广州地区花岗岩残积土全吸力段土-水特征研究

Full Spectrum of Soil-Water Characteristics Curve of Guangzhou Granitic Residual Soils

土-水特征曲线是研究非饱和土力学性质和水力特性的基础。以广州地区花岗岩残积土为研究对象,采用盐溶液蒸汽平衡法和滤纸法获得了残积土在脱湿阶段不同含水率下的基质吸力,探究非饱和残积土在低饱和度(高吸力)下的土-水特征和渗透特性,进而获得残积土在全吸力段的土-水特征曲线(SWCC)。结果表明SWCC曲线前期含水率随吸力的增加急速减小,后期减小趋势变缓。此外,结合试验数据,对比分析了现有多种SWCC模型对广州花岗岩残积土土-水特征的刻画,发现Fredlund-Xing模型适合描述该类非饱和土的土-水特征。最后,采用Fredlund-Xing模型获得的土-水特征参数,结合Mualem渗透模型,提出了适合广州地区的非饱和花岗岩残积土渗透系数预测模型。本项目研究成果为进一步研究广州地区非饱和花岗岩残积土的力学特性、水理特性提供了重要的基础。

Soil-Water Characteristic Curve(SWCC) is a fundamental concept for the studying of the mechanical properties and hydraulic characteristics of unsaturated soils.In this paper,a granitic residual soil in Guangzhou area was used in the laboratory study.The soil-water characteristics and infiltration characteristics of unsaturated residual soils at low saturation(high suction) were investigated by using the salt solution vapor balance method and the filter paper method to obtain the SWCC of residual soils at the full suction stage.The results show that the moisture content of the SWCC curve decreases sharply with the increase suction in the early stage and then decreases slowly in the later stage.In addition,the existing SWCC models were compared with the experimental data to characterize the soil-water characteristics of the residual granite soils in Guangzhou,and the Fredlund-Xing model was found to be suitable for describing the soil-water characteristics of these unsaturated soils.Finally,the soil-water characteristics obtained from the Fredlund-Xing model are combined with the Mualem infiltration model to propose a suitable model for predicting the infiltration coefficient of unsaturated granitic residual soils in Guangzhou.The research results of this project provide an important basis for the further research on the mechanical and hydraulic properties of unsaturated granitic residual soils in Guangzhou.