砂层在黄土中的减渗作用及其计算

本文根据非饱和土壤水的达西定律，对砂层在黄土中的减渗作用及在整个过程中使入渗率由非线性衰减阶段转为线性稳渗阶段的机理做了分析论述。在此基础上提出了不同砂层质地(中值粒径d50)与埋深条件下稳渗率，D的计算方法，建立了砂层质地的中值粒径d50及埋深Z与吸力值Sm的关系。根据水量平衡原理，得到了入渗过程中由非线性衰减阶段开始进入稳渗阶段的时间t1。经试验资料验证，以上计算式不仅计算精度较好，且具有一定的实用性，特别是在缺少土、砂水分运动参数的情况下，仅需积水入渗试验资料即可通过计算取得所需结果。

Infiltration reduction effect of sand layer in loess

According to the Darcy's law for infiltration in unsaturated soil, the infiltration reduction effect of sand layer and the mechanism of infiltration rate changing from nonlinear attenuate stage into linear stage in the process of infiltration are analyzed. Based on the experimental data a new method for calculating the steady infiltration of sand layers with different textures (characterized by medium grain diameter d50) and located at different level is proposed. By applying the principle of water balance, the time duration for infiltration changing from nonlinear stage into steady infiltration is obtained. The validity of the calculation method is verified by experimental result. The method is easy to be applied in practice especially when the parameters of soil and moisture movement are unknown.