南海北部深水区表层沉积物工程性质的统计特征分析

针对从中国南海北部海域某深水区采集的表层沉积物柱状样，进行了沉积物微观结构的扫描电镜测试、矿物成分的X射线衍射试验以及物理和力学性质的统计学分析。结果表明，该深水区海底表层沉积物通常为有机质软黏土，具有高含水率、低密度、高孔隙比、高液限、高可塑性、低强度等典型特征。统计分析和假设检验表明，沉积物的物理和力学指标均呈现变异性，且后者普遍高于前者。相对密度、含水率、液塑限和塑性指数服从正态分布；容重、碳酸盐含量、不排水抗剪强度、灵敏度接近假设检验结果，近似服从正态分布。研究结果可为深水海底工程结构设计的海床土性参数取值提供参考。

Statistical characteristics analyses on engineering properties of surface sediments in the deep-water of northern South China Sea

The microstructure and mineral composition of the samples of surface sediments from a deep-water field in the northern South China Sea are investigated via SEM and XRD; meanwhile, statistical analyses are performed on the physical and mechanical properties of the sediments. It is found that the surface sediments are generally soft organic clay, characterized by high water content, low density, high void ratio, high liquid limit, high plasticity, low strength, etc. Moreover, the properties of such deep-sea sediments exhibit an inherent variability. Statistical analyses and hypothesis testing indicate that the variability of mechanical properties is usually more pronounced than that of physical properties. The specific gravity, natural water content, plastic and liquid limit, and plasticity index basically obey normal distributions, while the unit weight, carbonate content, undrained shear strength and sensitivity match well with hypothesis testing results, approximately following normal distributions. The present results on the statistical features of deep-sea sediments may provide a reference for geotechnical design of subsea structures in deep waters.