净平均应力对非饱和重塑黄土渗水系数的影响

为了研究净平均应力对非饱和重塑黄土渗水系数的影响,本文借助考虑净平均应力影响的广义土水特征曲线,应用间接方法预估渗水系数。对重塑黄土试样进行了四个控制净平均应力为常数而基质吸力逐步增大的三轴收缩试验。采用Van Genuchten模型对试验获取的土–水特征曲线进行拟合,通过拟合的连续曲线预测了不同净平均应力下非饱和重塑黄土的渗水系数。结果表明:净平均应力对土–水特征曲线的影响有明显规律,同一基质吸力下,净平均应力越大,试样的体积含水率越小,在一定吸力范围内,体积含水率与取对数基质吸力的关系曲线近似呈直线;渗水系数随基质吸力的增大而减小,同一基质吸力下,净平均应力越大渗水系数越小,较低净平均应力下基质吸力与取对数渗水系数的关系曲线近似呈直线,随着净平均应力的增加,关系曲线变为明显的折线。所得的成果为预测黄土地区高填方的增湿变形、降雨入渗下的边坡稳定性评价等方面提供了科学依据。

Influence of net mean stress on permeability coefficient of unsaturated remolded loess

In order to study the influence of the net mean stress on the permeability coefficient of unsaturated remolded loess, an indirect method is used to predict the permeability coefficient through the generalized soil water characteristic curve which involves the effect of net mean stress on SWCC. To get the generalized soil water characteristic curve, four triaxial contraction tests are conducted for remolded loess samples by increasing matrix suction step by step and controlling the net mean stress as constant. Based on the measured generalized soil water characteristic curve, the Van Genuchten model for predicting the permeability coefficient of unsaturated soil is used. The permeability coefficient of every matrix suction under different net mean stresses is calculated. The results show that the permeability coefficient of unsaturated remolded loess decreases nonlinearly with the increase of the matrix suction in the semi-log coordinates. Under the same matrix suction, the smaller the net mean stress, the greater the permeability coefficient. The results may provide a useful basis for the deformation of high embankment and rainfall infiltration of slope stability evaluation in loess regions.