The role of railway traffic and extreme weather on slab track long-term performance

Abstract

Railway traffic is reaching new limits of train speed, axle load and frequency. To cope with these new demand standards, ballastless tracks emerge around the globe as high performance, long-life and low maintenance solutions. In addition, growing concerns with climate change require resiliency to extreme weather scenarios as anticipated characteristics for future slab track systems.With this goal in mind, an innovative and iterative train-track-soil system model (HI-Track) was tailored developed and validated using finite element modeling so that it can accurately simulate the short- and long-term response of the track under train and atmospheric actions. The modelling process encompasses the dual approach between two dedicated sub-models: a reduced dynamic model (DL-Track) and a detailed nonlinear model (SP-Track). The long-term effect is simulated through the interaction between these two sub-models. The proposed hybrid model simulates several years of track life and at each cycle, various parameters are updated using empirical mechanistic formulations to predict the evolution of concrete slab damage and the permanent deformation of the soil.Several scenarios of combinations of intense traffic (train speed and axle load) and extreme weather conditions (temperature and rainfall) were conducted to evaluate the resiliency performance of railway slab tracks to such events.Simulations performed enabled us to assess important results, revealing for instance that high speed traffic is conducive to faster concrete deterioration in the later years of the track, while freight causes an accelerated degradation in the early years that stabilizes afterwards. Heavy rainfall and flooding have a major impact on track settlement while negative temperature differentials are the main thermal cause for concrete deterioration in unit slab track systems.