Coastalock™ Performance on a Permeable Breakwater Slope: Model Tests on the Influence of a Permeable Core, Unit Modifications and Toe Support on the Hydraulic Performance of an Ecological Armour Unit

Coastal areas face increasing threat from erosion. The use of coastal protection structures is imperative to counter this. Concrete “armouring” is widely used due to durability and cost-effectiveness. Conventional methods of “armouring” result in habitat degradation and loss of biodiversity. ECOncrete developed Coastalock, an armour unit...

Assessing the Important Factors for Obtaining Technological Dominance in the Concrete Armour Unit Industry

The concrete armour unit industry exist for more than 70 years, in this period various units were developed. The first units derived their hydraulic stability on their own weight, later the units got more complex shapes and got interlocking capabilities. The first interlocking units were placed in a two-layer configuration, like Tetrapod and...

Homogeneous detached composite breakwater: CFD study of the design sensitivities in the 2D geometrical layout using a detached homogeneous low-crested structure to reduce sea wall overtopping

In this research OpenFOAM is used to model and determine the complex hydrodynamic behaviour of a Homogeneous low-crested structure (HLCS) consisting of cubipod artificial concrete elements. The validated model is used to gain insight in the design sensitivities of a two dimensional cross sectional layout to reduce sea wall overtopping. HLCS and...

Experimental investigation of the spatial and temporal variation of rocking armour units: Rocking Revisited V

The purpose of this MSc thesis is to do an experimental study into the spatial and temporal variation of rocking armour units. Armour units on a breakwater slope under wave loading can sometimes start to move back and forth, this phenomenon is known as rocking. Rocking can lead to significant impacts between armour units, which can result in...

Rocking revisited 4: Analysis of rocking-induced stresses for concrete breakwater armour units

When a breakwater is under heavy wave attack, the concrete armour units will occasionally move, causing a collision between two concrete armour units. This process is called rocking, and induces stresses in the concrete, that may lead to breakage of the concrete armour units. This MSc Thesis provides a probabilistic method to predict breakage of...

Rocking of single layer armour units: Rocking revisited 3

After the failure of several large breakwaters in late 1970’s and early 1980’s where the role of rocking and breakage of armour became apparent, the importance of understanding this rocking phenomenon is given a great emphasis. Single layer randomly placed armour units are widely used in breakwater designs as they are more economical due to the...

Stability Optimisation of the top armour row of a breakwater with Xbloc^Plus units

The Xbloc^Plus (referred to as Xbloc+) is a new, uniformly placed single layer armour unit, developed by Delta Marine Consultants (BAM Infraconsult). Although a breakwater armour layer with Xbloc^Plus combines material saving and easy placement with increased stability, the transition between the armour layer and the crest is...

Effect of irregularities in the under layer on the stability of Xbloc^Plus concrete armour unit

The Xbloc^Plus is a new type of single layer armour unit for breakwaters. The key difference between earlier single layer armour units is that the unit is not only placed in a regular grid, but also with a regular orientation. The main benefit of this is that it can directly be seen whether the unit is placed correctly. Additionally,...

Exploration into the mechanisms that govern the stability of an Xbloc^{+ v1} armour unit

In this MSc thesis it is investigated how the first version of concrete armour unit Xbloc⁺, Xbloc^{+ v1}, acquires its stability. The stability mechanisms are investigated by conducting two type of physical model tests. First, 23 dry pull-out tests are done to obtain insights into the aspects and mechanisms that influence the...

Rocking Revisited 1: Rocking of a Singe Cube on a Breakwater Slope

Prototype single layer armour units on a breakwater slope are observed to break. To predict when breakage occurs, the objective of this research project is to obtain knowledge on, and measurements of the rocking behaviour and failure mode of single layer armour units. A single cube on a breakwater slope is subjected to investigations. An...

The influence of the wave height distribution on the stability of single layer concrete armour units

The dimensions of single layer concrete armour units (interlocking armour units) are calculated with a similar stability relation as the stability relation for quarry stone. In these design formulas an 'average/significant' wave load is used (Hs). Since quarry stone gains its stability only from gravity, this type of armour unit is constructed...

Static and dynamic loads on the first row of interlocking, single layer armour units

Interlocking, single layer concrete armour units are placed in a specific grid depending on the type of armour unit. Within this grid, armour units are placed in horizontal rows. The number of horizontal rows of single layer armour units on a breakwater is limited to 20. This limit is proposed in order to prevent major settlements, which might...

Extraction Force Xbloc: Model Tests

This report describes the influence of the slope angle of a breakwater slope, the density of the concrete of the Xbloc armour unit, the vertical position of the Xbloc on the breakwater slope and the roughness of the under layer of the breakwater on the extraction force of an Xbloc armour unit. By testing the extraction force, indirectly the...

Stability of single layer armour units on low-crested structures

Two dimensional physical model tests are executed with Xbloc armour units on low crested structures to answer the objective. On the basis of findings in the literature study it can be expected that the stability of the Xbloc elements on low-crested breakwaters is a function of crest freeboard and crest width. The crest freeboard (Rc/Dn) varied...

Effect of the concrete density on the stability of Xbloc armour units

This thesis is about the influence of the specific weight on the stability of single layer interlocking armour units on rubble mound breakwaters. The hydraulic stability of the Xbloc armour unit is expressed by the stability number which is based on the assumption of dominance of lift, drag and gravity forces. If other forces have significant...

Concrete armour units for breakwaters: A study on the structural integrity

One of the most basic types of breakwaters is the rubble mound breakwater which in essence is a heap of stones consisting of a core of fine material covered by an armour layer of big rock or concrete elements. Mostly unreinforced, these concrete elements exist in different sizes and geometries varying from massive concrete cubes to more...

Kostenbeschouwing van conventionele golfbrekers met betonelementen

In een gebied als Nederland met een relatiefflauw oplopende kust, heeft de conventionele stortstenen golfbreker in het verleden de voorkeur gekregen boven andere typen golfbrekers. Binnen de brekerzone wordt de golfhoogte begrensd door de waterdiepte, wat de keuze ten aanzien van de conventioneIe stortstenen golfbreker bevestigt aangezien de...