A Tool for Estimating the Water Content of Unsaturated Railway Track Formation Layers

Water content is one of the causes of railway tracks’ poor performance. Implementing its effects into design and management numerical tools is not always straightforward because the relevant descriptive partial differential equations (PDEs) involved are highly nonlinear. The paper describes the creation of a surrogate model to predict water flow in rail-track layers or other multilayered systems, increasing performance of conventional 2D and 3D models so as to enhance their utility and validity for rail-track maintenance management. The model takes advantage of the mainly 1D vertical direction of infiltration through unsaturated layers and the mainly 1D horizontal direction for saturated flow in the lower layers to create an assemblage of one-dimensional domains using a co-simulation technique. Mathematical formulation is included for both of the 1D simulations and for the assemblage. 1D models are verified, and some results of the assembled model are compared with existing experimental results. Available results suggest a suitable predictive model for multilayer flow.