Seismic dynamics of offshore breakwater on liquefiable seabed foundation     

《Soil Dynamics and Earthquake Engineering》2015

Offshore structures, such as composite breakwaters, are generally vulnerable to strong seismic wave propagating through loose or medium-dense seabed foundation. However, the seismically induced failure process of offshore structures is not well understood. In this study, seismic dynamics of a composite breakwater on liquefiable seabed foundation is investigated using a fully coupled numerical model FSSI-CAS 2D. The computation results show that the numerical model is capable of capturing a variety of nonlinear interaction phenomena between the composite breakwater and its seabed foundation. The numerical investigation demonstrates a three-stage failure process of the breakwater under seismic loading. In this process, the far-field seabed can become fully liquefied first, inducing excessive settlement of the structure, followed by significant lateral movement and tilting of the structure when the near-field soil progressively liquefies. The study demonstrates great promise of using advanced numerical analysis in geotechnical earthquake design of offshore structures.  相似文献   

软土中吸力式桶形基础倾覆承载性能离心模型试验     

朱斌  应盼盼  邢月龙 《岩土力学》2015,36(Z1):247-252

输电杆塔和风电机组基础主要承受上部结构倾覆弯矩荷载,倾覆承载性能是该类基础设计中的关键问题。针对饱和软黏土地基中的杆式结构桶形基础,通过开展位移控制循环加载、位移维持加载、力控制循环加载和单调静力加载离心模型试验,研究其倾覆承载能力。试验发现,当桶形基础达到极限承载力时其转动中心位置约在桶盖正下方0.8倍桶裙高度处;当循环倾覆弯矩幅值与极限抗弯承载力比值小于3/5时,桶形基础在循环过程中转角的累积难以持续增长,并逐渐趋于稳定;循环加载作用下土与结构相互作用刚度出现明显弱化,所获得的桶形基础循环弱化因子阈值约为0.15;位移维持加载的峰值荷载-位移曲线与单调静力加载的荷载-位移曲线较为一致,位移维持加载的谷值荷载-位移曲线对应的承载力较峰值荷载-位移曲线对应的承载力明显偏小,减少约30%～40%。  相似文献   

Three-dimensional analysis of wave attenuation by a submerged, horizontal, bottom-mounted, flexible shell   总被引：1，自引：0，他引：1  

Fata D. E. Dewi  Stergios I. Liapis  Raymond H. Plaut   《Ocean Engineering》1999,26(9):988

The effectiveness of a submerged, bottom-mounted, flexible breakwater is investigated numerically. The structure is a horizontal, hemicylindrical shell filled with water. Potential flow is considered, and steady-state motions caused by monochromatic waves are studied. The three-dimensional response to normal and oblique waves is determined using the finite element method and a boundary integral method. Results are presented for a shell with a length of 150 m and a radius of 4 m, situated in water having a mean depth of 6 m. They indicate that the structure is effective in reducing the incident wave intensity over a wide range of frequencies.  相似文献   

Three-dimensional analysis of submerged, moored, horizontal, rigid cylinders used as breakwaters     

Timothy W. Mays  Raymond H. Plaut  Stergios I. Liapis 《Ocean Engineering》1999,26(12):687

Wave attenuation by moored cylinders is considered. The cylinders are submerged with their axes horizontal. Linear potential theory is applied. Three-dimensional motions of the cylinders subjected to normal and oblique monochromatic waves are determined using potential theory and a boundary integral method. Each cylinder has length 9.1 m (30 ft) and radius 1.5 m (5 ft), with its top 1.5 m (5 ft) below the still water line and its bottom 3.0 m (10 ft) above the seabed. Free-surface elevations are obtained for a single cylinder and for two cylinders in series. These configurations are effective wave barriers for a range of wave frequencies and incident angles.  相似文献   

空间节省型堰式沉箱波浪反射与结构优化试验研究     

胡馨月  李超  梁书秀  薛庆仁  刘华政  张家硕 《海洋工程》2023,41(2):144-152

为了同时提升消浪效果和节省海岸空间,对低反射防波堤进行改进,提出了一种空间节省型堰式沉箱结构。通过物理模型试验研究了堰式沉箱在规则波作用下的消能机理,然后采用单因子分析法分析了相对淹没深度、波陡和相对波高对反射系数的影响,并且利用SPSS软件对无因次参数进行非线性回归分析得到了反射系数计算公式。结果表明,内堰消浪室可以形成良好的波能耗散机制,随着有效消浪室个数的增多,消浪效果逐渐增强,使得反射系数的最小值和最大值较非透空直立结构分别降低了60%～90%和10%～30%。基于以上研究成果,给出关于特征水位与内堰的相对位置关系的合理建议,并总结了堰式沉箱结构的优化设计要点,对实际工程应用具有一定的指导意义。  相似文献   

