达成高速铁路岩溶隧道围岩稳定性分析

Stability Analysis on the Surrounding Rock of a Karst Tunnel in Da-Cheng High-Speed Railway

结合达(州)成(都)高速铁路某岩溶隧道工程,建立岩溶隧道三维实体模型,利用三维快速拉格朗日法FLAC3D对隧道底部含有溶洞的围岩稳定性进行数值模拟研究,并将数值计算结果与现场监测结果进行比较分析。研究结果表明:随着隧道施工接近并通过溶洞顶部,隧道拱顶处围岩向下变形,其值不断增大;拱腰处围岩沿隧道径向收敛,其值变化较小;仰拱处围岩最初向上变形,在隧道施工到溶洞顶部时变为向下变形,且其下沉值不断增大;围岩塑性区主要集中在隧道拱顶、仰拱底、拱腰和溶洞顶部处;溶洞顶部与隧道底部的塑性区有相互连通的趋势;隧道拱顶左右各约45°的范围、隧道底部以及溶洞周围的部位为应力释放区,拱腰处为应力增高区。

In combination with a karst tunnel in Da （Zhou）-Cheng （Du） High-speed Railway, 3D solid model of karst tunnel is established. By using the three-dimensional fast Lagrangian analysis of continua method FLAC3D, the surrounding rock stability of the tunnel with a karst cave in its bottom is simulated, and the numerical calculation results and field monitoring results are compared. Research results indicate that along with the tunnel is closed to and passed the karst cave, the surrounding rock of the crown is con- vergented toward the tunnel, and the settlement displacement value is continually increasing. The surrounding rock of arch crown is convergented radially toward the tunnel, the convergence displacement value has changed little. The convergence direction of surrounding rock of invert is up and its displacement is getting little. When the tunnel being constructed on the top of the karst cave, the convergence direction of surrounding rock of invert is down and its displacement is getting large. The surrounding rock plastic zones mainly concentrate on the vault and the invert and arch crown of tunnel and the top of the karst cave. The surrounding rock plastic zone of the top of the karst cave and the bottom of the tunnel tends to be connective. The range of 45^o of the crown of tunnel and the invert of tunnel and around the karst cave are stress releasing zones, arch crown is stress increasing zone.