Soil-water characterization and unsaturated shear strength of khon kaen

Khon Kaen Loess, being known as a collapsible soil, could cause hazards such as sudden collapse and settlement when subjected to wetting. This soil could be further examined with the use of soil-water characteristic curve – the relationship between the volumetric water content and the matric suction. This research presents an experimental study of unsaturated behavior of Khon Kaen Loess by means of the unsaturated triaxial apparatus. The soil-water characteristic curves were modelled using the curve fitting equations of Van Genuchten (1980) and Fredlund and Xing (1994). Additionally, the shear strength of unsaturated soil was explained using an extended Mohr-Coulomb failure criterion, which is fitted to the unsaturated shear strength equation by Fredlund et al. (1978). The research also employed the testing data of Khon Kaen Loess from previous study at Khon Kaen University. The research findings determined that the Fredlund and Xing (1994) model best fits for the soil-water characteristic curve of Khon Kaen Loess. The data analysis of the unsaturated shear strength shows that from the extended Mohr-Coulomb parameter values for Khon Kaen Loess could be derived.