Zhao Fengwen, Hu Jianhua, Liu Taoying, Zhou Tan, Ren Qifan
School of Resources and Safety Engineering, Central South University, Changsha 410083, China.
Zijin School of Geology and Mining, Fuzhou University, Fuzhou 350108, China.
Materials (Basel). 2023 Jul 1;16(13):4772. doi: 10.3390/ma16134772.
Nuclear magnetic resonance can only quantitatively obtain porosity and pore size distribution, but as a conventional microstructure observation technology, scanning electron microscope (SEM) can select different magnifications to observe the microstructure of backfill materials. However, the processing of SEM images is not deep enough. In this paper, Image-Pro Plus 6.0 software was used to extract the data from SEM images, and the parameters of the area, and the perimeter, aspect ratio and roundness of the pores in the SEM images were obtained. The fractal characteristics of the pores in the SEM image were obtained by using the slit island method fractal theory. The concretization and quantification analysis of the pores' complexity were achieved. A functional relationship model for the strength and pore parameters was constructed; thus, the influence law of pore characteristics on strength was quantitatively analyzed. The conclusions included: (1) Pore parameters indicate that most pores in backfill are irregular, and only a few pores are regular-however, the whole structure has good fractal characteristics (R > 0.96). (2) The fractal dimension of pores is directly proportional to the roundness, the aspect ratio, and the pore content of pores-which indicates that the complexity of pores is related to both pore shape and pore content. (3) The strength had a linear inverse relationship with the roundness, aspect ratio, pore content, and fractal dimension-which indicates that all characteristics of pores have a certain influence on the strength.
核磁共振只能定量获取孔隙率和孔径分布，但扫描电子显微镜（SEM）作为一种传统的微观结构观察技术，可以选择不同放大倍数来观察回填材料的微观结构。然而，SEM图像的处理深度不够。本文利用Image-Pro Plus 6.0软件从SEM图像中提取数据，得到了SEM图像中孔隙的面积、周长、长宽比和圆度等参数。利用裂隙岛法分形理论得到了SEM图像中孔隙的分形特征，实现了孔隙复杂性的具体化和量化分析。构建了强度与孔隙参数的函数关系模型，从而定量分析了孔隙特征对强度的影响规律。研究结论如下：（1）孔隙参数表明，回填材料中的大多数孔隙是不规则的，只有少数孔隙是规则的，但其整体结构具有良好的分形特征（R>0.96）。（2）孔隙的分形维数与圆度、长宽比和孔隙含量成正比，这表明孔隙的复杂性与孔隙形状和孔隙含量都有关系。（3）强度与圆度、长宽比、孔隙含量和分形维数呈线性反比关系，这表明孔隙的所有特征对强度都有一定影响。
