An investigation of seismic face stability of deep tunnels by using an axisymmetric finite element model

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Tezin Türü: Yüksek Lisans

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, İnşaat Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2018

Öğrenci: HANNAH ELIZABETH HADLEY

Eş Danışman: MUSTAFA TOLGA YILMAZ, HALUK SUCUOĞLU

Özet:

The static stability of tunnel faces has been widely studied, with the development of limit analysis and numerical modelling solutions. There has been limited research into seismic tunnel face stability. The aim of this study is to find the effect of seismic loading on tunnel face stability and suggest factors that could be used in design. A numerical model using the axisymmetric finite element method is developed to assess tunnel face stability under seismic loading. To verify the numerical analysis, it was compared with limit-analysis solutions of static tunnel face stability from literature. Earthquake forces were applied to the numerical model using the pseudo static method. Both drained and undrained behaviour of geological formations are considered in the numerical analyses. There was generally good agreement found between the numerical model and limit analysis solutions. The results suggest that seismic actions have a significant effect on tunnel face support pressure required for stability. The tunnel face support pressure necessary for stability was generally found to increase proportionally to the seismic coefficient. Using the results from the pseudo static analysis preliminary seismic design factors are proposed. The variation in tunnel face support pressure with seismic loading is generally small when compared to the uncertainty in the limit analysis solutions.