悬索桥锚碇桩式基础位移及受力分析

Displacement and Mechanical Analysis of Pile Foundation for Suspension Bridge Anchorage

悬索桥锚碇可以采用群桩基础替代常用的重力式基础,通过分析已建成工程实例锚碇桩基础的布置方式、直径、土体效应对桥梁位移的影响,证明大直径群桩比小直径群桩及斜桩刚度大,抵抗水平荷载能力强。采用考虑摩擦滑动的桩土单元的有限元法,分析马鞍山长江公路大桥管柱基础锚碇方案的水平位移、竖向位移和桩侧土体应力所处的力学状态,结果表明:管柱基础锚碇的水平位移可以满足大跨悬索桥正常工作需要,桩侧土体应力在弹性范围之内,不至于产生蠕变导致锚碇后期水平位移的增加。

The group pile foundation can be used to replace the commonly-used gravity type foundation for suspension bridge anchorage. On the basis of the analysis of influence of the layout, diameters and soil effect of the pile foundations for anchorages of several practical examples of completed suspension bridges on the displacement of the bridges, the rigidity and capacity of resistance to the horizontal load of large diameter group piles are verified to be greater and stronger than those of small diameter group piles and batter piles. By using the finite element method of pile-soil element that takes into account of frictional slip, the horizontal displacement, vertical displacement and the mechanical conditions of pile side soil stress of the cylindrical shaft founda- tion of Maanshan Changjiang River Highway Bridge are analyzed. The results of the analysis sug- gest that the horizontal displacement of the cylindrical shaft foundation can satisfy the normal working requirement of long span suspension bridge and the pile side soil stress is still in the elastic range, which will not cause creep and further lead to the increase of late period displacement of the anchorage.