An analysis and study of the influence of ion concentration on nuclear magnetic resonance response signal of frozen soil
XIE Meng-Ying1, ZHANG Wen-Bo1, TANG Ke-Xuan1, 2, LI Zhen-Yu1, LU Kai1
1.Institute of Geophysics and Geomatics,China University of Geosciences,Wuhan 430074,China; 2.China Water Resources Beifang Investigation,Design and Research Co.,Ltd.,Tianjin 300222,China
Abstract:The concentrations of ions will have a certain effect on the change of unfrozen water content of permafrost in the frozen-thaw process and therefore on the nuclear magnetic resonance response signal of frozen soil. In order to study the influence of the ion concentration on NMR signal, the authors made the samples with the mixture of NaCl solution and Malan loess in which NaCl values are different and initial water values are the same. By analyzing the NMR response characteristics of the samples at different temperatures, the authors summarized the influence of the ion concentration on the NMR response of permafrost. The results show that increasing the ion concentration will lead to the increase of the amplitude of the NMR signal, but will not affect the transverse relaxation time, and that, during the frozen-thaw process, the fluid will be affected by the temperature and ionic crystals. Samples of unfrozen water content will change in different temperature ranges, but when temperature is higher than 5℃ or lower than -20℃, unfrozen water content will tend to be stable.
谢梦莹, 张文波, 汤克轩, 李振宇, 鲁恺. 离子浓度对冻土核磁共振响应信号的影响分析及研究[J]. 物探与化探, 2017, 41(6): 1262-1267.
XIE Meng-Ying, ZHANG Wen-Bo, TANG Ke-Xuan, LI Zhen-Yu, LU Kai. An analysis and study of the influence of ion concentration on nuclear magnetic resonance response signal of frozen soil. Geophysical and Geochemical Exploration, 2017, 41(6): 1262-1267.