铁路大断面黄土隧道初期支护作用效果

以兰渝铁路胡麻岭隧道为工程背景，通过三维数值模拟结合典型断面现场监测，对铁路大断面黄土隧道初期支护的受力与变形特性进行综合研究，通过数值模拟得到黄土隧道在开挖扰动后初期支护的受力状态，将数值模拟结果和现场监控量测数据进行对比，获得典型断面围岩与锚杆轴力的变化规律，并对初期支护作用效果进行评价，找出施工过程中的薄弱环节，提出相应的优化措施．结果表明，数值计算与现场实测结果基本吻合，黄土地区隧道施工应坚持“及时支护、及早封闭”原则，确保开挖后围岩变形的稳定．

Initial support action effect of large section railway tunnel in loess

Based on Humaling tunnel, the mechanical and deformational properties of the initial support are comprehensive researched by in-situ monitoring and 3d numerical analysis, and the results of numerical simulation are compared with in-sire monitoring in order to get the state of stress which brought to the optimal parameters of initial support after excavation. The initial support effects can be evaluated. Meanwhile, several corresponding optimization measures am put forward aiming at the weaknesses of the initial support process. The practice proves that the mmputed results am basically oonsistent with the in-situ monitoring datum. It is suggested that the principle of ＂timely support, early closure＂ should be followed in order to ensure that the stability of surrounding rock deformation after excavation in Loess.