一维低渗透介质非达西渗流实验

One-dimensional column test for non-Darcy flow in low permeability media

该文选取黏质粉土、粉质重亚黏土、粉质重黏土1和粉质重黏土2四种细粒土样作为实验介质,开展一维土柱渗流实验,研究了低渗透介质中的渗流规律,并通过调节进出水端的水头差,同时观测出水流量,分析水力梯度和渗透流速之间的关系。实验结果表明:土样粒径的分布对渗流规律起决定性作用,即随着土样介质中黏粒含量的增大,渗流由达西流变为非达西流,且黏粒含量越高,非达西现象越明显,当渗透系数低于10–5cm/s数量级时,该非达西流中水力梯度和渗透流速满足二次方程关系。此外,对比粉质重亚黏土和粉质重黏土,可以明显发现渗流存在着启动水力梯度,且启动水力梯度会随着黏粒含量的增大而增大。

In this paper, one dimensional column tests have been conducted to investigate the seepage in low permeability media. Four different soil samples have been used in this study. The flow rates were measured under different hydraulic gradients, and the relationship between the flow velocity and the hydraulic gradient was analyzed. The results indicated that the distribution of the particle size of the soil has significant influence on the seepage flow. It was found the flow is Darcy flow when the content of the clay particle is relatively small, while the seepage flow may be non-Darcy flow if the content of the clay particle is relatively large. The relationship between the flow velocity and hydraulic gradient can be described by a second-order polynomial function quite well when the permeability coefficient is lower than 10^-5 cm/s. In addition, the startup hydraulic gradient has been found for the latter three soil samples. The startup hydraulic gradient increases as the content of the clay particle in- creases.