In this study we acquired a lot of Scan Electronic Microscope(SEM)images for silts in Yellow River submerged delta by using the SEM technique.By jointly using Photoshop and IPP (Image-Pro Plus) software,we obtained microstructure parameters for these silt samples.Then,guided by the fractal theory, we studied the fractal characteristics of silts by using the method of "Perimeter-Area",and discussed the influences ofthreshold and magnification on fractal dimension and how to select the appropriate values,and further pointed out the different environmental and engineering geological significances of different fractal dimensions.The results show that the particles and pores of silts in the Yellow River submerged delta have obvious fractal dimension characteristics,and the fractal dimension values vary from 1.6 to 1.8.The different fractal dimension values reflect the different wave disturbance intensity to certain extent.The frac-tal dimensions can represent the shear strength parameters,and silt cohesions and the angle of internal fric-tion values increase with increasing fractal dimension values.%以黄河水下三角洲海底粉土为研究对象,基于扫描电子显微镜技术获得了大量的海底粉土SEM(scanning electron microscopy)图像,综合运用Image-Pro Plus(IPP)和Photoshop图像处理软件来提取粉土的微观结构参数,以分形理论为指导,运用"周长-面积法"对海底粉土进行了分形特征研究,分析了阈值、放大倍数对粉土分形维数的影响及确定方法,并探讨了分形维数的环境及工程地质意义.研究结果表明,黄河水下三角洲海底粉土的颗粒及孔隙具有特殊的分形特征,分形维数为1.6~1.8;不同分维值在一定程度上反映了波浪扰动强度的不同;分形维数可以表征抗剪强度参数,粉土的黏聚力和内摩擦角随分维值的增大而增大.
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