Deformation of Granular Materials: A Look Within
Dr. Cino Viggiani
Combining x-ray tomography and 3D image analysis has finally opened the way for experimental micro-(geo)mechanics, allowing access to different scales of interest. In this talk a few examples will be presented of the kind of experimental results that can be obtained by means of x-ray micro tomography imaging. Images from x-rays can be analyzed either in a continuum sense (using 3D Digital Image Correlation) or looking at the individual particle kinematics. These advanced techniques offer us a look at what actually happens when a granular material deforms and eventually fails. However, there are issues when the scale of interest is very small, for example the characterization of grain-to-grain contacts (their orientations and evolution), or production of fines by grain breakage. These challenges will also be discussed through a few examples.
Cino Viggiani was born in Napoli (Italy), where he obtained a B.S. in Civil Engineering (1988), a Ph.D. in Geotechnical Engineering at the University of Roma “La Sapienza” (1994), and a H.D.R. (Habilitation) in Mechanics at Université Joseph Fourier, Grenoble, France (2004), where he is full Professor since 2004. In 2012 he was advanced to the rank of Professeur de Classe Exceptionnelle by the French National Council of Universities (CNU). He served in the capacity of Vice-President for Research in Physics and Engineering for four years (2007-2011), and he is now the Head of Laboratoire 3SR (since 2013). He is Editor of the International Journal Acta Geotechnica (Springer) since 2006. He is the author of about 130 scientific papers and delivered numerous keynotes and invited lectures worldwide. His research involves experimental investigations as well as theoretical and numerical modeling of the behavior of geomaterials, including localized failure and hydro-mechanical coupling. Applications are principally in geoenvironmental, petroleum, and civil engineering. On the experimental side, he has been developing and using quite a range of soils and rock testing apparatus, as well as advanced methods such as x-ray tomography and Digital Image Correlation.