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高校地质学报 ›› 2023, Vol. 29 ›› Issue (6): 894-901.DOI: 10.16108/j.issn1006-7493.2022056

• 工程地质学 • 上一篇    下一篇

化学老化生物炭对土体膨胀性和压缩性的影响及其机制

殷 悦,顾 凯*,卢 宇,沈征涛,施 斌   

  1. 南京大学 地球科学与工程学院,南京 210023
  • 出版日期:2023-12-20 发布日期:2023-12-18

Effects of Chemically Aged Biochar on Soil Swelling and Compression Characteristics and Its Mechanism

YIN Yue,GU Kai*,LU Yu,SHEN Zhengtao,SHI Bin   

  1. School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
  • Online:2023-12-20 Published:2023-12-18

摘要: 近年来,生物炭作为一种绿色环保的土体改性材料逐渐得到应用。土中的化学环境会改变生物炭理化性质,从而影响改性土体的体变特性。为掌握化学老化生物炭对膨胀土膨胀性和压缩性的影响,采用柠檬酸酸化法模拟木质生物炭在植物有机酸作用下的化学老化,并借助微观结构分析(扫描电镜和傅里叶红外光谱)对其机理进行了解释。结果表明:(1)生物炭老化作用对土体膨胀性的影响与生物炭粒径和掺量有关。当生物炭粒径较小时(< 0.25 mm),化学老化仅能进一步增强高掺量生物炭对膨胀土膨胀性的促进作用;而随着生物炭粒径的增加(0.25~1 mm),这种影响在低掺量条件下也会出现;(2)生物炭改性膨胀土压缩性对生物炭化学老化不敏感,其对生物炭掺量和粒径的变化较为敏感。生物炭加入膨胀土后可以显著降低其压缩性,并且这种降低随着生物炭掺量的增加和粒径的减小变得更加显著;(3)化学老化通过改变生物炭的比表面积和官能团数量影响膨胀土的亲水性,进而改变膨胀性;而外部荷载对膨胀土的压缩主要体现在孔隙的压密上,因此土体压缩对生物炭的化学老化不敏感。

关键词: 生物炭, 化学老化, 膨胀土, 膨胀性, 压缩性

Abstract: In recent years, biochar has been widely applied as a green and environmentally friendly soil modification material. After the addition to the soil, the physicochemical properties of biochar would be changed by the chemical environment of the soil, thus affecting the volume deformation characteristics of the modified soil. In order to explore the effects of chemically aged biochar on the swelling and compression characteristics of expansive soil, woody biochar was soaking into citric acid solution to simulate the chemical oxidation by plant organic acids, and its mechanism was explained by microstructural analysis (Scanning electron microscopy and Fourier transform infrared spectroscopy). The results show that: (1) The effect of aged biochar on soil swelling behavior is closely related to its particle size and dosage. When the particle size of biochar was fine (<0.25 mm), the enhanced promotion effect of aged biochar on the swelling of expansive soil was only observed in the presence of more biochar; while the enhanced promotion effect was occurred at low dosage with the increase of biochar particle size (0.25-1 mm); (2) The compressibility of biochar amended expansive soil is independent of the chemical aging of biochar, but related to the biochar dosage and particle size. Biochar could reduce the compressibility of expansive soil significantly, and this reduction becomes more pronounced with increasing biochar dosage and decreasing particle size; (3) Chemical aging affects the hydrophilicity of the expansive soil by changing the specific surface area and number of functional groups of biochar, thus the changed swelling properties of the soil; by contrast, the compressibility of the soil is more sensitive to changes in pore structure.

Key words: biochar, chemical aging, expansive soil, swelling behavior, com pression behavior

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