Abstract: The research on the spatial distribution of muddy interlayers is of great significance in engineering practice and science,however, the published works mainly focus on qualitative description. The objective of this work is to quantitatively investigate the spatial distribution and geometrical morphology of muddy interlayers. By taking the high slope excavation sections of Yunnan Yuxi municipal solid waste incineration power plant as an example, the point clouds of excavation sections and muddy interlayers were obtained by Leica ScanStation C10 3D laser scanner and ROMER RA-7520-2 arm 6-axis 3D measuring instrument, and the 3D spatial distribution, orientation, spacing, roughness, and geometrical morphology of muddy interlayers were analyzed after post-processing of the point cloud data using Cyclone and Geomagic Wrap software. The results show that most of the muddy interlayers are laterally distributed in the whole scanning section, and only a few are locally distributed. The mean inclination and mean dip angle of the muddy interlayers are 196.41°±5.51° and 22.27°±2.23°, respectively. The spacing varies from 3.7 to 49.1 cm with an average of (20.4±12.0) cm. The thickness of different lateral positions of muddy interlayers in different layers and the same layer is different, the thickest is about 20 mm, and the thinnest is less than 1 mm. For the typical area of the top surface of muddy interlayers, the plane fitting deviation is between -22.4 mm and 32.5 mm, and the roughness coefficient along the interlayer trend ranges from 5.67 to 16.77 with an average of 10.11±3.25. The ratio of surface area to volume of muddy interlayers is between 5.14 and 5.86 cm^-1. These findings suggest that it is feasible to study the spatial distribution and geometrical morphology of muddy interlayers in rock slopes by using the 3D laser scanning technique. In the high slope of Yuxi municipal solid waste incineration power plant, at the macroscopic level, the muddy interlayers are characterized by relatively straight, approximately parallel to each other, non-isometric distribution, small spacing, many layers, and thin thickness, while at the microscopic level, the muddy interlayers have rough top surface with relatively smooth bottom and complex three-dimensional geometrical morphology.

Key words: soft interlayer, muddy interlayer, spatial distribution, geometrical morphology, three-dimensional laser scanning