Calculation of in-situ blocks volume distribution of rock masses with full persistent joints using 3D point cloud data obtained by digital joint mapping techniques

The advent of new technologies in the field of three-dimensional mapping of outcrops has made it possible to provide precise geometrical information of the rock mass structures to identify and survey discontinuities. This research presents a process where using dense cloud data obtained from digital 3D mapping techniques and by integrating capabilities of some software, the orientation and spacing of persistent discontinuities of rock mass and the volume distribution of rock blocks are calculated. Here, at first, the points belonging to each discontinuity plate are examined by performing the coplanarity test and categorized by statistical methods. In addition, the discontinuities that are perpendicular to the surfaces of rock mass outcrop and the discontinuity plane is not visible were visually identified along their trace line. After identifying the points belonging to each discontinuity sets, points were clustered according their spatial distributions and a single plane fitted to the points belonging to each cluster. So, all visible discontinuities in rock mass, by the assumption of persistent, were geometrically simulated. On the other hand, a volumetric 3D model of rock mass was created using point cloud data. By geometric combination of generated joint planes and volumetric model of rock mass, rock blocks were created and block volume distribution diagram was obtained. In order to validate the method presented here, a geometric model with orthogonal regular joint system with accurate analytical solution was applied, and also the results were compared with the previous block volume estimation methods.