Effect of initial support of excavation on seismic performance of cut and cover structures

---

Tezin Türü: Yüksek Lisans

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

Tezin Onay Tarihi: 2011

Öğrenci: HAMİDREZA REZAEİ

Danışman: ALP CANER

Özet:

Cut and cover construction is one of the fastest and cheapest methods for constructing rectangular shallow tunnels. Construction of cut and cover structure in soil usually starts with installation of the initial support of excavation system, which may consists of rigid type of initial supports such as tangent piles or secant piles. These systems usually remain in place after completion of the final structure. However, to simplify the design, it is a common practice to ignore the contribution of initial support. In this study the effect of initial support of excavation on the seismic performance of cut and cover tunnels is investigated by means of a detailed dynamic finite element analysis. Three different tunnel geometries, three soil types and three acceleration histories were considered Results of the study show that depending on the soil stiffness (soft, medium, or stiff soil), the dynamic response of the tunnel deformations are affected significantly by the initial support of excavation. The effect of the initial support diminishes as the quality of the soil improves. Therefore, dynamic analyses are recommended for the final design of this type of structures especially in soft soils.