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土壤水分特征曲线反映了土壤含水率与吸力之间的关系,是研究土壤水分流动和溶质运移的基础数据。对于砂性土,提出一种测定水分特征曲线的简易试验方法,即对砂柱进行逐级排水,获得排水量与自由面(潜水面)高度的关系曲线,将其转化为水分特征曲线。采用这种砂柱试验测定了地大粗砂的土壤水分特征曲线,得到了良好的“S”型曲线,能够用Van Genuchten公式进行拟合。砂柱试验结果与压力膜仪法实测的和Arya-Paris模型间接推求的土壤水分特征曲线具有一致性。与现有测定方法相比,砂柱实验具有原理简单、准确度较高、成本低的优势。
Soil water characteristic curve reflects the relationship between soil water content and suction, and is the basic data to study soil water flow and solute transport. For sandy soil, a simple test method for measuring water characteristic curve is proposed, that is, the sand column is drained step by step, and the relation curve between the displacement and the height of free surface (diving surface) is obtained, which is converted into the water characteristic curve. This sand column test was used to determine the soil water characteristic curve of the large grit, and a good “S” curve was obtained, which can be fitted by the Van Genuchten formula. The results of the sand column are in agreement with the soil moisture characteristic curves indirectly determined by the pressure-filmometer method and the Arya-Paris model. Compared with the existing measurement methods, sand column experiment has the advantages of simple principle, high accuracy and low cost.