浅埋长大输水隧洞下穿省道建设施工技术研究

Research on construction technology for shallow-buried,long-distance water conveyance tunnels passing underneath provincial roads

云南省滇中引水工程楚雄段4标段下穿S218省道,位于省道正下方的最小埋深仅为20m。为最大程度减小隧洞施工对S218省道的影响,保证隧洞施工安全、质量和进度,提出了包括采用超前固结及洞周注浆、超前支护及加强初期支护等措施在内的浅埋长大输水隧洞下穿省道施工建设技术,并结合现场量测结果,分析了该技术的现场实施效果,以及该技术的效益情况。结果表明,该技术能提高滇中红层软岩的承载能力,同时恢复或构成完整的岩体结构,进而形成连续的结构体,有利于后期系统锚杆、锁脚锚杆加固时锚固力的传递,大幅度提高加固质量和效果,有效控制隧洞变形,同时实现较小超挖,大大提高施工效率和质量,节约项目成本。

In the Central Yunnan Water Diversion Project,Section 4 of the Chuxiong segment passes underneath the S218 provincial road,with a minimum burial depth of just 20m directly below the road.To minimize the impact of tunnel construction on the S218 road and ensure the safety,quality,and progress of the tunnel construction,construction technology for shallow-buried,long-distance water conveyance tunnels passing underneath provincial roads was proposed.This included measures such as advanced consolidation and grouting around the tunnel,advanced support,and strengthened initial support.Combined with on-site measurement results,the effectiveness of this technology in practice and its benefits were analyzed.The results show that this technology can improve the bearing capacity of the soft rock and weak surrounding rock in the red beds of central Yunnan,while also restoring or forming a complete rock structure,thereby creating a continuous structural body.This is advantageous for the transfer of anchoring force during subsequent system anchoring and foot-lock anchoring reinforcement,greatly improving the quality and effectiveness of the reinforcement.It effectively controls tunnel deformation,achieves minimal over-excavation,greatly enhances construction efficiency and quality,and saves project costs.