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我国黄土厚度大,黄土地区地下水位深,降雨量少,黄土多处于非饱和状态,土-水特征曲线是非饱和黄土应力状态、强度及渗透性研究的基础。以陇东高原马兰黄土为试验对象,采用张力计法测定原状土样的土-水特征曲线,采用三种理论模型对试验数据拟合,其中Gardner模型简单、参数少,但Fredlund&Xing模型拟合效果最好。基于已测得的土-水特征曲线,采用Childs&Collis-Geroge预测非饱和渗透系数的模型,计算得到非饱和黄土渗透系数与基质吸力或含水率的关系,发现黄土从饱和到非饱和,其渗透系数急剧降低,黄土非饱和渗透系数与基质吸力或体积含水率的关系均可用指数函数表示。本文对典型黄土土-水特征曲线的研究及渗透性的预测为黄土工程问题,如降雨入渗的边坡稳定性评价、非饱和地基湿陷变形计算等提供理论基础。
The thickness of loess in China is large, the groundwater level in the loess area is deep, the rainfall is small, and the loess is mostly in the unsaturated state. The soil-water characteristic curve is the basis of stress state, strength and permeability of unsaturated loess. The soil-water characteristic curves of undisturbed soil samples were measured with tension meter method. Three theoretical models were used to fit the experimental data. The Gardner model is simple with few parameters, but the fitting results of Fredlund & Xing model the best. Based on the measured soil-water characteristic curves, a model of unsaturated permeability coefficient predicted by Childs & Collis-Geroge was used to calculate the relationship between the permeability coefficient of unsaturated loess and the matrix suction or moisture content. The results show that from saturated to unsaturated, the permeability coefficient Drastic reduction, unsaturated soil permeability coefficient and the relationship between the matrix suction or volumetric moisture content can be expressed as an exponential function. The study on the soil-water characteristic curve of typical loess and the prediction of its permeability provide the theoretical basis for loess engineering problems, such as slope stability assessment of rainfall infiltration and calculation of collapse deformation of unsaturated soil.