Dynamic responses of train under deformation caused by underpass shield tunnel construction based on stochastic field theory基于随机场理论的下穿盾构隧道施工变形条件下列车动态响应

In previous research on railway traffic safety in subgrade sections, the physical parameters of foundation soil are often considered deterministic parameters. To explore the influence of the stochastic field characteristics of the soil around the shield tunnel of the subway on the traffic safety of the existing railway on the ground, an analytical model of the train-track-shield tunnel-foundation soil coupling system was established. The physical and mechanical parameters of the foundation soil are randomly assigned based on the stochastic field theory, and the probability density evolution information of the dynamic responses of the train such as the wheel load reduction rate (WLRR) and the carriage acceleration are obtained. Based on the probability density evolution theory, the dynamic response analysis of the train running on the ground under the deformation condition for shield tunnel construction is carried out. The main results show that: the distribution of ground settlement in the shield tunnel construction section is approximately normal distribution, the maximum value of the mean value and standard deviation of the ground settlement both appear at the centerline of the shield tunnel, while the maximum value of WLRR appears in the descending segment on both sides of the peak of the ground settlement. When the train speed increases, the width of distribution of the vertical acceleration probability density contour line of the carriage body gradually increases, and the corresponding probability density distribution when the upper limit of the vertical acceleration takes the maximum value is still approximately normal. The distribution range of WLRR exceeds the limit requirement of 0.8 at the train running speed reaching 300 km/h. The carriage body acceleration meets the requirement of 1.3 m/s2 under the condition of train speed below 300 km/h. In order to meet the traffic safety guarantee rate of 99.74%, which is three times the standard deviation, it is recommended that the running speed of ground train in the shield tunnel construction section does not exceed 250 km/h.