Localized compaction in Tuffeau de Maastricht

by

Abstract

Compaction bands have been observed in different kinds of materials (e.g., rocks, soils, metallic foams, cellular materials). They are usually promoted by a relatively high porosity, as well as by high mean stress levels. However, the inelastic mechanisms controlling localized compaction at the micro-scale can differ from one material to another. For instance, buckling of thin walls has been observed in metallic foams or honeycomb structures. In the case of geomaterials, due to their natural variability, the microstructural origin of compaction localization is still an open question, often complicated by the coexistence of multiple inelastic processes (e.g., pore collapse, grain crushing, and degradation of cementation bonds). Full-field nondestructive measurements have the potential to identify these micro-mechanisms and assess their relative role.  In this talk I will present some selected results from a large experimental study of compaction banding in Tuffeau de Maastricht, a bioclastic sedimentary limestone exhibiting up to 52% of porosity. Triaxial compression tests were performed at confining pressures ranging from 1 to 5 MPa, on samples cored perpendicular and parallel to the bedding plane. Systematic use of x-ray micro tomography combined with the use of advanced image analysis and Digital Image Correlation (DIC) provides quantitative 3D information about the strain field inside a sample and its evolution during a test.

Biography

Professor Cino Viggiani has about 20 years of research experience in geomechanics. He works at Laboratoire 3SR (of which he was the Director for five years) in the research team "GéoMécanique", which currently includes 22 permanent faculty members, 3 post-doctoral students and 30 PhD students. 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 innovative soils and rock testing apparatus and experimental techniques – in particular, Digital Image Correlation and x-ray tomography.  

Professor of Outstanding Quality at Université Grenoble-Alpes, Cino Viggiani has been offered a visiting Professor position at Georgia Tech, USA (2011), the University of Kumamoto, Japan (2011), the University of Sydney, Australia (2012 and 2019). In 2015, he was Distinguished Visiting Fellow of the Royal Academy of Engineering at the University of Edinburgh, UK. Since 2018, he is a Visiting Professor at IROAST (International Research Organization for Advanced Science and Technology) in Kumamoto, Japan. He is author of over 200 scientific papers, including 86 peer-reviewed Journal papers and about 140 refereed publications in Books, International Workshops and Conferences. His work is highly cited, with a google scholar h-index of 39, and 32 papers with more than 50 citations (of which 14 with more than 100 citations). He has delivered over 20 keynote and invited lectures worldwide.

 The significance of his contribution to Geomechanics is also demonstrated by his involvement in various National and International Research Boards: he is, or has been, Member of the Scientific Council of the French-Italian University, Scientific Expert for the French Ministry for Research and Innovation, Member of the Mechanics and Engineering Section of the French National Council of University, Member of the Board of Directors of the European Association ALERT-Geomaterials (of which he is the President since 2018), of the Advisory Board of the Scottish Joint Research Institute ECOSSE and of the Technical Committee TC105 “Geo-Mechanics from Micro to Macro” of the International Society for Soil Mechanics and geotechnical Engineering – just to mention a few.

In 2007 Cino created and has since directed the international masters program in Geomechanics, Civil Engineering and Risks in Grenoble (all courses are given in English – which is quite an achievement for a French university!). Since 2007-2008, more than 300 students have attended this masters program from more than thirty different countries.

Last, but not least, he was one of the four Editors of the International Journal Acta Geotechnica (Springer) since its creation in 2006 until 2017. The impact factor of this journal rose to 2.801 in 2016, which is remarkable and resulted in the journal being ranked 5th out 32 SCI (Science Citation Index) journals in the "engineering/geological" field. This journal has become, in a relatively short time, one of the high quality journals of the field. In 2018, Cino left his editorial role with Acta Geotechnica and has created, together with eight colleagues, a new fully open-access journal, Open Geomechanics.

For enquiries, please contact Ms Rebecca Yau at Tel: 2358 7164.