Effect of sustained shear on overburden stress correction in liquefaction resistance evaluation

Abstract

The Kσ correction factor has been routinely applied in the evaluation of liquefaction resistance of soils subjected to an overburden stress level other than 100 kPa. Its current prediction form is a function of, primarily, the overburden pressure and the relative density of the soil. Hence, its application is limited to free-field level ground condition. This study focuses on the effect of sustained shear stress, which exists in the soil layer under non-free-field or sloping ground condition, on the Kσ correction factor. The findings are largely based on a comprehensive cyclic triaxial test database with the effective confining pressure and the sustained shear stress ranged up to 500 kPa and 200 kPa respectively. The test program was performed for very loose to medium dense sand. The results show that Kσ is strongly dependent on the amount of sustained shear, in which the effect is exaggerated in more contractive soil. The observations are well supported by other test data in the literature. The study sheds light on the potential need of updating the prediction form of the Kσ correction factor.