Assessment of the Liquefaction Susceptibility of Fine-Grained Soils

TLDR

Chinese criteria fail to predict liquefaction in fine‑grained soils, as evidenced by past earthquakes where liquefied soils did not meet the clay‑size criterion. Cyclic tests confirm that fine‑grained soils liquefied in the Kocaeli earthquake and that plasticity index, rather than clay‑size, best predicts susceptibility, with loose soils having PI < 12 and wc/LL > 0.85 being vulnerable, PI 12–18 and wc/LL > 0.8 more resistant, and PI > 18 at low confining stresses not liquefying, while also revealing the influence of confining pressure, initial shear stress, and stress path.

Abstract

Observations from recent earthquakes and the results of cyclic tests indicate that the Chinese criteria are not reliable for determining the liquefaction susceptibility of fine-grained soils. Fine-grained soils that liquefied during the 1994 Northridge, 1999 Kocaeli, and 1999 Chi-Chi earthquakes often did not meet the clay-size criterion of the Chinese criteria. Cyclic testing of a wide range of soils found to liquefy in Adapazari during the Kocaeli earthquake confirmed that these fine-grained soils were susceptible to liquefaction. It is not the amount of “clay-size” particles in the soil; rather, it is the amount and type of clay minerals in the soil that best indicate liquefaction susceptibility. Thus plasticity index (PI) is a better indicator of liquefaction susceptibility. Loose soils with PI<12 and wc∕LL>0.85 were susceptible to liquefaction, and loose soils with 12<PI<18 and wc∕LL>0.8 were systematically more resistant to liquefaction. Soils with PI>18 tested at low effective confining stresses were not susceptible to liquefaction. Additionally, the results of the cyclic testing program provide insights regarding the effects of confining pressure, initial static shear stress, and stress-path on the liquefaction of fine-grained soils.