Evaluating the Influence of Boring the Single and Twin Tunnel on Surface Displacement

Generally, the earth was initially influenced by pressure from natural stresses and any disturbance such as tunnel boring has disrupted such a stress situation and causing the displacement in the ground. If such displacement is not in the standard area, it may cause problems in the surface and sub-surface structures, and occasionally followed by many damages. Boring the tunnel in the earthy grounds may develop horizontal and vertical displacement surrounding the tunnel. Such displacement might attain to the surface of the ground and damage the existing structures on the surface; thus, this study investigates and calculates the effect rate of any geotechnical parameters of the soil such as contraction of the tunnel section, placement depth and distance of the tunnels from each other. According to the results, by increasing the contraction of the tunnel section, the ground subsidence has been increased and by increasing the diameter of the tunnel, the ground surface is initially inflated and then subsided. By increasing the placement depth, the ground subsidence will be initially increased and then in the lower depths it will be reduced and by increasing the distance between tunnels in the twin tunnel, the surface of the ground has been inflated. The obtained results have been explained more by using the tables.