Long-term settlement of tunnels induced by subway moving load in soft soil districts

In order to investigate the long-term settlement of rail tunnels caused by subway operation, the data of indoor cyclic triaxial tests performed on the saturated soft clay are analyzed. The effect of initial K₀-consolidated stress state on power exponent of index calculation model for axial plastic cumulative strain calculation is evaluated, and a new empirical model is proposed to simulate the cumulative plastic strain of soft clay under K₀-consolidated condition, which extends the existing empirical formulation. The validity of the model is verified based on the data of cyclic triaxial tests performed on Shanghai typical saturated soft clay and parameters of the model are determined. The model can better describe the law of axial cumulative plastic strain development under different consolidated conditions. Based on the layer-wise summation method, a new way of load application, which combines the finite difference numerical model and the continuous single-layer beam model, is adopted to calculate the long-term settlement of one tunnel in Shanghai.