Modelling of Train Vibration Induced Settlement to Metro Tunnel in Saturated Clay

摘要

The cyclic loading generated by train vibration is considered as one factor influencing the long-term settlement of metro tunnels built in saturated soft clay.To investigate the effect of train vibration on tunnel settlements, a dynamic constitutive model named Cyclic Mobility model and soil-water coupled theory for saturated soil are adopted to capture the evolution of excess pore pressure and resulting consolidation process in saturated clay through finite element analysis.Furthermore, boundary permeability conditions around tunnel lining are also taken into account to model the leakage cases in reality.Numerical results show that excess pore pressure accumulates rapidly to a peak after a period of train vibration and then dissipates gradually to a stable value in the long term.The majority of tunnel settlement is from static consolidation during train interval rather than dynamic consolidation process during train vibration.Boundary permeability plays an important influence on the accumulation and subsequent dissipation of excess pore pressure while no evident influence on the ultimate tunnel settlement.Rationality of numerical results and possible improvements are discussed.