Evaluating the Effects of Overburden Stress on Soil Liquefaction: Insights from Cyclic Test Data

This study investigates the effect of overburden stress (effective confining stress) on liquefaction triggering using the largest cyclic test dataset ever applied to this crucial topic. The dataset includes 225 overburden stress correction factor (Kσ) values derived from a wide range of confining stresses, relative densities, and fine contents. Our analysis reveals that specimen preparation methods, particularly tamping and compaction, significantly affect Kσ values. Compaction stresses due to tamping and compaction induce an overconsolidation ratio that changes with confining pressure, which may produce a larger apparent effect of confining pressure on Kσ. We propose a new model for estimating Kσ for clean, normally consolidated sands, which shows less dependence on confining pressure and relative density than existing models. The effect of fines content on Kσ could not be isolated from other effects because fine-grained specimens in prior research were generally prepared using tamping and compaction methods. The proposed Kσ model is intended to isolate the effect of overburden stress, enabling its use in liquefaction triggering models where different effects are accounted for by distinct correction factors.