高桩承台桩基波浪受力分析

Analysis of Wave Loads on the Grouping Pile Foundation with Slab Merged in Water

以深海桥梁建设中广泛采用的群桩基础为研究对象,发展了淹没承台下桩柱波浪作用力的工程计算方法。分析了承台效应系数随淹没深度、承台尺寸等参数的变化规律,并在时域内计算了波浪对桩柱的作用。承台与波浪的绕射问题采用基于势流理论和特征函数展开的解析法,绕射场内桩柱波浪力的计算采用Morison公式,通过与数值模拟的计算结果进行对比,验证了该方法的正确性。结果表明:不同的承台尺寸会使承台效应系数随浸入深度的变化有所改变。合力将随入射波数的增加而减小,合力点的变化将在特定波数下出现拐点。桩柱上波浪合力的最小值出现于承台迎浪一侧,最大值出现于承台背浪一侧及垂直于入射方向的承台两侧与背浪侧30°角范围内。承台的存在使得桩柱上的波向力出现偏向性并产生相位差,此时的群桩系数可取为0.7。

In order to get the wave loads on pile groups with slab merged in water ,an engineering approach was proposed .Three coefficients in terms of slab effect were discussed and a time-domain analysis of wave forces acting on piles was conducted .Wave diffraction from a slab was obtained by the potential theory and eigenfunction expansion method ,while wave loads on piles were evaluated by Morison formula .The wave force on pile obtained by the proposed method and the numerical simulation are in good agreement ,w hich shows a good reliability of the proposed method .The result shows that ,owing to the size of slabs ,there exist some differences in the changing rule of slab effect varying with the submerged depth .The resultant force decreases with the rise of incident wave number ,and the changing trend of its acting point appears an inflection point at some wave number .The minimum force acting on piles lies in the meeting-wave side of the slab ,while the maximum one arises at the back side or in the scope of 30 degrees between the axis of slab ,which is perpendicular to the incident wave ,and the back side .The presence of slab causes the deflexion and phase difference of inline force .Meanwhile ,the grouping piles coefficient can be taken as0.7.