Subgrades and embankments of railroads on unsaturated clay are subjected to not only climatic variation (and its corresponding volume change), but also to increasing dynamic train loading. Shrink/swell soils are known to exacerbate railroad track conditions. In this study, field investigation, laboratory tests, and numerical modeling are integrated to advance current understanding the impact of shrink/swell soil on railroad behavior. A test site in Texas at an actual union pacific (UP) railroad section was selected to study in detail the interactions between railroad dynamic loading, natural (shrink/swell) foundation soils, local topographic conditions (controlling the drainage), and climatic variations. A comprehensive set of ongoing laboratory tests are being conducted to investigate hydraulic, volumetric, and dynamic soil properties. The ongoing study examined soil hydro-mechanical and dynamic properties and the results obtained from the laboratory tests are to be used in numerical modeling which can help in extrapolating the behavior of railroad on shrink/swell soils in various scenarios. Using the aforementioned (field, laboratory, and numerical) methodologies, the actual behavior of railroad under different weather conditions and dynamic loading is studied; the mechanism of railroad deformation due to train loading and weather change is examined; and dynamic numerical models are validated for simulations of future study.
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