Stability analyses of earth cuts for cut & cover tunnels - limit analysis versus limit equilibrium method

Abstract

Cut & cover tunneling method is an easy and inexpensive method which has been used worldwide for centuries. Feasibility studies which have been undertaken in Esfahan city subway project in Iran show the possibility of using this method in some geological units without using any kind of stabilization method. In this study, it is aimed to analyze the stability of earth cuts in some sections of the project. There are several methods available for performing stability analysis [1]; the majority of these may be categorized as limit equilibrium methods. Another relatively new technique is limit analysis method, which considers the stress-strain relationship. In this respect, the stability of earth cuts were analyzed, using both limit Equilibrium and limit analysis methods. In using the limit equilibrium method, the stability of the earth cuts was analyzed by assuming the anticipated failure plane as planer and circular. In stability analysis by the limit analysis method, the logarithmic-spiral failure plane method was employed.