Advanced Numerical Simulation of Dynamic Behavior of Railway Infrastructure Under Extreme Conditions

Railway infrastructure presents structural diversity, material variability and performance evolution characteristics during its long-term service. Its physical–mechanical property and dynamic behavior show inevitable complexity, degradation and insecurity under vehicular, structural and environmental effects, etc. To reveal the dynamic performance of railway infrastructure accurately and efficiently subject to extreme conditions, numerical simulation plays an important role from labor-economic saving, timely forecast and computer-aided aspects. This chapter firstly presents the background of numerical simulation of railway infrastructure, where the importance and necessity of the dynamic simulation are demonstrated. And then, the railway infrastructure is categorized into train-track-bridge, train-track-subgrade, and train-track-tunnel interaction systems by regarding train-induced vibration as the most general form. Corresponding simulation models are established by theoretical approaches of vehicle-track coupled dynamics and finite element method, etc. Based on the dynamics models, the extreme conditions, such as crosswind, seismic motion, extreme temperature, and severe soil deformation, etc., can be further considered to reveal the critical behavior, formulate safety criteria, and make maintenance decision of railway infrastructure. Following this, the authors present newest research on constructing a unified model to characterize and evaluate the train-track-substructure interaction by regarding railway infrastructures as an entire system. At last, the conclusion and prospects are given.