贵州六威高速某特长隧道冒顶处置技术研究

Treatment of a Roof Collapse in an Extra Long Highway Tunnel Excavation in Liuwei Expressway Project,Guizhou

依托工程为都匀至香格里拉国家高速贵州境六盘水至威宁段之玉舍隧道工程。针对TZK16+315～TZK16+330段冒顶坍塌问题,开展了洞内外冒顶处置技术方法研究,取得了显著的成效,为同类工程提供了有效的参考。(1)掌子面坍塌后,及时进行反压回填处理,并对坍塌影响段已施作的初期支护段及时施作钢筋混凝土二衬。(2)地表塌腔处回填3m厚C15混凝土密实,稳住周边塌腔周边岩体,防止二次坍塌,并施作截水沟。(3)对坍塌体段采用预留核心土法开挖,按S-Ta衬砌设计施工作业。

This paper presents a case history of the treatment of roof collapse in an extra long highway tunnel excavation in Liuwei National Expressway,which connects the Duyun and Shangri-La in Guizhou Province between Liupanshui and Weining.The collapse occurred between Station TZK16+315 and TZK16+330 and a special outside tunnel treatment method was utilized.The collapse mitigation techniques included:1)Backfill operation should be implemented immediately after the roof collapse and the second concrete lining reinforcement support should be applied in the collapse affected zone;2)at least three meters thick C15 lean concrete should be backfilled at the collapsed area for the purpose of stabilizing the surrounding rock mass and minimizing the potential collapse.Drainage ditch should be installed around the collapsed area;3)In the excavation of the collapsed area,the circular excavation around the backfilled lean concrete should be performed.The excavation is similar to STa lining operation.