软岩偏压铁路隧道大变形处治施工技术

受地形、水文地质条件以及规划平面要求等因素的影响,在软弱偏压岩体中进行隧道开挖支护的工程越来越多。软弱岩体特征复杂、岩性多变、围岩破碎,隧道施工时易发生大变形。以下贵坪隧道工程为研究背景,通过现场观察和分析监测结果,分析大变形的基本特征,并归纳总结地形偏压严重、围岩软弱破碎和施工方法不当是引起下贵坪隧道大变形的主要影响因素,针对隧道大变形的特点提出施工方法调整和支护措施加强、浅埋偏压段洞外减载反压及初期支护变形拆换3项大变形控制措施,确保隧道施工及后期安全稳定。

Construction Technology on large Deformation Treatment of Eccentrically loaded Tunnel in Soft Rock

Restricted by the terrain condition,hydrogeological condition,and the planning plane requirements,more and more tunnels are excavated and supported in soft and eccentric compression rocks.However,soft rocks are characterized by complex,variable and fragmentized,which tend to induce large deformation in tunnel construction.Xiaguiping Tunnel is taken as a project case in this paper.Based on site observation and monitoring results,the basic characteristics of the large deformation of this tunnel are analyzed.And through summarizing,the paper points out that: the terrain with seriously eccentric compression,the weak and broken surrounding rocks and the inappropriate construction methods are the main factors which have induced the large deformation of this tunnel.Finally,directing at the characteristics of the large deformation of this tunnel,three control measures are proposed in this paper to ensure the construction safety and operation safety,including adjusting the construction methods and improving the support measures,deloading and counter pressuring to the shallowly-buried eccentrically-loaded section,and removing the deformed primary supporting.