Derivation of a New Model for Prediction of Wave Overtopping at Rubble Mound Structures

2015

Coastal Engineering

Self Cite

Pile-supported structures commonly found in both offshore (e.g. offshore oil and gas platforms) and coastal environments (e.g. sea bridges, piers and jetties) are generally built by means of a group of piles in different arrangements. The correct prediction of the wave loading of closely-spaced piles of these structures is vital for both safety and economical viewpoints. Unlike single isolated piles, where a large number of studies are available together with the well-known Morison equation which is still widely applied for the calculation of wave-induced force, less research studies have been made on wave-pile group interactions. In fact, no reliable wave load formula is yet available for the prediction of wave-induced forces on a slender pile, for which the pile diameter (D) is generally less than about 0.2 times the wave length (L), within a pile group. In this study, new wave load formulae for the prediction of wave-induced force on a slender pile in pile groups with different arrangements are developed using a series of laboratory data obtained from systematic model tests conducted in the 2 m-wide wave flume of Leichtweiss-Institute for Hydraulic Engineering and Water Resources (LWI) in Braunschweig, Germany. For the analysis of the laboratory data and the development of the new prediction formulae, an artificial intelligence (AI)-based computational tool, named "hybrid M5MT-GP model", is implemented. The new hybrid model and the new wave load formulae allow us to systematically assess the pile group effect (K G ) as a function of the flow regime (KC number) and the relative spacing (S G /D) for each tested pile group arrangement. The results show that the pile group effect needs to be considered in calculating wave loads on the slender piles in pile groups, unless K G = 1 where there is no interference effect between neighbouring piles and piles in the group can be treated as a single isolated pile. The accuracy of the new formulae in predicting pile group effect K G is confirmed by the statistical indicators using agreement index I a , correlation coefficient CC and scatter index SI.

mentioning

confidence: 99%

Wave load formulae for prediction of wave-induced forces on a slender pile within pile groups

Bonakdar

Oumeraci

2015

Coastal Engineering

Self Cite

“…In order to improve the prediction accuracy, Verhaeghe et al (2008) developed a 2-phases neural prediction model to classify and quantify the overtopping rate. However, by contrast to empirical approaches, ANN models lacks transparency and do not provide physical insight (Jafari and Etemad-Shahidi, 2012).…”

Section: Introductionmentioning

confidence: 99%

Prediction of wave overtopping at vertical structures

Shaeri

Jafari

2016

Coastal Engineering

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Prediction of wave overtopping rate is an important step in the functional design of vertical coastal structures. In this study, scaling arguments and data mining approaches were used to derive formulae for the prediction of wave overtopping rate at vertical and nearly vertical structures. An extensive database mainly selected from the CLASH including impulsive and non-impulsive, low and high freeboard and composite structures were used for formula development. The obtained dimensionless overtopping rates were compared with those of existing formulae. The performances of formulae were assessed quantitatively using laboratory experiments, and it was shown that the developed formula is more accurate than the previous ones. In addition, the developed formula was validated using field measurements. Results indicated that the developed formula which considers the effects of all governing parameters performs better than the previous empirical formulae in predicting the overtopping rate in both laboratory and field experiments.

“…Recently, decision tree has been successfully used in the field of ocean and coastal engineering (e.g. ; Kambekar and Deo, 2010;Jafari and Etemad-Shahidi, 2012). In this study, once the basic regimes are classified by the decision tree, nonlinear multi-variable regression is used to develop the formulas.…”

Section: Introductionmentioning

confidence: 99%

New formulae for prediction of wave overtopping at inclined structures with smooth impermeable surface

Jafari

2014

Ocean Engineering

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Reliable prediction of wave overtopping rate has an important role in the design and safety assessment of coastal structures. In this study, the selected data from the CLASH database were used to provide new formulas for the estimation of wave overtopping at simple sloped inclined seawalls or dikes with smooth impermeable surface. To develop the formulas, the decision tree approach together with the nonlinear regression provided by SPSS was used as a novel procedure. The conventional governing parameters were used as the input and output variables. The accuracy of the new formulas was then compared to those of previous ones and the measurements. It was shown that the presented formulas outperform the existing ones in the prediction of small and large scale overtopping rates at inclined impermeable coastal structures such as dikes and seawalls.