基于高密度均匀分布的4 280个钻孔资料,结合广州海岸变迁史及¹⁴C测年试验成果,深入研究了广州南沙区软土的空间分布特征。并依据成因时代和沉积环境,将南沙软土划分为两大层,其中上层为全新世软土层,¹⁴C年龄约为1 500~8 500 a;下层为更新世软土层,¹⁴C年龄约为34 000~45 000 a。同时对南沙区软土基本物理力学参数进行了统计和分析,对比研究了上下两层软土工程性质的差异。研究结果表明:南沙软土分布面积约718 km²,占全区总面积的91.6%,平均厚度15~20 m,普遍具有含水量高、孔隙比大、抗剪强度低、压缩性强、渗透性弱等特点;相较于下层软土,上层软土的厚度、含水率、孔隙比、压缩系数更大,抗剪强度更低,粉细砂含量较少。

The distribution characteristics of soft clay in Nansha, Guangzhou were examined based on the data of 4 280 boreholes with high density and uniform distribution in association with the coastal history of Guangzhou and ¹⁴C test results. According to the genetic age and sedimentary characteristics, the soft clay in Nansha was divided into two layers. The upper layer was formed in Holocene, whose ¹⁴C age was 1 500-8 500 years, and the lower layer was formed in Pleistocene, whose ¹⁴C age was 34 000-42 000 years. The engineering properties of the two layers were systematically compared via statistical analysis on the physical and mechanical parameters. The research results unveiled that the soft clay in Nansha covers an area of 718 square kilometers, accounting for 91.6% of its total area, with an average thickness of 15-20 m. In general, the soft clay in Nansha is of high water content, large void ratio, low shear strength, strong compressibility and weak permeability. Compared with the lower layer, the upper soft clay has higher thickness, void ratio, pore ratio and compression coefficient, lower shear strength and less fine sand content.