Chaoyangmen-Dongdaqiao tunnel of Beijing metro Line 6 underpasses the existing Chaoyangmen station of metro line 2 and Chaoyangmen Bridge which was under construction. The project is very difficult and safety control is of great importance. In order to investigate the project's influence on surrounding rocks and existing structures, to guarantee the safe operation of existing structures and to effectively control surface settlement, different options for the project were proposed and software MIDAS-GTS was utilized to do 3D simulation by whicb deformation control effect on surrounding rocks and buildings was analyzed. Based on control standard of existing structural settlement, an optimized option was put forward that excavation should be carried out from both sides of the tunnel and horizontal jetting piles should be set up from both sides of the existing station. The option can be regarded as theoretical basis for the design and construction of the project.%北京地铁六号线朝阳门-东大桥区间隧道下穿既有地铁二号线朝阳门站和二环主路朝阳门桥施工,工程难度极大,施工安全控制极为重要.为研究新建隧道施工过程对围岩与既有结构的影响,保证施工期间既有结构的安全使用、有效控制地表沉降,针对本工程拟定了不同施工方案并采用有限元计算软件MIDAS-GTS进行三维仿真模拟,分析其对围岩与下穿建筑物的变形控制效果.依据既有结构沉降控制标准.最终提出采用新建隧道与既有车站零距离刚对刚接触、自隧道两侧同时开挖、在既有车站两侧同时施做水平旋喷桩的方案.该方案将为六号线下穿既有车站和扩大基础桥梁的设计与施工提供理论依据.
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