Seimic Elastoplastic Analysis And Research On The Performance Index Of Metro Shield Tunnel Based On Pushover Method

As the sustained development of the national economy, the construction of urban subway is constantly emerging. In the engineering, safety and durability of the structure should be considered, especially when the structure is destroyed by earthquake. Once the urban subway is destroyed, it would cause serious consequences. For instance, the structure could lose a certain proportion of its performance, and more seriously, it may bring huge economic losses and cause threats to the safety of people. Now, the concept of seismic design is no longer confined to the structure with a strong bearing capacity. More factors should be concerned. As a result, the method of seismic design based on the performance is getting more and more attention. According to the project of Xiamen Metro, elastoplastic analysis is adopted in this thesis to analyze the seismic performance of shield tunnel which is commonly used in the urban subway construction. Then, the author gives qualitative description to the different level of seismic performance of shield tunnel. At last, the quantitative index of performance is determined. The main work of the paper is as follows:(1) Use two methods (elastoplastic dynamic history method and static elastoplastic method) to calculate the force of cross section according to the engineering examples. Based on the calculation results of the dynamic history method, make comparison between the two methods to study the applicability of the pushover method in the seismic analysis of shield tunnel.(2) According to the project of Xiamen Metro, study the earthquake response of the shield tunnel segment, as well as the influence of the different factors in practical engineering on the internal force and deformation of the segment which is into plastic stage.(3) Proposed the quantitative index of performance lever which suits the circular shield tunnel:Firstly, analyze the failure mechanism of the shield tunnel under earthquake, and summarize the failure mode of the shield tunnel. Then, based on the failure mode and combined with the certain way to divide the performance lever of shield tunnel, put forward the appropriate performance quantitative index.(4) Do numerical calculation and statistic analysis according to the performance quantitative index of circular shield tunnel under different performance conditions. Tentatively put forward the limit value of performance quantitative index applied to the circular shield tunnel.