Water-salt migration rules in chlorine saline soil under precipitation infiltration
-
摘要: 为探究降水入渗导致氯盐渍土盐分流失问题,以人工配置的不同含盐(氯化钠)量粗粒土和细粒土为研究对象,通过自行设计的室内降水入渗模拟试验装置,获取了14种工况下近500组试验数据,对比分析了降水入渗次数、土样粒径与含盐量对土样水盐迁移特性的影响;建立了降水入渗作用下土体盐分迁移与水分迁移之间的联系,确定了入渗影响深度,揭示了水分与盐分经降水入渗作用后在土柱中的分布特征。研究结果表明:对于细粒盐渍土,随着降水入渗次数从1~4的增加,其含水率和含盐量的峰值点均明显向下发生移动,盐分将逐渐向土柱中底部积聚;对于粗粒盐渍土,2次降水入渗后,含水率在土柱高度范围内分布较为均匀,且降水入渗次数的继续增加并没有改变这种均匀性,而盐分将随着水分快速向土柱底部积聚;氯盐渍土这种“盐随水走”关系与其易溶于水有关,所以氯盐渍土填料路基应加强防水措施,特别是粗粒土填料,虽然其可压实性优于细粒土,但浸水后溶陷强烈,病害更为严重;一定范围内含盐量的增大不会改变细粒土或粗粒土水盐迁移的整体规律,但会降低土体水盐迁移的速率,与含盐量较低的细粒土相比,含盐量较高的细粒土的水分与盐分峰值点出现深度均滞后5~15 cm;在降水入渗相同条件下,不同含盐量细粒土盐分迁移的相对增大幅度不同,但盐分上升绝对量基本相同,说明不同含盐量细粒土中水分所能携带的盐分是一定的。Abstract: To explore the salt loss of chlorine salt soil caused by precipitation infiltration, the artificially configured coarse-grained soils and fine-grained soils with different salt (sodium chloride) contents were taken as the research objects, nearly 500 groups of test data were obtained under 14 conditions by the self-designed simulation test device for laboratory precipitation infiltration, and the effects of water infiltration times, soil particle size, and salt content on the water-salt migration characteristics of soil samples were compared and analyzed. The relationship between salt migration and water migration under the action of precipitation infiltration was established, the depth of infiltration effect was determined, and the distribution characteristics of water and salt in the soil column after precipitation infiltration were revealed. Research results show that for fine-grained saline soil, with the increase in precipitation infiltration times (1-4), the peak points of moisture content and salt content move significantly downward, and the salt will gradually accumulate to the middle and bottom of the soil column. As for coarse-grained saline soil, the moisture content is relatively uniform within the height range of the soil column after the second precipitation infiltration, and the continuous increase of precipitation infiltration times does not change this uniformity, while the salt will quickly accumulate to the bottom of the soil column with the moisture. The "salt along with water" relationship of chlorine saline soil is related to its easy dissolution in water, so the subgrade filled with chlorine saline soil should strengthen waterproof measures, especially coarse-grained soil filler. Although coarse-grained soil has better compactability than fine-grained soil, it is strong of collapsibility after soaking water, and the disease is even more serious. The increase in salt content within a certain range does not change the overall law of water-salt migration in fine-grained or coarse-grained soil but will reduce the migration rates of water and salt. Compared with the fine-grained soil with low salt content, the depths of peak points of water and salt of fine-grained soil with higher salt content will lag behind 5-10 cm. Under the same condition of precipitation infiltration, the relative increment in salt migration of fine-grained soil is different for different salt contents, but the absolute increment is basically the same, indicating that the salt carried by water in fine-grained soils with different salt contents is certain.
