南海岛礁吹填钙质砂渗透特性试验研究

Experimental study on permeability of calcareous sand for islands in the South China Sea

南海吹填钙质砂的渗透性对于岛礁地下淡水的形成至关重要。通过室内常水头渗透试验研究了吹填钙质砂的级配、孔隙比和渗透性之间的相互关系,开展了相同级配钙质砂在不同孔隙比下的渗透性试验,研究了不均匀系数和曲率系数对钙质砂渗透系数的影响规律。试验结果表明,钙质砂的渗透系数和10~e(e为孔隙比)有很好的线性关系,并且与不均匀系数、曲率系数和颗粒粒径都有很好的相关性;通过对室内试验结果考虑多因素的分析,建立了钙质砂渗透系数计算模型,该模型公式可为岛礁吹填土层的渗透性评估和新填岛礁地下淡水的形成分析提供参考。

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.