Effect of pH on Physical and Mechanical Properties and Microstructure of Collapsible Loess
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摘要: 酸碱污染严重影响岩土工程长期稳定性。利用无侧限抗压强度、湿陷性试验、抗剪强度试验，研究不同pH值对黄土物理力学性能的影响，并采用XRD、SEM进一步探究不同pH值对黄土的影响机理。试验结果表明，与对照组相比（pH=7），pH值降低导致矿物成分衍射峰强度明显下降，且pH=3与pH=5中孔与大孔分别占比93.3%、89.9%，进而使无侧限抗压强度、湿陷性、抗剪强度下降。随pH值增加，在碱性环境中会生成大量胶凝物质，矿物成分衍射峰强度提高，与pH=7相比，pH=9与pH=11微孔与小孔分别增加25.0%、59.96%，使黄土物理力学性能得到提升。酸污染会降低黄土物理力学性能，而碱污染可提高黄土物理力学性能，可为黄土地区酸碱污染防治提供参考依据。Abstract: Acid-base pollution seriously affects the long-term stability of geotechnical engineering. Unconfined compressive strength, collapsibility test, and shear strength test were used to study the effect of different pH values on the physical and mechanical properties of loess. XRD and SEM were used to further explore the mechanism of the effect of different pH values on loess. The test results showed that compared with the control group (pH=7), the decrease in pH led to a significant decrease in the intensity of the diffraction peaks of the mineral components, and the proportion of medium and large pores in pH=3 and pH=5 was 93.3% and 89.9% respectively, which in turn led to a decrease in the unconfined compressive strength, collapsibility, and shear strength. With the increase of pH, a large amount of gelling material is generated in the alkaline environment and the intensity of the diffraction peak of mineral composition increases. Compared with pH=7, the micropores and small pores of pH=9 and pH=11 increase by 25.0% and 59.96% respectively, which improves the physical and mechanical properties of the loess. Acid pollution will reduce the physical and mechanical properties of loess, but alkali pollution can improve the physical and mechanical properties of loess, which can provide a reference basis for the prevention and control of acid and alkali pollution in loess areas.
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Key words:
- pH /
- loess /
- unconfined compressive strength /
- coefficient of collapsibility /
- shear strength /
- XRD /
- SEM
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表 3 孔隙直径变化
pH值 孔径分布百分比/% ≤1 μm 1～4 μm 4～16 μm >16 μm pH=3 1.12 5.58 12.61 80.69 pH=5 2.37 7.73 13.40 76.50 pH=7 6.92 12.12 40.49 40.47 pH=9 8.46 16.94 38.30 36.30 pH=11 9.11 38.44 26.62 25.83 
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[1] 杨 凯. 湿陷性黄土地区桥梁主要病害及对承载能力的影响究[D]. 兰州: 兰州交通大学, 2016. [2] 高懿琼,骆正山,毕傲睿,等. 湿陷性黄土区长输管道耦合协调危险性评价[J]. 灾害学,2020,35(4):20-23,92. doi: 10.3969/j.issn.1000-811X.2020.04.005 [3] 张 坤,王毅红,兰官奇,等. 不同地域生土基材料抗压强度试验研究[J]. 硅酸盐通报,2019,38(4):1128-1134,1147. [4] 孙银磊,汤连生,刘 洁. 非饱和土微观结构与粒间吸力的研究进展[J]. 岩土力学,2020,41(4):1095-1122. [5] 蒋明镜. 现代土力学研究的新视野−宏微观土力学[J]. 岩土工程学报,2019,41(2):195-254. [6] 何维山,许 琦,刘长春. 黑方台黄土塬区地面变形成因分析[J]. 东华理工大学学报(自然科学版),2010,33(3):281-285,289. [7] 李坤泓. 干湿及冻融循环交替作用下压实黄土变形特性的试验研究[D]. 北京: 北京交通大学, 2021. [8] 杨 惠. 黄土湿陷特性的微观研究进展及方法[J]. 科学技术创新,2019,(21):27-28. doi: 10.3969/j.issn.1673-1328.2019.21.018 [9] ZHENG F,SHAO S J,WANG S H. Effect of freeze-thaw cycles on the strength behaviour of recompacted loess in true triaxial tests[J]. Cold Regions Science and Technology,2021,181:103172. [10] 潘 泰,赵贵涛,黄 英. pH值对云南红黏土力学特性及微观结构的影响[J]. 硅酸盐通报,2021,40(10):3427-3434,3441. doi: 10.3969/j.issn.1001-1625.2021.10.gsytb202110034 [11] HIDEO K. Relationship between microstructure and degree of hardening of air-dried maji-soils under different pH conditions[J]. Soil Science and Plant Nutrition,2004,50(2):269-275. doi: 10.1080/00380768.2004.10408477 [12] ALTIN O,ZBELGE H,DOGU T. Effect of pH in an aqueous medium on the surface area, pore size distribution, density, and porosity of montmorillonite[J]. Journal of Colloid and Interface Science,1999,217(1):19-27. doi: 10.1006/jcis.1999.6271 [13] 冯 立,张茂省,胡 炜,等. 黄土垂直节理细微观特征及发育机制探讨[J]. 岩土力学,2019,40(1):235-244. [14] GB/T 50123―2019 土工试验方法标准[S]. 北京: 中国计划出版社, 2019. [15] 郭倩怡,王友林,谢婉丽,等. 黄土湿陷性与土体物性指标的相关性研究[J]. 西北地质,2021,54(1):212-221. [16] GB 50025―2018 湿陷性黄土地区建筑规范[S]. 北京: 中国建筑工业出版社, 2018. [17] 方立智. 降雨条件下新型固化剂改良黄土边坡稳定性研究[J]. 合成材料老化与应用,2022,51(5):103-105, 7. [18] 孔令荣,黄宏伟,张冬梅,等. 不同固结压力下饱和软粘土孔隙分布试验研究[J]. 地下空间与工程学报,2007,(6):1036-1040. doi: 10.3969/j.issn.1673-0836.2007.06.012 [19] 许梦伊,郑剑香. 通过pH值调节圆柱形纳米孔进行压力驱动的离子分离[J]. 粘接,2022,49(10):140-144. doi: 10.3969/j.issn.1001-5922.2022.10.034 [20] 罗金波,房 雷,路少山,等. 水泥土挤密桩处理湿陷性黄土地基研究[J]. 粘接,2022,49(3):149-152. doi: 10.3969/j.issn.1001-5922.2022.03.034 -
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