STUDY ON SITE MONITORING OF LARGE-SECTION HIGHWAY TUNNELS WITH SMALL CLEAR SPACING
大断面小净距公路隧道现场监测分析研究

Heshang tunnel is the first large-section highway tunnel with small clear spacing in Fujian Province.It is critical to make a comprehensive monitoring on the mechanical characteristics of the tunnel during construction.According to its characteristics,some monitoring tasks have been performed in Heshang tunnel,including the ground settlement,crown settlement,convergence,surrounding rocks displacement,surrounding rocks pressure and internal force in lining,etc.Based on the measured data,the deformation and stress properties of surrounding rocks and supporting system are analyzed;the interaction time-space range in the construction of two-arch tunnels with small clear spacing is presented;and the best time of support and secondary lining is given.Meanwhile,the real-time monitoring information is applied to optimizing the supporting system.The experiences and conclusions presented can be adopted in the design,construction and research of similar tunnels.