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由于干湿循环、剪切或其它作用,自然界土壤表面发育着大量裂隙。裂隙相互连接形成网络,裂隙网络是一个随机无序的系统,常规统计方法描述裂隙的分布特征存在很大的难度。网状土体裂隙一般具有分形特征,可以用分维数来进行描述。用数码相机拍摄土体表面的裂隙,将其转换成灰度图像,并结合分形理论,建立了摄影法测定土体裂隙分维数的方法,得到了土体裂隙的分维数。根据表征单元体的物理意义,建立了基于分维数估算表征单元体的方法,并对实例进行了分析。研究表明:分维数随裂隙密度,裂隙宽度和次一级裂隙发育程度的增大而增大;表征单元体与裂隙的密度均匀性和隙宽均匀性相关,基于分维数估算表征单元体的方法简便可行。
Due to the wet-dry cycle, shear or other effects, a large number of fractures are developed on the soil surface in nature. The fissures are interconnected to form a network, and the fissure network is a randomly disordered system. It is very difficult to describe the distribution characteristics of fissures by conventional statistical methods. Mesh soil fractures generally have fractal characteristics, can be used to describe the fractal dimension. A digital camera is used to photograph the crack in the soil surface and convert it into a grayscale image. Based on the fractal theory, a fractal dimension of the soil crack is determined by the method of photography. According to the physical meaning of characterization unit, a method of unit characterization based on fractal dimension was established, and the examples were analyzed. The results show that the fractal dimension increases with the increase of fracture density, fracture width and the development degree of secondary fissure. The density homogeneity of cell and fracture is related to the uniformity of gap width. Based on fractal dimension estimation, The method is simple and feasible.