地铁盾构隧道下穿既有铁路对股道沉降的影响分析及桩筏加固技术

The Influence of Subway Shield Tunnel under the Existing Railway on the Track Settlement and the Technology of Pile Raft Reinforcement

针对北京地铁6号线富水砂层地区地铁盾构隧道下穿京承铁路工程项目,运用Plaxis 3D这一先进的岩土有限元分析软件,构建一个基于小应变土体硬化刚度本构(HSS)的动态掘进模型。该模型旨在深入分析桩筏加固方案对盾构施工过程及其对京承铁路的关键性影响。研究表明,在不采取任何保护措施的情况下,盾构隧道穿越股道将导致股道纵向沉降超出黄色预警值4mm的标准,最高沉降值达到5.2mm。然而,当实施桩筏加固方案时,沉降的最大值显著降低至1.5mm,从而证实了该加固方案在确保京承铁路行车安全方面的显著效果。

For the project of Subway Shield Tunnel under the Beijing–Chengde Railway River in the water-rich sand Line 6,Beijing Subway area,a dynamic tunneling model based on small strain soil hardening stiff ness constitutive(HSS)is constructed by using Plaxis 3D,an advanced fi nite element analysis software.The paper aims to analyze in depth the key of the pile-raft reinforcement scheme to the shield construction process and its impact on the Beijing–Chengde Railway River Delta.It is pointed out that the longitudinal settlement of the tunnel will exceed the yellow warning value by 4 mm and the maximum settlement will reach 5.2 mm without any protective measures.However,the maximum settlement gets signifi cantly reduced to 1.5 mm when the pile-raft reinforcement scheme is implemented,thus confi rming the signifi cant eff ect of the reinforcement scheme in ensuring driving safety in Beijing–Chengde Railway.