为探究CaCl2溶液对红黏土渗透系数的影响,通过X射线衍射(XRD)试验、渗透试验、热分析试验和扫描电镜(SEM),对红黏土试样受不同浓度(0.0、0.1、0.3、0.5、1.0 mol/L)的CaCl2溶液饱和后的渗透性进行了试验分析。结果表明:当孔隙溶液浓度从0.0 mol/L增加到0.5 mol/L时,红黏土的渗透系数先降低后升高;此后随着孔隙溶液浓度的增加,渗透系数呈下降趋势;利用热分析试验,得到红黏土在加入不同浓度CaCl2溶液后强结合水的含量,其强结合水含量的变化与红黏土渗透系数的变化有着紧密的联系;利用扫描电镜(SEM)观测了不同浓度CaCl2溶液下土样的微观结构,Ca2+增大了红黏土矿物结合水膜厚度,导致土的有效孔隙减少,从而降低了土体的渗透性。该研究成果可为红黏土作为隔离墙隔离污染物提供数据参考。
Abstract
XRD test, permeability test, thermal analysis test and scanning electron microscope (SEM) were performed to investigate the effect of CaCl2 solution on the permeability coefficient of red clay. The red clay specimens were saturated by CaCl2 solutions of different concentrations (0.0, 0.1, 0.3, 0.5 and 1.0 mol/L). Results reveal that when the pore solution concentration increases from 0.0 mol/L to 0.5 mol/L, the permeability coefficient of red clay decreases before increasing. Afterwards, the permeability coefficient presents a decreasing trend with the increase of pore solution concentration. Through thermal analysis tests, the content of strongly bound water of red clay saturated with different concentrations of CaCl2 solution was obtained. The changes in the content of strongly bound water is closely related to the change of permeability coefficient of red clay. The microstructure of soil samples in different concentrations of CaCl2 solution was observed by scanning electron microscopy (SEM). Ca2+ increases the thickness of the mineral-bound water film of the red clay, which leads to the declining of effective pore space, thus reducing the permeability of the soil. The findings can be used as a data reference for the use of red clay as a barrier to isolate pollutants.
关键词
红黏土 /
氯化钙溶液 /
渗透系数 /
XRD /
渗透试验 /
热分析试验 /
SEM /
强结合水
Key words
red clay /
calcium chloride solution /
permeability coefficient /
XRD test /
permeability test /
thermal analysis test /
strongly bound water
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参考文献
[1] 马田田, 韦昌富, 陈 盼, 等. NaCl溶液对土体持水特性影响的试验研究[J]. 岩土力学, 2015, 36(10): 2831-2836.
[2] MITCHELL J K,SOGA K. Fundamentals of Soil Behavior[M]. Edition 3. New York: Wiley, 2005.
[3] 沈胜强, 杜延军, 张 润, 等. 基于改进滤失试验的CaCl2溶液作用下膨润土滤饼渗透系数[J]. 东南大学学报(自然科学版), 2016, 46(增刊1): 179-183.
[4] NAEINI S A, JAHANFAR M A. Effect of Salt Solution and Plasticity Index on Undrain Shear Strength of Clays[J]. International Journal of Materials and Metallurgical Engineering, 2011, 5(1): 92-96.
[5] WIDJAJA B, SETIANTO K M. Effect of NaCl and CaCl2 Solutions on the Liquid Limit, Plastic Limit, and Plasticity Index of Clay[J]. IOP Conference Series: Materials Science and Engineering, 2019, 508: 012045.
[6] CHEN W C, HUANG W-H. Effect of Groundwater Chemistry on the Swelling Behavior of a Ca-Bentonite for Deep Geological Repository[J]. Physics and Chemistry of the Earth, Parts A/B/C, 2013, 65: 42-49.
[7] ANSON R W W, HAWKINS A B. The Effect of Calcium Ions in Pore Water on the Residual Shear Strength of Kaolinite and Sodium Montmorillonite[J]. Géotechnique, 2002, 52(5): 379-381.
[8] 张 芹, 颜荣涛, 韦昌富, 等. 孔隙溶液对粉质黏土界限含水率的影响[J]. 岩土力学, 2015, 36(增刊1): 558-562, 608.[9] 颜荣涛, 梁维云, 杨德欢, 等. 氯化钠溶液对粘性土的强度影响[J]. 桂林理工大学学报, 2017, 37(1): 88-93.
[10] 陈永贵, 雷宏楠, 贺 勇, 等. 膨润土-红黏土混合土对NaCl溶液的渗透试验研究[J]. 中南大学学报(自然科学版), 2018, 49(4): 910-915.
[11] 孙德安, 张 龙. 盐溶液饱和高庙子膨润土膨胀特性及预测[J]. 岩土力学, 2013, 34(10): 2790-2795.
[12] 高子瑞, 陈 涛, 徐永福. 盐溶液对膨润土膨胀性的影响[J]. 岩土力学, 2018, 39(1): 249-253.
[13] 郭招群, 刘俊新, 甘建军, 等. 盐溶液对高庙子钠基膨润土膨胀性能的影响[J]. 西南科技大学学报, 2017, 32(3): 22-26, 102.
[14] 杨秀娟, 汪 源, 樊恒辉, 等. 孔隙溶液酸碱度对重塑黄土工程性质的影响研究[J]. 长江科学院院报, 2018, 35(9): 92-97.
[15] 蔡 念, 曹丽文, 商敬秋. 无机盐溶液渗流过程中化学作用对粉砂渗透性的影响[J]. 科学技术与工程, 2018, 18(16): 312-317.
[16] 谢 刚, 邓明毅, 张 龙. 黏土结合水的热分析定量研究方法[J]. 钻井液与完井液, 2013, 30(6): 1-4, 91.
[17] 邓明毅, 刘洋洋, 谢 刚, 等. 钠蒙脱土结合水的热分析定量研究方法[J]. 钻井液与完井液, 2018, 35(2): 17-22.
[18] 张 龙, 邓明毅, 冯泽远, 等. 无机盐对蒙脱土结合水的影响[J]. 应用化工, 2015, 44(2): 243-246.
[19] SHACKELFORD C D, BENSON C H, KATSUMI T, et al. Evaluating the Hydraulic Conductivity of GCLS Permeated with Non-Standard Liquids[J]. Geotextiles and Geomembranes, 2000, 18(2/3/4): 133-161.
[20] GB/T 50123—2019,土工试验方法标准[S].北京:中国计划出版社,2019.
[21] 王 勇, 曹丽文, 温文富, 等. 生活钠铵盐污染对黏性土水理力学性质的影响[J]. 工业建筑, 2013, 43(9): 83-87.
[22] 李善梅,刘之葵,牟春梅,等.论红黏土有效孔隙比的确定方法[J]. 桂林理工大学学报,2017,37(3):429-436.
[23] 李广信, 张丙印, 于玉贞. 土力学[M]. 2版. 北京: 清华大学出版社, 2013.
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