The permeability of calcareous sand is important for the formation of underground fresh water on the reclaimed islands in the South China Sea.The relationships among gradation

void ratio and permeability of calcareous sand were studied through a series of permeability tests with constant head in laboratory.Soil samples with different void ratios but the same particle size distribution were examined to probe the influence of uniformity coefficient and curvature coefficient on permeability.The experimental results show that a linear relationship exists between permeability coefficient and void ratio of calcareous sand.Correlations were observed among with the permeability coefficient

the uniformity coefficient

curvature coefficient

and particle size.A formula was developed for the determination of permeability coefficient of calcareous sand by analyzing lab data.The equation provides references for the assessment of soil permeability and the formation of underground fresh water on the recently reclaimed islands and reefs.