黄土夹砂层的持水机制  

Water-holding mechanism of sand layer in loess

作　　者：陈建生[1,2] 张健[1] 詹泸成[1] 黄德文[1] 张超[1] 张家甫 CHEN Jiansheng ZHANG Jian ZHAN Lucheng HUANG Dewen ZHANG Chao Zhang Jiafu(College of Civil and Transportation Engineering, Hohai University, Nanjing 210098, China College of Earth Sciences and Engineering, Hohai University, Nanjing 210098, China)

机构地区：[1]河海大学土木与交通学院,江苏南京210098 [2]河海大学地球科学与工程学院,江苏南京210098

出　　处：《河海大学学报（自然科学版）》2016年第5期412-417,共6页Journal of Hohai University(Natural Sciences)

基　　金：国家重点基础研究发展计划(973计划)(2012CB417005)

摘　　要：为研究黄土高原西北干旱区农业采用的＂压砂＂保墒方法机理,进行3种室内土柱（均质土柱、夹3 cm厚砂层的土柱、夹5 cm厚砂层的土柱）的降雨入渗试验,并建立微观模型对夹砂层阻水现象进行分析。通过烘干法和MAT253稳定气体同位素质谱仪测定土柱不同深度2个时间点（13 d、197 d）的含水率和土壤水的δD、δ18O,得到不同时间含水率随深度变化规律和土壤水δD～δ18O关系。结果表明：（a）黄土中夹砂层的存在起到了减缓水流下渗的作用,而不是阻止水分下渗。（b）夹砂层的这种阻水效果一方面是由于砂层薄膜水的持水量远小于黄土,从而阻滞了水流的下渗;另一方面是由于在介质突变界面处过水断面面积突然减小,以致降低了水流的下渗速度。In order to study the mechanism of agricultural soil moisture conservation through sand injection in the northwest arid region of the Loess Plateau,rainfall infiltration tests on three kinds of indoor soil columns（ a homogeneous soil column,a soil column with a 3 cm-thick sand layer,and a soil column with a 5 cm-thick sand layer） were performed,and the water-resisting phenomenon of the sand layer was analyzed through establishment of a micro model. The water contents in different layers of soil columns at two times（ 13 days and 197 days） and theδD and δ18O values of soil water were measured with the drying method and MAT253 gas isotope ratio mass spectrometer. The change in water content with the depth and the relationship between δD and δ18O of soil water were obtained. The results show that the sand layer can retard water infiltration rather than prevent water infiltration.The reasons for this are that the water- holding capacity of sand is far less than that of loess,retarding water infiltration,and the sudden decrease in the wetted cross-sectional area at the interface with abruptly changed medium causes the water infiltration velocity to decrease.

关 键 词：黄土夹砂层 含水率 同位素 持水机制 微观层面 薄膜水运移 

分 类 号：S278[农业科学—农业水土工程]