ABSTRACT
Fines are believed to affect both cyclic strength and penetration resistance of soils, and the interrelationship is not well understood. Since observations during strong earthquakes in China and publication of so-called “Chinese Criteria” in 1979, some clayey silts or silty clays are considered susceptible to strength loss during shaking, even leading to liquefaction. Clayey and silty mixtures containing between 15 and 25 percent fines of varying consistency are worthy of a little extra conservatism; their residual strength may be only 5 or less percent of their peak shear strength, and they do not behave dilatively. The beneficial contribution of plasticity to the cyclic strength of fine-grained soils is very slight. Gradation appears to be a more influential factor with triggering of liquefaction; consistency limits may be better correlatable to post-liquefaction strength. Reduction in shear strength from peak to residual was found to be less with increased fines content and plasticity.
