Stability analyses of old railway embankments on soft soils are commonly made using conventional limit equilibrium method (LEM) based on undrained strength of the subsoil. Alternatively it is possible to use effective strength parameters. According to the Finnish Railroad authorities (RHK), one has to use also the finite element method (FEM) for the effective stress analysis if the clay content in the subsoil is above 35 %. The reason for this is that one should account for the failure induced pore pressure. However, no guidelines are yet given on how this should be done.

This study compares stability analyses based on limit equilibrium method and finite element method applying strength reduction method (SRM) and gravity increase method (GIM). Analyses contain three old railway embankments constructed on clayey subsoil. FEM analyses (program Plaxis) will be accomplished using the simple Mohr-Coulomb material model and the more sophisticated Soft Soil model. The focus of the study is on how to account for the failure induced pore pressure.