Experimental study of effects of non-plastic fines on liquefaction properties of saturated sand

Laboratory tests on the liquefaction properties of saturated sand with different contents of non-plastic fines were performed by a hollow cylinder apparatus. Results show that: (1) The maximum void ratio e(max) and minimum void ratio e(min) decrease and then increase, reaching minimum at 20% and 40% respectively. (2) As fines content increases from 0% to 20%, volumetric strain increases. When fines content increases from 20% to 40%, volumetric strain decreases. Afterwards, volumetric strain increases again when fines contents are between 40% and 60%. Finally, volumetric strain decreases when fines content is more than 60%. (3) The sand with larger fines content has smaller peak strength. Stress-strain curves transform from strain-hardening behavior to a perfect elastic-plastic stress-strain behavior. The phase transformation angle reaches minimum at fines content of 30%. (4) The larger fines content is, the smaller number of cycles and strain to liquefaction are. (5) Liquefaction resistance curve and cyclic resistance ratio have the same trend. They decrease when fines content increases from 0% to the threshold fines content of 30%, and increase when fines content increases from 30% to 50%, and decrease sharply at fines content of 60%, and then increase with increasing fines content. The threshold fines content is about 40%.