高地应力凝灰岩地层铁路隧道支护结构大变形的原因及其整治  

Causes and Renovation for Large Deformation in Supporting Structure of Railway Tunnel in Tuff Formation under High Geostress

作　　者：王树英[1,2] 阳军生[1,2] 李习平[1] 

机构地区：[1]中南大学土木工程学院,湖南长沙410075 [2]中南大学高速铁路建造技术国家工程实验室,湖南长沙410075

出　　处：《中国铁道科学》2014年第5期47-54,共8页China Railway Science

基　　金：国家自然科学基金青年基金资助项目(51208516);国家科技支撑计划项目(2012BAK24B02);中国博士后科学基金资助项目(2014M550424)

摘　　要：针对贵昆铁路三联隧道施工中出现多处支护结构大变形的现象,采用现场地应力测试、数值分析和现场监测的方法,研究高地应力强风化凝灰岩地层隧道支护结构大变形的原因及其整治方案。通过现场地应力测试得知:隧道围岩最大主应力为6.87MPa,远大于岩体单轴抗压强度,高地应力状态是诱发强风化凝灰岩地层隧道支护结构大变形的主要因素。数值分析结果表明:隧道开挖对地应力的影响主要局限于1倍洞径范围之内,在隧道右下侧基底围岩上产生高达17.5%的剪应变,仰拱与边墙过渡段二衬的安全系数小于1.0;数值分析结果与现场地应力测试结果和破检揭露情况基本吻合。采用加深仰拱的方案整治仰拱破损段后,仰拱二衬结构安全系数的最小值达到1.9,监测显示隧道结构处于安全状态。该方案成功地应用于后续相似地层隧道区段的施工中。Large deformation developed on tunnel support in strongly weathered tuff deposit in Sanlian Tunnel of Gui-Kun Railway. The causes of the large deformation developed in the support structure and the renovation measures were studied based on field geostress measurement, numerical simulation and insitu monitoring. According to field geostress test, the maximum principal stress in the surrounding rock of tunnel was 6.87 MPa which was far larger than its uniaxial compressive strength. High geostress was the main reason to cause the large deformation of tunnel support in strongly weathered tuff deposit. Numerical simulation showed that the change of geostress due to tunneling was limited to one time of tunnel diameter. High shear strain of up to 17.5% developed in the ground below the right invert, and the safety factor in the changeover part between the invert and the side wall was lower than 1.0. The numerical results ba- sically agreed with field geostress measurement and exposition. The failed invert was dismantled, and an invert with greater depth was rebuilt. Thanks to the adjustment of tunnel structure, the field monitoring indicates that the minimum safety factor of the secondary lining is 1.9, so the rebuilt invert is in the safe state. The deep invert scheme has been successfully applied in the later tunnel construction section with similar ground.

关 键 词：铁路隧道 高地应力 凝灰岩地层 支护结构 结构大变形 围岩应力 安全系数 

分 类 号：U451.4[建筑科学—桥梁与隧道工程] U457.2[交通运输工程—道路与铁道工程]