Integrating Discontinuity Trace and Facet Orientation Measurements for Improved Discontinuity Data Analysis

Discontinuities, which are ubiquitous in most rock masses, influence the engineering properties and behaviors of all but the weakest of rock types. Thus, the properties of the discontinuities become of prime importance when dealing with rock masses. The orientation of the discontinuities is arguably the most important property in many instances. The analysis of discontinuity data basically involves building models that represent the discontinuities. These models are in most cases based on the fact that geological processes usually generate one or more (typically at least three) clusters of nearly parallel discontinuities in a rock mass. Discontinuities manifest themselves in rock cuts and outcropping as fracture surfaces ‘facets’ that can be measured by LiDAR (Light Detecting and Ranging) or fracture ‘traces’ that can be measured from optical imaging methods. Measurements of the orientation of facets are recorded in terms of dip direction and dip angle. Traces, however, are recorded with trend and plunge, which unlike facet measurement, are a two dimensional measurement that represents the intersection of the fracture surface with a rock cut/outcrop surface. This paper presents geometrical methods of integrating facet orientations measured from LiDAR point cloud data and trace orientations measured from optical images for better characterization of systematic discontinuity orientations