【摘要】：處于地球表面的土壤,尤其是耕作層土壤,受外界因素影響其接觸角可能會發(fā)生改變。通過試驗(yàn)對不同接觸角的壤質(zhì)砂土中的孔隙水-氣形態(tài)分布狀況進(jìn)行研究,試驗(yàn)結(jié)果表明:砂土顆粒與孔隙水間的接觸角增大會使表層土壤中水封閉土層厚度減小,但接觸角增大到一定值后,水封閉層的厚度不再發(fā)生變化。隨著接觸角的增大,氣封閉層的厚度不斷減小。與連續(xù)固體表面不同,砂土顆粒的接觸角小于90°甚至降低至36°也會出現(xiàn)明顯的斥水現(xiàn)象,但隨著砂土中飽和度的增大,斥水現(xiàn)象會消失,砂土斥水與親水轉(zhuǎn)化時對應(yīng)的飽和度與水封閉向雙開敞轉(zhuǎn)化時對應(yīng)的飽和度基本一致,因此,砂土親水與斥水轉(zhuǎn)化時對應(yīng)的臨界含水率與孔隙水氣分布形態(tài)密切相關(guān),通過理想模型對兩種不同水-氣形態(tài)下土壤的基質(zhì)吸力變化分析可以發(fā)現(xiàn),產(chǎn)生這種現(xiàn)象是因?yàn)楫?dāng)土壤由水封閉變?yōu)殡p開敞時,水-氣交界面在液體側(cè)的曲率中心消失(接觸角小于90°),氣-液界面引起的基質(zhì)吸力恒為"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 擄or even decreases to 36 擄, 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 擄), and the matrix suction caused by the gas-liquid interface is always "positive".
【作者單位】： 云南農(nóng)業(yè)大學(xué)水利學(xué)院;
【基金】：國家自然科學(xué)基金項(xiàng)目(41662021、51209182)
【分類號】：S152.7
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本文編號：2520480