上海城市轨道交通建设至今近20年,经历了从无到有到加速发展的过程.现已建成并投入运营的城市轨道交通网络已达425 km,其中地下线路占70％,且绝大部分隧道都是采用盾构法施工.隧道所处地层都是高含水量、高空隙比、高灵敏度和低强度的软弱黏性土层及含承压水的粉砂层.由于盾构施工对地层的扰动、隧道邻近建筑活动的影响、长期列车振动的作用,以及持续不断的大地沉降,隧道很易发生渗漏和不均匀沉降.%Shanghai urban rail transit constructions have nearly 20-year history, experiencing through a process from scratch to speeding-up development. The 425 km rail transport networks have been built and put into operation, of which 70 percent are underground lines, and most of the tunnels are constructed by shield. Tunnel formation is the soft clay with high water content, high voids ratio, high sensitivity and low strength and the silty sand layer with confined water.
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