Maximum safe freight train speed on railway embankments under rapid drawdown conditions based on coupled stress-seepage slope stability analysis

Abstract

The rapid drawdown of the water level adjacent to a railway embankment can reduce its stability, which could compromise the safety of train movements. To investigate the effect drawdown on railway embankments as a function of train speed, a coupled finite element-based model was developed accounting for simultaneous deformations, stresses and seepage. To determine maximum safe train speeds, a comprehensive study was carried out that included slope parameters (e.g. railway embankment height, natural slope height, slope ratio), rapid drawdown ratios, and external freight train loads as a function of speed. The models used the shear strength reduction technique, in which the factor of safety for each model was obtained. Generally, steeper natural slopes with lower railway embankments built upon them are more prone to failure, thus severely limiting train movements when a drawdown condition occurs. However, for a large number of cases, mainly for flatter slopes, a safe passage can be achieved by limiting train speed, while tall railway embankments appear to be able to withstand drawdown conditions without a considerable reduction in train operating speeds. The results of findings are summarized in a table and it is hoped that the study will be useful to increase the safety of freight train operations, particularly in cases when there is a sudden change or an unusual event in the waterways adjacent to a railway embankment.