Prediction of Unsaturated Hydraulic Conductivity of Cement-stabilised Laterite Soil under Climate-Induced Wetting and Drying Cycles

Abstract

Climate change, characterised by rising temperatures and changing precipitation patterns, significantly impacts the geotechnical behaviour of soil. This includes alterations in soil’s shear strength, compressibility, and permeability, which in turn affect soil structure and its ability to manage water absorption and retention. Increasing soil moisture can generally reduce permeability by filling finer pores and decreasing pore system connectivity. However, the impact of unsaturated conditions on the soil’s permeability is often overlooked in design compared to saturated conditions. Hence, changes in temperature and rainfall patterns may affect water infiltration into the soil, potentially reducing groundwater recharge and increasing flood risks. Johor, Malaysia, has extensive tropical soil coverage (tropical region), which serves as the focus of this study. Hence, the research aims to elucidate how climate change influences both unstabilised and cement-stabilised laterite soils’ permeability by conducting the falling head permeability tests to determine saturated hydraulic conductivity (ksat), while unsaturated hydraulic conductivity (kunsat) is derived using GeoStudio (SEEP/W) based on experimental data from soil-water characteristic curve (SWCC) and ksat under varying matric suctions. Results indicate that both saturated and unsaturated conditions significantly affect the permeability coefficient of unstabilised and cement-stabilised laterite soils, with the substantial reduction in permeability largely attributed to the effect of saturation and stabiliser. Thus, predicting unsaturated permeability coefficients in the context of climate change is crucial for effective disaster management, as it will improves infrastructure design, enhances risk assessments, and supports community preparedness, ultimately fostering more resilient societies capable of withstanding the challenges of a changing climate.