Research on the Scheme for Construction of Large Span Three-arch Tunnel Underpass Building

Research purposes:A large span three-arch underpass five-floors building is formed when a connecting line to depot beside the two main lines in the between Andemen Station and Ningdanlu station of Nanjing metro.For construction of it,the design is complex,there are many construction steps and construction procedure changes frequently.The most important thing is the safety of excavation and the five-floors building.The divisional excavation construction is usually adopted for three-arch tunnel,but different methods of excavation and lining process have different influences on strata and upper building,so it is necessary to do research on the order of construction process for the purposes of guaranteeing the construction safety and reducing the influence on the building.Research conclusions:Through making simulation analyses of 5 construction schemes for three-arch and comparing the strata settlements and structure internal force of each scheme,the result shows that the scheme of excavation,side lining in advanced and then constructing middle tunnel is the best scheme compared with the other scheme,such as the scheme of excavation,the mid-pilot excavation,then side lining and finally constructing the main tunnel.Using this method,the strata and upper building have least settlement and the support structure has least inner force.