隧道下穿施工影响下浅埋桥基稳定性的尖点突变评价方法研究

A Study on Stability of Shallow Bridge Foundation During Tunnel Undercrossing Construction with Cusp Catastrophe Theory

新建隧道下穿既有桥梁基础,特别是浅埋桥基时会对其产生不利影响,将尖点突变理论引入隧道下穿施工影响下浅埋桥基的稳定性评价,根据浅埋桥基系统失稳特点确定尖点突变模型的控制变量和状态变量,由尖点突变势函数推导出桥基结构的行为曲面方程,建立描述隧道下穿施工影响下浅埋桥基失稳的数学模型;然后根据该模型将桥基稳定性状态分为稳定阶段、不稳定阶段和失稳破坏阶段,并将各阶段的划分界限严格量化,作为结构的失稳判据;最后将此方法应用于某工程实例,分析结果和工程监测结果的对比表明该方法具有良好的分辨能力与准确性,为开挖施工影响下的浅埋桥基稳定性评价提供了一条新的思路与方法。

New tunnel undercross construction would bring adversely affects to the existing bridge foundation,especially to shallow bridge foundation.The cusp catastrophe theory is led to the stability assessment of the shallow bridge foundation.First the control variable and the state variable are determined according to the instability characteristics of the shallow bridge foundation,and the mathematical model which reflects the instability process of the shallow bridge foundation is established;then the stability state of shallow bridge foundation is divided into stable phase,unstable phase and failure phase,and quantify the various phases as structure instability criterion.Last,the method is applied to an engineering project;the results indicate that this method has a good ability to distinguish and accuracy,and it provides a new thinking and method to stability assessment of shallow bridge foundation under excavation construction affecting.