Predictive modeling and experimental assessment of static liquefaction potential in unsaturated sandy soils

This study investigates the static liquefaction behavior of unsaturated sandy soils through experimental analysis and predictive modeling, focusing on the combined effects of saturation degree before shearing (Sr), initial mean effective stress (p'₀), and state parameter ($\psi$). A novel saturation control methodology was developed for triaxial testing, enabling adjustment of Sr (85–100 %). Experimental results show that the highest liquefaction risk occurs when mean effective stress causes $\psi$ to reach its maximum value ($\psi$_max) for the first time. Additionally, an analysis of the relationship between peak deviatoric stress (q_peak) and the corresponding axial strain (ε_peak) further highlights the critical role of saturation degree (Sr) in influencing soil strength and deformation limits, emphasizing the importance of strain control as a liquefaction prevention measure. Moreover, a predictive model for the pore pressure ratio (Ru) was developed, incorporating the saturation degree (Sr), state parameter ($\psi$) and initial mean effective stress (p'₀). Based on this model, a 3D iso-surface (Ru = 0.95) was constructed to define the liquefaction boundary, providing a clear representation of the conditions under which liquefaction is more or less likely to occur.