| Na2SO4对古尔班通古特沙漠细沙盐结皮特性的影响 |
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| 引用本文： | 王大环,李诚志,李沼鹈.Na2SO4对古尔班通古特沙漠细沙盐结皮特性的影响[J].环境科学研究,2018,31(11):1979-1986. |
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| 作者姓名： | 王大环 李诚志 李沼鹈 |
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| 作者单位： | 1.新疆大学干旱生态环境研究所, 新疆 乌鲁木齐 830046 |
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| 基金项目： | 新疆维吾尔自治区自然科学基金项目（No.2014211B012） |
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| 摘 要： | 盐晶体胶结土壤颗粒形成的一层盐结皮层质地致密且强度较高，具有较高的抗风蚀能力，在土壤风蚀治理中具有重要作用.盐结皮特性与盐的种类及质量分数有关，为探究w（Na2SO4）对结皮特性的影响，选取古尔班通古特沙漠东南缘流动风沙土的主要颗粒（100~200 μm），于70℃下在烘箱内进行13个w（Na2SO4）的12 h胶结试验，即风沙土中w（Na2SO4）为0.1%、0.2%、0.5%、1.0%、2.0%、3.0%、4.0%、5.0%、6.0%、7.0%、8.0%、10.0%、12.0%，分析w（Na2SO4）对风沙土盐结皮的表观、抗压强度及韧性特征3个抗风蚀能力指标的影响.结果表明:①随着w（Na2SO4）的增大，结皮表面颜色由红棕色变为浅红棕色再变为灰白色，表面盐晶越来越多.②w（Na2SO4）≤ 3.0%时结皮表面平整，4.0%~7.0%时结皮表面呈现起伏"波浪状"，≥ 8.0%时结皮表层遭孔隙应力破坏并脱离土体.③w（Na2SO4）≤ 3.0%时，样品抗压强度随着w（Na2SO4）的增加呈线性上升；≥ 3.0%时受孔隙压力破坏的影响，结皮抗压强度随w（Na2SO4）的增加反而下降.④结皮的韧性与w（Na2SO4）存在密切关系，w（Na2SO4）≤ 3.0%时，韧性随w（Na2SO4）的增加而增大，≥ 3.0%时韧性随w（Na2SO4）的增加反而减小.沙漠中风沙土主要组成物质是细沙（100~200 μm），且主要粒径沙土结皮特性与自然风沙土的结皮最相似.所以，若采用质量分数为3.0%的Na2SO4胶结风沙土形成盐结皮，具有较好的抗压强度和韧性，且表面平整无破坏，胶结体具有较好的抗风蚀性能，可用作流动沙地的治理.
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| 关 键 词： | 风沙土 盐结皮 抗压强度 韧性 结晶压力 古尔班通古特沙漠 |
| 收稿时间： | 2018/1/29 0:00:00 |
| 修稿时间： | 2018/5/29 0:00:00 |
Na2SO4 Crust Characteristics in Fine Sand Collected in the Gurbantunggut Desert |
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| WANG Dahuan,LI Chengzhi and LI Zhaoti.Na2SO4 Crust Characteristics in Fine Sand Collected in the Gurbantunggut Desert[J].Research of Environmental Sciences,2018,31(11):1979-1986. |
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| Authors: | WANG Dahuan LI Chengzhi and LI Zhaoti |
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| Affiliation: | 1.Institute of Arid Ecology & Environment of Xinjiang University, Urumqi 830046, China2.School of Resources and Environment Science, Xinjiang University, Urumqi 830046, China3.Key Laboratory of Oasis Ecology Ministry of Education, Xinjiang University, Urumqi 830046, China |
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| Abstract: | Salt crust on soil is formed by the cementing of salt crystals and soil particles. Salt crusts with dense texture and high intensity have high resistance performance to wind erosion. Thus, they play a key role in the control of wind erosion of sandy soils. The characteristics of salt crusts are closely related with the salt types and content. In order to investigate the effects of Na2SO4 content on salt crust characteristics, a series of cementing experiments were performed between sandy soils (particle size of 100-200 μm) from the southeastern margin of the Gurbantonggut Desert and Na2SO4 at 13 mass fraction (w(Na2SO4)=0.1%, 0.2%, 0.5%, 1.0%, 2.0%, 3.0%, 4.0%, 5.0%, 6.0%, 7.0%, 8.0%, 10.0%, 12.0%, respectively). The experiments were conducted at 70℃ in an oven for 12 hours. The effects of salt content on the performance, density and toughness of the crusts were analyzed. The results showed that:(1) Along with the increase of Na2SO4 content, the amount of salt crystals on the crust surface increased, and the color of the crust surface changed from reddish brown to pale red brown and then to white. (2) The surface of the crust was smooth when w(Na2SO4) ≤ 3.0%, and rough when the w(Na2SO4)=4.0%-7.0%. The crust surfaces ruptured due to pore stress and delaminated from the soil when the w(Na2SO4) ≥ 8.0%. (3) The resistance to compression increased linearly with the increase of Na2SO4 content when the w(Na2SO4) ≤ 3.0%, but the trend was opposite when w(Na2SO4)>3.0% due to breakage from pore pressure. (4) The toughness of the crust was closely related to the mass fraction of Na2SO4. The toughness increased with the increase of Na2SO4 content when w(Na2SO4) ≤ 3.0%, but the trend was reversed when w(Na2SO4)>3.0%. Fine sandy particles with size between 100-200 μm were the main composition of desert soils. Moreover, the crust characteristics developed with the fine sands were most similar to that developed with natural sands. In conclusion, the crust cemented with 3.0% Na2SO4 had a good resistance capability toward wind erosion, which could be used to control the mobility of sand due to its smooth surface and intact characteristics, and had the highest compressive resistance ability and toughness. |
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| Keywords: | sandy soil salt crust compression strength crystallization pressure |
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