不同坡度TBM隧道施工对开挖面稳定性的影响

The influence of TBM tunnel construction with different slope on the stability of excavation surface

近些年来TBM隧道施工被广泛应用于地铁隧道的建设中,由于线路规划需要和地形条件的限制,在一些特殊地段可采用纵坡隧道。TBM在迎坡掘进时,因为坡度的存在刀盘会与开挖面发生分离现象,导致开挖面前方岩土体在侧向土压力的作用下朝向刀盘移动,对开挖面稳定性造成不利影响。因此,以重庆轨道交通九号线刘家台站—鲤鱼池站迎坡段区间为依托,对大纵坡TBM隧道施工时引起的开挖面稳定性问题进行分析。采用数值模拟计算方法并结合现场实际工程项目,以隧道坡度作为变量设定多个模拟工况,分析了不同坡度值条件下开挖面处岩土体的应力变化规律及岩土体的横向、纵向、竖向变形规律,研究成果可为纵坡段TBM隧道施工时解决开挖面稳定性问题提供借鉴。

TBM tunnel construction is widely used in subway tunnel construction.Due to the limitation of route planning and terrain conditions,longitudinal slope tunnel can be used in some special sections.When the TBM shield machine is constructed under large slope conditions,the upward slope excavation and the downward slope excavation cause over-excavation of the soil above and below the excavation surface which is detrimental to the stability of the excavation surface and structural safety.Therefore,based on the longitudinal slope section between the Liyuchi Station and Liujiatai Station of Chongqing Rail Transit Line 9,this paper adopts numerical simulation calculation methods combined with actual field construction to solve the problem of excavation surface stability during large longitudinal slope TBM construction.The changes of principal stress near the grub face and the deformation laws of the soil around the grub face in the horizontal,vertical and longitudinal directions under different slope values are analyzed.The research results can provide reference for controlling the stability of the excavation surface in the TBM construction of the longitudinal slope section.