COMPUTER AIDED ANALYSIS AND DESIGN OF MIXED FACE TUNNELS

Abstract

The present study is an attempt to analyze the behavior of tunnels excavated through a medium consisting of hard as well as soft ground at the tunnel face, commonly known as Mixed Face Tunnels. First of all, a literature review of earlier work on similar topic has been done. Then, an example of such tunnels has been chosen for analysis which is located on the Antalya-Alanya D-400 highway along the coast of the Mediterranean Sea in Southern Turkey. The subject tunnel has been modelled for different orientations of discontinuity: Different combinations of tangential and normal stiffness at discontinuity have been taken into account for the analysis. Subject tunnel has been examined for deflections and stresses by making use of Finite Element Method based software package Abaqus/CAE 6.9. At first, tunnel has been studied without considering any support system. After this, an RCC liner has been provided as a support to the tunnel and further analyses have been carried out. A comparative study of results before and after installation of RCC liner has been done and suggested support system has been found quite effective to control horizontal, vertical as well as tangential displacements along the interface and tunnel periphery and also to withstand the stresses induced due to excavation