Wave load formulae for prediction of wave-induced forces on a slender pile within pile groups
Wave load formulae for prediction of wave-induced forces on a slender pile within pile groups
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DOI：
10.1016/j.coastaleng.2015.05.003
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发表时间：
2015-08
影响因子：
4.4
通讯作者：
Lisham Bonakdar;H. Oumeraci;A. Etemad-Shahidi
中科院分区：
文献类型：
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作者：
Lisham Bonakdar;H. Oumeraci;A. Etemad-Shahidi
在海上（例如海上石油和天然气平台）和沿海环境（例如海桥、码头和码头）中常见的桩支撑结构通常是通过一组不同排列的桩来建造的。正确预测这些结构的密距桩波荷载对安全性和经济性都具有重要意义。与单隔桩的大量研究以及目前仍广泛应用于计算波致力的著名Morison方程不同，对波桩群相互作用的研究较少。事实上，对于群桩内桩径D一般小于0.2倍波长L的细长桩，目前还没有可靠的波荷载公式来预测其波致力。在本研究中，利用在德国不伦瑞克的leichtweiss -水利工程和水资源研究所（LWI）的2米宽波浪水槽中进行的系统模型试验获得的一系列实验室数据，开发了新的波浪荷载公式，用于预测不同布置桩群中细长桩的波致力。为了分析实验室数据和开发新的预测公式，采用了一种基于人工智能（AI）的计算工具，称为“混合M5MT-GP模型”。新的混合模型和新的波浪荷载公式使我们能够系统地评估群桩效应（KG）作为流型（kc数）和每组试验桩的相对间距（SG/D）的函数。结果表明，在计算群桩中细长桩的波浪荷载时需要考虑群桩效应，除非kg = 1时相邻桩之间不存在干涉效应，群桩可视为单个隔震桩。采用一致性指数（accord index）、相关系数（correlation coefficient）和散点指数（scatter index）作为统计指标，验证了新公式预测群桩效应的准确性。
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 (KG) as a function of the flow regime (KCnumber) and the relative spacing (SG/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, unlessKG= 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 effectKGis confirmed by the statistical indicators using agreement indexIa, correlation coefficientCCand scatter indexSI.