Effect of Geological Stratification on Soil Liquefaction Potential: A Laboratory Study

Abstract

This study evaluates the effect of geological stratification on soil liquefaction potential through cyclic direct simple shear (CDSS) tests. Three different stratification models were considered: (i) a uniform distribution of fine particles (C2), (ii) fine particles concentrated in the upper and lower layers (C3), and (iii) fine particles concentrated in the middle layer (C4). Additionally, the study analyzed the impact of sand layer thickness on liquefaction resistance. The experiments were conducted under an initial consolidation stress of 100 kPa, with a cyclic stress ratio (CSR) of 0.1, and liquefaction was defined when the doubleamplitude shear strain reached 7.5%. The results indicate that the distribution of fine particles significantly influences liquefaction resistance. Specifically, the liquefaction resistance of C2 and C3 samples was similar, suggesting that different distributions of fine particles had no significant effect in these cases. In contrast, the C4 sample exhibited significantly higher liquefaction resistance, as the upper and lower sand layers acted as load-bearing zones, limiting the rapid development of excess pore water pressure. Furthermore, sand layer thickness played a crucial role in liquefaction resistance, with thicker sand layers increasing the number of cycles required for liquefaction. This indicates improved drainage capacity and greater soil stability under cyclic loading. A linear relationship between the number of liquefaction cycles and sand layer thickness was established, providing a predictive tool for assessing liquefaction potential based on geological stratification characteristics. The findings of this study offer valuable experimental insights for
evaluating liquefaction risks in naturally stratified soils and contribute to foundation design and soil improvement strategies in earthquakeprone areas.

Keywords: liquefaction resistance; geological stratification; cyclic direct simple shear test; excess pore water pressure; cyclic loading.