Preliminary support design for Ankara subway extension tunnel

This paper presents the results of preliminary support design of the subway tunnel for Ankara subway project in accordance with some empirical and numerical methods, using the phase 2D finite element method (FEM). The 5 m diameter subway tunnel will advance through slightly to moderately weathered dacite and weak zones. Rock masses were characterized in terms of rock mass rating (RMR), geological strength index (GSI) and Q System. Core samples were tested in the rock mechanics laboratory to determine uniaxial compressive strength, deformability parameters, unit weight, tensile strength and triaxial compressive strength properties. Finally, rock mass strengths were determined by empirical and numerical methods. Required support system was suggested.