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Coastal Engineering: Theory and Practice
height expected to be more or at locations wherein natural rocks are scanty,
artificial concrète armour blocks are considered. The Kd factor dépends on
the interlocking capacity of the blocks, and efforts hâve been to increase it
by varying the shape of the blocks.
5.5 Concrète Armour Layer Units
5.5.1 General
The most commonly adopted breakwaters are the S-type, in which the
decision on the sélection of artificial armour blocks particularly at locations, wherein, natural rocks are scanty is vital. Hence this section focuses
on the said aspect. The CAUs — concrète armour units were developed
in order to address this limitation to natural rocks. Though, the CAUs
are heavy, it is also designed for dissipating the wave energy by making
it porous.
Many types of armour unit shapes are available and each has its own
engineering performance characteristics. Armour blocks too hâve various
qualities that contribute to their stability. Some of the important ones are,
weight, interlocking, inter-block friction, hydraulic drag, permeability of
assembly etc. Typical armour units include the Dolos, Tribar, Tetrapod,
Accropode and block etc. The default armour unit is stone for both économie and aesthetic reasons. CAUs are used when the costs associated
with quarrying, transporting, and placing stone armour large enough to be
hydrodynamically stable exceed those of CAUs. A general idea about the
pros and cons of different armour units developed in the past decade are
discussed below.
The widely adopted forms of CAUs available are shown in Fig. 5.8.
5.5.2 Randomly placed armour units — stability factors
weight and interlocking
The randomly placed armour units hâve been in practice from 1950 and
hâve developed over the period for various advantages. These can be classified into three génération based on the shape, stability and year as follows.
First génération armour units
The shape of first génération armour blocks is quite simple in its shape and
the structure is usually formed by two layers or more in exceptional cases
and is placed in random. The stability of the block relies on its gravity and
Coastal Engineering: Theory and Practice
height expected to be more or at locations wherein natural rocks are scanty,
artificial concrète armour blocks are considered. The Kd factor dépends on
the interlocking capacity of the blocks, and efforts hâve been to increase it
by varying the shape of the blocks.
5.5 Concrète Armour Layer Units
5.5.1 General
The most commonly adopted breakwaters are the S-type, in which the
decision on the sélection of artificial armour blocks particularly at locations, wherein, natural rocks are scanty is vital. Hence this section focuses
on the said aspect. The CAUs — concrète armour units were developed
in order to address this limitation to natural rocks. Though, the CAUs
are heavy, it is also designed for dissipating the wave energy by making
it porous.
Many types of armour unit shapes are available and each has its own
engineering performance characteristics. Armour blocks too hâve various
qualities that contribute to their stability. Some of the important ones are,
weight, interlocking, inter-block friction, hydraulic drag, permeability of
assembly etc. Typical armour units include the Dolos, Tribar, Tetrapod,
Accropode and block etc. The default armour unit is stone for both économie and aesthetic reasons. CAUs are used when the costs associated
with quarrying, transporting, and placing stone armour large enough to be
hydrodynamically stable exceed those of CAUs. A general idea about the
pros and cons of different armour units developed in the past decade are
discussed below.
The widely adopted forms of CAUs available are shown in Fig. 5.8.
5.5.2 Randomly placed armour units — stability factors
weight and interlocking
The randomly placed armour units hâve been in practice from 1950 and
hâve developed over the period for various advantages. These can be classified into three génération based on the shape, stability and year as follows.
First génération armour units
The shape of first génération armour blocks is quite simple in its shape and
the structure is usually formed by two layers or more in exceptional cases
and is placed in random. The stability of the block relies on its gravity and