Keynote Lecture – Lifecycle assessment of geotechnical infrastructure
Contemporary geotechnical design and assessment of infrastructure assets, such as road and rail embankments and cuttings, are increasingly faced with requirements for lifecycle analysis of their long-term stability and serviceability. Being continuously exposed to atmospheric conditions, one critical aspect for the lifecycle analysis of these structures is the consideration of future climate change-induced weather patterns. Extreme rainfall, storm surges and droughts are progressively frequent features even in countries that have generally been considered to have a moderate climate. The second critical aspect is the knowledge of the current hydro-mechanical state of existing infrastructure. Most of it is several decades old and with an unknown process of initial construction. The principal methodology for assessing the long-term behaviour and possible adaptation of existing infrastructure assets is a predictive computational analysis, in conjunction with hydro-mechanical characterisation of the foundation soils and fill materials through laboratory and field testing. Using case studies, this paper brings together advanced geotechnical modelling of the transient hydro-mechanical behaviour of embankments and cut slopes and the modelling of changing rainfall patterns as an advanced hydraulic boundary condition to geotechnical modelling. The effect of vegetation is also considered to complete the water balance, together with rainfall, across the exposed surfaces of slopes and embankments. Challenges associated with the initiation of the current hydro-mechanical conditions in the soil are discussed and a successful modelling methodology is demonstrated. Further challenges are also presented associated with reproducing finer rainfall intensity series appropriate for simulations of short and intense rainfall that tends to cause damage. Their impact is demonstrated and discussed.