Simplified plastic settlement analysis of non-ballasted slab railroad track foundations on fine-grained soil

This study develops a simplified method to evaluate the plastic settlement of non-ballasted slab rail-road track foundations on fine-grained soil. Instead of three-dimensional finite element analysis, a two-dimensional plane strain model is utilized to deduce approximate deviatoric stress profiles for use in plastic strain calculation. From analysis examples of an embedded slab railroad track foundation, it is shown that the proposed method is computationally efficient, greatly reducing the computation load and time. This study also applies this method to perform a parametric study to investigate the design of prepared subgrade in reducing the plastic settlement. The results show that with the same prepared subgrade width as the foundation slab, the effect of the thickness or stiffness of the prepared subgrade on the reduction of settlement is limited; however, once the width of the prepared subgrade is larger than that of the slab, the effect of the prepared subgrade thickness or stiffness can be significantly enhanced.