Armor Damage of Overtopped Mound Breakwaters in Depth-Limited Breaking Wave Conditions

Armor damage due to wave attack is the principal failure mode to be considered when designing conventional mound breakwaters. Armor layers of mound breakwaters are typically designed using formulas in the literature for non-overtopped mound breakwaters in non-breaking wave conditions, although overtopped mound breakwaters in the depth-induced breaking wave zone are common design conditions. In this study, 2D physical tests with an armor slope H/V = 3/2 are analyzed in order to better describe the hydraulic stability of overtopped mound breakwaters with double-layer rock, double-layer randomly-place cube and single-layer Cubipod® armors in depth-limited breaking wave conditions. Hydraulic stability formulas are derived for each armor section (front slope, crest and rear slope) and each armor layer. The front slope of overtopped double-layer rock structures is more stable than the front slope of non-overtopped mound breakwaters in breaking wave conditions. When wave attack increases, armor damage appears first on the front slope, later on the crest and, finally, on the rear side. However, once the damage begins on the crest and rear side, the progression is much faster than on the front slope, because more wave energy is dissipated through the armored crest and rear side.

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ROCK ARMOR DAMAGE IN DEPTH-LIMITED BREAKING WAVE CONDITIONS

Coastal Engineering Proceedings ◽

10.9753/icce.v36.papers.21 ◽

2018 ◽

pp. 21

Author(s):

Josep R. Medina ◽

MarÃa P. Herrera ◽

M. Esther GÃ³mez-MartÃn

Keyword(s):

Double Layer ◽

Breaking Wave ◽

Power Relationship ◽

Bottom Slope ◽

Stability Number ◽

Wave Flume ◽

Physical Tests ◽

Wave Conditions ◽

Rubble Mound Breakwaters ◽

Hydraulic Stability

The armor layer of a mound breakwaters is usually designed with a formula derived from physical tests in non-breaking wave conditions; however, most rubble mound breakwaters are placed in the wave breaking zone where the highest waves break before reaching the structure. The hydraulic stability formulas developed for rock-armored breakwaters in non-breaking conditions are not completely valid to characterize the hydraulic stability of these structures under depth-limited wave attack. In this study, five series of 2D physical tests were carried out on a bottom slope m=1/50 to analyze the hydraulic stability of double-layer rock armored breakwaters in depth-limited breaking wave conditions. Measurements taken by 12 wave gauges placed along the wave flume were compared with estimations of Hm0, H2% and H1/10 obtained from numerical model SwanOne. The significant wave height, Hm0, estimated or measured at a distance 3hs from the toe of the structure was the best characteristic wave to relate armor damage with stability number. The six-power relationship between dimensionless armor damage and stability number, found in this study, explained more than 94% of the variance in the damage observations. This relationship is valid for conventional non-overtopping double-layer rock-armored breakwaters on bottom slope m=1/50 and depth-limited breaking wave conditions.

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Influence of Mild Bottom Slopes on the Overtopping Flow over Mound Breakwaters under Depth-Limited Breaking Wave Conditions

Journal of Marine Science and Engineering ◽

10.3390/jmse8010003 ◽

2019 ◽

Vol 8 (1) ◽

pp. 3 ◽

Cited By ~ 1

Author(s):

Patricia Mares-Nasarre ◽

M. Esther Gómez-Martín ◽

Josep R. Medina

Keyword(s):

Neural Networks ◽

Flow Velocity ◽

Water Depth ◽

Single Layer ◽

Breaking Wave ◽

Bottom Slope ◽

Coastal Structures ◽

Wave Characteristics ◽

Physical Tests ◽

Wave Conditions

The crest elevation of mound breakwaters is usually designed considering a tolerable mean wave overtopping discharge. However, pedestrian safety, characterized by the overtopping layer thickness (OLT) and the overtopping flow velocity (OFV), is becoming more relevant due to the reduction of the crest freeboards of coastal structures. Studies in the literature focusing on OLT and OFV do not consider the bottom slope effect, even if it has a remarkable impact on mound breakwater design under depth-limited breaking wave conditions. Therefore, this research focuses on the influence of the bottom slope on OLT and OFV exceeded by 2% of incoming waves, hc,2% and uc,2%. A total of 235 2D physical tests were conducted on conventional mound breakwaters with a single-layer Cubipod® and double-layer rock and cube armors with 2% and 4% bottom slopes. Neural networks were used to determine the optimum point to estimate wave characteristics for hc,2% and uc,2% calculation; that point was located at a distance from the model toe of three times the water depth at the toe (hs) of the structure. The influence of the bottom slope is studied using trained neural networks with fixed wave conditions in the wave generation zone; hc,2% slightly decreases and uc,2% increases as the gradient of the bottom slope increases.

