الفهرس 
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Abstract
In metro-rail projects, excavation depths may reach more than 40 meters in the construction of underground stations. In such cases, the dominant proposed excavation support system is the
diaphragm wall system. Secant piles, contiguous piles, Berlin walls, and other systems may be
proposed for use in the substructures as external accesses with depths up to 15 meters. selecting
the appropriate excavation support system is a crucial challenge for builders and designers.
Complex factors which are considered in the selection process and dependent on the subjective judgments of the construction practitioners based on their past expertise, create uncertainty and imprecision. The Analytic Hierarchy Process (AHP) is the most popular decision-making
technique. Despite its popularity and wide use in the decision-making field, it can’t deal with the uncertainty and vagueness associated with complex multi-criteria decision-making processes. To evaluate such complex decision-making problems, fuzzy set theory is combined with AHP
in this study to use the fuzzy AHP (FAHP) technique to deal with ambiguity and impression.To demonstrate the developed model’s applicability, Heliopolis and Kit Kat underground metro
stations are presented as case studies in the greater Cairo Metro. It was concluded that the
diaphragm wall system, although it is still more costly, but preferable.
Keywords: Tunneling projects, Excavation support systems, Alternatives evaluation, Fuzzy set theory, Fuzzy analytic hierarchy process.