Effect of freezing-thawing cycles on the microstructure of soils: A two-dimensional NMR relaxation analysis
Effect of freezing-thawing cycles on the microstructure of soils: A two-dimensional NMR relaxation analysis
复制标题
冻融循环对土壤微观结构的影响：二维核磁共振弛豫分析
DOI：
10.1016/j.coldregions.2018.11.014
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发表时间：
2019-02
影响因子：
4.1
通讯作者：
Long Tan
中科院分区：
文献类型：
--
作者：
Huihui Tian;Changfu Wei;Long Tan
土在冻融循环作用下的结构性劣化会对其工程性能产生显著影响。核磁共振（NMR）技术为研究土壤等含水多孔介质的结构演化提供了强有力的工具。在目前的工作中，三种土壤反复冻融循环下进行了试验。用核磁共振技术测定了吸附过程的T2分布曲线、T1-T2相关谱和log（T1/T2）分布，并计算了吸附水含量。吸附水含量的变化随土壤中砂粒含量的增加而增大，说明砂粒含量越高，土壤微结构的变化越明显。含砂量为30%的土壤的T2分布曲线没有明显变化，而含砂量较高（50%和70%）的土壤的T2分布曲线则有很大差异。此外，峰2从平坦峰变为尖锐峰，这意味着循环冻融后的微观结构更均匀。在冻融过程中，T1-T2相关谱的峰强度发生了显著变化，说明冻融过程中土壤中两个孔隙系统发生了水分交换。土壤的显著变化通常只发生在前5次冻融循环中。含砂量为70%的土壤微结构变异较大，其次为含砂量为30%和50%的土壤微结构变异较小，其变异程度排序与含砂量一致。
Structural deterioration of a soil subjected to freezing-thawing cycles can significantly influence its engineering performances. The nuclear magnetic resonance (NMR) technique provides a powerful tool for studying the structural evolution of water-saturated porous media such as soils. In the present work, three soils were tested under repeated freezing-thawing cycles. The process was monitored by measuringT2distribution curves,T1-T2correlation spectra and distributions of log (T1/T2) with NMR technique, and then adsorptive water contents were calculated. The variation of the adsorptive water contents increased as the fraction of sand in the soil increased, implying that the higher the sand content, the more significantly the soil microstructure varied. TheT2distribution curves for soil with sand fraction of 30% did not significantly change, whereas those for soils with higher sand fractions (50% and 70%) were quite different. In addition, Peak 2 changed from a flattened peak to a sharp peak, implying a more uniform microstructure after cyclic freezing-thawing. The peak intensity inT1-T2correlation spectra changed quite significantly during the freezing-thawing process, implying that the two porosity systems in the soil exchanged water during the process. Significant change of soils usually occurred only in the first 5 freezing-thawing cycles. The microstructure variation for soil with sand fraction of 70% was larger, and then soils with sand fractions of 30% and 50% were less in order, suggesting a ranking of variation degree in agreement with sand fraction.
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DOI：
--
发表时间：
2011
期刊：
--
影响因子：
--
作者：
Zhang Xiao-hong
通讯作者：
Zhang Xiao-hong
影响因子：
4.1
作者：
Zhong-Liang Zhang;Z. Cui
通讯作者：
Zhong-Liang Zhang;Z. Cui
DOI：
--
发表时间：
2005-03
期刊：
Lawrence Berkeley National Laboratory
影响因子：
--
作者：
G. Moridis;Y. Seol;Timothy J Kneafsey
通讯作者：
G. Moridis;Y. Seol;Timothy J Kneafsey
影响因子：
4.1
作者：
Kunio Watanabe;Tomomi Wake
通讯作者：
Kunio Watanabe;Tomomi Wake
影响因子：
2.5
作者：
B. A. Baldwin;J. Stevens;J. Howard;A. Graue;B. Kvamme;E. Aspenes;G. Ersland;Jarle Husebø;D. Zornes
通讯作者：
B. A. Baldwin;J. Stevens;J. Howard;A. Graue;B. Kvamme;E. Aspenes;G. Ersland;Jarle Husebø;D. Zornes