Soil-atmospheric boundary interaction is vital for the geotechnical design as the soil behaviour is moisture dependent, especially for expansive soils. Understanding the soil-atmospheric boundary interaction and the effect of climate change can be important for ensuring the resilience of geotechnical infrastructure. Thornthwaite Moisture Index (TMI) has been adopted in many geotechnical designs to account for the climate-induced moisture variations within the soil. The average TMI deducted from long-term climate data (continuous 25+ years) is often correlated with the design parameters such as the suction change depth and hence the characteristic surface movement. The behaviour of many structures can be influenced by shorter-term weather events and a shorter-term TMI may present a better correlation in such scenarios. However, high variability and the non-stationary character of a short-term TMI can be hindrances for any real-life application. This study assesses 1, 3, 6 monthly, and yearly TMI values estimated from 30 years of climate data. The result showed a significant difference exists between these monthly and annual average TMI values. This highlights the significance of incorporating short-term climate events and integrating climate change into geotechnical structures for the betterment of the built environment through safer, more resilient, and sustainable design.

Climate change is one of the major global challenges and it can have a significant influence on the behaviour and resilience of geotechnical structures. The changes in moisture content in soil lead to effective stress changes and can be accompanied by significant volume changes in reactive/expansive soils. The volume change leads to ground movement and can exert additional stresses on structures founded on or within a shallow depth of such soils. Climate change is likely to amplify the ground movement potential and the associated problems are likely to worsen. The effect of atmospheric boundary interaction on soil behaviour has often been correlated to Thornthwaite moisture index (TMI). In this study, the long-term weather data and anticipated future projections for various emission scenarios were used to generate a series of TMI maps for Australia. The changes in TMI were then correlated to the depth of suction change (Hs), an important input in ground movement calculation. Under all climate scenarios considered, reductions in TMI and increases in Hs values were observed. A hypothetical design scenario of a footing on expansive soil under current and future climate is discussed. It is observed that a design that might be considered adequate under the current climate scenario, may fail under future scenarios and accommodations should be made in the design for such events. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).