基于响应面法的基坑支护结构稳定可靠度分析

Analysis of Stable Reliability of Foundation Pit Supporting Structure Based on Response Surface Method

保证基坑支护结构的稳定性是基坑工程设计与施工中的重要课题,在基坑支护结构的设计中常采用的安全系数法是未考虑到设计参数的随机性与变异性的定值设计法,而将结构可靠度理论引入到基坑工程中来,则可以定量地考虑工程中实际存在的不确定性因素,因而能够对结构的可靠性作出更为客观和合理的判断。针对一重力式基坑支护工程实例,采用响应面法计算了3种基坑稳定性验算模式的可靠指标及失稳概率,并与一次二阶矩法的计算结果进行了对比分析;在此基础之上研究了土体参数,即变异系数、均值和相关系数等对稳定可靠指标的影响,从中总结了相关有益的结论。

Ensuring the stability of foundation pit supporting structure is an important subject in the design and construction of foundation pit engineering.The safety factor method often used in the design of foundation pit support structure is a fixed value design method which does not take into account the randomness and variability of design parameters.By introducing the theory of structural reliability into foundation pit engineering,the uncertainty factors in engineering can be considered quantitatively,and the reliability of the structure can be judged more objectively and reasonably.In view of a gravity foundation pit supporting project,the reliability index and instability probability of three foundation pit stability checking models are calculated by response surface method,and the results are compared with those calculated by first-order second-moment method.On this basis,the influence of soil parameters,such as coefficient of variation,mean value and correlation coefficient,on stability and reliability index is studied,and some useful conclusions are summarized.