基于光滑有限元的隧道掌子面稳定性分析

Stability Analysis of Tunnel Face Using the Smoothed Finite Element

隧道掌子面稳定是影响地下工程施工安全的重要问题之一。基于塑性上限和下限定理的极限分析方法是分析掌子面稳定性常用方法之一。其中,自适应混合常应力-光滑应变极限分析(MCSE-LA)方法在计算精度、效率以及收敛性方法已被证明比传统有限元极限分析方法具有一定的优势。基于此,首先验证自适应MCSE-LA在隧道掌子面稳定分析中的可行性,发现该方法求出的隧道掌子面稳定指标(稳定数)与传统有限元上限和下限法相同,同时,还可以通过基于最大剪应变率自适应网格加密技术获得掌子面失稳模式。另外,还将该方法用于分析隧道开挖未支护段长度对掌子面稳定性的影响,通过分析总结了稳定数随未支护长度的变化规律,对指导地下工程施工具有一定的意义。

Tunnel face stability is one of important issues affecting the safety of underground engineering construction.The limit analysis based on the upper and lower bound theorem is one of the commonly used methodologies for analyzing the stability of the tunnel face.Among such methods,the adaptive mixed constantsmoothed strain limit analysis(MCSE-LA)method has been proved to have certain advantages over traditional finite element limit analysis in terms of computational accuracy,efficiency,and convergence.Based on it,the feasibility of the adaptive MCSE-LA in the stability analysis of the tunnel face is verified first,and it is found that the stability index(stability number)of the tunnel face obtained by this method is the same as that of the traditional finite element limit analysis.At the same time,the failure modes of tunnel face can also be obtained by adaptive mesh refinement based on the maximum shear strain rate.In addition,this method is also used to analyze the influence of the length of unsupported section of the tunnel excavation on the stability of the face,and the change law of the stability number with the increase of the length is analyzed and summarized,which has certain significance for guiding the construction of underground engineering.