孔隙变化条件下黄土土水特征曲线预测模型

Prediction model for soil-water characteristic curve of loess under porosity change

黄土具有明显的大孔隙结构,浸水湿陷过程中内部孔隙不断变化,导致其浸水过程的土水特征曲线也动态变化。为简便预测孔隙变化条件下黄土的土水特征曲线,以孔隙体积函数为切入点,假定浸水引起孔隙变化对孔隙体积函数的影响规律,引入平移因子ξ和压缩因子ξ,通过平均孔隙半径建立平移因子和压缩因子与孔隙指标e之间的关系,基于初始孔隙状态推导得到不同孔隙条件下的孔隙体积函数,以Gardner模型为基础,引入孔隙指标建立考虑浸水孔隙变化的黄土土水特征曲线模型,当不考虑孔隙变化影响时本模型退化为Gardner模型。模型包含6个参数,均可通过试验确定,由初始状态对模型参数进行标定,并预测孔隙变化时黄土的土水特征曲线。研究表明模型预测结果与试验结果吻合较好,运用本模型可准确预测浸水引起的孔隙变化条件下黄土土水特征演化规律,这为建立黄土的本构模型奠定了良好的基础。

The loess has obvious macropore structure. The internal pores change continuously in the process of water immersion and collapsibility, resulting in the dynamic change of soil-water characteristic curve in the process of water immersion. In order to simply predict the soil-water characteristic curve of loess under different pore conditions, taking the pore volume function as the breakthrough point, assuming the influence law of the change of soaking pore on the pore volume function, and introducing the translation factor ξand the compression factor ξ, the relationship among the translation factor,the compression factor and the pore index e is established through the average pore radius, and the different pores are derived based on the initial pore state. Based on the Gardner model and introducing the pore index, the model for the soil-water characteristic curve of loess considering the change of soaking pore is established. When the influences of pore change are not considered, the model degenerates to the Gardner model. The model contains six parameters, which can be determined by experiments. The parameters of the model are calibrated by the initial state, and the soil-water characteristic curve of loess with pore change is predicted. The combination shows that the predicted results by the model are in good agreement with the test ones. The evolution law of the soil-water characteristics of loess under the change of soaking pore can be accurately predicted by using this model, which may provide preference for establishing the constitutive model for loess.