-
表 1 土样的基本物理力学参数
Table 1. Basic physical-mechanical parameters of soil samples
试验土样 比重 液限/% 塑限/% 塑限指数/% 最大干密度/(g·cm-3) 最佳含水率/% 细粒土样 2.70 11.3 21.7 10.4 2.09 9.3 粗粒土样 2.29 6.5 表 2 细粒土的颗粒组成
Table 2. Particle composition of fine-grained soil
颗粒组成各粒径(mm)所占百分比/% 不均匀系数 曲率系数 土的分类 5~2 2~0.5 0.5~0.25 0.25~0.075 0.075~0.002 <0.002 0.0 0.5 4.2 21.1 69.2 5.0 <5 1.21 含砂低液限粉土 表 3 粗粒土的颗粒组成
Table 3. Particle composition of coarse-grained soil
颗粒组成各粒径(mm)所占百分比/% 不均匀系数 曲率系数 土的分类 60~40 40~20 20~10 10~5 5~2 2~1 <1 0.0 8.3 17.1 23.2 22.1 4.0 25.3 >5 1.04 级配良好砾 表 4 试验工况设计方案
Table 4. Design schemes of test conditions
试验编号 试验土样 含盐量/% 降水入渗次数 备注 1 含砂低液限粉土
(细粒土)0.5 1 单次降水入渗强度为10 mm,降水入渗量为254 g 2 0.5 2 分2次分别加入254 g水,每次加水时间间隔10 d 3 0.5 3 分3次分别加入254 g水,每次加水时间间隔10 d 4 0.5 4 分4次分别加入254 g水,每次加水时间间隔10 d 5 2.0 1 单次降水入渗强度为10 mm,降水入渗量为254 g 6 2.0 2 分2次分别加入254 g水,每次加水时间间隔10 d 7 2.0 3 分3次分别加入254 g水,每次加水时间间隔10 d 8 2.0 4 分4次分别加入254 g水,每次加水时间间隔10 d 9 级配良好砾
(粗粒土)1.0 1 单次降水入渗强度为10 mm,降水入渗量为572 g 10 1.0 2 分2次分别加入572 g水,每次加水时间间隔10 d 11 1.0 3 分3次分别加入572 g水,每次加水时间间隔10 d 12 3.0 1 单次降水入渗强度为10 mm,降水入渗量为572 g 13 3.0 2 分2次分别加入572 g水,每次加水时间间隔10 d 14 3.0 3 分3次分别加入572 g水,每次加水时间间隔10 d -
[1] 丁兆民, 张莎莎, 杨晓华. 粗颗粒盐渍土路用填料可用性指标研究[J]. 冰川冻土, 2008, 30(4): 623-631. https://www.cnki.com.cn/Article/CJFDTOTAL-BCDT200804015.htmDING Zhao-min, ZHANG Sha-sha, YANG Xiao-hua. Experimental studies of the applicability index of coarse-grained salty soil as an embankment filling[J]. Journal of Glaciology and Geocryology, 2008, 30(4): 623-631. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-BCDT200804015.htm [2] 冯忠居, 李维洲, 王廷武, 等. 新疆板块状盐渍土工程特性[J]. 交通运输工程学报, 2010, 10(6): 1-8. doi: 10.19818/j.cnki.1671-1637.2010.06.001FENG Zhong-ju, LI Wei-zhou, WANG Ting-wu, et al. Engineering characteristics of plate-like saline soil in Xinjiang[J]. Journal of Traffic and Transportation Engineering, 2010, 10(6): 1-8. (in Chinese) doi: 10.19818/j.cnki.1671-1637.2010.06.001 [3] 谭冬生, 孙毅敏, 胡力学, 等. 新建兰新铁路新疆段沿线盐渍土盐胀特性、机理与防治对策[J]. 铁道学报, 2011, 33(9): 83-88. https://www.cnki.com.cn/Article/CJFDTOTAL-TDXB201109017.htmTAN Dong-sheng, SUN Yi-min, HU Li-xue, et al. Salt expansion properties and mechanism of saline soil in Xinjiang Section of Lanzhou-Xinjiang Railway and preventive measures[J]. Journal of the China Railway Society, 2011, 33(9): 83-88. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-TDXB201109017.htm [4] 张莎莎, 王旭超, 杨晓华, 等. 含盐施工用水对路基填料工程特性的累加效应[J]. 交通运输工程学报, 2020, 20(6): 71-81. doi: 10.19818/j.cnki.1671-1637.2020.06.006ZHANG Sha-sha, WANG Xu-chao, YANG Xiao-hua, et al. Cumulative effect of saline construction water on engineering properties of subgrade filling material[J]. Journal of Traffic and Transportation Engineering, 2020, 20(6): 71-81. (in Chinese) doi: 10.19818/j.cnki.1671-1637.2020.06.006 [5] 冯瑞玲, 王随柱, 吴立坚, 等. 新疆硫酸盐渍土地区沥青路面鼓胀变形机理研究[J]. 岩土工程学报, 2021, 43(9): 1739-1745. