喀斯特地区桥梁桩基设计分析

Analysis on the Design of Bridge Pile Foundation in Karst Area

地下岩石层在外界环境影响下产生的喀斯特溶洞是桥梁设计选线经常面临的不良地质,溶洞不仅造成公路桥梁建设质量不稳定,还会导致桥梁桩基础承载力急剧下降。针对喀斯特地区桥梁桩基设计缺乏有效机理研究,喀斯特环境下桩基的承载特性分析有助于桥梁下部结构耐久性设计。文章依托广东省内某三跨预应力混凝土梁桥,借助ABAQUS软件进行喀斯特地区桥梁桩基单桩承载特性的有限元分析,为桥梁优化设计提供理论基础。研究结果表明,单桩承载力受溶洞高度的影响较小;单桩嵌岩段1 m时,桩土摩擦系数增大会导致桩侧摩阻力和极限承载力增大。

Karst caves generated by the underground rock layer under the influence of the external environment are the unfavorable geology often faced by route selection in bridge design.Karst caves not only cause the instability of highway bridge construction quality,but also lead to a sharp decline in the bearing capacity of bridge pile foundation.In view of the lack of effective mechanism research on the bridge pile foundation design in karst area,the analysis of bearing characteristics of pile foundation in karst environment is helpful to the durability design of bridge substructure.Based on a three-span prestressed concrete beam bridge in Guangdong Province,the finite element analysis of the bearing characteristics of the single pile of bridge pile foundation in karst area is carried out by means of ABAQUS software,which provides a theoretical basis for the optimization design of the bridge.The results show that the bearing capacity of the single pile is less affected by the height of karst cave.When the rock embedded section of the single pile is 1 m,the increase of pile-soil friction coefficient will lead to the increase of pile side friction resistance and ultimate bearing capacity.