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DESIGN AND CONSTRUCTION OF THE WESTERN BREAKWATER FOR THE OUTER PORT AT PUNTA LANGOSTEIRA (A CORUÃ‘A, SPAIN)

Coastal Engineering Proceedings ◽

10.9753/icce.v35.structures.14 ◽

2017 ◽

pp. 14 ◽

Cited By ~ 1

Author(s):

Antonio Corredor Molguero ◽

M. Esther GÃ³mez-MartÃn ◽

Enrique PeÃ±a ◽

Josep R. Medina

Keyword(s):

Design Process ◽

Double Layer ◽

Atlantic Coast ◽

Single Layer ◽

Significant Problem ◽

Stability Tests ◽

Final Design ◽

New Challenges ◽

Filter Thickness ◽

Hydraulic Stability

This paper describes the design process, hydraulic stability tests and construction of the CubipodÂ® armored Western breakwater at Punta Langosteira (Outer Port of A CoruÃ±a, Spain), located on the Atlantic coast of Spain. The environmental, geotechnical, economic and logistic conditions favored randomly-placed Cubipods for single-layer armoring of the trunk. 3D hydraulic stability tests were carried out to validate the final design of the Western Breakwater; two models were tested with single- and double-layer Cubipod armors in the trunk and roundhead, respectively. Single-layer 25- and 30-tonne CubipodÂ® armors were used for the trunk section and a double-layer 45-tonne CubipodÂ® armor was used for the roundhead. During this project, new challenges were overcome, such as constructing a transition between single and double-layer armors, and manufacturing and handling of 45-tonne Cubipods. The transition in the armor thickness was solved by modifying the filter thickness under the main armor, to ensure a homogeneous external armor profile. Breakwater construction finished in November 2016 with no significant problem or delay in the original schedule.

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Predicting the overall horizontal bearing capacity of jack-up rigs using deck–foundation–soil-coupled model

Proceedings of the Institution of Mechanical Engineers Part M Journal of Engineering for the Maritime Environment ◽

10.1177/1475090220925908 ◽

2020 ◽

pp. 147509022092590

Author(s):

Qilin Yin ◽

Jinjin Zhai ◽

Sheng Dong

Keyword(s):

Bearing Capacity ◽

Failure Mode ◽

Double Layer ◽

Soft Clay ◽

Coupled Model ◽

Single Layer ◽

Horizontal Load ◽

Foundation Soil ◽

Failure Envelopes ◽

Jack Up

The overall bearing capacity of a jack-up rig under horizontal load is conducted using finite element models that consider the deck–foundation–soil interaction. In these models, the simplified horizontal load acts on the deck and increases until the platform loses its stability. The effects of the self-weight of the platform W and load direction α on the ultimate horizontal bearing capacity Hult are investigated, and W- Hult failure envelopes under different α conditions are obtained. Two typical seabed types, including the double-layer seabed of sand overlying soft clay and the single-layer seabed of sand, are considered. The results show that a critical self-weight Wcritical exists in the double-layer seabed. Based on Wcritical, the failure of the platform presents two different modes. When W < Wcritical, the windward leg is pulled up, and Hult increases with the increase in W. When W > Wcritical, the failure mode is the leeward leg or legs puncturing the bearing sand layer, and Hult decreases with the increase in W. In the single-layer seabed, the failure mode is the windward leg being pulled up, and Hult increases with the increase in W throughout the whole range. The W- Hult envelopes in these two types of seabeds are basically the same when W < Wcritical.

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Hydraulic stability of rock armors in breaking wave conditions

Coastal Engineering ◽

10.1016/j.coastaleng.2017.06.010 ◽

2017 ◽

Vol 127 ◽

pp. 55-67 ◽

Cited By ~ 10

Author(s):

Maria P. Herrera ◽

M. Esther Gómez-Martín ◽

Josep R. Medina

Keyword(s):

Breaking Wave ◽

Wave Conditions ◽

Hydraulic Stability

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Cubipod® Armor Design in Depth-Limited Regular Wave-Breaking Conditions

Journal of Marine Science and Engineering ◽

10.3390/jmse6040150 ◽

2018 ◽

Vol 6 (4) ◽

pp. 150 ◽

Cited By ~ 4

Author(s):

