Portal slope stability assessment of a proposed highway tunnel in northeastern Turkey

Sopaci, E.
Akgün, Haluk
This paper presents an application of the rock mass classification systems, namely, Geomechanics Classification System (RMR), Geological Strength Index (GSI) and the newly adapted A-RMR for the characterization of the rock masses surrounding the portals of the Ordu Peripheral Highway Tunnel. In order to characterize the rock masses, which mainly consist of flysch (mostly alternation of sandstone, marl and siltstone) and pyroclastics (agglomerate and tuff), engineering geological investigations have been carried out in three stages as surface, subsurface and laboratory investigations along the tunnel route. Sixteen boreholes with a total length of 1497 m have been drilled along the tunnel route to assist and verify rock mass classifications. Approximately, seventy five rock core samples have been obtained for rock mechanics tests. The shear strength and geomechanical properties of the rock masses were assigned as a result of a synthesis of the results of laboratory testing, GSI, RMR and the newly adapted A-RMR methods. The information provided from all investigations has been gathered and handled for the characterization of the rock masses governing the portal slope stability of open-cut excavations of the tunnel. Kinematical and limit equilibrium analyses of the tunnel portals have been employed for portal slope stability considerations.
ISRM International Symposium on Rock Mechanics 2009 (19 - 22 Mayıs 2009 )


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Citation Formats
E. Sopaci and H. Akgün, “Portal slope stability assessment of a proposed highway tunnel in northeastern Turkey,” The University of Hong KongHong Kong; China, 2009, Accessed: 00, 2021. [Online]. Available: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85055024677&origin=inward.