Design Method Of Metro Station Built By The Cover-excavation Method

Construction of the urban rail transit is one of the important measures to solve the conflict of the city traffic. However, it will influence the environment and obstruct the traffic to build the metro station in the busy streets. As a result, the cover-excavation method is adopted as an effective solution. Presently, the complete loading calculation mode is widely used as the design method of the metro station, but the vertical load from the temporary road surface system isn't taken into account. In fact, the design requirement of the station structure is usually obtained in the construction process, so it is necessary to study the whole-process design method which can reflect the load status of the station structure built by the cover-construction method.In order to consider the loading succession in the construction period and the service period of the station structure, the incremental calculation method is adopted to analyze the loading process of the station structure and to obtain the reasonable design requirements. The elastic-plastic spring is used to simulate the interaction between the structure and the soil when we analyze the horizontal and vertical load-bearing effect of the structure. We assume that the elastic limit of the equivalent horizontal spring is related with the embedded depth, and the influence of the displacement of the retaining wall is taken into consideration. In addition, the calculation method of the vertical and tangential coefficient of subgrade reaction is discussed, and this paper puts forward the simplified calculation method of the tangential coefficient of subgrade reaction.The whole-process analysis method can be used to simulate the different loading state of the structure in construction period and service period, and can be regarded as an effective analysis tool in the design of the metro station built by the cover-excavation method.