岩溶区桥基拱形结构跨越方案设计

Design of Arch Structure across Bridge Foundation in Karst Area

岩溶地区桥梁基础的处理是国内外高速公路建设的重大技术难题之一。当桥基下方存在溶洞时,传统方案一般采取充填溶洞、改变桥墩跨度、桩基穿越溶洞、绕避等措施,但当桥址位置不能变更且不可避免要经过大型溶洞时,传统方案从经济、施工难度上考虑都不甚合理,而拱形结构跨越溶洞方案可以有效地解决此类问题。本文以坳背湾大桥为例,重点探讨了在该岩溶区桥基采用拱形结构跨越溶洞方案时合理拱型、拱轴线、拱高的选取方法,通过自行开发的拱结构内力计算程序,分析了主拱圈内力的大小和分布情况,并对坳背湾大桥拱形结构进行了设计,结果表明该方案切实可行且具有推广性,对岩溶地区和采空区的桥梁建设有一定的参考意义和使用价值。

Bridge foundation treatment in karst areas is one of the important technical problems of expressway construction at home and abroad.When there is a large cave under the bridge,the traditional measures are filling the cave,changing the pier span,cutting across the cave with piles,bypassing the cave and so on.But when the bridge location cannot be changed and the bridge will inevitably go through a large cave,the traditional program might not be reasonable in the consideration from the economic and construction difficulty.However,the arch structure across the cave can effectively solve those problems.With the example of Aobeiwan Bridge,this paper makes an investigation on the selection method of arch,arch axis and vector height.The paper also analyzes the distribution of internal forces in the arch and designs the arch structure of Aobeiwan Bridge.The results show that the scheme is feasible and has good replicability.This program has certain significance and value for bridge construction in karst area and gob area.