WAVE-INDUCED LOADING OF SUBMERGED CORE-LOC ARMOUR UNITS TOMASZ KOZLOWSKI Thesis submitted to the University of Ottawa in partial Fulfillment of the requirements for the degree of Master of Applied Science Department of Civil Engineering Faculty of Engineering University of Ottawa © Tomasz Kozlowski, Ottawa, Canada, 2021 ABSTRACT This study investigates the relationship between wave-induced hydrodynamics and the resulting loading on Core-Loc concrete armour units below the still water level in a breakwater structure. Physical modelling experiments were performed at the National Research Council in Ottawa in which a 3D-printed 12 cm Core-Loc armour unit was instrumented and fixed in place within a rubble mound structure. Testing featured simultaneous measurement of force on this instrumented unit, pressure head at the base of the unit, and flow velocities below the SWL. Two main scenarios were tested, the isolated unit and fully armoured scenarios, under a range of regular waves and irregular sea states. Analysis of force development on the instrumented unit indicates that maximum slope-normal forces (both into and away from the structure) are associated with extremes in pressure head above the instrumented unit, while slope-parallel force extremes (both upslope and downslope) occur at times of the fastest change in water level. These loadings are consistent with Morison’s equation and imply drag dominance in the slope-parallel direction and inertia dominance in the slope-normal direction. Significant differences in forces were observed between isolated (no neighbouring units) and embedded (with neighbouring units) armour unit test cases. The presence of the armour layer significantly increased the normal force exerted on the unit and reduced the parallel force. Irregular sea state testing shows force peaks following normal distribution. Analysis of flow above the armour layer showed that force, flow velocity and flow acceleration are symmetrical in the slope-parallel direction, but largely asymmetrical in the slope-normal direction, with the flow velocity and force on the unit in particular experiencing large asymmetries. Wave height analysis indicated that each wave height follows a similar force development pattern with a magnitude proportional to wave height. Wave period analysis showed the formation of small secondary waves as the period increases. Wave steepness affected the peak force loading of the instrumented unit in a mostly linear fashion up to the critical Iribarren number. ii ACKNOWLEDGEMENTS I wish to express my sincere gratitude to my supervisors, Dr. Ioan Nistor and Dr. Andrew Cornett. Their persistent support, guidance, and experience were essential to the realization of this project. I am grateful for their leadership, technical expertise, and attention to detail, without which the goals of this project would not have been realized. I would like to acknowledge as well the work of the project team that preceded me and with whom I was afforded the privilege of working alongside, including Steven Douglas, Derek Eden, Adrian Simpalean, as well as colleagues at Imperial College London. This research was conducted at the National Research Council of Canada’s Ocean, Coastal and River Engineering Research Centre. The assistance of the technical staff at NRC-OCRE is acknowledged with appreciation. This study would not have been possible without the support of Baird & Associates, as well as grant funding received for the project from NSERC-CRD. Additionally, while not directly related to this thesis, I would like to thank Drs Hofland and Bricker for hosting me at TU Delft during the summer of 2019. Finally, I would like to thank my friends, family, and in particular my fiancée Brenda, for their unwavering support throughout the course of this study. iii Table of Contents Abstract ............................................................................................................................................ii Acknowledgements ......................................................................................................................... iii Table of Figures ............................................................................................................................... vi Table of Tables ................................................................................................................................ ix List of Symbols ................................................................................................................................ ix List of Abbreviations and Acronyms ............................................................................................... xi 1 Introduction ............................................................................................................................. 1 1.1 Research Needs ................................................................................................................ 2 1.2 Scope ................................................................................................................................ 3 1.3 Novelty and Contributions ............................................................................................... 4 1.4 Thesis Structure ................................................................................................................ 4 2 Literature Review .................................................................................................................... 5 2.1 Rubble mound breakwaters ............................................................................................. 5 2.1.1 Breakwater Types ..................................................................................................... 5 2.1.2 Geometry of Breakwater Cross-sections and Typical Features ................................ 7 2.1.3 Armourstone ............................................................................................................. 7 2.1.4 Concrete Armour Layer Properties ........................................................................... 9 2.1.5 Core-Loc Armour Units ........................................................................................... 10 2.1.6 Breakwater Failure Modes of Main Armour Layer ................................................. 11 2.2 Armour Layer Design ...................................................................................................... 13 2.2.1 Damage Number Nod and Nd ................................................................................... 14 2.2.2 Hudson Formula ...................................................................................................... 14 2.2.3 Van der Meer Formula ............................................................................................ 15 2.2.4 Accropode Stability ................................................................................................. 16 2.2.5 Core-loc Stability ..................................................................................................... 17 2.2.6 Stability Comparison of Concrete Armour Units .................................................... 18 2.3 Breakwater Hydrodynamics ........................................................................................... 19 2.3.1 Hydraulic Conditions ............................................................................................... 19 2.3.2 Breakwater Flow Patterns ...................................................................................... 23 2.3.3 Flow Velocities ........................................................................................................ 23 2.3.4 Flow Forces ............................................................................................................. 24 iv 2.3.5 Pull-out Force .......................................................................................................... 27 2.3.6 Externally Induced Force......................................................................................... 27 2.4 Motivation for Current Research ................................................................................... 29 3 Methodology ......................................................................................................................... 35 3.1 Experimental Facility ...................................................................................................... 35 3.2 Wave Flume .................................................................................................................... 35 3.3 Concrete Armour Units .................................................................................................. 37 3.4 Test Conditions ............................................................................................................... 40 3.5 Experimental Procedure ................................................................................................. 44 3.6 Instrumentation ............................................................................................................. 44 3.7 Wave Synthesis and Generation .................................................................................... 45 3.8 Scale Effects .................................................................................................................... 47 3.9 Data Processing .............................................................................................................. 47 3.9.1 Load Cell Signals .....................................................................................................