平行裂隙沿程水头损失规律的实验研究

Experimental study of the law on hydraulic headloss in paralleled fractures

为了研究管道-裂隙介质水动力过程,利用不同隙宽及横向宽度的平行裂隙进行室内模拟试验,探究单一平行裂隙中水流流动产生的沿程水头损失随裂隙宽度及横向宽度的变化规律。结果表明:当隙宽小于1.84 mm时,沿程水头损失与流速呈一次函数关系,并且沿程水头损失随裂隙宽度的增大而减小。通过对比管道层流沿程水头损失公式与立方定律,发现管道和裂隙在计算沿程水头损失时主要差别在于后者忽略横向宽度的影响,指出裂隙长宽比在确定管道与裂隙界限中起重要作用。同时通过分析试验所取得的数据,得出裂隙沿程水头损失随裂隙长宽比的增大呈现先减小后增大的趋势,并建立沿程水头损失随裂隙长宽比变化的经验公式。

To study the hydrodynamic process in conduit-fracture medium,some parallel fractures are made to examine the frictional head loss in paralleled fractures with different apertures and widths through laboratory experiments. The results indicate that the hydraulic head loss can be approximated by a linear function of the flow velocity when aperture is wider than 1. 84 mm,and the hydraulic head loss also increases with the decreasing apertures. By comparing the formula of laminar flow in a circular conduit and the cubic law,it is found that the main difference between these two formulas is the influence offracture width. The result shows that the ratio of aperture to fracture width plays a significant role in determining the limit between the pipeline and fissure line. It is also found that the hydraulic head loss in paralleled fractures decreases first,and then increases with the increasing length-width ratio. An empirical function of the hydraulic head loss,represented by the ratio of aperture to fracture width is obtained.