Three-dimensional dynamic survey of moving granular masses with photogrammetric techniques.

The experimental research, carried out at the Laboratory of Applied Geology, Department of Geosciences of the University of Padua, investigates the possibility to describe, with photogrammetric techniques, the evolution of the surface of a moving granular mass. The study is inserted in the research activity aimed at understanding the phenomena of movement of dry and wet granular masses: dense snow avalanches, rock avalanches, debris flows. The obtained experimental data can contribute to the description of the material rheology and to the calibration of physical-mathematical-numerical models in view of their application in the field. The experimental apparatus consists of a support flume, eight digital cameras with fixed focal length lenses, a lighting system and a system for fast image acquisition. The synchronization of the survey of the frames from the cameras has been obtained by a NI hardware control system and a proper software written in LabView. The velocity of images transfer has been optimized using Raid technology. The paper describes the details of the designed experimental apparatus and some results.