Description:

A Micro-Mechanical Study of Cemented Granular Materials

Cemented Granular Materials are a ubiquitous material both in nature and as the result of an engineering effort to enhance the properties of natural soils. Their behavior at the engineering scale is lead by processes occurring at the scale of individual grains and cement bonds. This seminar outlines a combination of novel analytical, numerical and experimental tools, which explore this micro-to-macro hierarchy. Analytically, a micro-inspired continuum model is introduced. This model can successfully predict stress-strain responses as well as the onset and development of localisation patterns, which are studied though regularized finite elements. Experimentally, an x-ray CT testing campaign and a suite of bespoke image processing developments are presented, which focus on measuring the evolution of grains and cement scale structures consistently with the internal variables of the analytical model. The limits of x-ray CT are then overcome thanks to a novel bi-modal tomograph combining x-ray and neutrons, recently developed by the author.

Biography:
Alessandro Tengattini received his undergraduate degree in Civil Engineering at Politecnico of Milan and his PhD in Geotechnical Engineering from the University of Sydney. He is currently the responsible for the construction and operation of NeXT, a multi-million dollar neutron and x-ray Tomograph (https://next-grenoble.fr/) at the ILL (the most powerful neutron source in the world). 

His work is focused on Cemented Granular Materials employing a micro-to-macro approach through a combination of analytical (thermo-mechanical micro-ispired constitutive modeling), numerical (enriched finite elements and material point method) and experimental (tomography of in-operando tests) tools. This last endeavor brought him to develop a novel instrument capable of multi-modal neutron and x-ray tomography, which has recently secured several millions of dollars in funding for further upgrades.

He has received multiple awards for his work, including the Ioannis Vardoulakis PhD Prize from ALERT-Geomaterials, the W(H)YDOC PhD Prize (International Workshop of Young Doctors in Geomechanics, Paris) as well as the Australian Geomechanics Society research award.