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC202109025.htmFENG Rui-ling, WANG Sui-zhu, WU Li-jian, et al. Bulging deformation mechanism of asphalt pavement in sulfate saline soil areas of Xinjiang[J]. Chinese Journal of Geotechnical Engineering, 2021, 43(9): 1739-1745. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC202109025.htm [6] 石建勋, 刘新荣, 杨保存. 地下水位及运移盐分对路基冻胀变形的影响研究[J]. 山东大学学报(工学版), 2009, 39(增2): 22-25. https://cpfd.cnki.com.cn/Article/CPFDTOTAL-ZGYJ200912003004.htmSHI Jian-xun, LIU Xin-rong, YANG Bao-cun. A study on influence of water table and salinity movement on frost heaving metamorphosis of roadbed[J]. Journal of Shandong University (Engineering Science), 2009, 39(S2): 22-25. (in Chinese) https://cpfd.cnki.com.cn/Article/CPFDTOTAL-ZGYJ200912003004.htm [7] 刘锋, 胡江洋, 刘军勇, 等. 连续降雨入渗作用下非饱和土路基稳定性研究[J]. 路基工程, 2020(1): 55-60. https://www.cnki.com.cn/Article/CJFDTOTAL-LJGC202001012.htmLIU Feng, HU Jiang-yang, LIU Jun-yong, et al. Study on the stability of unsaturated soil subgrade under continuous rainfall infiltration[J]. Subgrade Engineering, 2020(1): 55-60. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-LJGC202001012.htm [8] 张彧, 邹美思, 徐安花, 等. 温度对盐渍土抗剪强度和变形特性的影响[J]. 中国公路学报, 2020, 33(5): 66-78. https://www.cnki.com.cn/Article/CJFDTOTAL-ZGGL202005006.htmZHANG Yu, ZOU Mei-si, XU An-hua, et al. Effect of temperature on shear strength and deformation characteristics of saline soil[J]. China Journal of Highway and Transport, 2020, 33(5): 66-78. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-ZGGL202005006.htm [9] 邴慧, 何平. 不同冻结方式下盐渍土水盐重分布规律的试验研究[J]. 岩土力学, 2011, 32(8): 2307-2312. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201108011.htmBING Hui, HE Ping. Experimental study of water and salt redistributions of saline soil with different freezing modes[J]. Rock and Soil Mechanics, 2011, 32(8): 2307-2312. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201108011.htm [10] XU Xiang-tian, WANG Yu-bing, BAI Rui-qiang, et al. Effects of sodium sulfate content on mechanical behavior of frozen silty sand considering concentration of saline solution[J]. Results in Physics, 2016, 6: 1000-1007. doi: 10.1016/j.rinp.2016.11.040 [11] XU Xiang-tian, WANG Yu-bing, BAI Rui-qiang, et al. Comparative studies on mechanical behavior of frozen natural saline silty sand and frozen desalted silty sand[J]. Cold Regions Science and Technology, 2016, 132: 81-88. doi: 10.1016/j.coldregions.2016.09.015 [12] HAN Yan, WANG Qing, WANG Ning, et al. Effect of freeze-thaw cycles on shear strength of saline soil[J]. Cold Regions Science and Technology, 2018, 154: 42-53. doi: 10.1016/j.coldregions.2018.06.002 [13] 周凤玺, 周立增, 王立业, 等. 温度梯度作用下非饱和盐渍土水盐迁移及变形特性研究[J]. 岩石力学与工程学报, 2020, 39(10): 2115-2130. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX202010015.htmZHOU Feng-xi, ZHOU Li-zeng, WANG Li-ye, et al. Study on water and salt migration and deformation properties of unsaturated saline soil under temperature gradient[J]. Chinese Journal of Rock Mechanics and Engineering, 2020, 39(10): 2115-2130. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX202010015.htm [14] 汪为巍, 杨保存, 王荣. 