土体干缩裂隙网络定量分析

土体干缩裂隙网络定量分析对深入研究裂隙发育机制及正确评价裂隙土的工程性质有重要意义。在室内对三组不同土体开展了干燥试验,采用数字图像处理技术对获得的裂隙图像进行了二值化、除噪和骨架化等预处理操作,提出了一整套与裂隙网络几何形态特征密切相关的量度指标体系并进行了定量分析,借助概率密度函数,从统计学角度探讨了关键量度指标的分布特征。结果表明：土质对干缩裂隙网络的几何形态特征有重要影响,表面裂隙率、裂隙节点个数、裂隙总长度、裂隙平均宽度和土块个数通常随黏粒含量和塑性指数的增加而增加；量度指标之间既有区别又有联系,如表面裂隙率与裂隙平均宽度存在正相关性,裂隙条数受节点个数的控制,土块个数越多,则对应土块平均面积越小,表面裂隙率越大,分形维数也越大；单位面积内的节点个数、土块个数和表面裂隙率可作为定量描述裂隙网络几何形态特征的基本指标；裂隙长度、宽度和土块面积的平均值与它们的主要分布范围及最可几值之间存在较好的相关性。

Quantitative analysis of soil desiccation crack network

The quantitative analysis of soil desiccation crack network is significant to the investigation of crack mechanisms and the evaluation of engineering properties of cracked soils. In this study, desiccation tests are conducted on three different soils under temperature controlled conditions, and the obtained desiccation crack patterns are subjected to several pre-processing operations, e.g., binarization, noise elimination and skelotonization, by employing the image processing technique. A series of parameters are proposed and measured to describe the geometrical and morphological characteristics of the desiccation crack pattern. Based on the statistical method, a probability density function is introduced to quantify the distribution characteristics of some important crack parameters. The results show that the desiccation crack pattern is significantly influenced by physical properties of soils. The surface crack ratio, number of nodes, total crack length, average crack width and number of clods generally increase with the increasing clay content and plastic index. The physical meaning of quantitative parameters show some differences but linked to each other. For example, there is strong and positive correlation between the surface crack ratio and the average crack width; the number of crack segments is conditioned by the number of nodes; the average area of clods decreases with their increasing number; and the fractal dimension of desiccation crack network increases with the increasing surface crack ratio. For a general crack pattern, the number of nodes per unit area, number of clods per unit area and surface crack ratio can be recommended as the three basic parameters for the quantitative analysis. The results of statistical analysis indicate that the average values of the crack length, width and clod area are strongly related to their distribution ranges as well as the most probable values determined by the probability density functions.