强降雨作用下软土隧道仰坡稳定性分析  

Stability analysis on portal slope of soft soil tunnel under heavy rainfall

作　　者：熊齐欢 袁青 于锦 杨林 XIONG Qihuan;YUAN Qing;YU Jin;YANG Lin(CCCC Second Harbor Engineering Co.,Ltd.,Wuhan 430048,China;Key Laboratory of Large-span Bridge Construction Technology,Wuhan 430048,China)

机构地区：[1]中交第二航务工程局有限公司,湖北武汉430048 [2]长大桥梁建设施工技术交通行业重点实验室,湖北武汉430048

出　　处：《人民长江》2022年第12期151-156,共6页Yangtze River

摘　　要：针对软土区的隧道仰坡安全与稳定性问题,采用室内直剪试验的方法分析了不同饱和度土体的抗剪强度指标,并建立了坡积粉质黏土和全风化凝灰熔岩黏聚力、内摩擦角与其饱和度之间的数学关系。采用有限元分析方法对福州市董奉山隧道仰坡进行数值模拟,分析了明洞开挖、隧洞暗挖和降雨过程中隧道仰坡的渗流场和边坡稳定性情况。分析结果表明:随着降雨时间的持续,边坡土体基质吸力逐渐降低,边坡稳定性状态也随之恶化,当降雨时长达到10 h时边坡进入极限平衡状态,降雨时长超过18 h后隧道仰坡形成贯通性塑性滑面;同时,洞口暗挖段施工有利于降低隧道仰坡水位线,有利于边坡的自稳。因此软土区隧洞仰坡的安全和稳定与降雨和地下水变化有重大关系,隧洞施工过程中应加强地表、地下水的截排工作。Aiming at the safety and stability of tunnel portal slope in soft soil area,the shear strength indexes of soil with different saturation were analyzed by direct shear test,and a mathematical relationship between cohesion,internal friction angle and saturation of slope silty clay and fully weathered tuff lava was established.The numerical simulation of the portal slope of Dongfengshan tunnel was carried out by using the FEM to analyze the seepage field and slope stability of the tunnel portal slope under condition of open tunnel excavation,tunnel conceal excavation and rainfalls.The analysis results showed that with the continuous rainfall,the suction of the soil matrix of the slope gradually decreased and the stability of the slope also deteriorated.When the rainfall lasted for 10 hours,the slope entered into the limit equilibrium state,and when the rainfall lasted for more than 18 hours,the tunnel portal slope was about to fail.However,the construction of the concealed excavation section at the portal was conducive to reducing the water level of the tunnel portal slope.Therefore,the safety and stability of the tunnel portal slope in soft soil area were closely related to rainfall and groundwater changes,so the interception and drainage of surface and groundwater should be strengthened during tunnel construction.

关 键 词：隧洞仰坡 非饱和土 降雨入渗 土体含水量 土体强度 边坡稳定 

分 类 号：U451.2[建筑科学—桥梁与隧道工程]