PBA大直径盾构隧道扩挖车站施工的关键技术

Study of key techniques of metro stations construction using PBA based enlarging large diameter shield tunnel

北京地铁十四号线采用外径为10 m的大直径土压平衡盾构进行地铁施工.由于盾构隧道扩挖车站施工具有盾构设备利用率高、建设进度快、环境影响小的优势,将台站采用盾构隧道已形成的中洞结合PBA法(洞桩法)扩挖而成,解决了盾构区间施工速度快与车站施工速度慢之间相互矛盾的问题.本文重点分析PBA大直径盾构隧道扩挖车站的工法特点,明确车站结构形式及施工步序,对施工过程中盾构掘进控制、管片拼装与拆除、纵梁与管片的连接、初支及二衬施作等关键技术进行了研究.施工完成后,实测数据显示地表沉降满足控制要求.研究结果可为类似工程提供参考及借鉴.

Beijing subway line 14 is carried on the construction with a large diameter earth-pressure balance shield. Take the conflict that shield zone excavates fast but station constructs slow into account,Jiangtai station is excavated with PBA（Pile-Beam-Arch） method using the shield tunneling hole. The shield tunnel enlarged excavation method has advantages such as high equipment utilization,faster construction progress and smaller environmental impact. This paper analyzes the features of PBA large diameter shield enlarged excavation method,clear the station structure and sequence of construction steps,research key technologies such as shield tunneling control,segments assembled and dismantled,connection of stringers and segments,the facilities of initial support and secondary lining during construction process. After construction is completed,the measured data show that the surface subsidence meets the control requirements. The results can provide a reference for similar projects.