Internal Instability and Fluidisation of Subgrade Soil under Cyclic Loading

Abstract Rapid globalisation and the rise in population have substantially increased demand for rail infrastructure which been critical transporting passengers freight across landmasses over a century. The surge often leads to construction of railway lines along with unfavourable soil conditions result different forms substructure challenges such as uneven track deformations, ballast degradation, subgrade mud pumping. A widespread site investigation eastern coast New South Wales, Australia, indicated prevalence holes or bog tracks. field studies suggest that low-to-medium plasticity soils are highly susceptible pump when subjected heavy axle loads under impeding drainage conditions. Subsequent laboratory investigations conducted on remoulded samples collected from sites sharp cyclic axial strains excess pore pressures internal redistribution moisture content governing mechanism Numerical simulations performed using discrete element method coupled computational fluid dynamics show at high hydraulic gradient, there is substantial loss contact network upward migration particles. role plastic fines inclusion geosynthetic layer between also discussed this paper. It was observed addition 10% cohesive resistance On other hand, inclusions not only assist dissipating but inhibit fine