粒度对非饱和土土水特征曲线滞回特性的影响

Influence of Unsaturated Soil Granularity on Hysteretic Behavior of Soil-water Characteristic Curve

为了研究粒度对非饱和土土-水特性的影响,利用GCTS土-水特征曲线仪对三种不同粒度的西安黄土、青藏黏土、新疆黄土分别进行了增减湿循环试验,采用Gardner模型拟合得到三种土的土水特征滞回曲线,根据滞回度的概念,定量的衡量土的滞回水平的强弱,进一步研究了固体颗粒的粒度对非饱和土土水特征曲线滞回特性的影响。结果表明:有效粒径越大,土水特征曲线的滞回度越大(滞回水平越强),不均匀系数越大,土水特征曲线的滞回度越小(滞回水平越弱)。究其原因是土颗粒之间孔隙尺寸大小对增减湿瓶颈效应和接触角效应的影响。

In order to explore the effects of soil granularity on soil-water characteristics of unsaturated soil, soil-water characteristic curves(SWCC) of Xi’an loess, Qinghai-Tibet clay and Xinjiang loess were tested in laboratory under drying-wetting cycle. A GCTS soil-water characteristic apparatus was used for the measurement of soil-water characteristic hysteretic curves. The experimental data was nonlinearly fitted by using Gardner equation. Soil-water characteristic hysteretic curves were obtained. From a quantitative point of view, a proposed degree of hysteresis was utilized to measure the hysteretic level of different kinds of soil. Influence of granularity on soil-water characteristic hysteretic behavior was analyzed in the viewpoint of particle size and grain composition. It is found that the degree of hysteresis is related to effective grain size and uniformity coefficient through data analysis. Results indicate that if the soil has bigger effective grain size, its soil-water characteristic hysteretic level is stronger. And if the soil has higher uniformity coefficient, it has weaker soil-water characteristic hysteretic level. In the viewpoint of bottle effect and contact angle effect, it is concluded that granularity impacts on soil-water characteristic curves as a result of soil pore size change.