Factors Influencing the Liquefaction Resistance of Saturated Gravelly Wide-Graded Coral Soils

Surveys of historical site liquefaction damage and the construction experience for island and reef engineering have demonstrated that the materials at sites with recently occurring or potential earthquake-induced liquefaction of coral soils are broadly graded noncohesive soils. However, the reported research on the liquefaction resistance of such soils has primarily been based on experimental results and understanding related to coral sand. Materials from coral soils at three engineering sites across different maritime areas were selected for this study, with consideration of their gradation characteristics, to investigate the characteristics of liquefaction resistance in coral soils at actual engineering sites. Seven sets of samples with varying physical states were prepared and subjected to saturated undrained testing using large-scale dynamic triaxial equipment. The liquefaction resistance curves of coral soils were derived based on the compliance of rubber membranes. Firstly, the rationality of the experimental results was confirmed by comparing them with the seismic conditions recorded at coral soil liquefaction sites during historical earthquakes. Subsequently, a systematic analysis was conducted to examine the differential impacts of factors such as relative density, gravel content, sites in different sea area, and the fines content on the liquefaction resistance of coral soils. Further, a multifactorial variance analysis revealed that the influence of these factors on the liquefaction resistance of coral soils is not statistically significant. The findings indicate that the unique particle structure of coral soils, along with the soil skeleton they form, mitigates the effects of these factors on liquefaction resistance during the liquefaction process. This discovery offers valuable technical insights and research directions for the further exploration of methods to characterize the liquefaction resistance of coral soils.