混合土层吸力筒沉贯阻力算法研究及应用     

黄锐  马远刚  王翔  何成园  孙国光 《海洋工程》2023,41(1):152-158

为补充DNVGL-RP-C212规范关于混合土层内吸力筒沉贯阻力计算参数的不确定描述,基于长乐外海风电场多个吸力筒基础的沉贯负压监测成果,对黏土—砂混合土层内吸力筒沉贯阻力算法进行研究。提出了基于黏粒含量确定侧阻力修正系数kf的算法,引入桩基工程中基于静力触探试验（CPT）的fs计算桩侧剪切强度的经验算法,并对其进行修正,用于计算吸力筒的沉贯侧阻力。对两种算法的准确性进行了验证,对其可靠性进行比较,提出了以前者计算结果为准,后者计算结果作为校核依据的建议。  相似文献   

中长周期波作用下的斜坡堤胸墙波浪力试验研究     

姜云鹏  韩新宇  吴进  陈汉宝  董胜 《海洋工程》2023,41(4):82-90

在印度洋、大西洋沿岸,海岸工程设计波浪周期多在14 s以上,具有显著的中长周期波特征。通过以往工程项目的试验结果发现中长周期波下,规范计算的斜坡堤胸墙波浪力明显小于试验结果。因此,通过系列物理模型试验研究了中长周期波下的斜坡堤胸墙波浪力。分析斜坡坡度、肩台宽度和波浪条件对胸墙波浪力的影响。通过将试验结果与我国现有规范中的经验公式计算所得结果进行对比,发现规范更适用于胸墙底淹没的情况,而对于肩台出水情况,规范计算结果小于试验结果。由此提出了一种新的波浪力计算方法,计算准确度得到明显提高。  相似文献   

Numerical study on the interaction among a nonlinear wave,composite breakwater and sandy seabed     

Dong-Soo Hur  Chang-Hoon Kim  Jong-Sung Yoon 《Coastal Engineering》2010

Most previous investigations related to composite breakwaters have focused on the wave forces acting on the structure itself from a hydrodynamic aspect. The foundational aspects of a composite breakwater under wave-induced cyclic loading are also important in studying the stability of a composite breakwater. In this study, numerical simulations were performed to investigate the wave-induced pore water pressure and flow changes inside the rubble mound of the composite breakwater and seabed foundation. The validity and applicability of the numerical model were demonstrated by comparing numerical results with existing experimental data. Moreover, the present model clearly has shown that the instantaneous directions of pore water flow motion inside the seabed induced by surface waves are in good agreement with the general wave-induced pore water flow inside the seabed. The model is further used to discuss the stability of a composite breakwater, i.e., the interaction among nonlinear waves, composite breakwater and seabed. Numerical results suggest that the stability of a composite breakwater is affected by not only downward shear flow generating on the seaward slope face of the rubble mound but, also, a high and dense pore water pressure gradient inside the rubble mound and seabed foundation.  相似文献   

Experimental Study of A Pile-Restrained Floating Breakwater Constructed of Pontoon and Plates   总被引：3，自引：3，他引：0  

王永学  董华洋  刘冲 《中国海洋工程》2010,24(1):183-190

A pile-restrained pontoon-plate floating breakwater is proposed in this paper.The laboratory physical-model tests are conducted to investigate the wave-dissipation property and heave-motion response of a model.The influence of the model′s geometric parameters including relative pontoon width,plate width,number of plates and pontoon draft on wave-dissipation performance and heave-motion response are discussed,as well as the correlation between these two factors.The result indicates that wave-dissipation performance of the proposed structure is better than the pontoon structure:its transmission coefficient and heave-motion height are reduced by 0.2 and 0.3,respectively,in comparison with those of the pile-restrained pontoon model at a relative pontoon width of 0.2.  相似文献   

T型防波堤与波浪相互作用数值研究     

何军  蒋昌波  李冬  邓斌 《海洋工程》2010,28(1)

针对T型透空式防波堤,通过浪高仪采集防波堤前后不同位置波面变化曲线,使用声学多普勒流速仪(NDV)测量不同位置流速随时间的变化,并分析了其相位平均流速的分布。基于VOF法的二维波浪数值水槽,对规则波作用下T型防波堤附近的动力特性进行了计算,水槽模型试验结果和数值模拟结果对比表明,数值计算结果与实验值吻合较好。采用该模型进一步对T型防波堤附近波浪场、流线、紊动动能、紊动动能耗散率变化以及不同尺寸的防波堤消浪效果进行模拟计算,重点分析了入射波高、防波堤入水深度和防波堤宽度变化的影响。  相似文献