Centrifuge modeling of seismic response of normally consolidated deep silt deposit

Observations from recent earthquakes in Taiwan and Turkey have shown that current methodology to determine the liquefaction susceptibility of fine-grained soils is no longer sufficient to quantify seismic hazard, and that low plasticity fine-grained soils such as silts could also cause adverse effects on the performance of civil infrastructures. It is very important to understand the dynamic behavior of silt deposit because most of coastal areas, where there are many ongoing construction activities, consist mainly of silts, which might be vulnerable to earthquake loadings. This paper presents the experimental results of centrifuge tests on reconstituted specimen to investigate the dynamic response of normally consolidated deep silt deposit in Seattle area. The experimental sequence and preparation of the artificial silt deposit are described in detail. The recorded downhole accelerations are utilized to identify variation of shear modulus and damping ratio with shear strain amplitude via inverse analysis techniques applied to dense instrumentation arrays in a dynamic centrifuge model test.