新建地铁隧道近距离下穿运营地铁线路施工及安全管控

Construction and Safety Control of New Metro Tunnels Passing under Existing Operational Metro Lines in Close Proximity

新建青岛地铁8号线青岛北站—沧口站区间近距离下穿既有运营地铁3号线,初期支护距3号线底板结构仅0.4 m,在不影响既有地铁3号线正常运营的前提下,施工难度极大。通过构建三维有限元模型,模拟新建线路下穿施工全过程,制定针对性措施:采用非爆破机械开挖减小震动;加强超前支护和及时支护封闭成环,控制沉降;自动化监测快速反馈3号线结构变形信息以指导现场施工。通过现场技术手段和安全管控手段,下穿施工期间3号线隧道结构最大沉降仅2.11 mm,道床最大沉降仅1.55 mm,满足沉降控制要求,施工期间未对地铁3号线的安全运营产生影响。相关工程经验可为今后小净距、小角度、长距离下穿既有运营地铁工程的设计、施工提供借鉴。

The running tunnel between Qingdao North Station and Cankou Station of the new Qingdao Metro Line 8 passes under the existing operational Metro Line 3 in close proximity,with the distance between the initial support of new metro tunnel and the bottom floor structure of Line 3 being only 0.4 m,which is extremely challenging for construction without affecting the normal operation of the existing Metro Line 3.By constructing a 3D finite element model,this paper simulates the full construction process of the new running tunnel passing under the operational ex⁃isting line.And relevant targeted measures are prepared:using non-blasting mechanical excavation to reduce vibra⁃tion;strengthening advance support and fast-closing support ring to control settlement;and automatic monitoring structural deformation of Line 3 to provide rapid feedback and guide on-site construction.Through on-site technical and safety control means,the maximum settlement of the tunnel structure of Line 3 during the underpass construc⁃tion was only 2.11 mm,and the maximum settlement of the track bed was only 1.55 mm,which satisfied the require⁃ments for settlement control without affecting the safe operation of Metro Line 3 during the construction period.The relevant engineering experience can provide a reference for design and construction of similar tunnel works passing under existing operational metro tunnels with small clearance,small angle and long distance.