Stability Number of Additionally Placed Armor Unit (Tetrapod) Covered on Existing Two-Layered Tetrapod Rubble Mound Structures: Pattern Placing Condition

The stability number for rubble mound breakwaters is a function of several parameters and depends on unit shape, placing method, slope angle, relative density, etc. In this study two different densities for cubes in breakwater armour layers were tested to determine the influence of the density on the stability. The experimental results show that the stability of high density blocks were found to be more stable and the damage initiation for high density blocks started at higher stability numbers compared to normal density cubes.

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IRREGULAR WAVE TESTS FOR COMPOSITE BREAKWATER FOUNDATIONS

Coastal Engineering Proceedings ◽

10.9753/icce.v18.128 ◽

1982 ◽

Vol 1 (18) ◽

pp. 128 ◽

Cited By ~ 1

Author(s):

Katsutoshi Tanimoto ◽

Tadahiko Yagyu ◽

Yoshimi Goda

Keyword(s):

Wave Height ◽

Significant Wave Height ◽

Irregular Waves ◽

Stability Number ◽

Regular Waves ◽

Significant Wave ◽

Irregular Wave ◽

Concrete Blocks ◽

Rubble Mound ◽

The Stability

The stability of armor units for the rubble mound foundations of composite breakwaters has been investigated under the action of irregular waves. The tests establish that irregular waves are more destructive than regular waves, when the height of regular waves is set equal to the significant wave height. The stability number, defined by Hudson, for quarry stones and concrete blocks with simple shapes is formulated on the basis of irregular wave tests. The stability number is expressed by two parameters of h'7/7]/3 and K, where h' is the crest depth of the rubble mound foundation, #1/3 is the design significant wave height, and K is a parameter for the combined effects of the relative water depth and the relative berm width of the rubble mound foundation to the wavelength. The design mass of armor units can be calculated by the stability equation with the stability number. The application of the proposed method to the results of the irregular wave tests demonstrates that the damage percent for the quarry stones is at most 3.5% at the design condition and the damage progresses rather gradually for the action of higher waves. On the other hand, the damage of the concrete blocks almost jumps beyond the design wave height. In particular, the drastic damage is often caused in the case of high rubble mound foundations. The proposed method is confirmed, however, to be applicable for the ordinary low mound foundations with a sufficient safety.

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Least Squares Support Vector Mechanics to Predict the Stability Number of Rubble-Mound Breakwaters

Water ◽

10.3390/w10101452 ◽

2018 ◽

Vol 10 (10) ◽

pp. 1452 ◽

Cited By ~ 6

Author(s):

Nuray Gedik

Keyword(s):

Neural Networks ◽

Artificial Neural Networks ◽

Least Squares ◽

Soft Computing ◽

Support Vector ◽

Stability Number ◽

Experimental Works ◽

Rubble Mound ◽

The Stability ◽

Rubble Mound Breakwaters

In coastal engineering, empirical formulas grounded on experimental works regarding the stability of breakwaters have been developed. In recent years, soft computing tools such as artificial neural networks and fuzzy models have started to be employed to diminish the time and cost spent in these mentioned experimental works. To predict the stability number of rubble-mound breakwaters, the least squares version of support vector machines (LSSVM) method is used because it can be assessed as an alternative one to diverse soft computing techniques. The LSSVM models have been operated through the selected seven parameters, which are determined by Mallows’ Cp approach, that are, namely, breakwater permeability, damage level, wave number, slope angle, water depth, significant wave heights in front of the structure, and peak wave period. The performances of the LSSVM models have shown superior accuracy (correlation coefficients (CC) of 0.997) than that of artificial neural networks (ANN), fuzzy logic (FL), and genetic programming (GP), that are all implemented in the related literature. As a result, it is thought that this study will provide a practical way for readers to estimate the stability number of rubble-mound breakwaters with more accuracy.

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Experiments on Stability of Tetrapods on Rear Slope of Rubble Mound Structures under Wave Overtopping Condition

Journal of Korean Society of Coastal and Ocean Engineers ◽

10.9765/kscoe.2021.33.6.357 ◽

2021 ◽

Vol 33 (6) ◽

pp. 357-366

Author(s):

Young-Taek Kim ◽

Jong-In Lee

Keyword(s):

Water Level ◽

Design Process ◽

Weight Ratio ◽

Stability Number ◽

Wave Overtopping ◽

Design Standard ◽

Side Slope ◽

Rubble Mound ◽

The Stability ◽

Design Water Level

In this study, hydraulic model tests were performed to investigate the stability of armor units at harbor side slope for rubble mound structures. The Korean design standard for harbor and fishery port suggested the design figures that showed the ratio of the armor weight for each location of rubble mound structures and it could be known that the same weight ratio was needed to the sea side and harbor side (within 0.5H from the minimum design water level) slope of rubble mound structures. The super structures were commonly applied to the design process of rubble mound structures in Korea and the investigation of the effects of super structures would be needed. The stability number (Nod = 0.5) was applied (van der Meer, 1999) and it showed that the armor (tetrapod) weight ratio for harbor side slope of rubble mound structures needed 0.8 times of that for sea side slope.

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