土压盾构近距离并行在建隧道施工方案与措施

Construction Scheme and Measures for Earth Pressure Shield near Parallel Tunnel under Construction

兰州地铁2号线出入线暗挖隧道与主线公定区间在接收端存在并行段,原设计方案采用“暗挖完成后再行盾构施工”,但由于受拆迁、地质条件和环境等因素影响,暗挖施工进度滞后。为优先保证主线公定区间隧道如期贯通,将原设计方案变更为“左线接收端影响范围45 m暗挖暂停开挖,待盾构先行贯通后,再行开挖”。具体措施:(1)对影响范围内暗挖区域采用洞内深孔WSS注浆等措施;(2)盾构管片增加环向支撑;(3)在施工影响范围45 m内布设测斜孔,实时监测盾构掘进过程对暗挖隧道的影响。采用变更后的方案与措施,公定区间左线盾构在并行段安全出洞,在保证兰州地铁2号线总体工程目标的前提下,未对暗挖隧道结构产生影响。该方案对同类型工程具有参考和指导意义。

There are the parallel sections at the receiving end of the underground excavation tunnel and the public defined section of the main line of Lanzhou Metro Line 2.The"shield construction after the completion of underground excavation"was adopted in the original design scheme.However,due to the influences of demolition,geological conditions and environment,the progress of underground excavation construction lagged behind.In order to give priority to ensuring the completion of the tunnel in the public defined interval of the main line as scheduled,the original scheme is changed to"the underground excavation within the influence range of 45m at the receiving end of the left line shall be suspended,and the excavation shall be carried out after the first completion of the shield tunnel".The specific measures(1)In-hole deep hole WSS grouting and other measures are adopted in the affected area;(2)The shield segment increases the circumferential support;(3)Incline holes are laid within the construction affected range of 45m to monitor the influence of shield tunneling process on underground tunnel in real time.By adopting the modified scheme and measures,the shield in the left line of the public decided interval is safely tunneling out of tunnel in the parallel section.On the premise of ensuring the overall construction and financing goal of Lanzhou Metro Line 2,the tunnel structure has not been affected.The scheme has reference and guiding significance for similar projects.