城市地铁单拱大跨断面结构设计安全论证

本文利用Mjdas—GTs岩土及地下工程设计与施工分析软件，对重庆地铁单拱大跨断面进行有限元模拟。对开挖工法采用二维地层一结构模型模拟各开挖工序，得出定性的评价；对初期支护安全度按破损阶段验算截面强度．进行安全系数的评价；对二次衬砌按概率极限状态设计法，进行承载能力极限状态及正常使用极限状态的验算，并进行混凝土抗裂计算。结果表明。重庆地区类似地层采用双侧壁导坑法麓工大跨断面安全可行．麓工阶段中开挖中部核心土是双侧壁工法的关键工序。结论对城市地铁大跨度暗挖设计和施工具有参考与指导意义。

Research and analysis for the design of single arch long-span tunnel in Chongqing Metro

Single arch long-span tunnel in Chongqing metro is simulated by a finite element software called Midas--GTS. Adopting FEM to carry out 2D numerical simulation on whole excavation process and obtaining qualitative assessment. Adopting plastic stage design method to assess the safety coefficient of preliminary bracing, Adopting probability limit states design method fo assess the ultimate and the service-ability limit states then proceeding anti-crack calculation. Results indicated that it is suitable to use both side drift method in the construction of single arch longspan tunnel, the mid-partition is a key load-carrying member in the procedure. All the obtained conclusions can be reference and guide to the urban tunnel.