NAP-OF-THE-OBJECT FOR COLLECTING STRUCTURE SURFACE AND ROUGHNESS ANALYSIS OF HIGH-STEEP ROCK SLOPES

To analyze the influence of sampling size and sampling spacing on the evaluation results of structural surface roughness,this paper takes the structural surface on the left bank of the high steep slope of the Sequ Special Bridge in the section from Chengdu to Linzi on the Sichuan-Tibet line as the research object. The 3D coordinates and surface texture data of the slope are obtained with the nap-of-the-object. The 3D reconstruction of the slope and the point cloud processing are realized indoors. 37 structural surface information are artificially extracted from the point cloud model and the structural surface mesh reconstruction is performed with MATLAB. The variations of roughness in different sizes and intervals are described based on the Z_2S method. The analysis results show that the scale effect and interval effect of structural surface roughness are obvious; the increase in the sampling interval can reduce the effective sampling size value. Thus,a smaller sampling interval should be selected when conducting roughness research,and the sampling size should be greater than or equal to the true effective sampling size value. In addition,this paper is a case of the application of the nap-of-the-object in the field of structural surface data collection and is a useful supplement to the research on structural surface roughness characteristics.