Abstract: In order to explore liquefaction resistance and related test technology of hydraulic fill coralline soils at artificial island and reef engineering sites, the phenomenon of unsteady state saturation in the liquefaction tests of hydraulic fill coralline soils was pointed out, and a cyclic triaxial liquefaction test method was proposed based on optimized saturation method and membrane compliance correction technology. Four groups of high-degree compaction samples with different gravel contents prepared by hydraulic fill coralline soils in an artificial island site were taken into the study, and the corrected liquefaction resistance curves of the studied materials were obtained. By comparing with the ground motion conditions of historical liquefaction sites, the occurrence of in-situ liquefaction was reproduced, and the rationality of the test results was verified. The study points out the liquefaction risk of the actual island and reef engineering sites in the South China Sea, analyzes the differences of the influence of gravel content on the liquefaction resistance of continental gravel soils and hydraulic fill coralline soils, proposes a gravel content based modified formula for the liquefaction resistance of hydraulic fill coralline soils, and provides a simplified estimation method for the liquefaction resistance of hydraulic fill coralline soils.

Key words: hydraulic fill coralline soils, unsteady state saturation, gravel content, large-scale dynamic triaxial apparatus, membrane compliance correction