Influence of irregularities in the rock underlayer on the stability of Xbloc<sup>Plus</sup>

Journal article (2020)

Authors

Ileen van den Berg Student, Dutch Process Innovators
Bas Hofland Hydraulic Structures and Flood Risk - CEG
Bas Reedijk Delta Marine Consultants
Research Group
Hydraulic Structures and Flood Risk (CEG) (TU Delft)
Copyright: © 2020 Ileen van den Berg, Bas Hofland, Bas Reedijk
DOI
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https://doi.org/10.1016/j.coastaleng.2020.103637
XblocPlus Breakwater Armour layer stability Placement irregularity Single-layer units
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Published Date

2020

Language

English

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Faculty

Civil Engineering & Geosciences

Department

Hydraulic Engineering

Research Group

Hydraulic Structures and Flood Risk

Abstract

Many rubble mound breakwaters are nowadays made with an armour layer consisting of single layer interlocking elements. The stability of these armour layers could well be influenced by the irregularity of the rock underlayer, as that influences the degree of interlocking. Especially for the new types of regularly placed armour, this might be an important factor for the stability. However, this aspect has not been studied widely yet. Therefore, this paper investigates the influence of irregularities in the underlayer on the stability of a type of single layer breakwater elements. Model tests have been conducted in which the irregularities in the underlayer were systematically varied. The irregularities in the underlayer and the orientations of breakwater elements were measured with 3D-scanning. The breakwater armour unit used in the tests is the XblocPlus. A new failure mechanism, not previously observed for breakwater elements, was found to initiate damage. Causing the armour to be pushed outward by a combined effect of the weight of the upper armour and the excessive hydraulic pressure of the remaining water under the armour layer. Especially large-scale convex (i.e. protruding outwards) undulations in the cross-shore direction influenced the stability of the armour layer. This influence has been quantified.