Engineering Geological Assessment and Preliminary Support Design for Cankurtaran Tunnel, NE Turkey

Abstract

The main purpose of this study is to determine the geotechnical properties of the rock masses and to suggest the convenient support design for the Cankurtaran (Hopa-Artvin) tunnel, NE Turkey. The detailed geotechnical investigations were carried to define the rock masses that mainly consist of sedimentary, pyroclastic, and volcanic units. Empirical and numerical methods were utilized and results were compared for safe tunnel design. The RMR, Q, and NATM systems were used as empirical methods to characterize the rock masses and to determine the support design. The performance of suggested support design, induced stress distributions and deformations were controlled using the finite element method (FEM). It was concluded that the empirical support design was not successful to prevent deformations developed around the tunnel in very poor rock masses under great in-situ rock stresses. Therefore, a new support design was suggested and, its performance was also checked using the FEM analyses. Finally, it is concluded that the empirical and numerical methods should be combined for more realistic and safe support design