Assessment of silty sand liquefaction potential using hollow torsional tests-An energy approach

This research presents an investigation into the effect of fines content on the cyclic resistance ratio (CRR), dissipated energy up to liquefaction occurrence and excess pore water pressure generation of Firouzkooh silty sands from the shear stress and strain energy viewpoint. Sixty stress-controlled cyclic hollow torsional tests were conducted to directly measure excess pore water pressure generation at different levels of cyclic stress ratio (CSR). The specimens were tested under three different confining pressures (sigma(')(3) =60, 120, and 240kPa), and different fines content at a constant relative density (D(r)=60%). The observed relations between dissipated strain energy per volume and different parameters such as pore water pressure are demonstrated. Based on the experimental evidence presented in this study, it can be concluded that the amount of cumulative dissipated energy, required for liquefaction occurrence, is independent of CSR for the specimens with constant relative density and confining pressure. On the other hand, effective confining pressure and fines content have strong effects on the accumulated strain energy. (C) 2011 Elsevier Ltd. All rights reserved.