Seismic Compression of As-Compacted Fill Soils with Variable Levels of Fines Content and Fines Plasticity

Seismic compression is defined as the accrual of the contractive volumetric strains in unsaturated soils during strong shaking from earthquakes, and has been recognized as a major cause of seismically induced damage. As a result, there has been an increasing demand within the engineering profession for seismic compression analysis procedures. Existing methods for estimating seismic compression susceptibility included procedures proposed by Tokimatsu and Seet in 1987 and Stewart and Whang in 2003. However, these two procedures are limited in their applicability because they only apply for a few specific soil characteristics. Accordingly, there is a major research need for laboratory testing to develop relations between volumetric strains, applied shear strains and number of strain cycles (termed volumetric strain material model) that cover a broad range of soil types.

The principal objective of this research was to perform laboratory simple shear testing to provide insight into the seismic compression of sands, non-plastic silt-sand mixtures, and high fines content/high plasticity sandy clays, and then to develop volumetric strain material models for those soils. A total of 14 different clean sands, 8 silty sands, and one relatively plastic clay were tested.