Study On Anti-Seismic Performance Of Different Cross-Sectional Shapes About Running Tunnel In Chengdu Metro

With the quickly development of the city construction, the subway has been an important of the modern lifeline engineering. And the anti-seismic performance of subways has become more important for us. Therefore, the research on its seismic security is of great economic and social significance. In this thesis, based on the running tunnel of Chengdu Metro Line NO.1, the anti-seismic performance of the different cross-sectional shapes was analyzed by dynamic finite element method. Main research work of this thesis including the following several aspects:1. At first, it is explained about the background of Chengdu Metro, then the mechanism of the seismic damage of the subway and underground structure, existing methods and content of seismic analysis of the subway and underground structure were briefly summarized. And the dynamic finite element method was introduced importantly.2. Under the influence of different factors, the anti-seismic performance of the circular cross-section and horseshoe shape cross-section of the subway tunnel were analyzed with dynamic finite element method respectively. The rule of variation about anti-seismic performance in corresponding parameters such as the lining stiffness, lining thickness and depth of burial was researched. And anti-seismic performance of the circular cross-section and horseshoe shape cross-section were compared.3. A two-dimension beam spring model of shield tunnel was build up to study the difference between the anti-seismic performance of the single tunnel and the double.4. Considering the impact of the joints between segments, a model was build up to study the rule of variation about anti-seismic performance in corresponding parameters such as joint stiffness and segment thickness and the anti-seismic performance of circular cross-section compared to homogeneous model.By the analysis of the calculating results, it showed:The three kinds of parameters have the similar effects on the anti-seismic performance of different cross-sectional shapes, but also have some differences. Under the same conditions, there are some differences in anti-seismic performance between the circular cross-section and horseshoe shape cross-section, especially at the mutations or the weak position.For the shield tunnel, through the comparison of different calculation models, we can find the existence of the joints and segments has large influence to anti-seismic performance as well as the variation of their Parameters.