岩溶区桥梁基桩极限承载力的突变求解方法  

Determination of Ultimate Bearing Capacity of Pile in Karst Region Based on Catastrophe Theory

作　　者：龚先兵[1,2] 赵明华[1] 杨明辉[1] 吴立坚[3] 

机构地区：[1]湖南大学土木工程学院,湖南长沙410082 [2]湖南省高速公路管理局,湖南长沙410001 [3]交通运输部公路科学研究院,北京100088

出　　处：《公路交通科技》2012年第11期53-57,74,共6页Journal of Highway and Transportation Research and Development

基　　金：国家自然科学基金项目(51278184);教育部博士点基金项目(20070532008)

摘　　要：分析了岩溶区桥梁基桩极限承载力组成特性及桩端破坏模式,将其极限承载力分为桩侧土体极限侧阻力、嵌岩段极限侧阻力及端阻力3部分。其中,桩侧土体极限侧阻力由各土层极限摩阻力求和可得,嵌岩段极限承载力则引入Hoek-Brown岩石强度准则,采用岩体质量评价指标进行描述。而后,针对岩溶区基桩工程的特点,结合突变理论的基本概念,建立了岩溶区基桩的力学简化模型及其势能函数的表达形式,并导出岩溶区桥梁基桩桩端极限阻力的尖点突变模型的分叉集方程。在此基础上,根据下伏溶洞顶板失稳破坏条件,求解分叉集方程导得岩溶区桥梁基桩桩端极限荷载的表达式,由此提出了岩溶区桥梁基桩极限承载力的确定方法。工程实例对比分析表明该方法的可行性。First, the constitution characteristics of ultimate bearing capacity of bridge foundation pile and failure mode at bottom of pile in Karst region were analyzed. The ultimate bearing capacity was divided into three parts： soil ultimate lateral resistance, Rock-socketed ultimate resistance and end resistance. Soil ultimate lateral resistance can be obtained by the sum of ultimate friction of each soil layer. Rock-socketed ultimate resistance was described by rock mass quality, introducing Hoek-Brown rock strength criterion. Then, aiming at the engineering characteristics Of pile, the simplified calculation model and its potential energy expression of the pile were established by introducing catastrophe theory, and the bifurcate equation of the cusp catastrophe model of ultimate resistance of the pile bottom was also obtained. On this basis, according to the necessary instability conditions of cave roofs under pile, the expression of ultimate load at pile bottom was obtained by solving the bifurcate equation, and the determination of ultimate bearing capacity of pile in Karst Region was proposed. Finally, the feasibility of the new method was verified by contrastive analysis in engineering projects.

关 键 词：桥梁工程 基桩 突变理论 极限承载力 

分 类 号：U443.15[建筑科学—桥梁与隧道工程]