Liquefaction Resistance and Cyclic Response of Air Injected-Desaturated Sandy Soil

Desaturation of in-situ saturated sandy soils is emerging as a new cost effective and environment friendly liquefaction mitigation technique. In the present study, stress controlled undrained cyclic triaxial tests have been conducted on air injected-desaturated sandy soil and various important issues such as number of cycles required for initial liquefaction, cyclic strength of desaturated sand, modes of failure, evolution of pore pressure, have been explored in detail. Number of cycles required for initial liquefaction increased exponentially with decrease in degree of saturation. Cyclic strength of desaturated sand with degree of saturation of 80% is found to be twice that of saturated sand, for relative density of 40%. Assessment of performance of desaturated sand under various earthquake records revealed that desaturated sand with degree of saturation of 70% can prevent liquefaction during moderate to strong earthquakes having peak ground acceleration as high as 0.30 g. Further, sample with high degree of saturation underwent cyclic mobility failure. In samples with low degree of saturation, two types of cyclic softening failures demarcated by two distinct phase transformation trends were observed. A pore pressure model proposed by Konstadinoun and Georgiannou (2014) has been modified to predict the pore pressure evolution in desaturated sand.