重庆深埋特大断面隧道变形特征及施工工法比选

Deformation Characteristics and Construction Method Comparison of Deep-buried Super-large Section Tunnel in Chongqing City

依托重庆轨道交通18号线歇台子站地下工程,借助有限差分软件建立三维围岩-结构数值模型,分析了城市深埋特大断面(492.84 m2)隧道结构采用三种分部开挖法所引起的隧道围岩变形和应力分布。结果表明:台阶法和交叉中隔墙法施工所产生的拱顶沉降变化趋势基本一致,采用双侧壁导坑法施工所产生的拱顶沉降比其他两种方案小;台阶法与交叉中隔墙法仰拱隆起变化趋势稍有差异,但最终值接近,双侧壁导坑法所产生的仰拱隆起最小。实践中采用双侧壁导坑法施工后隧道围岩位移较小,整体结构安全稳定。

Based on the underground project of Xietaizi station of Chongqing city rail transit line No.18,a three-dimensional numerical model of surrounding rock structure was established by using the finite difference software,and the deformation and stress distribution of surrounding rock caused by three kinds of partial excavation methods for urban deep-buried tunnel structure with super large section(492.84 m2)were analyzed.The results show that the change trend of vault settlement caused by bench method and cross diaphragm method is basically the same,and the vault settlement caused by double side drifts method is smaller than the other two methods.The change trend of inverted arch heave of bench method and cross diaphragm method is slightly different,but the final value is close,and the inverted arch heave produced by double side drifts method is the smallest.In practice,the surrounding rock displacement of the tunnel was small after the double side drifts method was adopted,and the overall structure is safe and stable.