桥梁新、旧基础协同作用荷载重分配预加载系统

A Preloading System of Load Redistribution for Joint Action of New and Old Bridge Pile Foundations

为保证美国亚历山大-汉密尔顿大桥新桩基础在施工后能和原桩基础协调工作,设计了1套荷载重分配预加载系统,将现有上部结构条件下的荷载在新、旧桩基础间重新分配,即对原有桩基础进行卸载,并将这部分荷载同步转移到新桩基础,使新、旧桩基础的承载力处于相对的动态平衡状态。该项技术的运用保证了对现有桥梁上部结构的承载,在新桩基础的沉降基本稳定后,浇筑新、旧桩基础承台间后浇带,将承台连成整体,使新、旧桩基础的协同作用在分担桥梁上部结构新增荷载前实现,从而达到桥梁上部结构改造后新、旧基础的协同作用。

To ensure that the new pile foundations of the Alexander Hamilton Bridge, America could work jointly with the old pile foundations after construction, a preloading system of load redistribution was designed and the load under existing conditions of the superstructure of the bridge was hence redistributed between the new and old pile foundations. That was, the old pile foundations were firstly unloaded and the part of the load from the foundations was at the same time transferred to the new pile foundations to keep the bearing capacity of both the new and old pile foundations in a state of relative dynamic balance. The utilization of the technique as de- scribed guaranteed the bearing capacity necessitated by the superstructure and after the settlement of the new pile foundations was basically stable, the parts between the piles caps of the new and old pile foundations were then cast with concrete to connect each two pile caps into an integrity, to realize the joint action of the new and old pile foundations before they were to share the newly added load from the superstructure and to finally achieve the joint action of the new and old pile foundations after completion of the rehabilitation of the superstructure.