原位“Darcy实验”方法研究与实践

在室内Darcy实验原理和装置的基础上,设计了一套原位“Darcy实验”装置,原位试验条件满足Darcy定律的假定条件,能够应用Darcy定律确定包气带浅表层土的渗透系数.与室内“Darcy实验”相比,原位“Darcy实验”的测试结果更能准确地反映结构性土野外状态下的渗透性能.与其它原位试验相比,该方法在获取渗透系数方面具有试验装置简单、操作方便、观测数据直观的优点.应用该方法在中国西北部半干旱的黄土台塬开展了3组测试,成功地求取了区内包气带浅表层饱和黄土的垂向渗透系数,并将测试结果与双环试验、室内渗透试验、抽水试验及颗粒分析方法求得的渗透系数结果进行对比分析,发现应用原位“Darcy实验”求取的渗透系数更能准确地反映包气带浅表层土的渗透性能.同时,总结和探讨了一套原位“Darcy实验”的技术方法.

An in-situ "Darcy Test" method for measuring hydraulic conductivity of sediments in the shallow vadose zone

A set of devices for the in-situ "Darcy Test" was designed based on the theory and assumptions of the indoor Darcy Test. The permeability of the soil in the shallow vadose zone can be calculated with Darcy's Law based on the in-situ "Darcy Test". Compared with the indoor Darcy test, permeability can be calculated by considering the soil nature structure with the in-situ "Darcy Test". Furthermore, data can be recorded directly and the experimental operations are easier with the in-situ "Darcy Test" in comparison with the other in-situ tests. Three groups of in-situ "Darcy Test" were implemented in the loess plateau of northwestern China. The loess vertical permeability in the shallow vadose zone of the study area was obtained. The test results were compared with the results from double-ring infiltration test, indoor Darcy Test, pumping test and grain-size analysis. It is shown that the permeability in the shallow vadose zone can be calculated more accurately with the in-situ "Darcy Test". Finally, the in-situ "Darcy Test" method and techniques were summed up and established.