A Study On Construction Technology Of Shield Tunneling In Upper-Soft Lower-Hard Ground

The underground engineering will be vigorously developed in the21st century, the shield driving method will be more and more widely applied in the construction of urban subway project. But the shield tunnel through upper-soft lower-hard ground is still a problem in the engineering construction, if we don’t use scientific construction technology in project, there are ground settlement, the destruction of underground pipeline and buildings (Structures) inclination or even collapse accident caused by tunnel construction. Based on the shield tunneling traversing upper-soft lower-hard ground of Shenzhen Subway Line5, this thesis studies ground settlement caused by tunnel construction, the key technology of shield construction, and the mechanical properties of the segment, by utilizing a comprehensive method of On-site technical research, FLAC3D numerical simulation, and field test. The main contents of this article are as follows:(1) Established a three-dimensional numerical simulation model of the shield construction, the dynamic process of the shield through upper-soft lower-hard ground is investigated, Soil pressure impacting on ground settlement and the mechanical properties of the segment are analyzed in the shield construction process, some disciplines are get by Summarized.(2) Based on the technical research of shield construction site and a large number summary of field data, the section of shield machine, the technology of Soil reinforcement and the section of reasonable technology parameter of shield tunneling are researched, the control technology of the shield tunneling traversing upper-soft lower-hard ground is finally refined.(3) Through installing the testing component of segment at the scene, the stress state of segment is monitored at any time, the testing data is investigated, and the stress changing regularity of segment is refined with the shield construction. The stress state of segment is investigated by the theoretical calculations. Finally, some law will be summarized by analyzing the field test of segment, the theoretical analysis and the numerical simulation of segment.