1,720,997 research outputs found
Laser Scanning for the definition of high resolution topography in the Apuan Alps (IT) marble district
No full textGeomatics and Distinct Elements Numerical Methods for analyzing the stability of a rock slope in the Apuan Alps marble district (Italy)
No full textTecnologie geomatiche per l'analisi di stabilità dei fronti rocciosi tramite modellazione numerica ad elementi distinti
No full textWith the increasing awareness to the geological risks, the study of rock slope stability plays a key role in the Earth Sciences, especially in areas with high vulnerability for the presence of infrastructures and human activities. These issues require an accurate analysis of the geological processes which knowledge can be obtained from several independent or integrated measurement techniques; nowadays, Digital Terrestrial Photogrammetry (DTP) and Laser Scanning (LS) are some of the most widespread techniques used in studying the slope stability. The engineering-geological data and the geometrical setting of the rock slopes and discontinuities (ex. attitude and spacing) are needed to study the geological risk related to the stability of natural or artificial fronts. DTP and LS allow to get this information also in inaccessible sites and they permit to manage data within a GIS. In addition, it is always necessary to know the physical-mechanical properties of intact material and joints; such information come either from laboratory or in situ tests and from engineering-geological surveys. Data collected by traditional methods and recent geomatics techniques, have allowed an accurate analysis of slope stability by means of distinct elements numerical modeling; in such a way the mass stress has been evaluated and the possible failure mechanisms recognized
UAV and DGPS surveys as support to mining activities: the case of Sa Pigada Bianca area (Ittiri, Italy)
No full textScopo del presente lavoro è stato quello di creare la nuova topografia di dettaglio della concessione mineraria sita nell’area di Sa Pigada Bianca (Comune di Ittiri, Sassari – Italia). La necessità di conoscere in maniera accurata, quindi mediante una cartografia di grande scala, la morfologia delle aree di estrazione e di ripristino ha spinto gli Autori a preferire la realizzazione di un volo fotogrammetrico da UAV (Unmanned Aerial Vehicle o drone) rispetto ad una presa aerea tradizionale o ad un rilievo topografico classico. Per poter riferire la nuova carta topografica prodotta a quella ufficiale della Regione Sardegna è stato eseguito un rilievo GPS in modalità differenziale di appoggio al lavoro fotogrammetrico effettuato col drone, verificandone preventivamente la conformità con i punti trigonometrici ufficiali.
A partire dall’interpretazione dei dati stereoscopici, delle nuvole di punti tridimensionali georiferite e delle ortofoto prodotte è stata creata, mediante stereorestituzione digitale, una nuova cartografia dell'area di studio alla scala 1:1.000 con indicati i gradoni, i cigli, le scarpate, i fronti e tutti gli elementi distintivi delle coltivazioni e delle pareti residue. La planimetria contiene inoltre anche gli elementi caratteristici della rete idrografica, i punti quotati, le isoipse con equidistanza pari a 1 metro ed i toponimi
Slope stability analysis and rock fall simulation for the assessment of geological risk of a railroad line
No full textIl rilievo geostrutturale dei fronti rocciosi: confronto tra accuratezze di dati provenienti da Fotogrammetria Digitale Terrestre e Laser Scanning
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“Cone method” and 2d simulation for rock fall risk assessment in the Marina Piccola bay (Capri Island Italy)
No full textWith the increasing awareness to the geological risks, the study of rocky slopes plays a key role in the earth sciences, especially in areas of high vulnerability due to the presence of infrastructures and human activities. The present paper describes the stability and runout analyses carried out in the Marina Piccola bay (Capri Island - Italy), an urban and touristic area sited at the foot of “Grotta delle Felci cliff” (a rocky slope 200 meters high and 300 meters wide). The integration among various types of survey and analysis methodologies allowed the application of a modern approach for the risk assessment that can be useful in the decision process concerning the choice of the most appropriate mitigation works. Regards to the survey techniques, terrestrial laser scanning and digital close-range photogrammetry were used to produce digital elevation models, oriented stereo-images, orthophotos and accurate positions and volumes of rocky wedges located on the slope overhanging the area.
Thanks to this data, the spatial distribution of rock fall density, velocities and kinetic energies was modeled by means of the “cone-method”. Rock falls historical evidences, recognized by the use of aerial photogrammetry and fieldwork activities, confirmed the accuracy of results obtained from the method application and allowed, through a further 2D rock fall runout analysis, the calculation of the dissipation energy that a protection work would need to mitigate the risk in the area
Application of distinct elements methods for rocky slope stability analysis in the Carrara Marble District (Apuan Alps)
No full textTopographic mapping and geological study of Melka Kunture palaeolithic site
No full textIn order to aid the archaeological researches at Melka Kunture prehistoric area (Ethiopia), a geological survey was carried out with the goal of producing the new geological map at the scale of 1:10,000. In addition, the topographic map at the same scale was created from the stereorestitution of two couples of Standard Stereo IKONOS II, 1 m pan-sharpened, satellite imageries. The scenes cover an area of about 100 km2 around the site and the produced topographic map was used as reference cartography. Rational Polynomial Coefficients allowed the images orientation, those accuracy was improved by the use of Ground Control Points measured through Differential GPS surveys. The images aerial triangulation allowed to create the Digital Elevation Model of the whole archaeological area and consequently to produce the orthophotomap. Additionally, following to the CORINE Land Cover
Nomenclature, this image was used to classify the area land use that was mapped into the topographic sheet. Concerning the geology, the area was object of detailed studies as testified by more than 170 geological stops that were executed in the most representative outcrops. Each of them was characterised by accurate description tables, panoramic and detailed pictures and by the measurement of 3D coordinates. During fieldwork activities also more than 80 rock samples were collected for petrographic and micropalaeontological analyses.
Geological mapping was supported by the study of the Digital Elevation Model and the photointerpretation of stereo- and ortho-images that allowed also to identify the most evident geomorphological and structural features. According to the reference system of the Ethiopian 1:50,000 topographic maps, the produced data was projected into the national UTM coordinate system (Spheroid Clarke 1880 - Datum Adindan - Zone 37 N)
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