Smart Rocking Armour Units

Smart Rocking Armour Units

Hofland, Bas (TU Delft Hydraulic Structures and Flood Risk; Deltares)
Arefin, Syed Shamsil (Institute of Water Modelling)
van der Lem, Cock (Royal HaskoningDHV)
van Gent, Marcel (Deltares)

2018

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.

Rocking
concrete armour units
rubble mound breakwater
gyroscope sensor

http://resolver.tudelft.nl/uuid:871621c7-02e1-4317-98ec-f608d9e0917a

Proceedings of the 7th International Conference on the Application of Physical Modelling in Coastal and Port Engineering and Science (Coastlab18): Santander, Spain, May 22-26, 2018

Institutional Repository

conference paper

© 2018 Bas Hofland, Syed Shamsil Arefin, Cock van der Lem, Marcel van Gent