拼宽桥梁沉降差容许值的确定及降低沉降差的措施

桥梁拼宽改造中新旧桥梁基础沉降差会给桥梁上部结构带来不利影响。文中讨论了桥梁拼宽的方案及其对桥梁结构行为的影响，提出了新旧桥梁沉降差容许值的概念，以及沉降差容许值的确定原则和方法，并通过对典型工况的分析给出了沉降差容许值的建议值。根据相关工程实践，总结了降低沉降差的措施，包括采用合适的基础类型、延迟接缝施工时间和对接缝部位进行防裂处理。

Determination of Allowable Limit and Measures of Reduction for Settlement Difference Between New and Old Foundations of Bridge Widening Projects

The settlement difference between new and old foundations of bridge widening projects can bring disadvantage effects to the superstructures of bridges.The scheme to spell the bridge＇s wide and its influence on the behavior of bridge structures is first discussed in this paper.And then the concept of the allowable limit of the settlement difference between old and new bridges,and the principle and the method of determining allowable limit of settlement differences are put forward.Through the a-nalysis of typical case study,the suggested values of allowable limit of settlement differences are a-chieved.At last,according to the relevant engineering practices,the measures to reduce the settle-ment differences,including choosing the appropriate base types,delaying the time of joint construc-tion and preventing cracks in the joint parts,are summed up.