STABILITY OF TRIPLE TUNNELS IN COHESIVE-FRICTIONAL SOIL SUBJECTED TO SURCHARGE LOADING

Abstract

 The stability of triple circular and square tunnels in cohesive-frictional soils subjected to surcharge loading has been numerically investigated assuming plane strain conditions. The centre-to-centre distance appears as a new problem parameters. A continuous loading is applied to the ground surface, and a smooth interface condition is modelled. For a series of tunnel size-to-depth ratios and material properties, rigorous lower-and upper-bound solutions for the ultimate surcharge loading are obtained by applying finite element limit analysis techniques. For practical stability, the results are presented in the form of dimensionless stability charts.