粉煤灰对膨胀土未冻水含量的影响——基于低场核磁共振技术检测  

Effect of fly ash on unfrozen water content in expansive soil:based on low-field nuclear magnetic resonance technology

作　　者：李湘炜 姚亚锋 樊华[1,2] 林键 LI Xiangwei;YAO Yafeng;FAN Hua;LIN Jian(Anhui Key Laboratory of Architectural Structure and Underground Engineering,Anhui Jianzhu University,Hefei 230601,China;School of Civil Engineering,Anhui Jianzhu University,Hefei 230601,China;School of Civil Engineering,Nantong Vocational University,Nantong 226007,China)

机构地区：[1]安徽建筑大学建筑结构与地下工程安徽省重点实验室,安徽合肥230601 [2]安徽建筑大学土木工程学院,安徽合肥230601 [3]南通职业大学建筑工程学院,江苏南通226007

出　　处：《广西科技大学学报》2024年第2期40-47,共8页Journal of Guangxi University of Science and Technology

基　　金：安徽省自然科学基金青年科学基金项目(2208085QE142)资助。

摘　　要：为探究冻融循环条件下粉煤灰对膨胀土未冻水含量的影响,利用低场核磁共振(nuclear magnetic resonance,NMR)技术对不同粉煤灰掺量(3%、6%、9%、12%和15%)的改性膨胀土进行T2谱测定,分析不同温度下改性膨胀土的孔隙结构变化特征,并得出不同粉煤灰掺量的改性膨胀土未冻水含量的变化规律。试验结果表明:改性膨胀土相较于原状土,微、小孔隙的孔径分布在掺灰比为9%的试样出现降低,其余掺灰比的试样出现增长,掺灰比为6%的试样最显著;中孔隙增幅最显著的是掺灰比为12%的试样,大孔隙增幅最显著的是掺灰比为3%的试样;在冻结过程中,掺灰比为9%的试样未冻水含量在下降阶段变化最快,在融化阶段变化速率最慢;掺入粉煤灰降低了土壤的相变温度,且抑制土体冻结过程中的未冻水含量。In order to investigate the effect of fly ash on the unfrozen water content of expansive soils under freeze-thaw cycle conditions,this study used low-field nuclear magnetic resonance(NMR)technology to determine the T2 spectrum of modified expansive soils with different fly ash admixtures(3%,6%,9%,12%and 15%),analyze the characteristics of the changes in the pore structure of the modified expansive soils with different temperatures,and derive the evolutionary pattern of the unfrozen water content of the modified expansive soils with different fly ash admixtures.The test results show that:compared with the original soil,the pore size distribution of the modified expanded soil with small pores decreased in the specimen with 9%of ash ratio,increased in the rest of the specimens,and increased most significantly in the specimen with 6%of ash ratio;that of the modified expanded soil with medium pores increased the most significantly in the specimen with 12%of ash ration;that of the modified expanded soil with large pores increased the most significantly in the specimen with 3%ash ratio.During the freezing process,the unfrozen water content of the specimen with the ash ratio of 9%changed the fastest in the descending stage,and the slowest in the thawing stage.The addition of fly ash reduced the soil phase transition temperature and inhibited the content of unfrozen water during soil freezing.

关 键 词：核磁共振(NMR) 未冻水 改性膨胀土 冻融循环 

分 类 号：TU445[建筑科学—岩土工程]