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Coastal Engineering: Theory and Practice
as wave overtopping or non-over topping type. In the case of an overtopping
types, a crown wall over the top of the breakwater or seawall is positioned
at the crest élévation of the structure. Although empirical relationship exist
to détermine the weight of the individual armour block, its stability is usually ascertained through physical model tests. At certain locations, berms
on the sea side are also employed. The physical modeling is carried out
also to investigate the extent of wave run-up over the structure, overtopping, reflection, absorption and transmission of waves. Such tests are carried
out in flumes. However, the layout of breakwaters, like its length, height
and orientation with respect to wave direction for the formation of artificial harbours are finalized through three-dimensional wave tanks, in which
the interaction of Coastal structures as well as their stability under oblique
waves are determined. In both two and three D tests, a larger scale factor
is adopted to reduce the errors in matching the results doser to that could
be in the field.
Although, this chapter is devoted to rubble mound structures, it is
equally important to hâve a broader idea on breakwaters.
5.2 Types of Breakwaters
Breakwaters are broadly classified as mound type, vertical type and composite type. A mound type breakwater does not produce substantial wave
reflection, attributed to the incident wave energy breaking on a slope of
rubble or concrète armour layer and they tend to dissipate most of the
incoming wave energy. Vertical breakwaters can either stand on sea bed
or can be built on artificial rubble mound foundations termed as composite breakwaters. On the other hand, vertical breakwaters reflect the incident wave energy as the breakwater is impervious/non-porous. Composite
breakwaters are employed in locations, where, the tidal fluctuations are significant; so that they function as mound type during the low tide and as
vertical type during the high tide. Based on the location it serves, breakwaters can further be classified as detached, headland, nearshore and shore
connected breakwaters. They may emerge, submerge the MSL or may be
floating.
• Type S called sloping breakwater because its seaward face has a slope of
1:1 or flatter. These breakwaters basically are of rubble mound.
• Type V called vertical breakwater, because it has a vertical or nearly
vertical seaward face.
Coastal Engineering: Theory and Practice
as wave overtopping or non-over topping type. In the case of an overtopping
types, a crown wall over the top of the breakwater or seawall is positioned
at the crest élévation of the structure. Although empirical relationship exist
to détermine the weight of the individual armour block, its stability is usually ascertained through physical model tests. At certain locations, berms
on the sea side are also employed. The physical modeling is carried out
also to investigate the extent of wave run-up over the structure, overtopping, reflection, absorption and transmission of waves. Such tests are carried
out in flumes. However, the layout of breakwaters, like its length, height
and orientation with respect to wave direction for the formation of artificial harbours are finalized through three-dimensional wave tanks, in which
the interaction of Coastal structures as well as their stability under oblique
waves are determined. In both two and three D tests, a larger scale factor
is adopted to reduce the errors in matching the results doser to that could
be in the field.
Although, this chapter is devoted to rubble mound structures, it is
equally important to hâve a broader idea on breakwaters.
5.2 Types of Breakwaters
Breakwaters are broadly classified as mound type, vertical type and composite type. A mound type breakwater does not produce substantial wave
reflection, attributed to the incident wave energy breaking on a slope of
rubble or concrète armour layer and they tend to dissipate most of the
incoming wave energy. Vertical breakwaters can either stand on sea bed
or can be built on artificial rubble mound foundations termed as composite breakwaters. On the other hand, vertical breakwaters reflect the incident wave energy as the breakwater is impervious/non-porous. Composite
breakwaters are employed in locations, where, the tidal fluctuations are significant; so that they function as mound type during the low tide and as
vertical type during the high tide. Based on the location it serves, breakwaters can further be classified as detached, headland, nearshore and shore
connected breakwaters. They may emerge, submerge the MSL or may be
floating.
• Type S called sloping breakwater because its seaward face has a slope of
1:1 or flatter. These breakwaters basically are of rubble mound.
• Type V called vertical breakwater, because it has a vertical or nearly
vertical seaward face.