杭州地铁盾构施工中地表位移及变化规律研究

Study on Surface Settlement and Its Law of Hangzhou Metro Shield Construction

杭州地铁盾构施工多处在淤泥、淤泥质土等软土层中。在实测数据的基础上，分析了地铁盾构施工地表沉降在纵向和横向上的变化规律、沉降范围以及沉降槽宽度系数和最大沉降量与隧道埋深问的关系。分析结果表明，地表沉降根据沉降大小和盾构机头的位置在轴线方向上分三个阶段，即盾构机到达前0—40m、到达后0～50m和后盾构等三个阶段。以盾构机头为中心，地表沉降的纵向影响范围为前40m、后50m，横向上为左右两侧各20m。盾构施工期间地表位移主要表现为沉降，但也有隆起，盾构到达后的20—50m为沉降发生的主要阶段，后盾构阶段沉降稳定，但也存在部分回弹现象。沉降槽宽度系数随着埋深的增加影响范围增大，而地表最大沉降量则随着埋深的增加减小。文中得到的结论对于杭州等软土地区地铁盾构施工、监测和设计等具有一定的指导作用和理论意义。

Hangzhou metros are being constructed mainly in such silt and mucky soil as soft layers. Longitudinal and traverse surface settlements and variation law, settlement scope, settlement trough and relationship between maximum settlement and tunnel depth are analyzed during Hangzhou shield construction based on field datum. The results show that surface settlements are divided into such three stages as 0 ~ 40 m before shield machine, 0 - 50 m after and post-shield construction stage according to settlement magnitude and location of shield machine. Longitudinal settlement scope is 40 m before, 50 m after machine, and traverse scope is each side of 20 m of machine. Surface settlements ,which are mainly caused at stage of 20- 50 m after shield machine ,as well as heaves , can be seen during shield construction while settlements accompanying upheavals are stable at stage of post-shield construction. Settlement trough coefficients increase with tunnel depths, and maximum settlement decreases with depth. The gained conclusions have theoretical significance and guidance for design, supervising and shield construction.