Chapter IV
Design of rubble mounds breakwater
53
Rubble mound breakwaters are made up of several distinct layers that work together to dissipate
wave energy and maintain stability. The key components of a rubble mound breakwater include:
• Core: Its main function is to form the basis for the upper layers and to reduce the
transmitted energy. Most of the times consist of quarry run (stones 1 to 500kg) with
relatively large gradation (Papadopoulos D. 2012).
• Filter layer (under-layer/secondary armor layer): They are used as an interface
between core and armor layer in order to prevent the core material to be washed out
through the pores of the armor layer (Papadopoulos D. 2012).
• Armor layer: This layer is responsible for withstanding the forces imposed by the wave
action during design conditions. Here, in case that natural stones are used, the gradation
is lower. Apart from natural stones, when the design conditions are very demanding (high
design wave height) or when there is a lack of natural material concrete armor units are
used (Papadopoulos D. 2012).
• Toe bund: It serves as a lower wedge for the armor layer, limiting the risk of slipping of
this layer, and offers of the latter, and it offers additional security against scouring at the
toe of the structure (SHARP, N and al 1997).
• Bedding layer: In some cases, when constructing breakwaters in deep areas, a bedding
layer may be required to provide a stable foundation for the breakwater structure. The
bedding layer consists of low-cost materials chosen based on the hydrodynamic
conditions and stability requirements of the breakwater. The weight and composition of
the bedding layer are determined to ensure proper support and stability for the
breakwaterj(SHARP, N and al 1997).
By combining these layers, rubble mound breakwaters effectively dissipate wave energy, protect
coastal areas, and maintain stability over time. The specific design and composition of each layer
depend on various factors such as wave conditions, site-specific requirements, and available
construction materials. Proper design and construction practices are crucial for the effective
performance and longevity of rubble mound breakwaters.
IV.3. Design of rubble mounds breakwaters
The design of maritime structures requires the definition of criteria that give the expected
behavior of the structure. Many empirical methods for the prediction of the size of armor stone
required for stability under wave attack have been proposed one of them the stability formulae
developed by Hudson (1953), Van der Meer (1988b).
For both formulas we will determine:
- Weight, thickness and number of blocks per square meter for the breakwater.
- Weight and thickness of filters.
- Design of Toe bund.
Design of rubble mounds breakwater
53
Rubble mound breakwaters are made up of several distinct layers that work together to dissipate
wave energy and maintain stability. The key components of a rubble mound breakwater include:
• Core: Its main function is to form the basis for the upper layers and to reduce the
transmitted energy. Most of the times consist of quarry run (stones 1 to 500kg) with
relatively large gradation (Papadopoulos D. 2012).
• Filter layer (under-layer/secondary armor layer): They are used as an interface
between core and armor layer in order to prevent the core material to be washed out
through the pores of the armor layer (Papadopoulos D. 2012).
• Armor layer: This layer is responsible for withstanding the forces imposed by the wave
action during design conditions. Here, in case that natural stones are used, the gradation
is lower. Apart from natural stones, when the design conditions are very demanding (high
design wave height) or when there is a lack of natural material concrete armor units are
used (Papadopoulos D. 2012).
• Toe bund: It serves as a lower wedge for the armor layer, limiting the risk of slipping of
this layer, and offers of the latter, and it offers additional security against scouring at the
toe of the structure (SHARP, N and al 1997).
• Bedding layer: In some cases, when constructing breakwaters in deep areas, a bedding
layer may be required to provide a stable foundation for the breakwater structure. The
bedding layer consists of low-cost materials chosen based on the hydrodynamic
conditions and stability requirements of the breakwater. The weight and composition of
the bedding layer are determined to ensure proper support and stability for the
breakwaterj(SHARP, N and al 1997).
By combining these layers, rubble mound breakwaters effectively dissipate wave energy, protect
coastal areas, and maintain stability over time. The specific design and composition of each layer
depend on various factors such as wave conditions, site-specific requirements, and available
construction materials. Proper design and construction practices are crucial for the effective
performance and longevity of rubble mound breakwaters.
IV.3. Design of rubble mounds breakwaters
The design of maritime structures requires the definition of criteria that give the expected
behavior of the structure. Many empirical methods for the prediction of the size of armor stone
required for stability under wave attack have been proposed one of them the stability formulae
developed by Hudson (1953), Van der Meer (1988b).
For both formulas we will determine:
- Weight, thickness and number of blocks per square meter for the breakwater.
- Weight and thickness of filters.
- Design of Toe bund.