拱隧一体结构跨越巨型溶洞段处治技术研究

Research on Treatment Technology for Arch Bridge-tunnel Integrated Structure Spanning a Large Karst Cave Section

依托贵南高铁甲良三号隧道工程,针对隧道下方开挖揭示的巨型溶洞,提出采用拱隧一体结构跨越巨型溶洞段的施工方案,通过数值模拟结果和现场实测数据,分析拱隧一体结构施工过程中围岩及支护结构的变形规律。研究表明:由于溶洞左右分布规模不同,隧道右侧水平变形大于左侧,拱顶沉降实测稳定值为6.03 mm,占沉降控制值的12.06%,水平收敛值为3.05 mm,占收敛控制值的6.10%,隧道变形满足要求;隧底基坑开挖及支护是处治过程中的关键环节,现场监测数据显示,钢支撑轴力最大值为277.15 kN,钢支撑最终收敛值为4.97 mm,基坑最大竖向位移为2.50 mm,拱隧一体结构施工完成后,拱圈结构最大竖向位移为7.14 mm,均未达到监测预警值,表明溶洞处治过程中隧道围岩及支护结构变形可控,验证了拱隧一体结构跨越巨型溶洞段处治的安全性。

Based on the Jialiang No.3 Tunnel project of the Guiyang-Nanning High-speed Railway,a treatment plan utilizing an arch bridge-tunnel integrated structure to span a large karst cave section was proposed,targeting the large karst cave revealed during tunnel excavation.Numerical simulation results and field measurement data were analyzed to study the deformation patterns of surrounding rock and support structures during the construction of the arch bridge-tunnel integrated structure.The study indicates that,due to the uneven distribution scale of the karst cave on both sides,the horizontal deformation on the right side of the tunnel is greater than that on the left.The measured stable settlement value at the arch crown is 6.03 mm,accounting for 12.06%of the settlement control value,and the horizontal convergence value is 3.05 mm,representing 6.10%of the convergence control value,indicating that the tunnel deformation meets the requirements.Excavation and support of the foundation pit at the tunnel bottom are critical stages in the treatment process.Field monitoring data showed that the maximum axial force of the steel support was 277.15 kN,the final convergence value of the steel support was 4.97 mm,and the maximum vertical displacement of the foundation pit was 2.50 mm.Upon completion of the arch bridge-tunnel integrated structure construction,the maximum vertical displacement of the arch structure was 7.14 mm,all within the monitoring alert values.These results demonstrate that the deformation of the surrounding rock and support structure during the karst cave treatment is controllable,validating the safety of using the arch bridge-tunnel integrated structure to span the large karst cave section.Keywords:Karst tunnel;Arch bridge-tunnel integrated structure;Surrounding rock stability;Numerical simulation;Field monitoring Research on Causes and Countermeasures of Water Leakage in Subway Tunnels in Coastal Area ZHANG Yu1 ZHOU Lu1 SUN Xiaohe2 LI Jun1 SHI Chenghua2 LIU Shengli1(1.Guangzhou Metro Design and Research Institute Co.,Ltd,Guangzhou 5100102;2.School of Civil Engineering,Central South University,Changsha 410075)Abstract:Focusing on the issue of water leakage in subway tunnels in coastal areas,this study investigates the leakage conditions during both the construction and operation stages of multiple lines of the Fuzhou Metro.The causes of water leakage are analyzed,and prevention measures are proposed.The study results indicate that during the construction stage,water leakage in subway stations is more severe than in shield tunnels,whereas during the operation stage,the opposite is true.The main leakage areas in subway stations are sidewalls and baseboards,while leakage in shield tunnels is concentrated at segment joints.The primary causes of station leakage are construction-related,including poor pouring quality of enclosure structures,damage to waterproof membranes,and improper treatment of construction joints.The causes of shield tunnel leakage can be categorized into four aspects:installation and construction,transportation and maintenance,material quality,and structural issues,with installation and construction problems being the most critical.To mitigate water leakage in shield tunnels,the structural design should account for construction proficiency.When construction levels are low,flat joints should replace shear key joints to significantly reduce segment damage and water leakage.