Study of the Interaction between Two Parallel Tunnels in the Case where the Second Tunnel is excavated after the Construction of the First Tunnel

摘要

This paper investigate by using the finite element program Plaxis 2D, the respective influence between two neighboring tunnels in terms of structural forces and ground movements, in the situation where the second tunnel is excavated after the construction of the first tunnel. In the first time, the settlement trough obtained by the numerical model for the case where the first tunnel is constructed, is studied by analyzing the ground loss parameter and the trough width parameter. Then, the settlement trough is evaluated by using various empirical and analytical method's namely the method's of Peck 1969, Chow 1994 and Loganathan & Poulos 1998 and comparison is performed between the results of these method's and the numerical model. The study of the settlement trough induced by the construction of the two tunnels, show that the tunnel no1 influence the behavior of tunnel no2 leading to an increase of ground loss induced by the construction of the second tunnel compared to the case when the second tunnel is constructed without presence of the first tunnel. In the other hand, the study of the structural forces in the tunnel lining show the respective influence between the two tunnels. Indeed, the construction of the second tunnel influence significantly the distribution of axial force in the lining of the first tunnel, leading to an increase in the maximum magnitude of axial force. Moreover, disturbances occur in the envelope of the axial force, particularly in the left springline of the tunnel no1. For tunnel no2, the results obtained show that the presence of tunnel no1, has a limited influence on the distribution of structural forces. Nevertheless, we find that the presence of the tunnel no1 induces a slight increase of the maximum axial force in the lining of the second tunnel.