Verification of empirically determined support systems of The Kiliçlar Highway Tunnel by numerical modelling


Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Geological Engineering, Turkey

Approval Date: 2011

Student: GÖZDE ÇELİK

Supervisor: TAMER TOPAL

Abstract:

The aim of this study is to determine the geological and geotechnical characteristics of Kılıçlar Tunnel on Ankara-Kırıkkale Highway, to suggest the appropriate support and excavation systems and verify these suggested support systems via numerical modeling. The length of Kılıçlar Tunnel is 1110 m. The width of tunnel is 16 m, the height is 10 m and the maximum overburden height is 90 m. Since Ankara-Kırıkkale Highway consists of 2x3 lanes, the tunnel is designed as a twin tube tunnel. Kılıçlar Tunnel is planned to be excavated in Gabbro-Diabase and Serpentinite named as Artova Ophiolite Complex. The rock mass is classified by using RMR, Q and NATM classification systems and support systems are determined by using these classification methods. In addition to empirical approaches, 2D finite element analyses are conducted to check the stabilities of seven sections through the tunnel. Results of those analyses pointed out that the support materials determined empirically (4-6 m long bolt with intervals of 1-2 m, 10-20 cm shotcrete, steel sets (wherever required)) are compatible with those recommended after numerical modelling (4-5 m long bolt with intervals of 1.5-2.0 m, 10-20 cm shotcrete, steel sets for entrance and exit sections). Furthermore, the stabilities of the tunnel portals are also studied by numerical analyses and limit equilibrium analyses. Based on the stability analyses performed for both portals, no slope failure is expected at cut slopes with 1H/3V for forehead and for 1H/2V for side slope.