This research program addresses a ground failure phenomenon known as liquefaction that can result when certain soil deposits, such as loose saturated sands, are subjected to the strong ground motions induced by earthquakes. Structures built in or on ground that liquefies are very prone to failure. Most of the laboratory research on liquefaction has involved experiments on saturated clean sands, whereas most of the natural deposits susceptible to liquefaction range from silty sands to sandy silts. There is, therefore, a need to address in the controlled environment of the laboratory the more difficult problem of the liquefaction of silty soils. The objective of this research program is to understand the liquefaction characteristics of silty soils. One of the main goals is to establish threshold limits for the liquefaction potential of silty soils in terms or grain size and soil plasticity: the motivation is to improve the understanding of the liquefaction characteristics of these soils, as well as their use in remedial measures to improve the resistance to liquefaction at a particular site. The post- cyclic (that is, post-earthquake) behavior is also being investigated: it determines the ability of the soil deposit to function satisfactorily as a foundation material after the ground shaking and resulting liquefaction has subsided. The results obtained from this research project will provide the basis for a reasonable estimate of the dynamic stability of a wider range of naturally occurring soil deposits. The post-cyclic studies should provide insights into the phenomenon of delayed failure and permanent deformations of soil deposits subjected to earthquake shaking.
