铁氧化物对桂林黏土界限含水率的影响

Effect of Iron Oxides on Consistency Limits of Guilin Clay

摘要

为了探究铁氧化物对黏土界限含水率的影响,选用桂林地区普通黏土作为母质土,制备了铁氧化物与 NaNO₃ 混合土样以及单掺 NaNO₃ 土样,开展了界限含水率试验。 研究了不同温度和掺量条件下土样界限含水率的变化规律,并结合颗粒分析试验及土样微观试验阐明了铁氧化物对土颗粒的影响机理。 试验结果表明,NaNO₃ 会降低桂林黏土的界限含水率,且其加入量越大,界限含水率的降幅越明显,土样的液限、塑限和缩限均同步降低。 而铁氧化物能够提高桂林黏土在加入 NaNO₃ 后的液限、塑限和缩限,且液限增幅最大,其次是塑限和缩限;这一增强作用随铁氧化物浓度增加而加强,随温度升高而减弱。 混合土样在 105 ℃下烘干 48 h 后,铁氧化物对土样液限、塑限和缩限的影响作用基本消失。 高温干燥会改变铁氧化物与土颗粒间的连接方式并影响颗粒粒径,从而对土体的界限含水率产生影响。

Abstract

To investigate the effect of iron oxides on consistency limits of clayey soil, the ordinary clay from Guilin was selected as the parent soil for this study, and mixed soil samples of iron oxides and NaNO ₃ as well as soil samples added with NaNO ₃ alone were prepared. Tests were conducted to study the variation of consistency limits under different temperature and dosage conditions, and the particle size analysis and microstructural test were conducted to explain the mechanism of iron oxides’ influence on soil particles. The test results showed that NaNO ₃ reduced the consistency limits of Guilin clay. The greater the dosage was, the more obvious the reduction in consistency limits was. The trends of liquid limit, plastic limit and shrinkage limit changes were consistent. Iron oxides increased the liquid limit, plastic limit and shrinkage limit of Guilin clay after the addition of NaNO ₃, and the liquid limit increased the most, followed by plastic limit and shrinkage limit. This enhancement effect intensified with the increase of iron oxide concentration and weakened with the rise of temperature. After drying the mixed soil at 105 ℃ for 48 hours, the effect of iron oxides on liquid limit, plastic limit and shrinkage limit was nearly eliminated. High-temperature drying alters the interaction between iron oxides and soil particles and affects the particle size, thereby influencing the consistency limits of soil.

关键词

桂林黏土 / 铁氧化物 / 界限含水率 / 温度 / 钠离子

Key words

Guilin clay / iron oxides / consistency limits / temperature / sodium ion

参考文献

[1] SPAGNOLI G, FEINENDEGEN M . Relationship between measured plastic limit and plastic limit estimated from undrained shear strength, water content ratio and liquidity index[J]. Clay Minerals, 2017, 52(4): 509-519.

[2] NAGARAJ H B, REESHA B, SRAVAN M V, et al. Correlation of compaction characteristics of natural soils with modified plastic limit[J]. Transportation Geotechnics, 2015, 2: 65-77.

[3] 刘芠君, 肖桂元, 张祥宇, 等 . 稻壳灰固化红黏土的路用性能及微观机理[J]. 河北工程大学学报(自然科学版), 2022, 39(3): 16-22.

[4] LIU W J, XIAO G Y, ZHANG X Y, et al. Road performance and micro mechanism of rice husk ash modified red clay [J]. Journal of Hebei University of Engineering ( Natural Science Edition), 2022, 39 (3): 16-22.

[5] 王璐莹, 秦雷, 吕宪国, 等 . 铁促进土壤有机碳累积作用研究进展[J]. 土壤学报, 2018, 55(5): 1041-1050.

[6] WANG L Y, QIN L, LYU X G, et al. Progress in researches on effect of iron promoting accumulation of soil organic carbon [J]. Acta Pedologica Sinica, 2018, 55 (5): 1041-1050.

[7] CHEN S A, HEANEY P J, POST J E, et al. Hematite—goethite ratios at pH 2—13 and 25—170 ℃: a time—resolved synchrotron X—ray diffraction study[J]. Chemical Geology, 2022, 606: 120995.

[8] WHITAKER A H, AUSTIN R E, HOLDEN K L, et al. The structure of natural biogenic iron ( oxyhydr) oxides formed in circumneutral pH environments[J]. Geochimica et Cosmochimica Acta, 2021, 308: 237-255.

[9] ZHANG X W, LIU X Y, KONG L W, et al. Role of free iron oxides in the physicochemical and mechanical properties of natural clay [J]. Engineering Geology, 2022, 303: 106665.

