Energy-Based Assessment of Cyclic Liquefaction Susceptibility of Air-Injected Desaturated Sand Considering Initial Stress Anisotropy

As a cost-effective and environmentally friendly technique for enhancing the liquefaction resistance of sandy soils, the air-injection method has attained widespread application in multiple soil improvement or desaturation strategies. This study reports undrained cyclic loading experiments on reconstituted, slightly desaturated sand specimens under either isotropic or anisotropic consolidation to examine the effects of the presence of injected air and initial stress anisotropy on the energy-based assessment of pore pressure and liquefaction resistance. The results exhibited three different cyclic response patterns for the saturated/desaturated specimens with distinct deformation mechanisms, revealing that the sand has a higher degree of stress anisotropy and lower degree of saturation typically being more dilative and less susceptible to cyclic liquefaction. The energy-based liquefaction potential evaluation indicates that the accumulative energy is mathematically correlated with the pore pressure, thus establishing a unified energy–pore pressure relationship for both saturated and desaturated sand. Furthermore, the energy capacity for triggering cyclic failure demonstrates a consistently rising trend with an increase in the consolidation stress ratio and a reduction in the degree of saturation, which seems closely linked to the cyclic liquefaction resistance. This result signifies the potential applicability of an energy-based approach to quantify the liquefaction susceptibility of desaturated in situ soils using strength data from conventional stress-based analyses.