MULTIPLE TUNNEL INTERACTION PROBLEM OF THE SINGAPORE MASS RAPID TRANSIT SYSTEM.

Abstract

An analysis of interaction of a four-tunnel grouping spanning Raffles Place and City Hall Stations of the Singapore Mass Rapid Transit System has been conducted using Dames and Moore's SAGE program. The analytical model employs a finite difference grid with 2304 degrees of freedom in discretising the ground around tunnels. Linear elastic, perfectly plastic constitutive behaviour is assumed, and an angle of dilation psi equals 0 models zero volume change at yield. The model highlights several features of practical design significance. For instance, the traditional practice of superimposing surface settlements of individual tunnels can result in total settlements differing substantially from those that take proper account of tunnel interaction.