宝鸡地区非饱和黄土水力参数试验研究

Experimental Study on Hydraulic Parameters of Unsaturated Loess in Baoji Area

我国黄土分布广泛,且多处于非饱和状态,土-水特征曲线和渗透系数函数是研究非饱和黄土工程地质特性的重要水力参数。利用瞬时释放和吸入法(TRIM法)对陕西省宝鸡地区非饱和黄土进行土-水特征曲线试验;并采用van Genuchten模型、Fredlund&Xing模型和Gardner模型对试验数据进行了拟合,其中van Genuchten模型整体拟合效果最好。试验结果表明:在脱水与吸水过程中,土-水特征曲线呈现出明显的滞回效应。以测得的土-水特征曲线为基础,采用Childs&Collis-Geroge预测模型,求出了黄土在非饱和状态下的渗透函数方程。结果表明:非饱和黄土的渗透系数与体积含水率呈正相关,与基质吸力呈反比关系,且两者均可以用指数函数表示。这为本区黄土工程地质问题,如在降雨作用下的边坡稳定性评价等提供了可靠的水力参数。

Loess in China is widely distributed and always in unsaturated state.Soil-water characteristic curve and permeability coefficient function are important hydraulic parameters of researches on engineering geological characteristics of unsaturated loess.Experiments on unsaturated loess of Baoji area in Shanxi provinc by the method of TRIM are presented,and the experimental data are then simulated with van Genuchten model,Fredlund Xing model and Gardner model,of which van Genuchten model has the best overall fitting effect.The experiments show that the soil-water characteristic curve has obvious hysteresis effect during the drying and wetting process.Based on the measured soil-water characteristic curve,the permeability coefficient function of loess under unsaturated condition is built by Childs Collis-Geroge prediction model.The results show that the permeability coefficient of unsaturated loess is positively correlated with volume water content,while having inverse correlation with matric suction,and both the relationships can be expressed in exponential function.The study on soil-water characteristic curve and unsaturated permeability coefficient provides engineering geological problems of loess in this area,such as the slope stability evaluation under rainfall effect,with reliable hydraulic parameters.