基于流固耦合效应的深水群桩基础模态分析  

Modal analysis for deep water pile-group foundation under the effect of fluid structure interaction

作　　者：顾颖[1] 巫绪涛[1] 方诗圣[1] 王文洋[1] 

机构地区：[1]合肥工业大学土木与水利工程学院,合肥230009

出　　处：《应用力学学报》2015年第5期828-832,899-900,共5页Chinese Journal of Applied Mechanics

摘　　要：为研究流固耦合作用下深水群桩基础的固有频率及振动模态,依托某实际工程,用ANSYS软件建立水体作用下群桩的有限元模型;对基础结构与流体相互作用的深水群桩分别采用直接耦合法、单向耦合法、双向耦合法进行分析,并通过与已有实验结果对比,验证了三种计算方法的可靠性;分析计算了不同水体淹没深度时群桩基础固有频率与振动模态的变化规律。研究表明:在水体作用下,群桩基础各阶频率均随淹没深度的不断增加而逐渐减小,直接耦合法和双向耦合法计算水深从0m变化至19m时的一阶频率降幅分别为2.61%和4.00%;群桩基础的湿模态振动特性与干模态有显著区别,例如在基于双向耦合法情况下,干模态三阶扭转频率比湿模态大7.58%;当水体的淹没深度超过群桩基础1/3时流固耦合效应对群桩基础的振动特性影响开始增大;群桩基础的扭转频率受流体影响要比弯曲频率大,在其设计时更需考虑群桩的扭转频率受流体的影响程度。To study the inherent frequencies and vibration modes of deepwater pile-group foundation under fluid structure interaction, based on an actual engineering project, and finite element analysis software ANSYS is used, pile-group models under water are built in this paper. Inherent frequencies and vibration modes of deepwater pile-group foundation in different fluid-depths are calculated with direct fluid-structure interaction(direct FSI), unidirectional fluid-structure interaction(unidirectional FSI) and bidirectional fluid-structure interaction(bidirectional FSI) methods, respectively. The results are confirmed by test. Research results indicate that: Under water, pile-group's frequencies reduce gradually with the water depth increasing, when the water depth changes from 0m to 19 m, the first order frequency's reductions are 2.61% and 4.00%, respectively, with direct FSI and bidirectional FSI methods. Pile-group's wet modes have significant difference with dry modes, for example, based on bidirectional FSI method, the third order frequency of dry mode is 7.58% larger than the one of the wet mode. When the fluid-depth reaches nearly one-third of the pile-group foundation, the effect of fluid-structure interaction begins to increase. Torsional frequencies of foundation suffer the fluid impact more than bendingfrequency, which therefore needs to be more considered during design.

关 键 词：深水群桩基础 流固耦合 直接耦合法 双向耦合法 模态分析 

分 类 号：U443.13[建筑科学—桥梁与隧道工程] U441.3[交通运输工程—道路与铁道工程]