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《建筑科学与工程学报》[ISSN:1673-2049/CN:61-1442/TU]

卷:

40卷

期数:

2023年02期

页码:

129-137

栏目:

岩土工程

出版日期:

2023-03-30

文章信息/Info

Title:

Analysis on microscopic mechanism of sulfate saline soil improved by inorganic materials

文章编号:

1673-2049(2023)02-0129-09

作者:

杨晓华¹,王利鑫¹,张莎莎¹,谢山杰²

(1. 长安大学 公路学院,陕西 西安 710064; 2.中铁第四勘察设计院集团有限公司,湖北 武汉 430063)

Author(s):

YANG Xiaohua¹, WANG Lixin¹, ZHANG Shasha¹, XIE Shanjie²

(1. School of Highway, Chang'an University, Xi'an 710064, Shaanxi, China; 2. China Railway Siyuan Survey and Design Group Co., Ltd., Wuhan 430063, Hubei, China)

关键词:

盐渍土;  无机材料改良;  微观机理;  X射线衍射;  扫描电镜

Keywords:

saline soil;  inorganic material improvement;  microscopic mechanism;  X-ray diffraction;  scanning electron microscope

分类号:

TU973.2

DOI:

10.19815/j.jace.2021.09121

文献标志码:

A

摘要:

为了深入探讨无机材料改良硫酸盐渍土的微观作用机理,针对易溶盐含量为1.61%的硫酸盐渍土采用石灰、石灰+粉煤灰、石灰+火山灰3种不同配比的无机材料进行改良,通过化学成分分析试验、X射线衍射试验和扫描电镜试验,研究其改良前后化学、矿物成分变化,并对无机材料改良硫酸盐渍土的微观作用机理及微观结构进行了分析。结果表明:加入改良材料后硫酸根离子含量显著降低,石灰改良土中下降了41.37%,石灰+粉煤灰改良土下降了44.64%,石灰+火山灰改良土中下降了59.75%,有效减少了芒硝的形成,从总含盐量和硫酸根离子含量来看,石灰+火山灰组合改良剂的改良效果最佳; 改良前后土中变化最明显的元素是钙元素,石灰改良土中增加了73.28%,石灰+粉煤灰改良土中增加了30.17%,石灰+火山灰改良土中增加了27.59%,钙元素一部分以碳酸钙的形式存在,另一部分以硫酸钙和其他矿物形式存在; 改良后土中石英、方解石和碳酸钙的衍射强度增强,低矮的非晶物相增多,盐渍土中矿物成分更加复杂; 在改良初期土中有针状结构物生成,说明土中硫酸盐与改良材料发生了反应,随着时间的推移针状物逐渐消失,硫酸根离子含量也进一步降低,土体的整体强度进一步得到加强; 改良28 d后盐渍土的表观孔隙率大幅降低,其中石灰改良土下降了53.19%,石灰+粉煤灰改良土下降了54.33%,石灰+火山灰改良土下降了51.14%,土中大孔隙减少,小孔隙增多,孔隙大小变得相对均匀; 改良前后粗粒硫酸盐渍土的结构不变,以单粒结构为主,而细粒硫酸盐渍土改良前土颗粒排列方式难以辨认,改良后土颗粒以面面接触为主堆叠在一起。

Abstract:

In order to deeply explore the microscopic mechanism of sulfated saline soil improved by inorganic materials, three inorganic materials with different ratios of lime, lime + fly ash, and lime+volcanic ash were used for the improvement of sulfate saline soil with a soluble salt content of 1.61%. Through chemical composition analysis test, X-ray diffraction test and scanning electron microscope test, the chemical and mineral composition changes before and after the improvement were studied, and the microscopic mechanism and microstructure of the inorganic material to improve the sulfate saline soil were analyzed. The results show that sulphate ion content significantly decreases after adding the improved materials. The lime modified soil decreases by 41.37%, the lime+fly ash modified soil decreases by 44.64%, and the lime + volcanic ash modified soil decreases by 59.75%, which effectively reduces the formation of glauber's salt. In terms of salt content and sulfate ion content, the lime+volcanic ash modifier has the best improvement effect. The most obvious element in the soil before and after the improvement is calcium. The calcium in the lime-improved soil increases by 73.28%, lime+fly ash modified soil increases by 30.17%, and the lime+volcanic ash modified soil increases by 27.59%. One part of the calcium element exists in the form of calcium carbonate, and the other part exists in the form of calcium sulfate and other minerals. The diffraction intensity of quartz, calcite and calcium carbonate is enhanced, the low amorphous phases increase, and the mineral composition in the saline soil is more complex. Needle-like structures are formed in the soil at the beginning of the improvement, indicating that the sulfate in the soil has reacted with the improved material. As time goes by, the needles gradually disappear, the sulfate ion content is further reduced, and the overall strength of the soil is further strengthened. The apparent porosity of the saline soil after 28 d improvement is greatly reduced. The lime-improved soil decreases by 53.19%, lime+fly ash modified soil decreases by 54.33%, and lime+volcanic ash modified soil decreases by 51.14%. Large pores in the soil decreases, small pores increases, and the pore size becomes relatively uniform. For the coarse-grained sulfate saline soil before and after improvement, the structure of the soil remains unchanged, and is dominated by a single-grain structure, while the arrangement of the soil particles before the improvement of the fine-grained sulphate saline soil is difficult to identify, and the soil particles after the improvement are mainly stacked in surface-to-surface contact.

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相似文献/References:

[1]乔宏霞,路承功,李 宇,等.宁夏盐渍土地区现场暴露混凝土耐久性损伤评价试验[J].建筑科学与工程学报,2016,33(06):44.
　QIAO Hong-xia,LU Cheng-gong,LI Yu,et al.Experiment on Durability Damage Assessment of Concrete Field Exposed in Saline Soil Area of Ningxia[J].Journal of Architecture and Civil Engineering,2016,33(02):44.

备注/Memo

备注/Memo:

收稿日期:2021-09-15
基金项目:国家自然科学基金项目(41807245); 陕西省自然科学基础研究计划项目(2019JM-147); 中央高校基本科研业务费专项资金项目(300102219219)
作者简介:杨晓华(1961-),男,工学博士,教授,博士生导师,E-mail:xiaohuay@126.com。

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更新日期/Last Update: 2023-03-20