2022 D.H. Trollope Medal Winner presentation
Dr Davide E. Guccione
About the D. H. Trollope Medal
Named after David Hugh Trollope, whom was one of the pioneers and leaders of Australian geomechanics and teachings , this biennial award is made to the author of an outstanding paper on either theoretical or applied geomechanics that details research that has arisen from their recent doctoral studies.
Dr Guccione is the recipient of the award for his paper “Predicting the fragmentation survival probability of brittle spheres upon impact from statistical distribution of material properties” which he published, alongside his co-authors Oliver Buzzi, Klaus Thoeni, Stephen Fityus and Anna Giacomini, in 2021 in the International Journal of Rock Mechanics and Mining Science.
Abstract of the paper
Fragmentation of rocks upon impact during rockfall is a phenomenon that is poorly understood, scarcely researched and difficult to predict. However, to adequately predict the outcomes of rockfall events, it is essential to know whether a given block is likely to fragment given the impact conditions and what will be the outcome of the fragmentation process; that is, the number, size and trajectory of fragments. To date, there is no model or data that can be used to fully answer these questions. This paper presents the first theoretical model that can predict the fragmentation survival probability of brittle spherical blocks upon dynamic impact (i.e. drop tests) from the statistical distribution of material properties, determined from a range of standard quasi-static tests. Considering that survival probabilities tend to follow a Weibull distribution, the model focuses on predicting the two Weibull parameters, commonly known as the shape parameter (m) and the scale parameter (here, the critical kinetic energy). The model is based on theoretically-derived conversion factors used to turn the critical work required to fail disc samples in quasi-static indirect tension into the critical kinetic energy to cause failure of spheres at impact in drop tests. The mechanistic conversion factors specifically account for the shape and size of the specimens tested and the increase of strength under dynamic loading (strain rate effect). Three series of drop tests were conducted (on spheres of three different diameters) and complemented by extensive material characterisation testing in order to validate the novel predictive model. The variability of material properties was characterised, and it was found that the material strength found by the characterisation tests generally follows a Weibull form, but the survival probability distribution of the drop tests seems to be linear. The predicted conversion factors were first compared against their experimental counterparts before validating the prediction of survival probability of the spheres upon dynamic impact (in drop tests). It was found that it is possible to predict the survival probability of artificial rock of three different diameters (50 mm, 75 mm, 100 mm) and two different strengths upon impact solely from the statistical information coming from Brazilian tests and with an average relative error of less than 9%.
About the presenter
Davide holds a Master and a Bachelor degree in Civil Engineering from the University of Parma in Italy and a Diploma of Mining and Geoenvironmental Qualified Industrial Technician (Caltanissetta, Italy). He recently completed his PhD in Civil Engineering at the University of Newcastle entitled “An experimental investigation of fragmentation occurrence and outcome in the context of rockfall”. During his PhD he won the AGS NSW Research Award in 2020 from the Australian Geomechanics Society. He is currently a Research Associate at the University of Newcastle three research projects related to rockfall and slope monitoring. He also works as casual academic at the same University teaching a Geology course for Civil and Environmental Engineers. He is also the recipient of the ARC Industry Fellowship 2023 in collaboration with Rocscience.
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