Method for automated discontinuity analysis of rock slopes with three-dimensional laser scanning

Three-dimensional (3D) laser scanning data can be used to characterize discontinuous rock masses in an unbiased, rapid, and accurate manner. With 3D laser scanning, it is now possible to measure rock faces whose access is restricted or rock slopes along highways or railway lines where working conditions are hazardous. The proposed method is less expensive than traditional manual survey and analysis methods. Laser scanning is a relatively new surveying technique that yields a so-called point cloud set of data; every single point represents a point in 3D space of the scanned rock surface. Because the density of the point cloud can be high (on the order of 5 mm to 1 cm), it allows for an accurate reconstruction of the original rock surface in the form of a 3D interpolated and meshed surface using different interpolation techniques. Through geometric analysis of this 3D mesh and plotting of the facet orientations in a polar plot, it is possible to observe clusters that represent different rock mass discontinuity sets. With fuzzy k-means clustering algorithms, individual discontinuity sets can be outlined automatically, and the mean orientations of these identified sets can be computed. Assuming a Fisher's distribution, the facet outliers can be removed subsequently. Finally, discontinuity set spacings can be calculated as well.