LAUSR

Abstract Railways are one of the largest transportation networks in the world. One of the key subgrade problems of railway track is associated with progressive shear failure (PSF). To-date, limited number of studies have addressed failure mechanism associated with the PSF, especially extending the mechanics of unsaturated soils. In this paper, the PSF mechanism is studied with the aid of computer program that was developed using a Visual Basic program in AutoCAD, extending Mohr-Coulomb failure criteria within the unsaturated soil mechanics framework. Simulation results suggest several parameters that include stress distribution, matric suction, cohesion, coefficient of lateral earth pressure at rest, and coefficient of residual friction as well as the angle of internal friction have a significant effect on the PSF and the shape of failure planes in the subgrade. The PSF in subgrade can be reduced by optimizing the combination of these parameters. The simulation results suggest the PSF can be well simulated with the Mohr-Coulomb failure criteria.