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通过对卵石床面进行高精度的扫描,分析了在室内水槽实验和野外河床的卵石排列的结构特征。本研究采用了两种分析方法,分别是倾斜指数以及方位角和倾斜角分析方法。倾斜指数是个非常敏感和有效的方法,这个方法能有效判断床面卵石的排列特征。但是这个方法的限制在于需要高精度的数据源。倾斜指数与有效粒径之间存在正相关关系,这个关系能够用来推断历史粗化床面剪切力。方位角和倾斜角分析方法是基于单个网格的统计特征来描述床面结构。然而,这个方法的缺点就在于是基于网格的方位特征而不是基于卵石颗粒。本文运用了一个改进的方位角和倾斜角分析方法,该方法基于自动颗粒提取,并在此基础上分析了卵石颗粒的统计特征。改进的方位角和倾斜角分析方法在新采集的长江上游卵石河床表现出更加明显的优势。
Through the high-precision scanning of the pebble bed, the structural characteristics of pebble arrangement in the laboratory and in the field of riverbed in the interior were analyzed. Two types of analysis methods were used in this study, namely, the slope index and azimuth and tilt angle analysis methods. Tilt index is a very sensitive and effective method, this method can effectively determine the arrangement characteristics of bed pebbles. However, this method is limited by the need for high-precision data sources. There is a positive correlation between the slope index and the effective particle size, and this relationship can be used to infer the historical coarsening of the bed surface shear force. Azimuth and tilt analysis methods describe the bed structure based on the statistical characteristics of a single grid. However, the downside of this approach is that it is based on the orientation characteristics of the mesh rather than on pebble particles. In this paper, an improved azimuth and tilt angle analysis method is used. The method is based on automatic particle extraction, and on this basis, the statistical characteristics of pebble particles are analyzed. The improved methods of azimuth and tilt analysis show more obvious advantages in the newly collected pebble beds in the upper reaches of the Yangtze River.