南疆盐渍土地区城区道路病害规律研究[J]. 岩土工程学报, 2013, 35(增1): 253-258. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC2013S1042.htmWANG Wei-wei, YANG Bao-cun, WANG Rong. Road diseases in southern saline soil areas of Xinjiang[J]. Chinese Journal of Geotechnical Engineering, 2013, 35(S1): 253-258. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC2013S1042.htm [15] 赵德安, 余云燕, 马惠民, 等. 南疆铁路路基次生盐渍化试验研究[J]. 岩土工程学报, 2014, 36(4): 745-751. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201404025.htmZHAO De-an, YU Yun-yan, MA Hui-min, et al. Secondary salinization of subgrade of southern Xinjiang railway[J]. Chinese Journal of Geotechnical Engineering, 2014, 36(4): 745-751. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201404025.htm [16] ZHANG Jun, WENG Xing-zhong, QU Bo, et al. Failure modes and mechanisms of pavements in saline foundations[J]. Proceedings of the Institution of Civil Engineers—Transport, 2018, 171(3): 174-182. [17] 耿鹤良, 杨成斌. 盐渍土化学潜蚀溶陷过程阶段化模型分析[J]. 岩土力学, 2009, 30(增2): 232-234. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX2009S2051.htmGENG He-liang, YANG Cheng-bin. Stage model analysis of progress of saline soil' chemical subsuface erosion dissolve settlement[J]. Rock and Soil Mechanics, 2009, 30(S2): 232-234. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX2009S2051.htm [18] 杨晓华, 张志萍, 张莎莎. 高速公路盐渍土地基溶陷特性离心模型试验[J]. 长安大学学报(自然科学版), 2010, 30(2): 5-9. https://www.cnki.com.cn/Article/CJFDTOTAL-XAGL201002003.htmYANG Xiao-hua, ZHANG Zhi-ping, ZHANG Sha-sha. Centrifugalize model test on dissolve collapse of saline soil under expressway[J]. Journal of Chang'an University (Natural Science Edition), 2010, 30(2): 5-9. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-XAGL201002003.htm [19] 陈肖柏, 邱国庆, 王雅卿, 等. 温降时之盐分重分布及盐胀试验研究[J]. 冰川冻土, 1989, 11(3): 231-238. https://www.cnki.com.cn/Article/CJFDTOTAL-BCDT198903005.htmCHEN Xiao-bai, QIU Guo-qing, WANG Ya-qing, et al. Salt redistribution and heave of saline soil during cooling[J]. Journal of Glaciology and Geocryology, 1989, 11(3): 231-238. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-BCDT198903005.htm [20] 冯瑞玲, 蔡晓宇, 吴立坚, 等. 硫酸盐渍土水-盐-热-力四场耦合理论模型[J]. 中国公路学报, 2017, 30(2): 1-10, 40. https://www.cnki.com.cn/Article/CJFDTOTAL-ZGGL201702001.htmFENG Rui-ling, CAI Xiao-yu, WU Li-jian, et al. Theoretical model on coupling process of moisture-salt-heat-stress field in sulfate salty soil[J]. China Journal of Highway and Transport, 2017, 30(2): 1-10, 40. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-ZGGL201702001.htm [21] 曹亚鹏, 文桃, 米海珍, 等. 硫酸盐渍土含水率单次递减条件下的盐胀特性[J]. 岩土力学, 2018, 39(3): 881-888. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201803015.htmCAO Ya-peng, WEN Tao, MI Hai-zhen, et al. Salt expansion properties of sulfate saline soils under one time decrease of water content[J]. Rock and Soil Mechanics, 2018, 39(3): 881-888. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201803015.htm [22] 包卫星, 谢永利, 杨晓华. 天然盐渍土冻融循环时水盐迁移规律及强度变化试验研究[J]. 