一种计算颗粒入渗深度的反滤料孔隙模型

为进一步理解反滤系统渗透侵蚀机制，预测流失颗粒在反滤料中的分布情况，本文提出一种人工填料处于密实状态的反滤孔隙网络模型，分别与文献中的2种反滤孔隙模型计算被保护土颗粒进入反滤层的入渗深度值及数值模拟方法进行对比分析，并通过工程案例进一步验证了新模型的可行性与适用性。结果表明，3种孔隙模型预测的入渗深度值中，Locke and Indraratna模型的值最大；当被保护土颗粒通过孔隙通道的概率较小时，新模型计算值小于Silveira模型的值；随着被保护土颗粒通过概率增加，新模型逐渐大于Silveira模型的计算值。新模型与Zou的数值模拟预测的最大入渗深度随着特征粒径比D15/d85的不同，其变化趋势相同；但受Zou数值模拟过程中土样尺寸及入渗时间的限制，尤其在特征粒径比接近或大于4（反滤准则临界值）时，两种方法预测结果差别较大。当反滤料级配设计包线确定后，孔隙模型为反滤层设计提供了一种新途径。

New filter void model for calculating infiltration depths of particles

To investigate further the seepage erosion mechanism and predict the distribution of particles washed away in the filter system, this paper develops a filter void network model for the dense state of filling soil. Predictions of this model are analyzed and compared with those of two previous models in the literature in terms of the depth of base particles infiltrating into the filter, as well as with numerical simulations; And its feasibility and applicability are verified further in an engineering case. The results show the model of Locke and Indraratna gives the largest infiltration depth among the three; our new model predicts a depth smaller than that of Silveira’s model when the probability of base particles passing the constriction is low, while it predicts infiltration depths increasingly greater than Silveira’s as the passing probability increases. Variation trends in its maximum infiltration depths at the characteristic particle size ratio D15/d85 are the same as those in Zou’s simulations, but a greater discrepancy appears between the two calculations due to the limitation of Zou’s in soil sample size and infiltration time, especially at a size ratio close to or greater than 4 (the threshold value in the filter criteria). Our void model is a new approach for the filter design of real projects when the filter gradation design envelope is confirmed.