M. Gómez-Martín ◽

María Herrera ◽

Jose Gonzalez-Escriva ◽

Josep Medina

Keyword(s):

Water Depth ◽

Wave Breaking ◽

Experimental Methodology ◽

Small Scale ◽

Breaking Wave ◽

Regular Wave ◽

Empirical Formulas ◽

Physical Tests ◽

Wave Conditions ◽

Deep Water Wave

Armor stability formulas for mound breakwaters are commonly based on 2D small-scale physical tests conducted in non-overtopping and non-breaking conditions. However, most of the breakwaters built around the world are located in breaking or partially-breaking wave conditions, where they must withstand design storms having some percentage of large waves breaking before they reach the structure. In these cases, the design formulas for non-breaking wave conditions are not fully valid. This paper describes the specific 2D physical model tests carried out to analyze the trunk hydraulic stability of single- and double-layer Cubipod® armors in depth-limited regular wave breaking and non-overtopping conditions with horizontal foreshore (m = 0) and armor slope (α) with cotα = 1.5. An experimental methodology was established to ensure that 100 waves attacked the armor layer with the most damaging combination of wave height (H) and wave period (T) for the given water depth (hs). Finally, for a given water depth, empirical formulas were obtained to estimate the Cubipod® size which made the armor stable regardless of the deep-water wave storm.

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Duct Attachment on Improving Breaking Wave Zone Energy Extractor Device Performance

Energies ◽

10.3390/en14196428 ◽

2021 ◽

Vol 14 (19) ◽

pp. 6428

Author(s):

Krisna Adi Pawitan ◽

Hideki Takebe ◽

Hanley Andrean ◽

Shuji Misumi ◽

Jun Fujita ◽

...

Keyword(s):

Wave Energy ◽

Impact Pressure ◽

Breaking Wave ◽

Wave Zone ◽

Power Generator ◽

Energy Part ◽

Flow Through ◽

Early Exploration ◽

Wave Angle ◽

The Impact

A challenging wave energy converter design that utilized the denser energy part of the nearshore breaking wave zone to generate electricity was introduced in 2016 by Shintake. The Okinawa Institute of Science and Technology Graduate University’s project aims to take advantage of breaking wave energy to harness electricity. The 2016 version of the device consisted only of a bare turbine and power generator. Early exploration of the design recorded short periods and high impact wave pressures were experienced by the structure, with the turbine unable to harvest energy effectively. Additional structure to not only reduce incoming impact pressure but also increase the duration of water flow through the turbine was needed. These are the main reasons behind incorporating the duct attachment into the design. This paper show that the duct is capable of halving the impact pressure experienced by the turbine and can increase the energy exposure by up to 1.6 times the bare turbine configuration. Furthermore, it is also said that wave angle (β) = 40° is the critical angle, although the duct still increases wave energy exposure to the power take-off up to β = 60°.

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Cracking at the fold in double layer coated paper: the influence of latex and starch composition

TAPPI Journal ◽

10.32964/tj18.2.93 ◽

2019 ◽

Vol 18 (2) ◽

pp. 93-99

Author(s):

SEYYED MOHAMMAD HASHEMI NAJAFI ◽

DOUGLAS BOUSFIELD, ◽

MEHDI TAJVIDI

Keyword(s):

Mechanical Properties ◽

Double Layer ◽

Starch Content ◽

Single Layer ◽

Double Layers ◽

Coated Paper ◽

Coated Papers ◽

Coating Layers ◽

Scanned Images ◽

Packaging Paper

Cracking at the fold of publication and packaging paper grades is a serious problem that can lead to rejection of product. Recent work has revealed some basic mechanisms and the influence of various parameters on the extent of crack area, but no studies are reported using coating layers with known mechanical properties, especially for double-coated systems. In this study, coating layers with different and known mechanical properties were used to characterize crack formation during folding. The coating formulations were applied on two different basis weight papers, and the coated papers were folded. The binder systems in these formulations were different combinations of a styrene-butadiene latex and mixtures of latex and starch for two different pigment volume concentrations (PVC). Both types of papers were coated with single and double layers. The folded area was scanned with a high-resolution scanner while the samples were kept at their folded angle. The scanned images were analyzed within a constant area. The crack areas were reported for different types of papers, binder system and PVC values. As PVC, starch content, and paper basis weight increased, the crack area increased. Double layer coated papers with high PVC and high starch content at the top layer had more cracks in comparison with a single layer coated paper, but when the PVC of the top layer was low, cracking area decreased. No measurable cracking was observed when the top layer was formulated with a 100% latex layer.

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