都安高速公路大断面隧道分部台阶法快速施工技术研究

Rapid Construction Technology of Sectional Step Method for Large Section Tunnel of Duyun-Anshun Expressway

都匀—安顺高速公路九家湾隧道为单洞4车道高速公路隧道,其最大开挖跨度约22.28m,高约14.15m,开挖断面面积为235.78m^(2),地层以下统栖霞组灰岩为主,原设计采用双侧壁导坑法和CD法施工。为提高施工效率,达到快速施工的目的,针对九家湾隧道具体地质情况,提出采用“先行中导洞开挖,后左、右侧导洞交错开挖”的分部台阶法施工,并成功应用于九家湾隧道施工。现场施工效果表明,隧道施工安全,施工进度快,技术经济效果良好。

Jiujiawan Tunnel of Duyun-Anshun Expressway is a single hole four-lane expressway tunnel,with the maximum excavation span of about 22.28m,a height of about 14.15m,and an excavation crosssection area of 235.78m^(2).Lower Qixia Formation limestone is the main part.The original design adopts the double side heading method and CD method for construction.In order to improve the construction efficiency and achieve the goal of rapid construction,according to the specific geological conditions of Jiujiawan Tunnel,this paper puts forward the construction method of step by step method of“first excavation of middle pilot tunnel,then staggered excavation of left and right pilot tunnels”,which was successfully applied to the construction of Jiujiawan Tunnel.The field construction results show that the tunnel construction is safe,the construction progress is fast,and the technical and economic effects are good.