Xbloc
Encyclopedia
An Xbloc is an interlocking concrete block or armour unit designed to protect shores, harbour walls, seawall
s, breakwaters
and other coastal structures from the direct impact of incoming waves
. The Xbloc model has been designed and developed by Delta Marine Consultants (DMC) since 2001 and has been subjected to extensive research by several universities.
A typical cross section of a breakwater slope is shown in the figure above. The cross section of a shore protection is similar, but instead of a core, the soil material is protected. In both structures, the armour layer is placed on top of a filter layer which covers the fine material in the core of the breakwater (or the soil material of the shore). This filter layer must prevent the fine material washing away through the pores in the armour layer. Near the seabed the armour layer is generally supported by a rock toe.
can be used to construct the Xbloc formwork
, steel moulds are preferred as they can be used repetitively to produce large numbers of armour units.
Due to the shape of the Xbloc unit, a relatively simple formwork can be used which is made of a limited number of different steel plates. Since a single Xbloc unit can weigh up to 45 tons, the construction is done as close as possible to the area of application.
In contrast with the placement of other interlocking concrete blocks, the Xbloc unit does not have very stringent specifications about the orientation of each unit on a breakwater slope. Because of the shape of the Xbloc, each of the 6 sides of the unit is efficiently interlocking. Therefore the blocks easily find a position that fully activates the interlocking mechanism. This increases the rate of placing armour units on a slope.
Due to the random structure and high porosity of an Xbloc breakwater, an artificial reef
is created for different kinds of vegetation and animals.
Concrete blocks used for the same purpose are listed below. Like Xbloc, most of these blocks are commercial developments and patent
ed.
In the numerical simulations the filtration motion of the fluid within the interstices, which normally exist in a breakwater, is estimated by integrating the RANS equations, coupled with a RNG turbulence model, inside the voids, not using a classical equations for porous media.
The breakwaters were modelled, as it happens in the full size construction or in physical laboratory test, by overlapping three-dimensional elements and the numerical grid was thickened in such a way to have some computational nodes along the flow paths among the breakwater’s blocks (AccropodeTM, Core-locTM, Xbloc).
Seawall
A seawall is a form of coastal defence constructed where the sea, and associated coastal processes, impact directly upon the landforms of the coast. The purpose of a seawall is to protect areas of human habitation, conservation and leisure activities from the action of tides and waves...
s, breakwaters
Breakwater (structure)
Breakwaters are structures constructed on coasts as part of coastal defence or to protect an anchorage from the effects of weather and longshore drift.-Purposes of breakwaters:...
and other coastal structures from the direct impact of incoming waves
Ocean surface wave
In fluid dynamics, wind waves or, more precisely, wind-generated waves are surface waves that occur on the free surface of oceans, seas, lakes, rivers, and canals or even on small puddles and ponds. They usually result from the wind blowing over a vast enough stretch of fluid surface. Waves in the...
. The Xbloc model has been designed and developed by Delta Marine Consultants (DMC) since 2001 and has been subjected to extensive research by several universities.
Use
Concrete armour units are generally applied in breakwaters and shore protections. The units are placed in a single layer as the outer layer of the coastal structure. This outer layer is called the armour layer. The function of the armour layer in these structures is twofold. Firstly, it must protect the finer material below the armour layer against severe wave action. Secondly, the armour layer must dissipate the wave energy in order to reduce the wave run-up, overtopping and reflection. These two functions require a heavy, but porous armour.A typical cross section of a breakwater slope is shown in the figure above. The cross section of a shore protection is similar, but instead of a core, the soil material is protected. In both structures, the armour layer is placed on top of a filter layer which covers the fine material in the core of the breakwater (or the soil material of the shore). This filter layer must prevent the fine material washing away through the pores in the armour layer. Near the seabed the armour layer is generally supported by a rock toe.
Construction
The Xbloc consists of non-reinforced concrete, similar to other single layer armour units. Although both wooden and steel mouldsMolding (process)
Molding or moulding is the process of manufacturing by shaping pliable raw material using a rigid frame or model called a pattern....
can be used to construct the Xbloc formwork
Formwork
Formwork is the term given to either temporary or permanent molds into which concrete or similar materials are poured. In the context of concrete construction, the falsework supports the shuttering moulds.-Formwork and concrete form types:...
, steel moulds are preferred as they can be used repetitively to produce large numbers of armour units.
Due to the shape of the Xbloc unit, a relatively simple formwork can be used which is made of a limited number of different steel plates. Since a single Xbloc unit can weigh up to 45 tons, the construction is done as close as possible to the area of application.
Placement and Interlocking Mechanism
The Xbloc armour unit derives its hydraulic stability from its self weight and by interlocking with surrounding units. Due to the highly porous armour layer constructed with Xbloc units, the energy of the incoming waves will be absorbed. The Xbloc armour layer is therefore able to protect the rock in the under layer from erosion due to waves.In contrast with the placement of other interlocking concrete blocks, the Xbloc unit does not have very stringent specifications about the orientation of each unit on a breakwater slope. Because of the shape of the Xbloc, each of the 6 sides of the unit is efficiently interlocking. Therefore the blocks easily find a position that fully activates the interlocking mechanism. This increases the rate of placing armour units on a slope.
Due to the random structure and high porosity of an Xbloc breakwater, an artificial reef
Artificial reef
An artificial reef is a human-made underwater structure, typically built to promote marine life in areas with a generally featureless bottom, control erosion, block ship passage, or improve surfing....
is created for different kinds of vegetation and animals.
Concrete blocks used for the same purpose are listed below. Like Xbloc, most of these blocks are commercial developments and patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....
ed.
Advanced Numerical Study
The Maritime Engineering Division University Salerno (MEDUS) developed a new procedure to study, with a more detailed and innovative approach, the interactions between maritime breakwaters (submerged or emerged) and the waves, by an integrated use of CAD and CFD software.In the numerical simulations the filtration motion of the fluid within the interstices, which normally exist in a breakwater, is estimated by integrating the RANS equations, coupled with a RNG turbulence model, inside the voids, not using a classical equations for porous media.
The breakwaters were modelled, as it happens in the full size construction or in physical laboratory test, by overlapping three-dimensional elements and the numerical grid was thickened in such a way to have some computational nodes along the flow paths among the breakwater’s blocks (AccropodeTM, Core-locTM, Xbloc).
See also
- Artificial reefArtificial reefAn artificial reef is a human-made underwater structure, typically built to promote marine life in areas with a generally featureless bottom, control erosion, block ship passage, or improve surfing....
- Breakwater (structure)Breakwater (structure)Breakwaters are structures constructed on coasts as part of coastal defence or to protect an anchorage from the effects of weather and longshore drift.-Purposes of breakwaters:...
- Coastal managementCoastal managementIn some jurisdictions the terms sea defense and coastal protection are used to mean, respectively, defense against flooding and erosion...
- Coastal erosionCoastal erosionCoastal erosion is the wearing away of land and the removal of beach or dune sediments by wave action, tidal currents, wave currents, or drainage...
- Ocean surface waveOcean surface waveIn fluid dynamics, wind waves or, more precisely, wind-generated waves are surface waves that occur on the free surface of oceans, seas, lakes, rivers, and canals or even on small puddles and ponds. They usually result from the wind blowing over a vast enough stretch of fluid surface. Waves in the...
- SeawallSeawallA seawall is a form of coastal defence constructed where the sea, and associated coastal processes, impact directly upon the landforms of the coast. The purpose of a seawall is to protect areas of human habitation, conservation and leisure activities from the action of tides and waves...