Experimental Investigation of Evaporation and Drainage in Wettable and Water-Repellent Sands
Experimental Investigation of Evaporation and Drainage in Wettable and Water-Repellent Sands
复制标题
可湿性憎水砂中蒸发与排水的实验研究
DOI：
10.3390/su7055648
复制
发表时间：
2015
期刊：
影响因子：
3.9
通讯作者：
T. Yun
中科院分区：
文献类型：
--
作者：
Dae Hyun Kim;H. Yang;Kwang Yeom Kim;T. Yun
本文介绍了用硅烷化人工改性表面润湿性的可湿性砂和拒水性砂的蒸发排水实验结果。在蒸发过程中进行二维光学和三维x射线计算机层析成像，并测量循环排水和渗透过程中的保水率，以评估润湿性和初始润湿条件的影响。无论润湿性和砂型如何，蒸发均在早期提前诱导其锋面，且疏水性渥太华砂的蒸发速率高于可湿性渥太华砂。与渥太华砂相比，朱文金砂粒径较小，颗粒形状不规则，但其蒸发速率与渥太华砂相似，与润湿性无关。当可湿性砂和拒水性砂自然接触时，拒水性砂有利于蒸发。三维x射线成像显示，可湿性砂中水膜的水力连接促进了蒸发锋向土壤的传播，从而使干燥锋深入土壤。在循环排水-入渗试验中，可湿性砂和拒水性砂在初始湿态时的保水性演变相似。然而，当条件最初干燥时，防水砂表现出较低的残余饱和度值。本研究的实验观察表明，在评估蒸发和排水行为时，表面润湿性可能不是唯一的因素，而疏水性程度、砂的类型和初始润湿条件是主要的。
This study presents experimental results on evaporation and drainage in both wettable and water-repellent sands whose surface wettability was artificially modified by silanization. The 2D optical and 3D X-ray computed tomographic imaging was performed during evaporation and the water retention during cyclic drainage and infiltration was measured to assess effects of wettability and initial wetting conditions. The evaporation gradually induces its front at the early stage advance regardless of the wettability and sand types, while its rate becomes higher in water-repellent Ottawa sand than the wettable one. Jumunjin sand which has a smaller particle size and irregular particle shape than Ottawa sand exhibits a similar evaporation rate independent of wettability. Water-repellent sand can facilitate the evaporation when both wettable and water-repellent sands are naturally in contact with each other. The 3D X-ray imaging reveals that the hydraulically connected water films in wettable sands facilitate the propagation of the evaporation front into the soil such that the drying front deeply advances into the soil. For cyclic drainage-infiltration testing, the evolution of water retention is similar in both wettable and water-repellent sands when both are initially wet. However, when conditions are initially dry, water-repellent sands exhibit low residual saturation values. The experimental observations made from this study propose that the surface wettability may not be a sole factor while the degree of water-repellency, type of sands, and initial wetting condition are predominant when assessing evaporation and drainage behaviors.