A Study On Construction Mechanics And Ground Surface Settlement Control Of Large-Span Metro Station

It can be predicted that a great deal of urban metro engineering projects will be constructed in the early-middle 21st century based on flourish metro engineering foreground nowadays. But at the same time many geotechnical problems will also come forth, such as the construction of multi-tunnels, the construction of large span tunnel, etc. At present whatever methods are adopted, it is still impossibe to avoid some bad influences on the related environment, for instance, causing surface subsidence, endangering the surrounding buildings and underground pipeline safety, some of which will bring serious financial losses or even heavy casualties. Therefore, how to ensure the security of the construction and control the surface subsidence effectively is an important issu in the urban metro construction areas.Based on the East Lake station taken by shallow tunneling method of Guangzhou Metro 6th Line, the paper mainly includs the following aspects:1. Expounding the large span tunnel construction methods, mechanical properties and the reason of surface subsidence by summing up the past experience and research. And all of these provided theoretical support for the shallow tunneling large span East Lake Station.2. Giving some suggestion on several kinds of tunnel construction methods which are suitable for the wide-span East Lake shallow tunneling Station preliminary by contrasting the similar projects. In order to meet the needs of the station construction, three-dimensional numerical simulation and model test are employed to ensure the security of construction and reduce the impact on the surrounding environment.3. Proving the rationality of three-dimensional numerical simulation and model testing through analying the returned monitoring data, which will provid the experience for later similar projects.According to the characteristics of East Lake station, the paper gives a reasonable construction method by numerical simulation and model test. The sucefull practice on the large span East Lake station proved that preceding pilot tunnels, large-volume excavation divided into small ones, excavation of flank before that of center, upper before lower, arch before wall, is a good method which could effiectivel reduce surface subsidecne and its adverse effect on djacent buildings, in addition, some other measures are also taken to lessen vlast-induced vibration in the ground and surrounding structures. In a word, all methodes and steps mentioned above have already proved efficiency and practicalness in projects..