In the Great East Japan Earthquake of March 11, 2011, liquefaction was not observed in areas where sand compaction piles (SCP) had been used for soil improvement, confirming the effectiveness of the compaction method. Recently, energy-based liquefaction determination methods have been developed for liquefaction determination in the design of SCP methods. In this study, hollow torsional shear tests were conducted under isotropic and anisotropic stress conditions with different fine-grain content and density. Then, liquefaction determination was conducted using both the FL and energy methods, and the validity of the obtained experimental results and the improvement effects were discussed from an energetic viewpoint. The results showed that the liquefaction strength ratio and the normalized cumulative loss energy increased with an increase in coefficient of earth pressure at rest. The liquefaction determination results suggest that the energy method may be more sensitive than the FL method in considering the improvement effect.
