Water and Energy International

The liquefaction of soil during earthquake can cause significant damage to infrastructure and loss of life. One factor that affects the liquefaction resistance of soils is the presence of low plastic and non-plastic fines, such as soft clay and silt particles respectively. The presence of non-plastic fines in sandy soils can significantly impact their liquefaction resistance, but the exact nature of this effect remains unclear. The objective of the study is to investigate the effect of non-plastic fines on the liquefaction resistance of Yamuna sand using cyclic simple shear equipment.

A laboratory parametric study utilizing cyclic simple shear tests under a stress control method was performed to explain the effects of non-plastic fines on the liquefaction resistance of Yamuna sand. Specimen failed either, in strain accumulation of Double amplitude (DA) 5% or pore water ratio (ru) close to 1. The fines content of the clean sand was systematically varied up to a maximum of 30% (i.e., 0%, 10%, 20% and 30%) with all test specimens being reconstituted using dry funneling method. Results indicate that for a constant value of relative density (i.e., 45%), the liquefaction resistance increases with increase in fines content up to a certain limit or a threshold value. This increase in liquefaction resistance is attributed due to the reduction in the void ratio or densification of material and subsequently, increase in the effective stress caused by the fines. Beyond the threshold limit of fines content of 20%, the trend is reversed due to increase of void content, and as a result the liquefaction resistance decreases with increase in fines content. The findings of this study have important implications for the design and construction of structures on sandy soils with varying percentages of non-plastic fines.