The Impact of Approach in Shallow Twin Tunnels on the Convergence

Underground construction in all developed cities is all-important for passenger transportation and tunnels excavating excavations in urban subways are usually in twin format. Most of the tunnels on the parallel excavations of twin tunnels had are located near the surface. The twin tunnel excavation would influence through the convergence of each tunnel. In this article, the author founded presents simplified relationships to help tunnel designers to find the optimum distance from tunnel center-to-center tunnels in order to minimize the effect of the twin tunnels convergence. The numerical investigation performed in this study, using the FLAC 2D finite difference element program, has made it possible to define five different scenarios to discuss the distance influence between center to center of the two tunnels. Finally, the relationship between several variables based on data from the Matlab software fit has been obtained.