基于NMR和SEM的软土微观结构特征试验研究

doi:10.12052/gdutxb.180065

摘要/Abstract

摘要： 软土的含水特性和微观结构是决定其物理力学性质的主要因素. 以南沙软土为研究对象，运用核磁共振和扫描电子显微镜两种微观结构试验方法，获取了软土的弛豫时间T₂谱图和扫描电子显微镜图像，总结了两种软土（淤泥和淤泥质土）的水相分布和孔径分布规律. 研究表明，南沙软土的T₂分布曲线呈双峰型，土中存在两种状态的水分，第一种状态水超过质量的99%，孔隙多、孔径小，孔径分布主要集中在0.1~20 μm的区间. 南沙软土常见的微观结构类型为絮状结构、蜂窝结构和凝块结构3类. 计算了平均孔隙半径、平均孔隙面积、面孔隙率、孔隙形状因子和孔隙分维数等微观结构参数. 最后，对比分析了两种测试方法和应用中需注意的几个问题.

关键词: 软土, 含水特性, 微观结构, 核磁共振试验, 扫描电子显微镜试验

Abstract: The moisture characteristics and microstructure of soft soil are the key factors in determining the physical and mechanical properties of soil. The relaxation time T₂ spectra and scanning electron microscope images of soft soil from Nansha District were obtained by means of nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). The water phase and pore size distribution of two types of soft soils were summarized based on SEM and NMR test results. The results show that the relaxation time T₂ distribution curve of Nansha soft soil is bimodal with two kinds of water in soil, the first state water being over 99% of the total water quality, and muck and mucky soil having many small pores mainly concentrated in the range of 0.1 μm to 20 μm. SEM images show that the three microstructure types of Nansha soft soil are in flocculent microstructure, honeycomb microstructure and clot microstructure. These methods also can calculate the microstructure parameters such as average pore radius, average pore area, surface porosity, pore shape factor and pore fractal dimension. The results of pore sizes obtained by the two methods are basically the same, but not completely consistent. Finally, the characteristics of the two methods and several issues in the application of SEM and NMR test are discussed.

Key words: soft soil, moisture characteristics, microstructure, nuclear magnetic resonance test, scanning electron microscopy test

中图分类号:

TU431

刘勇健, 伍建胜, 谢治堃. 基于NMR和SEM的软土微观结构特征试验研究[J]. 广东工业大学学报, 2018, 35(06): 49-56.

Liu Yong-jian, Wu Jian-sheng, Xie Zhi-kun. Experiment Study on Microstructure of Soft Soil in Nansha District Based on NMR and SEM Test[J]. Journal of Guangdong University of Technology, 2018, 35(06): 49-56.

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