Study of the Impact of Wetting Processes on Transport Infrastructure Performance

Extreme weather events attributed to climate change have been gradually causing engineered soils to experience larger and more frequent variations between unsaturated and saturated states by periodically changing their moisture and suction due to wetting (rainfall) and drying (evaporation). Geotechnical assets critical to the transport network are particularly vulnerable to the influence of these climatic conditions due to its impact on their performance including swelling, shrinkage and collapse. However, the implementation of unsaturated soil behaviour into practice is not commonplace despite its importance for increasing resilience of the transport network. This paper addresses the impact of wetting processes, mimicking periods of intense rainfall, on the performance of a typical Victorian rail embankment asset using the Barcelona Basic Model (BBM) implemented in a finite element platform (PLAXIS 2D). The embankment was subject to the simulation of increasing degrees of saturation followed by the application of rail traffic to investigate their effect on performance and serviceability. The transition between unsaturated and saturated conditions during the wetting process was shown to produce significant swelling and strength changes which were exacerbated by increased wetting owing to climate change. Settlement due the application of train loads similarly increased in future scenarios. The results not only demonstrate the importance of considering unsaturated modelling conditions when managing geotechnical assets but also its role in better accounting for the effects of climate change.