| With the improvement of people's living standard, the traditional mode of transportation has to support the daily massive transportation demand, and traffic jams, pollution and other problems are more and more serious. Subway appeared in various modern transportation, as a new typed green traffic mode, and its space saving, convenient traffic has great impact in modern transportation.The core part of subway construction is the tunnel excavation of underground basic transportation. At present, the tunnel excavation method is mine tunnelling method in most cases. Obviously, the excavation process design and the design of tunnel itself of tunnel excavation process directly affect the security and efficiency of the entire tunnel excavation. And the improper design of these factors will increase the risk of whole subway engineering, even cause serious loss of property and personal livies.In this paper, the metro tunnel excavation of subway between HuQuan and MingDu in Wuhan is taken as the geotechnical engineering background. FLAC3D, a powerful numerical simulation software, is used for all the calculations. As we know, the tunnel excavation step length and the buried method are two important factors in tunnel excavation, and the surface subsidence of shallow layer, the cross settlement tough are studied in this paper. By studying the stress of the soil and the influence to the building at bothside of the road, I can find the critical state of the excavation step length and improve the excavation method in tunnel excavation.The calculation and the study of the Critical state with different tunnel excavation step length and the buried method in this paper are not only helpful to design of the tunnel excavation in similar soils, but also standards to the detection in actual construction of tunnel excavation. |
