一个简化的土水特征曲面模型及其在非饱和渗流分析中的应用

Simplified soil water characteristic surface(SWCS) model and its applications to seepage analysis of unsaturated soil

土体变形对土水特征曲线(SWCC)的影响显著,采用初始孔隙比作为变形指标,利用VJ Tech固结仪对粉质砂土进行SWCC曲线的室内试验,研究了不同初始孔隙比对SWCC的影响。试验结果表明:不同初始孔隙比对SWCC的影响在低吸力范围比较显著,在高吸力范围则不明显。通过将孔隙比引入到与进气值有关的模型参数中对Fredlund-Xing模型进行了修正,建立了不同孔隙比影响下的基质吸力-含水率-孔隙比空间的土水特征曲面模型,即SWCS数学模型,并采用所提出的SWCS模型来预测土体变形后渗透系数的变化。采用所提出的SWCS模型分析了坝体心墙的压实程度对防渗效果的影响,模拟结果表明:当心墙的压实程度不同时,同一时刻心墙截面的流量与主要受饱和渗透系数支配,即与e3/(1+e)成正比。

To study the effect of soil deformation, the soil-water characteristic curves (SWCC) are tested using VJ Tech consolidation apparatus with the initial void ratio taken as the deformation index. The test results show that in low suction range the effect of the initial void ratio on SWCC is significant, while in high suction range the effect is not remarkable. By introducing the void ratio into the model parameter related to the air entry value, a new soil-water characteristic surface (SWCS) model is proposed based on the Fredlund-Xing model so that the new model can be utilized to predict the varied coefficient of permeability during soil deformation. The new model is also applied to the seepage analysis of a soil dam with core wall, and it is found that for different degrees of compaction, the seepage flow flux is dependent on the saturated coefficient of permeability or is proportional to e3/(1+e).