Historical developments and milestones in unsaturated soil mechanics

The development of soil mechanics for unsaturated soils began about two to three decades after the commencement of soil mechanics for saturated soils. The basic principles related to the understanding of unsaturated soil mechanics were formulated mainly in the 1970's. There were two series of conferences that played a dominant role in our understanding of unsaturated soils. These were the series of conferences on expansive soils from 1965 to 1992, and the series of conferences on unsaturated soil mechanics from 1993 to the present. The development of unsaturated soil mechanics has gone through several stages as it has moved towards implementation in standard geotechnical engineering practice. These stages are traced through an analysis of research papers published at a number of engineering conferences related to unsaturated soils. Key words: unsaturated soils, expansive soils, history, research papers, conference papers.