Displacement monitoring, displacement verification and stability assessment of the critical sections of the Konak tunnel, Izmir, Turkey

The main focus of this study is vertical displacement monitoring and verification along with preliminary support design for the four geotechnical sectors of the twin tube Konak tunnel that was constructed in a highly populated area in Izmir. The displacements of the tunnel that were obtained through numerical analysis were verified by comparing them with the displacements obtained by construction monitoring. In the study area, volcanics, pyroclastics and some sedimentary deposits (sandstone, mudstone and conglomerate) often intertongue with each other especially in the exit portal area. The accurate estimation of the shear strength and deformation parameters of these units is important for the displacement predictions and for the assessment of tunnel stability. Rock mass classification systems, namely, RMR, Q system and GSI have been employed to obtain the rock mass shear strength and deformation parameters along with performing empirical tunnel support design. Numerical analysis has been performed by using the finite element analysis for assessing tunnel support design and for predicting the vertical displacements at five different measurement points around the tunnel periphery and in the four geotechnical sectors of the tunnel