Experimental analysis of the basal force produced by a dry granular flow

Rock avalanches are catastrophic natural phenomena occurring in mountainous areas of our planet. They are defined as extremely rapid, massive, flow-like motions of frag-mented rock from a large rockslide or rockfall along a slope driven by gravity. They can pose great hazards to downslope areas, damaging buildings and infrastructures, and human life, often causing hundreds of victims. The danger of the phenomena is closely linked both to the high speeds with which the granular material is able to cover large distances and to the general absence of any explicit warning signals. Geophysical granular flows, like rock avalanches, exert basal forces that generate seismic signals. These signals can be acquired and subsequently used to better monitor and model these natural hazards. The goal of this thesis work is to present the results of ex-perimental tests conducted on dry granular flows in the Geotechnical Department of the University of Padova, going through the description of the preliminary activities that led to a simplified reproduction of rock avalanches in laboratory. Particularly, the features of different dry granular flows generated inside an inclined laboratory chute have been studied, analysing the acquired basal forces exerted by gravel particles on a glass moni-toring plate equipped with five piezoelectric force sensors. In practise, the analysis of the force signals could provide information about how large a rockslide is or how damaging it will be, helping the emergency services respond. Or, af-ter the event has been occurred, information about its duration and considerations about dynamic properties, like the rockslide’s energy or velocity. The results reported in this thesis work represent the base from which it will be possible to start with more detailed studies, maybe varying the operating conditions of the chute (e.g. inclination, roughness, presence of obstacles) and the involved granular materials.