富水砂层盾构隧道一种留置盾尾的接收工艺

Receiving Technology of Retaining Shield Tail in Shield Tunnel in Water Rich Sand Layer

南通轨道交通L2五一路站—园林路站盾构区间穿越地层主要为粉砂层。该地层的微承压水与隧道下方埋深50 m的粉砂层承压水连通,因此盾构接收易发生水土流失、隧道管片沉降变形、地面塌陷等安全事故。"水泥搅拌桩加固地层+洞门橡胶帘布止水"的盾构接收方法,很难应对不良水文地质风险。为最大限度减少盾构接收安全风险事故发生概率,在常规盾构接收方法基础上,根据水文地质特殊性,采用"水泥土加固地层+降水井降水+短套筒洞门密封止水+留置盾尾"盾构接收工艺,可以避免盾构机在接收过程中洞门渗漏、涌水涌沙等安全事故发生。这对类似工程具有借鉴价值。

The stratum of shield crossing between Wuyi Rd.station&Yuanlin Rd.station of Nantong Rail Transit L2 is mainly silty sand layer.The micro confined water in this stratum is connected with the confined water in the silty sand layer buried 50 m below the tunnel,so the shield receiving is prone to safety accidents such as water&soil loss,tunnel segment settlement&deformation,ground collapse,etc.The shield receiving method of cement mixing pile strengthening stratum+rubber curtain water stop at tunnel portalis is difficult to deal with adverse hydrogeological risks.To minimize the probability of safety risk accidents during shield receiving,based on the conventional shield receiving method and according to the particularity of hydrogeology,the shield receiving process of cement soil reinforcement of stratum+dewatering of dewatering well+sealing water stop of short sleeve tunnel door+retaining shield tail is adopted to avoid safety accidents such as tunnel door leakage,water&sand gushing during shield receiving.It has reference value for similar projects.