Terrestrial Remote Sensing techniques to complement conventional geomechanical surveys for the assessment of landslide hazard: The San Leo case study (Italy)

Spreafico, Margherita Cecilia; Perotti, Luigi; Cervi, Federico; Bacenetti, Marco; Bitelli, Gabriele; Girelli, Valentina Alena; Mandanici, Emanuele; Tini, Maria Alessandra; Borgatti, Lisa

doi:10.5721/eujrs20154835

Cited by 29 publications

(21 citation statements)

References 37 publications

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“…The rock slope involved in the 2014 failure extends vertically for about 110 m, and has been characterized using both traditional field techniques and remote sensing methods [56]. Geological investigations conducted prior to the failure evidenced the presence of a cave system at the base of the plateau, at the geological contact between the San Marino limestone and the Argille Varicolori clay shales (Figure 2a,b).…”

Section: Rock Slope and Clay Shale Characterizationmentioning

confidence: 99%

A Preliminary Investigation on the Role of Brittle Fracture in the Kinematics of the 2014 San Leo Landslide

et al. 2019

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The stability of high rock slopes is largely controlled by the location and orientation of geological features, such as faults, folds, joints, and bedding planes, which can induce structurally controlled slope instability. Under certain conditions, slope kinematics may vary with time, as propagation of existing fractures due to brittle failure may allow development of fully persistent release surfaces. In this paper, the progressive accumulation of brittle damage that occurred prior to and during the 2014 San Leo landslide (northern Italy) is investigated using a synthetic rock mass (SRM) approach. Mapping of brittle fractures, rock bridge failures, and major structures is undertaken using terrestrial laser scanning, photogrammetry, and high-resolution photography. Numerical analyses are conducted to investigate the role of intact rock fracturing on the evolution of kinematic freedom using the two-dimensional Finite-discrete element method (FDEM) code Elfen, and the three-dimensional lattice-spring scheme code Slope Model. Numerical analyses show that the gradual erosion of clay-rich material below the base of the plateau drives the brittle propagation of fractures within the rock mass, until a fully persistent, subvertical rupture surface form, causing toppling of fault-bounded rock columns. This study clearly highlights the potential role of intact rock fracturing on the slope kinematics, and the interaction between intact rock strength, structural geology, and slope morphology.provide kinematic release to blocks that were previously nonremovable [9]. The accumulation of brittle damage is a critical component in the development of footwall failures and large-scale, biplanar, and compound rockslides, due to the formation of a highly damaged transition zone at the interface between active and passive blocks [10][11][12]. Additionally, intact rock fracturing may cause the failure of nondaylighting rock wedges, due to the formation of a basal rupture surface caused by failure of rock bridges and coalescence of brittle cracks [13].The strength of intact rock is orders of magnitude higher than discontinuities; therefore, strength and size of intact rock bridges between discontinuities have a great impact on the stability of rock slopes [9]. A small amount (0.1-10%) of rock bridges favorably distributed within a rock slope strongly increases the stability of the slope [14,15]. Despite the major significance of intact rock bridges in controlling the behavior of rock masses, their characterization remains an extremely challenging task [14], and the deterministic quantification of the rock bridges existing along a rupture surface may be undertaken only after failure occurs [15][16][17]. Discrete fracture networks (DFNs) are consequently being increasingly employed in rock engineering to investigate the distribution and dimensions of rock bridges using a stochastic approach [18].In this paper, the effects of intact rock fracturing on the evolution of the kinematic freedom of rock slopes are investigated using the 2014 San...

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Section: Rock Slope and Clay Shale Characterizationmentioning

confidence: 99%

A Preliminary Investigation on the Role of Brittle Fracture in the Kinematics of the 2014 San Leo Landslide

et al. 2019

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“…of Bologna University on the San Leo rocky slab took place in 2013, in order to realize a complete 3D model of the cliff to support geological analyses; further activities of surveying and data processing are still ongoing (Spreafico et al, 2014;Spreafico et al, 2015a). The availability of a complete three-dimensional model, detailed and georeferenced, allowed to carry out analyses in order to extract the geometrical characteristics of the fractures (dip, dip direction and strike), even in areas that could be difficult to reach with traditional methods of geological survey.…”

Section: Tls and Gnss In Support Of The Geological Analysismentioning

confidence: 99%

Integration of Geomatics Techniques for Digitizing Highly Relevant Geological and Cultural Heritage Sites: The Case of San Leo (Italy)

Girelli

Borgatti

Dellapasqua

et al. 2017

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:The research activities described in this contribution were carried out at San Leo (Italy). The town is located on the top of a quadrangular rock slab affected by a complex system of fractures and has a wealth of cultural heritage, as evidenced by the UNESCO's nomination. The management of this fragile set requires a comprehensive system of geometrical information to analyse and preserve all the geological and cultural features. In this perspective, the latest Geomatics techniques were used to perform some detailed surveys and to manage the great amount of acquired geometrical knowledge of both natural (the cliff) and historical heritage. All the data were also georeferenced in a unique reference system. In particular, high accurate terrestrial laser scanner surveys were performed for the whole cliff, in order to obtain a dense point cloud useful for a large number of geological studies, among others the analyses of the last rockslide by comparing pre-and post-event data. Moreover, the geometrical representation of the historical centre was performed using different approaches, in order to generate an accurate DTM and DSM of the site. For these purposes, a large scale numerical map was used, integrating the data with GNSS and laser surveys of the area. Finally, many surveys were performed with different approaches on some of the most relevant monuments of the town. In fact, these surveys were performed by terrestrial laser scanner, light structured scanner and photogrammetry, the last mainly applied with the Structure from Motion approach.

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“…Noticeably, the scanners were used with the same resolution in order to obtain near equally dense point clouds. Similarly, both scanners have captured images to support identification during post-processing and to ensure providing enhanced quality end products (Spreafico et al 2015).…”

Section: Tlsmentioning

confidence: 99%

Slope stability and rock fall hazard assessment of volcanic tuffs using RPAS and TLS with 2D FEM slope modelling

Török¹,

Barsi²,

Bögöly³

et al. 2017

Preprint

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Abstract. Low strength rhyolite tuff forms steep cliffs in NE Hungary. A multi-dimensional approach including field analysis and laboratory tests was conducted to understand the mechanical properties of the tuff and to measure discontinuity 10 surfaces. With the help of RPAS (Remotely Piloted Aircraft System) and TLS (Terrestrial Laser Scanning), a digital terrain model (DTM) was generated, and the results of these surveys were compared. Cross sections and joint system data were obtained from DTM and used as input parameters for the slope stability analyses. The rocky slope was modelled by 2D FEM (Finite Element Method) software and potential hazards such as planar failure, wedge failure and toppling were identified.The paper demonstrates the usefulness of combined field analyses, geomechanical laboratory testing and various remote 15 sensing techniques (such as RPAS and TLS) in rock face stability calculations and failure mode analysis.

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Terrestrial Remote Sensing techniques to complement conventional geomechanical surveys for the assessment of landslide hazard: The San Leo case study (Italy)

Cited by 29 publications

References 37 publications

A Preliminary Investigation on the Role of Brittle Fracture in the Kinematics of the 2014 San Leo Landslide

A Preliminary Investigation on the Role of Brittle Fracture in the Kinematics of the 2014 San Leo Landslide

Integration of Geomatics Techniques for Digitizing Highly Relevant Geological and Cultural Heritage Sites: The Case of San Leo (Italy)

Slope stability and rock fall hazard assessment of volcanic tuffs using RPAS and TLS with 2D FEM slope modelling

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