From Table 15.4, the porosity of the cover layer is

37%.

The number of units per unit width of cover layer (equation (15.34)) is

N 38  2  (^1) 
2/3
57.
Figure 15.16 gives the profile of the sea wall, which is to be developed
further from model studies and other considerations such as site and eco-
nomic constraints.
(b) For the wave conditions and slope of the breakwater of Worked
example 15.3, using Van der Meer’s formula determine the mass of the
armour units for rough quarry stone and the wave run-up if the design storm
duration is 6.0 hours. Assume damage number for failure conditions as low.
Solution


1

3



0.5

2.3

From the above table on the peak period Tz8.16 s.

Nz6.03600/8.16 2700.

From Table 15.5, S2.0.P0.4 from Fig. 15.11.

For2.3, using equation (15.37) for run-up on rough slopes

1.00.4^ 0.13

0.2

 3

 2.30.4

D 50 0.93 m.

Mean mass of rocks M 50 0.93^3 2.652.13 103 kg.

2



2

7

0

0

2.17



1.65D 50

2.17



104.0

2650 9.81



20  103

37



100

20  103



2.65 103 9.81

668 COASTAL ENGINEERING