盾构隧道近距离下穿既有车站变形控制技术

Deformation Control Technology of Shield Tunnel Crossing Adjacent Existing Station

北京地铁12号线苏州桥站—人民大学站区间盾构隧道施工近距离下穿既有4号线人民大学站,新建盾构区间隧道与既有车站最近距离为2.86 m,且盾构施工时会切削废弃钢筋混凝土桩基,施工难度大、风险高,在北京地区内实属罕见。为了保证施工过程中既有线路的运营安全,采用数值模拟方法对既有车站变形进行分析并确定既有车站各结构在施工期间的变形预警值、报警值。以下穿区间前50 m作为试验段,从而确定合理的盾构参数。通过附加先行刀的方式实现了对盾构机刀盘的升级改造,提高了盾构机切削钢筋的效率,确保了盾构施工工期的按时完成。同时采用同步注浆与穿越后补注浆措施最终保证了轨道结构变形满足变形控制要求。

The construction of the s hield tunnel between Suzhou Bridge Station and Renmin University Station of Beijing Metro Line 12 crosses the adjacent Renmin University Station of the existing line 4.The nearest distance between the newly built shield tunnel and the existing station is 2.86 m.The waste reinforced concrete pile foundation will be cut during the shield construction which is difficult and risky and seldom in Beijing.In order to ensure the operation safety of the existing line,the deformation of the existing station is analyzed and the deformation warning value and alarm value of each part of the existing station during construction are determined by the numerical simulation method.Taking the underpass section 50 m before the construction as the experimental section,the reasonable shield parameters are determined.The upgrade and transformation of the shield cutter head are realized by adding the advance cutter,which improves the efficiency of the shield machine cutting reinforcement,and the shield construction period is completed on time.The synchronous grouting and supplementary grouting after crossing at the same time ensure the deformation of the track structure meets the deformation control requirements.