工程地质学报, 2006, 14(3): 380-385. https://www.cnki.com.cn/Article/CJFDTOTAL-GCDZ200603017.htmBAO Wei-xing, XIE Yong-li, YANG Xiao-hua. A laboratory test study on water and salt migration in natural saline soils and associated shear strength changes under freezing and thawing cycles[J]. Journal of Engineering Geology, 2006, 14(3): 380-385. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-GCDZ200603017.htm [23] 张彧, 房建宏, 刘建坤, 等. 察尔汗地区盐渍土水热状态变化特征与水盐迁移规律研究[J]. 岩土工程学报, 2012, 34(7): 1344-1348. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201207027.htmZHANG Yu, FANG Jian-hong, LIU Jian-kun, et al. Variation characteristics of hydrothermal state and migration laws of water and salt in Qarhan Salt Lake Region[J]. Chinese Journal of Geotechnical Engineering, 2012, 34(7): 1344-1348. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201207027.htm [24] 万旭升, 赖远明. 硫酸钠溶液和硫酸钠盐渍土的冻结温度及盐晶析出试验研究[J]. 岩土工程学报, 2013, 35(11): 2090-2096. https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201311023.htmWAN Xu-sheng, LAI Yuan-ming. Experimental study on freezing temperature and salt crystal precipitation of sodium sulphate soulotion and sodium sulphate saline soil[J]. Chinese Journal of Geotechnical Engineering, 2013, 35(11): 2090-2096. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTGC201311023.htm [25] 张虎元, 姜啸, 王锦芳, 等. 壁画地仗中盐分的毛细输送机制研究[J]. 岩土力学, 2016, 37(1): 1-11. https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201601001.htmZHANG Hu-yuan, JIANG Xiao, WANG Jin-fang, et al. A study on the mechanism of capillary-driven transport of soluble salt in mural plaster[J]. Rock and Soil Mechanics, 2016, 37(1): 1-11. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YTLX201601001.htm [26] 肖泽岸, 赖远明. 冻融和干湿循环下盐渍土水盐迁移规律研究[J]. 岩石力学与工程学报, 2018, 37(增1): 3738-3746. https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX2018S1066.htmXIAO Ze-an, LAI Yuan-ming. Study on water and salt transfer mechanism in saline soil under freezing-thawing and dry-wet conditions[J]. Chinese Journal of Rock Mechanics and Engineering, 2018, 37(S1): 3738-3746. (in Chinese) https://www.cnki.com.cn/Article/CJFDTOTAL-YSLX2018S1066.htm [27] BING Hui, HE Ping, ZHANG Ying. Cyclic freeze thaw as a mechanism for water and salt migration in soil[J]. Environmental Earth Sciences, 2015, 74(1): 675-681. [28] CARY J W, MAYLAND H F. Salt and water movement in unsaturated frozen soil[J]. Soil Science Society of America Journal, 1972, 36(4): 549-555. [29] CARY J W. A new method for calculating frost heave including solute effects[J]. Water Resources Research, 1987, 23(8): 1620-1624. [30] PADILLA F, VILLENEUVE J P. Modeling and experimental studies of frost heave including solute effects[J]. Cold Regions Science and Technology, 1992, 20(2): 183-194. [31] ZHANG Sha-sha, ZHANG Jian-suo, GUI Yi-lin, et al. Deformation properties of coarse-grained sulfate saline soil under the freeze-thaw-precipitation cycle[J]. Cold Regions Science and Technology, 2020, 17: 103121.