土压盾构浅覆土近距离上跨既有隧道施工技术

Construction technology of EPBS under shallow covering passing over existing metro tunnel at short distance

土压平衡盾构以其较为宽广的地层适应性及良好的施工安全性,在下穿上跨的叠合隧道中得到良好应用。以济南地铁2号线出入场线盾构上跨开源路站—烈士陵园站区间既有隧道施工为例,采用Midas GTS NX对盾构上跨既有隧道进行数值模拟,各地层采用摩尔-库仑本构三维实体单元模拟,盾构管片采用弹性本构二维板单元进行模拟。研究盾构浅覆土近距离上跨既有隧道的变形规律,针对性制定盾构掘进、监测方案,重点关注既有隧道变形量。研究表明,既有隧道在未加固的条件下,地层承载力满足隧道变形控制要求,施工监测数据与模拟数据吻合。

The Earth Pressure Balance Shield(EPBS)has been put to good use in superimposed tunnels where one crosses under and one passes over,due to its wide stratum adaptability and good construction safety.Using the construction of the depot entrance and exit line of Jinan metro line 2 where the shield passes over the existing tunnel between Kaiyuan Road station and Lieshilingyuan station as an example,Midas GTS NX is used to simulate the shield passing over the existing tunnel.Each layer is simulated using the threedimensional solid element of the Mohr-Coulomb constitutive model,and the shield segment is simulated using the twodimensional plate element of the elastic constitutive model.The deformation law of the shield under shallow covering at short distance above the existing tunnel is studied,to formulate a shield tunneling and monitoring plan and to focus on the deformation of the existing tunnel.The research shows that the stratum bearing capacity of the existing tunnel without reinforcement meets the requirements for deformation control,and the construction monitoring data matches the simulation data more closely.