ANALYSIS OF TUNNELS IN SQUEEZING GROUND CONDITION

Abstract

The aim of the present study is to determine the state of stress and strain in tunnels ated in squeezing ground. The proposed approach is based on analysis of tunnels in nass of strain softening type. The analysis is done using ANSYS 7.0. The analysis is with different mesh sizes, with and without considering the self-weight of the rock and with or without installation of the liner. As the first step to determine the state of stresses and strains, empirical ations and closed form solutions have been presented in literature review. However, drawbacks of the above methods, a need arises to analyze the problem realistically. e problem being geometrically (Large Deformations and Finite strains) as well as ially non-linear, finite element analysis approach has been used. A finite element analysis has been performed on several models with varying densities and contour plots for normal stresses, shear stresses and principal stresses Deen plotted which give complete state of stresses in the rock mass surrounding the I. The contour plots give a brief idea of the failed rock mass and deformations -ing around the tunnel. Load- Displacement curves and Displacement vs. stress curves at crown of the I have been plotted for the various cases considered. Displacement loading technique has been used for the analysis due to convergence ;ms encountered with force loading. Displacement increments of 5mm per load step applied using which 15% squeezing has been achieved.