为探究粉煤灰孔隙率计算方法及其孔隙多重分形特性，引入相似维数的概念推导其分形维数基本公式. 通过对试样制作模具进行加工以控制击实度，配制一定含水率的粉煤灰试样. 利用显微数码成像技术获取粉煤灰试样中孔隙和颗粒的直径、数量. 选定4个不同深度截面及两个剖面的上下端作为观测面，借助体式显微镜进行不同倍数下的成像，以分析三维空间范围内的孔隙率变化规律；采用专业图像处理技术给出试样孔隙率. 研究结果表明，粉煤灰试验的孔隙率沿深度方向有减小趋势，幅值变化约为30%，且其孔隙分布具有明显的多重分形特征.
In order to explore the calculation method of porosity and pore multi-fractal characteristics of fly ash，the concept of similar dimension is introduced to derive the basic formula of fractal dimension. By processing the sample mold to control the degree of compaction，a fly ash sample with a certain moisture content is configured. Secondly，the diameter and number of pores and particles in the fly ash sample are obtained by using digital microscopic imaging technology，and then the histogram of pores and particles can be obtained. Then 4 different depth sections are selected，whose upper and lower ends are used as the observation surface，and photos at different magnifications are taken with the help of a stereo microscope to analyze the distribution of the pore area ratio in the three-dimensional space；finally，professional image processing is used. The technique gives the porosity of the sample and compares it with the measured results. The research results show that the pore area ratio of the fly ash has a decreasing trend along the depth direction，the variation of which would be about 30%，and its pore distribution has obvious multifractal characteristics.