Open-cut Method And Cover Partial Excavation Method Subway Station Construction Monitoring And Numerical Simulation Analysis

In recent years, urban population is increasing, urban traffic congestion problem becomes more and more serious, therefore, many large and medium-sized cities are building subway in our country, make full use of underground space to alleviate the traffic problems. Subway construction is built in large population urban areas. And the depth of the subway foundation pits are generally reached more than ten meters, once an accident occurs, will lead to serious consequences. Therefore, we must ensure the safety of the subway construction process; the main is to ensure that the subway station deep foundation pit stability will be not destroyed in the process of construction. Numerical analysis can not only make up for the traditional theory of analysis and design calculation result but can not reflect the construction process of stress and displacement of foundation pit excavation changes shortcomings, and can be found in the construction of foundation pit in advance risk is weak, make the preventive measures in advance. At present, the hefei subway line 1 and line 2 are under construction. The article is based on Mingguang road station in hefei subway deep foundation pit construction as an example, has carried on the research and analysis of the following ways:Article is analyzed and summarized on open-cut method and covered excavation method used in subway construction of overseas and domestic research status. The mechanism of deformation of deep foundation pit in detail, the deformation of supporting structure, the surface subsidence and bottom heave of the main factors influencing the deformation of deep foundation pit are studied, and summarized the current research on the deep foundation pit stability theory and its calculation method at home and abroad.In the process of construction, has carried on the detailed analysis of the monitoring. Analysis of monitoring data, the palisade structure at the top, even the lateral wall, surface subsidence, building subsidence and subsidence of the uprightly post.In the process of the Mingguang road station construction, combined the open-cut method and cover partial excavation method, according to the actual situation of construction, the deepest foundation pit is 22.8 meters. Using large-scale finite element analysis software Midas GTS/NX to foundation pit excavation of construction process for three dimensional numerical simulation, it is concluded that the construction of the surface subsidence and the changing rule of the retaining structure. The maximum ground surface settlement appears in 15 m near the pit edge. And the values of maximum lateral wall occur in two-thirds of pit excavation depth, and present two small middle big ―pot-bellied form‖ trend.Mingguang Road Bridge section is original used open-cut excavation method; the actual construction process in order to reduce the influence on road traffic, the excavation method is changed cover excavation method. Build Mingguang Road Bridge standard interval are used two method numerical model analysis, obtained the difference of two method excavation period of construction in the process of surface subsidence, the changing rule of the retaining structure and strut axial forces. Through data analysis, it is concluded that open–cut excavation method changed to cover excavation method is reasonable and safe. By supporting structure optimization analysis, the rationality of the foundation pit supporting system is analyzed. Get to the wall of built-in depth of 35.2 m, steel support spacing is 6 m is economic and reasonable.