In-situ Properties of Soils at Paleoliquefaction Sites in the South Carolina Coastal Plain

Abstract

Examination of in-situ properties of soils at four paleoliquefaction sites in the South Carolina Coastal Plain (SCCP) indicated that the soil conditions at these sites are all consistent with liquefiable soils at other locations where liquefaction has been observed. The index properties of soils at locations where sandblows were encountered are not apparently different from those of neighboring locations where sandblows were not encountered. The source sands at the four sites are all loose to medium dense, poorly graded, fine sands. The mean grain sizes range from 0.15 to 0.2 mm and fines contents are less than 10%. They are all located at very shallow depth (1.3 to 3.7 m). An underlying clay layer directly beneath the source sands at all sites of liquefaction may amplify the ground motion and make the source sands more susceptible to liquefaction. We found that some of the soil properties for the paleoliquefaction sites in the SCCP differ from the currently used liquefaction evaluation curves that are based on data for Holocene soils from California, China, and Japan. To facilitate paleoliquefaction evaluation in the SCCP, penetration resistance and shear-wave velocity data at paleoliquefaction sites were carefully examined and compared with current standards to develop boundary curves for paleoliquefaction evaluation in the SCCP.