Study Of Effect Of Tunnel Excavation With The Glass Method On The Stability Of Artificail Fill Layer

The cost of the tunnel construction is high,and the construction technique is complex.In recent years,with the fast economic increase and technology development,the tunnel construction booms,which improved infrastructure and made traffic congestion ease in part.In this period,the collapse of the tunnel repeats many times.The accidents lead to huge losses.There are many reasons for these accidents. Poor geological conditions and unreasonable construction method are important factors. The mechanic properties of artificial fills are very poor for tunnel construction.At present,there are few researches on the effects on the stability of artificial fills, in which tunnels are constructed.In this thesis,the effects of tunnel construction on the stability of artificial fills are studied.This investingation is made with a engineering background of the construction of Subsea Tunnel in Dalian Bay Harbor.In the first part,some studies made by other researchers on the stability of strata are summarized.There are three theories:empirical formula,the analytical method and numerical analysis.Through evaluating characteristics of these three methods,the numerical method is choosed for the study.Numerical analysis is flexible,and the models are easy to be modified.It can easily consider:the different forms of soil to be excavated,changes of soil parameters during the process of excavation;the stress field and displacement field of strata,and so on.In the second part,for the separation and evaluation of the impaction on the stability of formation by the heterogeneity,the same method is used to simulate the construction of the tunnel.According to comparison of the conclusions,the glass method is selected.In the third part,the characteristics of artificial fills are reviewed.It is concluded that the vertical and horizontal layers of changes are an important aspect in the distribution of non-uniformity.In the forth part,a brief introduction to the basic principles and methods of MIDAS is given.Finally,some simulation results are compared with results of the analysis,and the effects of the heterogeneity on the stability of the artificial fill formation are obtained. The research results of this investingation can be used to guide real engineering project.