基于上限分析与随机响应面法的盾构隧道掌子面可靠度研究

Reliability Study of Shield Tunnel Face Based on Upper-Limit Analysis and Random Response Surface Method

为更全面准确评估孔隙水压力作用下盾构隧道掌子面的稳定性,提出一种基于极限分析原理的双对数螺旋线破坏机构为确定性模型,结合随机响应面原理的可靠度分析方法。该方法以孔隙水压力系数表示地下水引起的孔隙压力变化,通过上限分析得到隧道掌子面的安全系数;运用拉丁超立方技术对安全系数进行抽样,建立基于Hermite多项式展开的近似极限状态方程,在验证响应面有效性的基础上,进一步采用蒙特卡洛模拟法获取隧道掌子面失效概率特征。利用该方法分析了土体参数变异性、地下水位以及支护力对掌子面失效概率的影响,并将其应用于湘江隧道掌子面的可靠性研究中。结果表明:该方法可以有效地评估隧道掌子面的可靠性,并可为隧道掌子面支护力的选取提供理论参考。

To comprehensively and accurately evaluate the stability of a shield tunnel face under pore water pressure,a reliability analysis method for a double logarithmic spiral failure mechanism based on the limit analysis theorem and the random response surface theorem is proposed.The pore water pressure coefficient expresses the variation in pore pressure caused by groundwater,and the safety coefficient results obtained from the upper-limit analysis combined with the Latin hypercube sampling technique are used to establish the approximate limit state equation with Hermite polynomial expansion.Furthermore,the Monte Carlo simulation is used to obtain the failure probability characteristics of the tunnel face to verify the validity of the response surface method.The proposed method is used to analyze the influence of the variability of soil parameters,groundwater level,and support force on the failure probability of the tunnel face and applied to the reliability study of the tunnel face in the Xiangjiang tunnel.The results reveal that the proposed method can effectively evaluate the reliability of a tunnel face and provide a theoretical reference for selecting tunnel face support force in engineering.