泥水盾构砂土液化地层掘进姿态控制技术研究

Research on Driving At itude Control Technology of Slurry Shield Tunnel in Sand Liquefaction Stratum

当前城市地铁隧道普遍采用盾构法施工,但随着盾构施工过程中遇到的地层越来越复杂,对盾构施工技术提出了更高的要求。尤其是在特殊地层条件下,如隧道底部为在震动作用下易液化的粉细砂地层,泥水盾构掘进过程中出现盾体整体"下沉"情况,造成成型隧道管片出现破损、错台、渗水、漏砂及姿态超限等质量、安全问题。以广州地铁八号线北延段某一标出入段线区间盾构隧道为依托,研究砂土液化地层泥水盾构掘进过程中采用盾体底部惰性浆液注入为核心,加强过程参数控制等措施预防液化地层盾体下沉的施工技术。

Shield tunneling is widely used in urban metro tunnels at present. However,with the shield construction process encountered in the formation of more and more complex,higher requirements for shield construction technology are put forward. Especially under special stratigraphic conditions,for example,the bottom of the tunnel is a silty sand layer which is easy to liquefy under the action of vibration,overall“subsidence” of shield during slurry shield tunneling,the quality and safety problems such as damage,staggered platform,seepage,sand leakage and posture exceeding the limit of the formed tunnel segment are caused. Based on the shield tunnels in the north extension section of Guangzhou Metro Line 8,study on slurry injection at the bottom of shield body as the core of slurry shield tunneling in liquefied sand stratum,construction technology for preventing shield subsidence in liquefied formation by strengthening process parameter control and other measures.