Discontinuity spacing analysis in rock masses using 3D point clouds

The complete characterization of rock masses implies the acquisition of information of both, the materials which compose the rock mass and the discontinuities which divide the outcrop. Recent advances in the use of remote sensing techniques – such as Light Detection and Ranging (LiDAR) – allow the accurate and dense acquisition of 3D information that can be used for the characterization of discontinuities. This work presents a novel methodology which allows the calculation of the normal spacing of persistent and non-persistent discontinuity sets using 3D point cloud datasets considering the three dimensional relationships between clusters. This approach requires that the 3D dataset has been previously classified. This implies that discontinuity sets are previously extracted, every single point is labeled with its corresponding discontinuity set and every exposed planar surface is analytically calculated. Then, for each discontinuity set the method calculates the normal spacing between an exposed plane and its nearest one considering 3D space relationship. This link between planes is obtained calculating for every point its nearest point member of the same discontinuity set, which provides its nearest plane. This allows calculating the normal spacing for every plane. Finally, the normal spacing is calculated as the mean value of all the normal spacings for each discontinuity set. The methodology is validated through three cases of study using synthetic data and 3D laser scanning datasets. The first case illustrates the fundamentals and the performance of the proposed methodology. The second and the third cases of study correspond to two rock slopes for which datasets were acquired using a 3D laser scanner. The second case study has shown that results obtained from the traditional and the proposed approaches are reasonably similar. Nevertheless, a discrepancy between both approaches has been found when the exposed planes members of a discontinuity set were hard to identify and when the planes pairing was difficult to establish during the fieldwork campaign. The third case study also has evidenced that when the number of identified exposed planes is high, the calculated normal spacing using the proposed approach is minor than those using the traditional approach.

New York, N.Y. and vicinity, 1961 : Harlem, N.Y.-N.J. (8 Sheet Set) (Raster Image)

This layer is a georeferenced raster image of the United States Geological Survey 7.5 minute topographic sheet map entitled: New York and vicinity : Harlem, N.Y.-N.J., 1956. It is part of an 8 sheet map set covering the metropolitan New York City area. It was published in 1961. Scale 1:24,000. The source map was compiled from 1:24,000-scale maps of Mount Vernon 1956, Yonkers 1956, Central Park 1956, and Flushing 1955 7.5 minute quadrangles. Hydrography compiled from USC&GS charts 222 (1955), 223 (1954), 748 (1955), 226, 274, 745, 746, and 747 (1956). The image inside the map neatline is georeferenced to the surface of the earth and fit to the Universal Transverse Mercator (UTM) Zone 18N NAD27 projection. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. USGS maps are typical topographic maps portraying both natural and manmade features. They show and name works of nature, such as mountains, valleys, lakes, rivers, vegetation, etc. They also identify the principal works of humans, such as roads, railroads, boundaries, transmission lines, major buildings, etc. Relief is shown with standard contour intervals of 10 and 20 feet; depths are shown with contours and soundings. Please pay close attention to map collar information on projections, spheroid, sources, dates, and keys to grid numbering and other numbers which appear inside the neatline. This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.

New York, N.Y. and vicinity, 1961 : Oyster Bay, N.Y.-Conn. (8 Sheet Set) (Raster Image)

This layer is a georeferenced raster image of the United States Geological Survey 7.5 minute topographic sheet map entitled: New York and vicinity : Oyster Bay, N.Y.-Conn., 1955. It is part of an 8 sheet map set covering the metropolitan New York City area. It was published in 1961. Scale 1:24,000. The source map was prepared by the Geological Survey from 1:24,000-scale maps of Bayville 1954, Mamaroneck 1955, Sea Cliff 1954, and Hicksville 1954 7.5 minute quadrangles compiled by the Army Map Service. The Mamaroneck quadrangle was previously compiled by the Geological Survey in 1933 and 1934. Culture revised by the Geological Survey. Hydrography compiled from USC&GS charts 222 (1955), 223 (1954, 1955), and 224 (1954). The image inside the map neatline is georeferenced to the surface of the earth and fit to the Universal Transverse Mercator (UTM) Zone 18N NAD27 projection. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. USGS maps are typical topographic maps portraying both natural and manmade features. They show and name works of nature, such as mountains, valleys, lakes, rivers, vegetation, etc. They also identify the principal works of humans, such as roads, railroads, boundaries, transmission lines, major buildings, etc. Relief is shown with standard contour intervals of 10 and 20 feet; depths are shown with contours and soundings. Please pay close attention to map collar information on projections, spheroid, sources, dates, and keys to grid numbering and other numbers which appear inside the neatline. This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.

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"September 1973."