[10] SUN D A, GAO Y, ZHOU A N, et al. Soil—water retention curves and microstructures of undisturbed and compacted Guilin lateritic clay[J]. Bulletin of Engineering Geology and the Environment, 2016, 75(2): 781-791.

[11] GAO Y, HE W, ZHANG X Y, et al. Investigation on strength and deformation properties of lateritic clay[J]. Construction and Building Materials, 2024, 411: 134276.

[12] 杨荫华, 柏树田 . 红土干燥脱水不可逆性对物理力学性质的影响[J]. 岩土工程学报, 1982(4): 104-113.

[13] YANG Y H, BAI S T . Influence of irreversibility of desiccation of lateritic soils on their physico—mechanical properties[J]. Chinese Journal of Geotechnical Engineering, 1982(4): 104-113.

[14] 冯金良, 赵泽三, 高国瑞 . 无定形态游离氧化铁脱水老化对粘性土物理性质的影响[J]. 工程地质学报, 1993, 1(2): 85-92.

[15] FENG J L, ZHAO Z S, GAO G R . The effect of amorphous free ferric oxide on the physical properties of clay soil in the process of dehydration[J]. Journal of Engineering Geology, 1993, 1(2): 85-92.

[16] 孔令伟, 罗鸿禧 . 游离氧化铁形态转化对红粘土工程性质的影响[J]. 岩土力学, 1993(4): 25-39.

[17] KONG L W, LUO H X . Effect of the conversion in form of free iron oxide on the engineering property of the red clay [J]. Rock and Soil Mechanics, 1993(4): 25-39.

[18] WANG Y, CAO Z Z, NIU Y, et al. Macromechanics, microstructure and particle contact model of artificially cemented laterite[J]. Materials Express, 2021, 11(5): 732-739.

[19] 顾新运, 李淑秋, 徐拔和 . 温度对微晶氧化铁形成与性质的影响 [J]. 土壤学报, 1989, 26 (1): 9-15 + 101—102.

[20] GU X Y, LI S Q, HSU P H . Effect of temperature on the formation and properties of submicron iron oxides[J]. Acta Pedologica Sinica, 1989, 26(1): 9-15+101—102.

[21] 马世昌 . 化学物质辞典[M]. 西安: 陕西科学技术出版社, 1999.

[22] MA S C . Dictionary of chemical substances[M]. Xi′an: Shaanxi Science & Technology Press, 1999.

[23] 中华人民共和国住房和城乡建设部 . 土工试验方法标准:GB/ T 50123—2019[S]. 北京: 中国计划出版社, 2019.

[24] Ministry of Housing and Urban—Rural Development of the People′s Republic of China. Standard for geotechnical testing method:GB/ T 50123—2019[S]. Beijing: China Planning Press, 2019.

[25] 韦江杏, 邓羽松, 廖达兰, 等 . 桂东南花岗岩崩岗土壤界限含水率空间变异及影响因素[J]. 土壤学报, 2023, 60(3): 749-761.

[26] WEI J X, DENG Y S, LIAO D L, et al. Spatial variation and influencing factors of soil limiting water content of granite collapsing gullies in southeast Guangxi[J]. Acta Pedologica Sinica, 2023, 60(3): 749-761.

[27] 肖桂元, 朱杰茹, 徐光黎, 等 . NaCl 溶液引起红黏土界限含水率变化的试验研究[J]. 中南大学学报(自然科学版), 2021, 52(9): 3314-3321.

[28] XIAO G Y, ZHU J R, XU G L, et al. Experimental study on change of limit water content of red clay caused by NaCl solution[J]. Journal of Central South University (Science and Technology), 2021, 52(9): 3314-3321.

[29] 高明霞, 李鹏, 王国栋, 等 . 南坪水库筑坝土料分散机理及原因分析[J]. 岩土工程学报, 2009, 31 (8): 1303-1308.

[30] GAO M X, LI P, WANG G D, et al. Mechanism and reason of dispersivity of dam soil in Nanping Reservoir [J]. Chinese Journal of Geotechnical Engineering, 2009, 31(8): 1303-1308.

[31] NAMAYANDEH A, ZHANG W, WATSON S K, et al. Goethite and hematite nucleation and growth from ferrihydrite: effects of oxyanion surface complexes[J]. Environmental Science & Technology, 2024, 58 (13): 5952-5962.

[32] 陈家坊, 何群, 邵宗臣 . 土壤中氧化铁的活化过程的探讨[J]. 土壤学报, 1983, 20(4): 387-393.

[33] CHEN J F, HE Q, SHAO Z C . Study on the activation process of iron oxides in soil [J]. Acta Pedologica Sinica, 1983, 20(4): 387-393.

基金资助

国家自然科学基金资助项目(52169022)