investigation of about the effective parameters on the underground circular tunnel settlement using fem and plaxis software

tunnels are the famous underground structures. we can use the analytical, experimental and numerical methods to analysis the tunnels. numerircal methods such as fem, fdm, … are reliability, fast and are the best, special for the complex boundary conditons. finite element method (fem) and plaxis software used to parametric research of the effective elements on the tunnel settlemet. diameter of tunnel, depth of tunnel (the distance between the tunnel center to the ground surface), adjacent building loading and distance between the tunnel center to the building, water table, earthquake loading were the effective parameters on the tunnel structural behavior for the both of adhesive and cohesionless soils. settlement of the tunnel crest was investigated in this article. the results showed the increasing settlement with the tunnel diameter unless for the diameter 4 to 5 meters and reducing the settlement with the tunnel depth unless for the tunnel depth 15 to 20 meters for the undrained adhesive soil and the 6 stories building equivalent surcharge. the results showed reducing settlement with the tunnel diameter up to 4 meters for diameter and then increasing rapidly for the higher diameter values, also the settlement reducing with the tunnel depth until the depth 15 meters and then increasing with the tunnel depth for the higher values for the cohesionless soil and the 6 stories building equivalent surcharge too. the results showed the linear relationship between the crest settlement and the building surcharge. the results showed that the crest settlement increases with the distance (between tunnel center and building center) until about 50 meters and then constant. for two horizontal tunnel dugout, the settlement reduces up to 40 meters for the center to center distance and then increases, but this settlement relationship to the soil and tunnel properties.