Discontinuity interpretation and identification of potential rockfalls for high-steep slopes based on UAV nap-of-the-object photogrammetry. (September 2022)

• Record Type: Journal Article
• Authors: Wang, Wei; Zhao, Wenbo; Chai, Bo; Du, Juan; Tang, Luosheng; Yi, Xiawei
• Is Part Of: Computers & geosciences. Volume 166(2022)
• Publication Date: 2022-09
• Subjects: High-steep slope -- Nap-of-the-object photogrammetry -- Discontinuity interpretation -- Stability evaluation -- Rock cavity rate; ACD average cavity depth -- CDF cumulative distribution function -- DBSCAN density-based spatial clustering of applications with noise -- DJI Da-Jiang Innovations -- DP digital photogrammetry -- DSE discontinuity set extractor -- DSM digital surface model -- FM fast marching -- GCPs ground control points -- JCS joint compressive strength -- JRC joint roughness coefficient -- KML keyhole markup language -- PC point cloud -- PCA principal component analysis -- RCR rock cavity rate -- RGB red green blue -- RMR rock mass rating -- RTK real-time kinematic -- SfM structure-from-motion -- SMR slope mass rating -- SVM sample window method -- TDOM textured digital outcrop model -- TLS terrestrial laser scanning -- UAV unmanned ariel vehicle -- UCS uniaxial compressive strength; Environmental policy -- Periodicals; 550.5
• DOI: 10.1016/j.cageo.2022.105191
• Languages: English
• ISSNs: 0098-3004

Abstract

Abstract: Discontinuity extraction and interpretation of fractured masses is of high importance when analyzing rock slope stability. Regarding high-steep slopes, which are areas that are difficult to reach, traditional methods to obtain discontinuities, such as the sample window method (SWM), are unlikely to be implemented, resulting in challenges for the identification of potential rockfalls. With the development of the unmanned ariel vehicle (UAV) technology, discontinuity extraction can overcome by noncontact photogrammetry. However, there is still a lack of comprehensive and practical solutions to fulfill rockfall identification from field investigation to in-door analysis. For this purpose, a practical case study was carried out in Wanzhou, Chongqing, China, where a 400 m vertical rock slope prone to rockfall was collected as a typical example. The centimeter-level 3D Textured Digital Outcrop Model (TDOM) and dense Point Cloud (PC) were established using high-resolution photos acquired by nap-of-the-object photogrammetry. The discontinuity of the fractured mass was interpreted by fully taking advantage of both 2D images (texture information-dominated) and 3D PCs (depth information-dominated). Furthermore, a new parameter rock cavity rate (RCR) and the corresponding semiautomatic extraction method based on point clouds are proposed. Subsequently, the possibility of various failure modes and their joint combinations were determined by kinematic analysis. Finally, the rock slope stability was determined using a matrix that considers the slope mass rating (SMR) value and the parameter RCR. The proposed process flow and relevant techniques in this study provide an operable and practical solution for further application regarding discontinuity interpretation and potential rockfall identification on high-steep slopes. Highlights: A complete practical solution is proposed for discontinuity interpretation and rockfall identification from filed investigation to indoor analysis. A code "DisconExtration2D″ is developed for zoning of potential rockfalls, and 3D PC is used to extract the discontinuity features. A new parameter rock cavity rate (RCR) considering the failure mechanism is proposed, and the corresponding semi-automatic extraction method is developed. An assessment matrix considering both SMR-based stability and RCR is developed. Point cloud data with volume density of 10 4 –10 5 points per cubic meter is suggested for further similar applications.