The Research Of Large Cross-section And Ultra-shallow Subsurface Subway Station Construction Technology

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; 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:Through the data processing of Chongqing rail transit Hongqihegou station tunnel's monitor and control, analysis tunnel's headroom, ground surface, vault and shoring structure stress, get clearly terrene, vault and shoring structure's change in value curve, fits tunnel's headroom convergence regression curve.Through tunnel's numerical simulation, from vault sedimentation and horizontal convergence, shoring structure stress, surrounding rock plastic zone distribution aspects, optimizes the fittest construction method.Through numerical simulation of the actual excavation of the program, analyses the proportion of numerical simulation of construction sequence in each of various control the impact of the proportion of monitoring points, according to the present stage of the monitoring data after the excavation, anti-analyses the monitor data changes in tunnel 10 steps excavation process to provide the necessary support for the tunnel's excavation and support.