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Coastal Engineering: Theory and Practice
Underlayer design
The requirement of underlayer dépends on the size of armour stones. Let us
assume, one underlayer is required. If more than one underlayer is required,
the same design procedure will be repeated for each underlayers.
The weight of first underlayer stones is in the range of
to
Adopt, the range of underlayer stones with weights of 1.8 ton to 1.2 ton.
Thickness of underlayer: For any layer made up of rubble stones, there
should be minimum two layers. Let us adopt, two layers of underlayer
stones. Following the armour layer thickness calculation with a layer coefficient of one,
tui = 1.7 m
The diameter of underlayer stone is in the range of 0.77 m to 0.88 m.
Core layer
The weight of core layer stones m the range of — to — of the layer stone
10
15
weight placed above it.
Hence, here, the core stone weights are in the range of
to —,
6
1 00
225’
i.e., 180 kg to 80 kg.
Filter layer
Following the earlier step, the weights of filter layer stones which distributes
the entire rubble stone structure weight into the sea bed is — to — of the
,
.
6
10
15
core layer. Further, if the above design range does not satisfy with référencé
to the seabed sédiment characteristics, additional underlayer(s) need to be
introduced to reduce further the filter stone weight. Further, to avoid placing stones of size less than ten times that of a typical seabed sédiment mean
diameter, the minimum size of stones in the filter layer is defined in terms
of linear dimension instead of weight. Hence, adopt the range of filter layer
stones of 10 mm to 18 kg. The filter layer thickness is adopted as 300 mm.
Toe layer
The range of stone weights in the toe layer is
to ^|°-, i.e., 1.8 ton to
1.2 ton. Minimum width of toe is three layer thickness and the minimum
toe height is two layer thickness.
Thus, the width is arrived at 2.637 m and provide 3 m width. Height
(thickness) of toe layer is 1.758 m.
Coastal Engineering: Theory and Practice
Underlayer design
The requirement of underlayer dépends on the size of armour stones. Let us
assume, one underlayer is required. If more than one underlayer is required,
the same design procedure will be repeated for each underlayers.
The weight of first underlayer stones is in the range of
to
Adopt, the range of underlayer stones with weights of 1.8 ton to 1.2 ton.
Thickness of underlayer: For any layer made up of rubble stones, there
should be minimum two layers. Let us adopt, two layers of underlayer
stones. Following the armour layer thickness calculation with a layer coefficient of one,
tui = 1.7 m
The diameter of underlayer stone is in the range of 0.77 m to 0.88 m.
Core layer
The weight of core layer stones m the range of — to — of the layer stone
10
15
weight placed above it.
Hence, here, the core stone weights are in the range of
to —,
6
1 00
225’
i.e., 180 kg to 80 kg.
Filter layer
Following the earlier step, the weights of filter layer stones which distributes
the entire rubble stone structure weight into the sea bed is — to — of the
,
.
6
10
15
core layer. Further, if the above design range does not satisfy with référencé
to the seabed sédiment characteristics, additional underlayer(s) need to be
introduced to reduce further the filter stone weight. Further, to avoid placing stones of size less than ten times that of a typical seabed sédiment mean
diameter, the minimum size of stones in the filter layer is defined in terms
of linear dimension instead of weight. Hence, adopt the range of filter layer
stones of 10 mm to 18 kg. The filter layer thickness is adopted as 300 mm.
Toe layer
The range of stone weights in the toe layer is
to ^|°-, i.e., 1.8 ton to
1.2 ton. Minimum width of toe is three layer thickness and the minimum
toe height is two layer thickness.
Thus, the width is arrived at 2.637 m and provide 3 m width. Height
(thickness) of toe layer is 1.758 m.