Generaly, the ground is in pressure of natural stresses and every kind of change such as tunnel boring changes this situation and causes convergences in tunnel. In this study, the effect of twin tunnels boring in behavior of soil space has been researched. Ground response curve as a part of convergence-confinement method has studied in this research. The application of the method is design of deep tunnels. In this study the application has investigated in shallow tunnels. Then by using a finite element software(Phase2), modeling of single and adjacent tunnels in different conditions has been done. The conditions are simultaneous and nonsimultaneous face advancing of two adjacent tunnels. Modeling of the problem by Phase2 compared with Flac3D and agreement between results has shown. Analisys of results has shown that nonsimultaneous boring causes greater pressure in compare with simultaneous boring. Advancing of the first tunnel affects second tunnel and consequently the first point of GRC will be variable in different conditions. As the soil become stiffer and the distance between tunnel axes become greater, the GRC is similar to single tunnel conditions. If the distance will be greater than 2D(D is diameter of tunnels) in stiff soil, the GRC has an exact agreement in single and adjacent tunnels. In practice conditions that support is installed simultaneously by advancing tunnel, more delay between two faces causes more reduction of pressure in second tunnel. Because of installing support and causing normal condition, the reduction of pressure is happened. The results show that capacity of support is adequate and SRC are vertical. Finally the delay between faces of two tunnel equals 2D proposed. Key Words Convergence-Confinment Method,Ground Response Curve,adjacent tunnels,boring,tunnel deformation
