CIVIL ENGINEERING 365 ALL ABOUT CIVIL ENGINEERING



AbstractThis study presents the results of a laboratory test program that serves to improve the understanding of the liquefaction susceptibility and cyclic response of intact silts that span sand- and clay-like behaviors. Specimens were prepared from samples characterized with a plasticity index (PI) ranging from 0 to 39, fines content (FC) ranging from 29% to 100%, and overconsolidation ratio (OCR) ranging from 1.0 to 4.2, retrieved from five silt deposits in Western Oregon and Southwest Washington. The roles of PI, FC, and OCR on the 1D compression and monotonic and cyclic strength of nonplastic to plastic silts are identified. Hysteretic metrics proposed to quantify cyclic behavior provided an objective means to distinguish between qualitative judgments of sand-like, intermediate, and clay-like behavior. Prior soil index test-based liquefaction susceptibility criteria exhibited good to poor accuracy; modifications to existing criteria aligned with quantified hysteretic behavior, which together indicate that sand- and clay-like behavior is subject to the intensity and duration of cyclic loading. The variation of cyclic resistance ratio (CRR) and cyclic strength ratio, τcyc/su,DSS, with the number of loading cycles, N, to reach single amplitude shear strain, γ, of 3% and 3.75% is presented. The τcyc/su,DSS for Nγ=3%=10 and 30 appeared constant for PI≤11 and PI≥18 and equal to 0.63 and 0.54, and 0.82 and 0.76, respectively, with an apparent linear trend for 11

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