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冻融作用下改性软黏土微观孔隙结构及分形特征研究

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为研究冻融作用对软黏土的孔隙结构和分形特性的影响,以吉林省某地区软黏土为例,采用核磁共振(NMR)技术对不同冻融循环次数、压实系数及木质素纤维掺量下的软黏土进行了核磁共振试验.利用核磁共振T2频谱得到了软土试样的孔径分布(PSD),并引入分形理论描述了 PSD的分形特性.结果表明:随着冻融循环次数的增加,小孔隙所占比例下降,而中大孔隙所占比例显著提升,冻融循环的作用使得土样孔隙不断向较大孔径转化.土样的束缚流体孔隙分形维数值Dmin为0.167~0.445,可动流体孔隙分形维数值Dmax为2.832~2.957.可动流体孔隙的分形特征较束缚流体孔隙更明显,这表明冻融作用主要影响土样的大孔隙.分形维数随冻融循环次数的增加而增大,且增长速率逐渐减小,最后趋于稳定.束缚流体孔隙分形维数Dmin与压实系数没有明显的线性关系,而可动流体孔隙分形维数Dmax与压实系数呈负相关性.
Study on Micro-pore Structure and Fractal Characteristics of Modified Soft Clay Under Freezing-thawing Cycle
In order to study the influence of freeze-thaw action on the pore structure and fractal characteristics of soft clay,taking the soft clay in a certain area of Jilin Province as an example,Nuclear Magnetic Resonance(NMR)technology was used to test the soft clay under different freeze-thaw cycles,compaction coefficients and lignin fiber content.The Pore Size Distribution(PSD)of soft soil samples was obtained by T2 NMR spectrum,and fractal theory was introduced to describe the fractal characteristics of PSD.The results show that with the increase of freeze-thaw cycles,the proportion of small pores decreases,and the proportion of medium and large pores increases significantly.The role of freeze-thaw cycles makes the pores of soil samples continuously transform to larger pores.The fractal dimension of bound fluid pore of soil sample Dmin is between 0.167 and 0.445,and the fractal dimension of movable fluid pore of soil sample Dmax is between 2.832 and 2.957.The fractal characteristics of movable fluid pores are more obvious than those of bound fluid pores,which indicates that freezing and thawing mainly affect the macropores of soil samples.The fractal dimension increases with the increase of freeze-thaw cycles,and the growth rate gradually decreases,and finally tends to be stable.The fractal dimension Dmin of bound fluid pores has no obvious linear relationship with the compaction coefficient,while the fractal dimension Dmax of movable fluid pores has a negative correlation with the compaction coefficient.

freeze-thaw cyclesoft clayfractal dimensionNuclear Magnetic Resonance(NMR)pore structure

贺波、唐小东、陈峰、王能兴、高正来、金亮、周国山

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中国联合工程有限公司,浙江杭州 310000

冻融循环 软黏土 分形维数 核磁共振(NMR) 孔隙结构

浙江省科技计划项目

2022C03082

2024

公路工程
湖南省交通科学研究院

公路工程

CSTPCD
影响因子:0.942
ISSN:1674-0610
年,卷(期):2024.49(3)
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