Laboratory physical modelling of block toppling instability by means of tilt tests

In this paper we present a physical modelling approach where the stability of rock blocks against toppling in the field can be estimated using a tilt table, engineered rock models and 3-D-printed small-scale versions of a natural rock boulder. To achieve this goal, first, simple geometry rock elements are tilted and results interpreted according to analytical formulations. Then, more complex geometry engineered rock blocks, including some whose centers of gravity do not project on the center of the base element, are tested and results properly interpreted. Eventually, the 3-D-printed version of the rock boulder is produced from 3-D point clouds recovered in the field by means of a combination of photogrammetry and laser scanner techniques. Analytical formulations and numerical calculations have been used in order to validate the proposed approach, to explain the physical phenomena involved, and to allow for possible extension of the physical modelling results to different scenarios, such as those considering the influence of water or seismic loading on stability.