斥水性砂土水-气形态及其对斥水-亲水转化的影响分析
发布时间：2019-07-29 11:38
【摘要】：处于地球表面的土壤,尤其是耕作层土壤,受外界因素影响其接触角可能会发生改变。通过试验对不同接触角的壤质砂土中的孔隙水-气形态分布状况进行研究,试验结果表明:砂土颗粒与孔隙水间的接触角增大会使表层土壤中水封闭土层厚度减小,但接触角增大到一定值后,水封闭层的厚度不再发生变化。随着接触角的增大,气封闭层的厚度不断减小。与连续固体表面不同,砂土颗粒的接触角小于90°甚至降低至36°也会出现明显的斥水现象,但随着砂土中饱和度的增大,斥水现象会消失,砂土斥水与亲水转化时对应的饱和度与水封闭向双开敞转化时对应的饱和度基本一致,因此,砂土亲水与斥水转化时对应的临界含水率与孔隙水气分布形态密切相关,通过理想模型对两种不同水-气形态下土壤的基质吸力变化分析可以发现,产生这种现象是因为当土壤由水封闭变为双开敞时,水-气交界面在液体侧的曲率中心消失(接触角小于90°),气-液界面引起的基质吸力恒为"正"。
[Abstract]:The contact angle of soil on the surface of the earth, especially in the cultivated layer, may change under the influence of external factors. The distribution of pore water-gas morphology in loam sand with different contact angles is studied by experiment. the results show that the thickness of water sealing layer in surface soil decreases with the increase of contact angle between sand particles and pore water, but the thickness of water sealing layer does not change when the contact angle increases to a certain value. With the increase of contact angle, the thickness of gas sealing layer decreases. Different from the continuous solid surface, the contact angle of sand particles is less than 90 掳or even decreases to 36 掳, but with the increase of saturation in sand, the phenomenon of water repellent disappears, and the saturation corresponding to the transformation of water repellent and hydrophilic transformation is basically the same as that of water closed to double open transformation. The critical moisture content corresponding to hydrophilic and water repellent transformation of sandy soil is closely related to the distribution of pore water and gas. Through the analysis of the change of matrix suction under two different water-gas forms by ideal model, it can be found that this phenomenon is caused by the disappearance of the curvature center of the water-gas interface at the liquid side when the soil is closed to double open (the contact angle is less than 90 掳), and the matrix suction caused by the gas-liquid interface is always "positive".
【作者单位】： 云南农业大学水利学院;
【基金】：国家自然科学基金项目(41662021、51209182)
【分类号】：S152.7
，
本文编号：2520480
[Abstract]:The contact angle of soil on the surface of the earth, especially in the cultivated layer, may change under the influence of external factors. The distribution of pore water-gas morphology in loam sand with different contact angles is studied by experiment. the results show that the thickness of water sealing layer in surface soil decreases with the increase of contact angle between sand particles and pore water, but the thickness of water sealing layer does not change when the contact angle increases to a certain value. With the increase of contact angle, the thickness of gas sealing layer decreases. Different from the continuous solid surface, the contact angle of sand particles is less than 90 掳or even decreases to 36 掳, but with the increase of saturation in sand, the phenomenon of water repellent disappears, and the saturation corresponding to the transformation of water repellent and hydrophilic transformation is basically the same as that of water closed to double open transformation. The critical moisture content corresponding to hydrophilic and water repellent transformation of sandy soil is closely related to the distribution of pore water and gas. Through the analysis of the change of matrix suction under two different water-gas forms by ideal model, it can be found that this phenomenon is caused by the disappearance of the curvature center of the water-gas interface at the liquid side when the soil is closed to double open (the contact angle is less than 90 掳), and the matrix suction caused by the gas-liquid interface is always "positive".
【作者单位】： 云南农业大学水利学院;
【基金】：国家自然科学基金项目(41662021、51209182)
【分类号】：S152.7
，
本文编号：2520480
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