基于SEM土体微观结构研究中的影响因素分析

Factors affecting analysis of soil microstructure using SEM

通过对一系列SEM照片计算其表观孔隙率和土颗粒形态分维数,研究了阈值大小、分析区域大小、扫描点位置、放大倍率等因素对土体微观结构定量研究的影响,探讨了各因素的影响机理。研究发现在相对较小的阈值条件下得到的孔隙结构参数较接近真实情况,在相对较大的阈值条件下分析土颗粒的形态特征更具有代表性;合理的放大倍数是分析土体微观结构的关键因素,应根据研究对象和研究目的而定;基于分析结果,给出了合理的阈值和放大倍数的推荐值,并对扫描过程中相关的测试技术、观察技术和图片处理技术提出了建议;研究结果对今后研究人员如何利用SEM获得真实客观的土结构参数具有参考价值。

Based on a series of SEM images of soil, the apparent porosity and fractal dimension were calculated, the influences of threshold, analyzing size, scanning position and magnification on quantitative analysis results of soil microstructure were investigated, and their affecting mechanism were discussed. It was found that the pore structure parameters obtained at relative low threshold value were close to the real soil fabric. Relative high threshold value was necessary and reasonable when the morphological characters of soil particles were analyzed. Magnification played an important role in analyzing the microstructurc of soil by using scanning electron microscope （SEM）, and a reasonable magnification should be chosen on the basis of research subject and purpose. According to the obtained results, some useful threshold values and magnifications were recommended. The suggestions and comments related to testing, observing, and image analyzing techniques during scanning process were given. It was significant for obtaining real and objective microstructure parameters by using SEM.