考虑流固耦合群桩基础静动力响应分析

发布时间：2018-05-28 13:25

本文选题：深水群桩基础 + 静、动力特性　；参考：《合肥工业大学》2015年硕士论文

【摘要】：群桩基础作为跨海桥梁下部结构,为分析其静、动力响应,除考虑上部结构传递至群桩基础的重力荷载、长期流水作用外,还应考虑群桩基础处于海洋中受到的如波浪特殊动荷载。本文在查阅国内外相关文献后,依托实际跨海桥梁工程,取下部群桩基础与承台结构为研究对象,运用ANSYS Workbench软件建立有限元模型,分析其在考虑流固耦合作用时的静、动力响应特性,并得出以下结论：1、在进行群桩基础的静力分析时可知流速入口速度对群桩基础的静力特性的影响很大,两者呈线性正比关系；随着桩体的中心间距及桩体半径的增大,群桩基础最大应力及桩顶最大位移会减小,当桩径长比设计值大于0.06时,群桩基础安全隐患能降到最小；2、不论在静水或是波流场作用下群桩基础模态分析必须考虑流固耦合效应,在两种作用下得到的前四阶自振频率和振型是不同的,当考虑波流共同作用时,流体对群桩基础的阻尼增大,群桩基础的前四阶自振频率要小于静水中的自振频率,当静水水体的淹没深度超过群桩基础1/3时流固耦合效应开始加大；3、当分析改变波浪相关参数对群桩基础的模态影响时,对群桩基础前四阶自振频率影响最大的是波浪速度,影响最小的是波浪长度,波浪高度、长度和速度的改变对群桩基础的第四阶自振频率影响最大,而波向角的改变对群桩基础的第三阶自振频率影响最大；4、波浪高度的峰值时达到承台高度时,群桩基础的前四阶自振频率和振型改变将会趋向平缓,即在分析波浪高度对群桩基础模态的影响时,波高的有效值即波浪的峰值达到承台高度。
[Abstract]:In order to analyze the static and dynamic response of pile group foundation as the substructure of cross-sea bridge, in addition to considering the gravity load transferred from the superstructure to the pile group foundation, the effect of long-term flowing water is considered. Consideration should also be given to the special dynamic loads such as waves that the pile groups are subjected to in the ocean. After consulting the relevant literature at home and abroad, based on the actual cross-sea bridge engineering, taking the pile group foundation and cap structure as the research object, using ANSYS Workbench software to establish the finite element model, analyze its static when considering the fluid-solid coupling effect. The dynamic response characteristics and the following conclusions: 1. In the static analysis of pile group foundation, it is known that the velocity inlet velocity has a great influence on the static characteristics of pile group foundation, and the relationship between them is linear and positive. The maximum stress of pile group foundation and the maximum displacement of pile top will decrease with the increase of center spacing and radius of pile body. When the design value of diameter ratio of pile is greater than 0.06, the maximum stress of pile foundation and the maximum displacement of pile top will be decreased. The safety hidden danger of pile group foundation can be reduced to the minimum. No matter under the action of hydrostatic or wave-current field, the fluid-solid coupling effect must be taken into account in the modal analysis of pile group foundation, and the first four natural frequencies and modes obtained under the two kinds of action are different. When considering the interaction of wave and current, the damping of pile group foundation is increased, and the first four order natural vibration frequency of pile group foundation is smaller than that of static water. When the submerged depth of the hydrostatic water exceeds one third of the pile group foundation, the fluid-solid coupling effect begins to increase. When the modal effect of changing the wave related parameters on the pile group foundation is analyzed, the wave velocity is the most important factor affecting the first four natural frequencies of the pile group foundation. The change of wave length, wave height, length and velocity has the greatest influence on the fourth order natural vibration frequency of pile group foundation. The change of wave direction angle has the greatest influence on the third order natural vibration frequency of pile group foundation. When the peak wave height reaches the height of pile cap, the change of the first four order natural vibration frequency and vibration mode of pile group foundation will tend to be gentle. When analyzing the influence of wave height on the modal of pile group foundation, the effective value of wave height, i.e. the peak value of wave, reaches the height of pile cap.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U443.15

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