Engineers Australia

Assessment of the impact of climate change on expansive soil movements and site classification

Xi Sun, Jie Li and Annan Zhou


There is overwhelming evidence that climate change leads to a wide range of climatic and weather changes that can affect the performance of built infrastructures. Climate change is likely to have significant impacts on the performance of residential buildings constructed on expansive soils. The Thornthwaite Moisture Index (TMI) as a useful climate parameter has been widely employed to estimate the depth of design soil suction change (Hs) which is needed for the determination of characteristic ground movement (ys). Precipitation and temperature are the primary weather parameters required for the TMI computation. By applying the projected rainfall reduction and temperature increase in 2030, 2050 and 2070 in the TMI calculations, the effects of climate changes on expansive soil movements and site classification can be quantified by the use of the predicted TMI. In this study, TMI values of various areas of Victoria were calculated under A1B and A1FI emission scenario using climate projections generated from 23 climate models. These predicted TMI indices were then used to delineate TMI isopleth lines on the map of Victoria to visualise and compare climate conditions in 2030, 2050 and 2070. A case study was also carried out to assess the effect of climate changes on the magnitude of ground surface movements in the top five most densely populated cities (i.e. Sydney, Melbourne, Brisbane, Perth and Adelaide) in Australia for three specific years (i.e. 1990, 2030 and 2070). The results show that both Hs and ys values are expected to increase significantly with climate change.