大跨混凝土拱桥基础形式设计及结构验算方法探讨

Discussion on Foundation Form Design and Structure Checking Method of Long Span Concrete Arch Bridge

某370 m跨上承式混凝土拱桥为一无铰拱桥,基础形式设计以及结构验算方法影响到结构整体受力性能和安全性。文章介绍了该桥总体布置、施工方法以及桥位地质地形特征,在此基础上推出了3种基础形式方案,阐述了各方案的特点以及平立面布置。在综合比较工程量、工程复杂度以及工程风险的基础上推荐了嵌岩基础形式,并阐明其优缺点。文章还列举了现有设计规范手册中的嵌岩基础的结构验算方法,比较了2种嵌岩深度的计算方法,提出考虑拱脚剪力的计算方法偏于安全。文章还强调嵌岩深度基础除了深度外还必须验算轴力以及自身截面强度并给出计算要点。

A deck concrete arch bridge with a span of 370 m is a hingeless arch bridge, its foundation form design and structure computation methods will effect the structural behavior and safety of the bridge. In this paper, general layout, construction methods and geological characteristics of the bridge site are introduced firstly and three foundation form schemes are proposed for comparison with their characters, plane and facade layouts. Rock-socketed foundation is rec-ommended with its advantages and disadvantages set forth based on a comprehensive comparison of engineering quantity, engineering complexity and engineering risk. Subsequently checking computation methods of the rock-socketed founda-tion in current codes and handbooks are listed. Two rock-socketed depth computation methods are compared, and one with consideration of arch springing shearing force is considered safer. At last, checking computations of axial force and section strength are emphasized in the paper besides depth checking, and calculated main points shall be given.