A new methodological approach to assess the stability of discontinuous rocky cliffs using in-situ surveys supported by UAV-based techniques and 3-D finite element model: a case study

• Published in: Engineering geology Vol. 260; p. 105205
• Main Authors: Fazio, N.L., Perrotti, M., Andriani, G.F., Mancini, F., Rossi, P., Castagnetti, C., Lollino, P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 03.10.2019
• Subjects: Finite element model; Geomechanical survey; Geostructural setting; Sea cliff; Slope stability; UAV survey; Slope stability; Geostructural setting; UAV survey; Finite element model; Sea cliff; Geomechanical survey
• ISSN: 0013-7952; 1872-6917
• DOI: 10.1016/j.enggeo.2019.105205

This paper aims to present a new methodological approach for the stability assessment of coastal cliffs constituted of discontinuous rock masses. The method entails in situ specific geostructural and geomechanical surveys, three-dimensional UAV-based Photogrammetric structural models, laboratory geotechnical tests and, two- and three-dimensional finite element analysis (FEM). The application of the method to a case study is then presented and discussed; it regards a 600 m long sea rocky cliff located at Sant'Andrea (Melendugno, South of Apulia, SE Italy) and faced to the southern Adriatic Sea. Here the cliff is made up of an about 15 m-thick sequence of laminate calcisiltites alternate with bioturbated calcarenites belonging to the Uggiano la Chiesa Fm. (Middle-Upper Pliocene). The structural discontinuities detected with photogrammetry techniques were compared and validated with those derived from conventional in situ survey methods. Later on, the paper discusses assumptions and results of two- and three-dimensional finite element models developed to investigate the potential failure mechanisms of the sea cliff accounting for pre-existing weak planes or discontinuities with unfavourable orientation. The failure mechanisms obtained by both FEM analysis agree well with those typically observed in the study area. •Detailed 3-D geometrical survey of the cliff with UAV-based photogrammetry techniques;•Automatic detection of the most relevant fractures and joints from UAV surveys;•Geological, geostructural and geomorphological analysis of the cliff by means of in-situ surveys;•Detailed geotechnical characterization in the laboratory of the rock;•Failure mechanisms obtained with FEM analysis consistent with those typically observed in the study area;