Deformation of ballastless track and vehicle-track dynamic response affected by subgrade arch in red mudstone areas

Red mudstone, a pliant sedimentary rock, possesses the potential to instigate subgrade arching, a phenomenon brought about by its propensity for water absorption, expansion, and unique rheological properties. This deleterious occurrence impairs the smoothness of railway lines. Previous studies have primarily examined ballastless track behavior under operating speeds up to 350 km/h. Against this background, the present study aims to provide a preliminary adaptability exploration of ballastless track structures on red mudstone subgrades under a train speed of 400 km/h. To this end, this study endeavors to construct a static track-subgrade model, elucidating the deformation patterns of the track at various positions, amplitudes, and wavelengths of the arch. Additionally, a dynamic vehicle-track-subgrade model is devised to examine the dynamic response of both the vehicle and the track under speeds of 400 km/h. The findings of this investigation are as follows: i) When the subgrade stiffness is below 80 MPa, the vertical deflection of the track slab surpasses the allowable threshold. ii) Dynamic indices pertaining to both the train and the track structure exhibit an escalating trend with increasing arch amplitude of the subgrade. The vertical deflection of the track slab exceeds the threshold when the upper arch amplitude reaches 40 mm. Consequently, it is recommended to regulate the elastic modulus of the red mudstone subgrade to a value exceeding 80 MPa, while also undertaking necessary repair measures whenever the arch amplitude exceeds 40 mm.