盾构隧道地表沉降模糊随机可靠度分析

FUZZY STOCHASTIC RELIABILITY ANALYSIS OF GROUND SURFACE SETTLEMENT FOR SHIELD TUNNEL

盾构隧道施工引起地表沉降的传统计算方法已较为成熟,但为了合理描述盾构隧道施工引起地表沉降的多种不确定性,应同时考虑随机和模糊两种因素所带来的影响。基于Peck算式,并考虑影响地表沉降因素的随机性和模糊性,利用一次二阶矩法建立隧道施工引起地表沉降的可靠度算式,并针对工程实例,对盾构隧道地表沉降模糊随机可靠度进行计算分析。计算结果表明:对于同一允许最大沉降量,在不考虑变量随机性和模糊性的情况下,中心点法计算得到的可靠指标较验算点法偏大;随着允许沉降量的递增,中心点法和验算点法计算所得的可靠指标均呈现增大趋势,这与工程实际是一致的;而考虑随机性和模糊性因素影响的验算点法所得可靠指标呈下降趋势。通过与传统随机可靠度计算结果进行对比,得到了更为合理的结果。

The traditional calculation method of ground settlement caused by shield tunnel construction has been relatively ripe. In order to describe various uncertainties in shield tunnelling reasonably,stochastic and fuzzy factors should be considered simultaneously. In the paper,considering the fuzzy uncertainties of the parameters of stochastic variables,a fuzzy stochastic reliability analysis model was derived based on first-order second-moment method and the Peck formula. An example was given, and the results were compared with the traditional reliability analysis assessment. Under the condition that the fuzziness of random variables was not considered,it was demonstrated that the random reliability index based on the central point method was bigger than the random reliability index based on the design point method with the same allowable maximum settlement,and that the random reliability index increased with the increase of allowable maximum settlement,which was accordant with the actual engineering. Considering the fuzziness of random variables,the random reliability index would be decreased with the increase of allowable maximum settlements by using the design point method. More reasonable results could be obtained by comparing with the traditional stochastic reliability calculation results.