The study objective of this paper is analysis of different loads affecting the urban
railway tunnel systems to determine the optimum tunnel system (single tunnel or twin tunnel).
A case study is The Greater Cairo metro line No. 4, which passes under the River Nile in
Egypt land. Analysis of settlement and stresses was carried out using three different finite
element programs (Ansys, Plaxis and Rocscience Phase). We obtained optimum dimension
of the model for the different tunnel systems. Also, vertical and horizontal bed River Nile
settlements were computed for single and twin tunnel by the above mentioned programs.
The comparison between the two systems in terms of bending moments and settlement is
presented. Also, the procedures of construction of the twin tunnel underneath the River
Nile were discussed. Moreover, the effect of the train loads on the settlement profile and the
horizontal displacement of bed River Nile were evaluated for single and twin tunnel systems.
Based on the calculated result, higher stresses in bottom tunnel (twin tunnel system) increased
by 100% about stresses in a single tunnel. When trains pass through the tunnel, stresses
decrease about 10% for single tunnel and about 5% for twin tunnels.
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