固化盐渍土核磁共振微观特征
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摘要
采用核磁共振技术,对不同配比的水玻璃、石灰+粉煤灰及石灰+粉煤灰+水玻璃的固化盐渍土的微观特征进行检测,结合无侧限抗压强度试验,分析了各固化方案的盐渍土固化效果,讨论了强度成因的微观特征机制。结果表明,不同固化土的孔隙特征有较大差异。石灰+粉煤灰固化盐渍土大孔隙减少;石灰+粉煤灰+水玻璃固化盐渍土孔隙总体积减少,但同时有大孔隙生成;水玻璃固化盐渍土孔隙总体增多,但随水玻璃浓度增大,孔隙体积有所减小。石灰+粉煤灰+水玻璃固化盐渍土抗压强度远大于其他固化方案,但是其孔隙结构并不是最优,说明颗粒间的胶结情况对固化效果的影响远大于孔隙特征。
NMR technique was used to test the micro-structural characteristics of the saline soil solidified with different proportions of water glass, lime and fly ash, lime and fly ash and water glass respectively. Combined the unconfined compression strength tests, the solidified effect of saline soil was analyzed, and the microstructure characteristic mechanism of strength cause was discussed. The results showed that the pore characteristics of different solidified soil were quite different. The macro-pores in saline soil solidified with lime and fly ash were reduced, while the total pore volume in saline soil solidified with water glass, lime and fly ash was decreased, but the macro-pores were increased. The pores in saline soil solidified with water glass were increased, but the pore volume decreased with the increase of water glass concentration. The compression strength of the soil solidified with water glass, lime and fly ash was greater than that of other solidification schemes, but its pore structure was not optimal, which indicated that the effect of cement between particles on solidification was much greater than that of pore characteristics.
NMR technique was used to test the micro-structural characteristics of the saline soil solidified with different proportions of water glass, lime and fly ash, lime and fly ash and water glass respectively. Combined the unconfined compression strength tests, the solidified effect of saline soil was analyzed, and the microstructure characteristic mechanism of strength cause was discussed. The results showed that the pore characteristics of different solidified soil were quite different. The macro-pores in saline soil solidified with lime and fly ash were reduced, while the total pore volume in saline soil solidified with water glass, lime and fly ash was decreased, but the macro-pores were increased. The pores in saline soil solidified with water glass were increased, but the pore volume decreased with the increase of water glass concentration. The compression strength of the soil solidified with water glass, lime and fly ash was greater than that of other solidification schemes, but its pore structure was not optimal, which indicated that the effect of cement between particles on solidification was much greater than that of pore characteristics.
引文
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[2]吕擎峰,孟惠芳,王生新,等.改性水玻璃固化盐渍土强度及冻融循环耐久性试验研究[J].北京工业大学学报,2017,43(1):108-112.LüQing-feng,MENG Hui-fang,WANG Sheng-xin,et al.Research of strength and freezing-thawing durability of saline soil solidified by modified sodium silicate[J].Journal of Beijing University of Technology,2017,43(1):108-112.
[3]柴寿喜,王晓燕,仲晓梅,等.含盐量对石灰固化滨海盐渍土稠度和击实性能的影响[J].岩土力学,2008,29(11):3066-3070.CHAI Shou-xi,WANG Xiao-yan,ZHONG Xiao-mei,et al.Different salt contents effect on consistency and compactness of saline soil in inshore with lime[J].Rock and Soil Mechanics,2008,29(11):3066-3070.
[4]魏丽,柴寿喜,蔡宏洲.含盐量与固化材料掺量对固化盐渍土抗压强度的影响[J].工程勘察,2011,39(1):4-8.WEI Li,CHAI Shou-xi,CAI Hong-zhou.The influence of salt content and solidifying material content on compressive strength of solidified saline soil[J].Geotechnical Investigation&Surveying,2011,39(1):4-8.
[5]刘祖香,陈效民,李孝良,等.不同改良剂与石膏配施对滨海盐渍土离子组成的影响[J].南京农业大学学报,2012,35(3):83-88.LIU Zu-xiang,CHEN Xiao-min,LI Xiao-liang,et al.Effect of different amendments combined with gypsum application on ion composition in coastal saline soil[J].Journal of Nanjing Agricultural University,2012,35(3):83-88.
[6]刘军勇,张留俊.察尔汗盐湖地区盐渍土微观特征及其力学与强度表现[J].盐湖研究,2014,22(2):60-67.LIU Jun-yong,ZHANG Liu-jun.The micro-structure characters of saline soil in Qarhan salt lake area and its behaviors of mechanics and compressive strength[J].Journal of Salt Lake Research,2014,22(2):60-67.
[7]MITCHELL J K,SOGA K.Fundamentals of soil behaviour[M].New Jersey:John Wiley&Sons Inc.,2005.
[8]COLLINS K,MCGOWN A.The form and function of microfabric features in a variety of natural soils[J].Geotechnique,1974,24(2):223-254.
[9]TOVEY N K.A digital computer technique for orientation analysis of micrographs soil fabric[J].Journal of Microscopy,1990,120(3):303-315.
[10]冯忠居,成超,王廷武,等.荒漠极干旱区板块状盐渍土微结构变化对其强度特性的影响分析[J].岩土工程学报,2011,33(7):1142-1145.FENG Zhong-ju,CHENG Chao,WANG Ting-wu,et al.Effect of microstructural changes of plate-like saline soil on its strength in extremely arid desert area[J].Chinese Journal of Geotechnical Engineering,2011,33(7):1142-1145.
[11]于新,孙强.水泥石灰改良氯盐渍土强度特性试验研究[J].华东交通大学学报,2011,28(5):29-34.YU Xin,SUN Qiang.Experimental research on the strength performance of chlorine saline soil with cement and lime[J].Journal of East China Jiaotong University,2011,28(5):29-34.
[12]中华人民共和国水利部.GB/T50123-1999土工试验方法标准[S].北京:中国建筑工业出版社,1999.Ministry of Water Resources of the People’s Republic of China.GB/T50123-1999 Standard for soil test method[S].Beijing:China Architecture&Building Press,1999.
[13]李杰林,周科平,张亚民,等.基于核磁共振技术的岩石孔隙结构冻融损伤试验研究[J].岩石力学与工程学报,2012,31(6):1208-1214.LI Jie-lin,ZHOU Ke-ping,ZHANG Ya-min,et al.Experimental study of rock porous structure damage characteristics under condition of freezing-thawing cycles based on nuclear magnetic resonance technique[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(6):1208-1214.
[14]刘付华,柴寿喜,张学兵,等.二灰固化滨海盐渍土抗压强度的影响因素[J].湘潭大学自然科学学报,2006,28(2):118-122.LIU Fu-hua,CHAI Shou-xi,ZHANG Xue-bing,et al.Research on the influencing factors of compressive strength of solidified inshore saline soil using lime-ash[J].Natural Science Journal of Xiangtan University,2006,28(2):118-122.
[15]甘雅雄,朱伟,吕一彦,等.从水分转化研究早强型材料固化淤泥的早强机理[J].岩土工程学报,2016,38(4):755-760.GAN Ya-xiong,ZHU Wei,LüYi-yan,et al.Earlystrength mechanism of cementitious additives from perspective of water conversion[J].Chinese Journal of Geotechnical Engineering,2016,38(4):755-760.