基于NMR技术的盐渍化冻融土壤未冻水及孔隙水含量试验研究

发布时间：2018-04-11 14:50

本文选题：盐渍土 + 未冻水　；参考：《水土保持学报》2017年02期

【摘要】：为探讨盐渍化土壤在冻融过程中孔隙水及未冻水含量的变化规律,运用核磁共振仪(NMR)测定了不同盐渍土与不同NaCl饱和试样的孔隙水及未冻水含量,同时研究了不同土质对冻结过程中未冻水含量的影响,分析了冻融过程中的滞后现象。试验设置8个处理,即轻度盐渍化粉砂壤土、中度盐渍化壤土2种土壤类型和蒸馏水、0.2%、0.6%、1.0%NaCl 4种溶液。结果表明:(1)在盐渍土冻结过程中,大孔隙降幅速率小孔隙降幅速率,而盐渍土的融解先从小孔隙开始。(2)无论是轻度盐渍土还是中度盐渍土,1.0%NaCl饱和溶液的未冻水含量最大。饱和溶液为1.0%NaCl的中度盐渍土在冻融过程中出现二次突变,其二次突变温度点不一样,融解时二次突变温度高于冻结时二次突变温度。(3)比较不同土质对冻融过程中未冻水含量可知,壤土未冻水含量粉砂壤土未冻水含量。在冻融过程中,结合T_2分布曲线可知,孔隙水的减少先从大孔隙开始,孔隙水的增多先从小孔隙开始;NaCl饱和溶液的浓度越高,其未冻水含量越大,冻结温度越低;不同土质对土壤未冻水含量有所影响,壤土的未冻水含量明显高于粉砂壤土的未冻水含量;盐渍土壤在冻结和融化过程中存在滞后现象,在冻融过程中的滞后现象明显区间,随浓度的增大,所处的温度范围有降低趋势。
[Abstract]:In order to study the change rule of pore water and unfrozen water content in salinized soil during freezing and thawing, the pore water and unfrozen water content of different saline soil and different NaCl saturated samples were measured by NMR.At the same time, the influence of different soil quality on the content of unfrozen water in freezing process was studied, and the lag phenomenon in freezing and thawing process was analyzed.Eight treatments were set up in the experiment, that is, mildly salinized silt loam, moderate salinized loam, two soil types and distilled water 0.20.20.0.0.10% NaCl solution.The results show that in the freezing process of saline soil, the decreasing rate of large porosity is small, while the melting of saline soil begins with small pore. 2) the content of unfrozen water in saturated solution of 1.0 NaCl is the largest in mild saline soil and moderate saline soil, regardless of whether it is mild saline soil or moderate saline soil.In the process of freezing and thawing, a secondary mutation occurs in the medium salinized soil with saturated solution of 1.0%NaCl, and the temperature of the secondary abrupt change is different.The second mutation temperature during melting was higher than that during freezing. (3) the unfrozen water content of loam and silty loam was compared with the content of unfrozen water in different soil quality during freezing and thawing process, which indicated that the content of unfrozen water in silty loam was higher than that in frozen soil.In the process of freeze-thaw, combined with the distribution curve of T _ 2, it can be seen that the decrease of pore water starts from the macropore, the increase of pore water begins with the increase of the concentration of NaCl saturated solution, the higher the content of unfrozen water is, the lower the freezing temperature is.The content of unfrozen water in loam is obviously higher than that in silt loam, and the lag in freezing and thawing of salinized soil is obvious, and the lag in freezing and thawing is obvious in the process of freezing and thawing, and the content of unfrozen water in loam is obviously higher than that in silt loam.The temperature range decreases with the increase of concentration.
【作者单位】：内蒙古农业大学水利与土木建筑工程学院;
【基金】：国家自然科学基金项目(51369018);国家自然科学基金重点项目(51539005) 教育部留学回国人员科研启动基金项目([2013]693) 内蒙古自治区第五批“草原英才”工程项目([2015]56)
【分类号】：S155.293

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