Shaking-table tests on the liquefaction characteristics of organic matter-disseminated sand in island areas

Sand soli liquefaction can significantly reduce the bearing capacity of foundations, posing risks to the structural integrity of buildings and infrastructure. In this study, free-field shaking table tests were conducted to evaluate the liquefaction behavior of regional sandy soils from island environments under various sand types and acceleration conditions. The liquefaction characteristics of the sandy soil were analyzed by integrating macroscopic phenomena, pore pressure measurements, and acceleration data obtained from the tests. The results indicate that under seismic excitation, both types of sandy soil foundations experience deformation and settlement while exhibiting liquefaction phenomena such as flow failure, sand spouting, and water gushing. The ratio of excess pore pressure is positively correlated with peak loading values, while liquefaction susceptibility decreases with greater burial depth. Notably, organic matter-disseminated sand demonstrates slower excess pore pressure dissipation and persistent residual pressures, whereas standard sand exhibits rapid and complete dissipation. Acceleration measurements reveal a bottom-to-top amplification effect within soil layers. The amplification coefficient for acceleration increases alongside higher peak loading values, demonstrating a more pronounced amplification effect in shallower soil layers. Additionally, the cyclic stress ratio (CSR) rises with increased loading intensity, and organic matter-disseminated sand presents a heightened risk of liquefaction under identical conditions. Significance analysis underscores that peak ground acceleration magnitude exerts a greater influence on liquefaction potential than burial depth.