Recent Advances in Experimental Modelling of Unsaturated Soil Behaviour over a Whole Range of Paths and Modes of Deformation

The last few decades have been an era of intensive and sustained experimental efforts that has defined the threshold of our understanding of unsaturated soil behavior. The adoption of matric suction, (u

a

– u

w

), and the excess of total stress over air pressure, that is, net normal stress, (

σ

– u

a

), as the relevant stress state variables, has facilitated the investigation of key features of unsaturated soil behavior via the axis-translation technique. It is the relative success of this technique that has prompted researchers in the discipline to devote countless hours to fine-tuning myriad details of existing and standardized soil testing devices, and hence keep the focus of their efforts on expanding their testing capabilities. The present Theme Lecturer’s paper summarizes some of the most recent advances in experimental modeling of unsaturated soil behavior, over a whole range of suction-controlled paths and modes of deformation, accomplished at the University of Texas at Arlington. Its main sections are devoted to describing the test protocols and analyzing the key results from a series of suction-controlled resonant column, bender elements, biaxial (plane strain), true triaxial (cubical), and ring shear (large displacement) testing programs successfully conducted on compacted samples of sandy soils.