北京地铁小间距浅覆土平行盾构隧道施工技术

《地铁设计规范》GB50157—2003规定盾构法区间隧道覆土厚度一般≥1.0D(隧道外廓直径),平行隧道净距一般≥1D,不能满足要求时应进行特别分析。北京地铁亦庄线宋家庄—肖村区间有200m区段最小覆土厚度4.1m(0.68D),最小隧道水平净距仅3.0m(0.5D)。通过对工程地质情况和周边环境进行分析,在工程经验基础上结合数值模拟,对地层和隧道结构的受力变形特征进行了研究,确定了盾构施工参数和掘进控制技术。信息化施工保障在未进行地层加固的情况下通过了此风险源。沉降监测结果揭示了北京地区小间距浅覆土盾构隧道沉降规律。

The Study on Shield Construction Technology Used in Beijing Metro Shallow & Close-distance Parallel Tunnel

The code for design of metro GB50157—2003 stipulates that covering soil thickness of shield tunnel and distance between each parallel shield tunnel usually should not be less than one time maximum tunnel diameter which named D.When the clause is broken,supplementary research should be given.The shield driven tunnel from Songjiazhuang to Xiaocun in line Yizhuang for Beijing Metro has 200m length section where minimum covering soil thickness is 4.1m,ie.0.68D and the distance between each parallel tunnel is 3.0m,ie.0.5D.After analyzing engineering geology and surrounding circumstance,mechanic characteristics research of earth layer and tunnel structure is given based on numerical simulation and engineering experience.Then shield construction parameters and driving principle are determined.Without pre-reinforcing of natural ground,shield machine safely passes through the risk section using information construction management.The measured data from monitoring reveal settlement regularity of Beijing Metro shallow-close parallel tunnel.