Physical model tests were performed in a wave flume at Deltares with rock armoured slopes. A shallow foreshore was present. At deep water the same wave conditions were used but, by applying different water levels, the wave loading on the rock armoured slopes increased considerably with increasing water levels. This allows the assessment of effects of sea level rise. Damage has been measured by using Digital Stereo Photography (DSP) which provides information on each individual stone that has been displaced. Two test series have been performed five times. This allows for a statistical analysis of the damage to rock armoured slopes. The statistical analysis demonstrates the need to take the spreading around a mean damage into account in the design of rock armoured slopes. This is important in addition to characterising the damage itself by erosion areas and erosion depths. The relation between damage parameters such as erosion area and erosion depth has been obtained from the tests. Besides tests with a straight slope also tests with a berm in the seaward slopes have been performed. A method to take the so-called length effect into account has been proposed to extrapolate results from physical model tests to real structures. Use is made of standard deviations based on the presented model tests.@en

This paper describes a method to measure the rocking motion of lab-scale armour units. Sensors as found in mobile phones are used. These sensors, data-storage and battery are all embedded in the model units, such that they can be applied without wires attached to them. The technique is applied to double-layer units in order to compare the results to the existing knowledge for this type of armour layers. In contrast to previous research, the gyroscope reading is used to determine the (rocking) impact velocities. Two pioneer measurement series are described. From the readings both the temporal distribution of rocking can be inferred, as well as the spatial distribution. The temporal probability distribution for the rocking events seems logarithmic, with the impact velocity u2% being in the same order of magnitude as those reported earlier. These measurements indicate that for a randomly placed cube in an armour layer most rocking and most violent impact velocities occur about 2Dn under the waterline, instead of around the waterline. Moreover, the wave steepness is seen to have an effect on the rocking intensity. From the measurements with multiple units it can be seen that the measured impact velocity exhibits a large spatial variation among different units at an otherwise equal location.@en

In order to design reliable coastal structures, for present and future scenarios, universal and precise damage assessment methods are required. This study addresses this need, and presents improved damage characterization methods for coastal structures with rock armoured slopes. The data used in this study was obtained from a test campaign carried out at Deltares within the EU Hydralab+ framework. During these tests, advanced measuring techniques (Digital Stereo Photography) were used, which are able to survey the full extension of the structure and identify local variations of damage. The here proposed damage characterisation method is based on three fundamental aspects: clear damage concepts, precise damage parameters and high resolution measuring techniques. Regarding damage concepts, first the importance of the characterization width is studied. For damage parameters obtained from the maximum erosion depth observed in a given width (E3D,m), the measured damage increases continuously with increased characterization width. But for damage parameters obtained from width-averaged profiles (S and E2D), the measured damage reduces with increased characterization width. Second, a new definition of damage limits (damage initiation, intermediate damage and failure) is presented and calibrated. Regarding the damage parameters, the parameter E3D,5, which describes the maximum erosion depth within the characterization width, is recommended as a robust damage parameter for conventional and non-conventional configurations based on three main characteristics: its low bias, its low random error, the ability to distinguish damage levels and is its validity and suitability for all types of structures (conventional and non-conventional). In addition, the results from this study show that the damage measured with the damage parameter E3D,5 presents an extreme value distribution.@en

A method to quantify, analyse, and present the settlement of single-layer concrete armour layers of coastal structures is presented. The use of the image processing technique for settlement analysis is discussed based on various modelling studies performed over the years. The accuracy of the technique is assessed, and the application of the technique to various parts of coastal structures (trunk, roundhead, bed protection, crest element) and various types of armour units is discussed. Moreover, conclusions are drawn on the role of the toe structure on the stability of breakwater armour layers.@en