Study On Construction Technology Of Large Section And Three-dimensional Cross-section Of Excavation Transfer Station

With the rapid development of China's economy and the acceleration of the urbanization process, there are more subways in the urban transport. As a result of urban rail transport system subjected to environmental constraints, it is inevitable to build large-section of shallow tunnel. Particularly in recent years, there is a large number of large-section shallow underground projects in the central area of intensive buildings and heavy traffic density. In addition, a number of large-section shallow tunnels are also building in some passenger lines currently, Therefore, it is very important to study large-section shallow tunnel.First, monitoring data in the 3rd line Hongqihegou station Tunnel of Chongqing Subway is processed, and then the distribution of excavated rock stress and the large inter-station tunnel stability factors are discussed; and soil excavation program in the core pillar of the shape, width, and the lifting step aside from the optimization, then the intersection of the first support structure optimization.By making simulation and analysis to several construction methods for large span and shallow-buried tunnel through MIDAS/GTS software, optimizes the most appropriate construction method from the surface subsidence, the level of convergence as well as the distribution of plastic zones, etc.; the comparative analysis shows that the numerical simulation is consistent with the monitoring.The contents and the results of the study are as follows:First, list some excavation methods for the Chongqing hongqihegou Station,then select the first two-Side Heading wall arch law excavation program after sonsidering security, time, cost, and other aspects of construction.For large section tunnel excavation process of the core problems of soil pillar, respectively, the core of soil from the reserved pillar width, shape, and the lifting step aside from the three aspects of optimization, to determine the most suitable program of this project, namely:the original program one, the core of earth pillar width of 8 meters,1 meter away from the excavation step, the core territory reserved for the curved pillar shape, and successfully used for tunnel excavation.For cross intersection in the tunnel for tunnel excavation process of a stress concentration problem, the structure of the intersection of the first branch is optimized by the numerical results obtained in the B section Double Side Drift through, the need for facilities for the early double lining, and reinforce the vault lining can ensure construction safety.Tunnel through the Monitoring station data processing and analysis, the level of convergence of the tunnel, surface subsidence, settlement and support the arch structure analysis carried out by force, have been ground, the vault Yiji support structure and the change curve.