下穿高速公路浅埋大跨度黄土隧道施工措施研究

Research on construction procedure for shallow large-span tunnel undercrossing highway

依托郑西客运专线阌乡隧道,开展浅埋大跨黄土隧道优化施工研究。对隧道进入下穿高速公路前的地表沉降,拱顶下沉及初支钢架应力进行现场监测,结果表明,土体沉降及初支应力不能得到有效控制,现有的施工方案无法满足下穿段施工安全要求,需要及时对其调整;经综合分析,提出了减小开挖面积、侧导多台阶开挖、预留核心土、快速封闭及加强初期支护等一系列优化措施,并采用数值计算软件FLAC3D验证其安全性和可靠性。通过现场实施及监测结果的反馈,证明优化措施效果明显,保障了阌乡隧道顺利下穿连霍高速公路。研究成果为类似施工中采取相应措施控制土体沉降、保护周边建筑设施的安全使用提供了依据。

Wenxiang tunnel for Zheng-Xi Special Passenger Railway has been done a series of research on optimizing the construction method for shallow large-span loess tunnel.According to the field monitoring of ground settlement,vault settlement and primary support stress of the tunnel section before tunnel undercrossing the Lian-Huo expressway.The result indicates that soil settlement and primary support stress can not be controlled very well;and the current construction scheme needs to be reformed since it can not satisfy construction safety requirement.Through synthetical analysis,some optimized methods such as reducing excavation area,increasing excavation steps of pilot tunnel,reserving core soil,quick closure,reinforcing primary support,etc.have been used in construction;and their security and reliability are verified by numerical analysis software fast Lagrangian analysis of continua in 3 dimensions（FLAC3D）.From feedback of field implement and monitoring result,the effect of optimized methods is significant;and these methods ensure the undercrossing project implements successfully.These research results have high referential value for analogous project to control soil settlement and protect the safety of neighbouring building facilities.