大跨偏压小净距隧道分部导坑法施工力学效应

随着我国城镇化、机动化进程不断加快以及车辆的急剧增长,为了保证资源的合理、快速调配,势必会修建更多大跨隧道。对于埋深浅、围岩破碎的软弱地带,传统的施工方法已不能完全适应大跨隧道施工的要求。在浙江省50省道莲都段改、扩建工程路湾隧道的施工过程中总结了分部导坑开挖法,阐述了分部导坑法的施工原理、施工工艺流程及适用范围,分析了核心土临时支护的稳定性和合理曲率形式,最后与双侧壁导坑法进行模拟对比。结果表明,分部导坑法与双侧壁导坑法所用工程材料一致,但开挖后拱顶与水平位移均较双侧壁导坑法小,并可有效地解决因双侧壁导坑法开挖时扰动拱部范围围岩而引起的坍塌、冒顶等问题,改善了作业环境,保障了施工安全,同时分部导坑法可多工序循环流水作业,避免施工相互干扰,可提高施工效率;最后分析了小净距隧道先、后行洞分部导坑法施工的合理间距,可为同类工程提供参考和借鉴。

Study on Construction Mechanical Effect of Division Pilot Method in Large Span Tunnel with Small Interval of Bias

With the accelerating of our urbanization and motorization process and the sharp increase of the vehicle, there will be bound to build more large-span tunnels to ensure the rational and rapid deployment of resources. But for the weak zone of shallow and broken wall rock, traditional construction methods can not fully meet the requirements of large span tunnel construction. The division of pilot tunnel excavation method in the process of change and expansion construction at Zhejiang provincial highway 50 lotus period road bay tunnel is summarized, and its construction principle, construction process and application scope are expounded. Stability and reasonable curvature form of core soil temporary support is discussed, and compared with the results of double side drift method by numerical simulation. Results show that the engineering materials used for the pilot tunnel method is consistent with double side drift method, but the vaults displacement and horizontal displacement after excavation are relatively smaller than that of double side drift method. The method can effectively solve problems such as collapse, roof caving that due to the double side drift excavation method disturbances the arch surrounding rock. The division of pilot tunnel method can improve the working environment, protect the safety of construction. It also can be operated cyclic and line produced to avoid mutual interference in construction, and improve the efficiency of construction. Finally, the reasonable spacing of small clear distance tunnel construction is analyzed by using the division of pilot tunnel method. The method can provide reference for similar projects.