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Combined 4D experimental grain-scale characterisation of grain-strains, force transfer and kinematics in natural granular material (sand) under load

Objective

Granular materials, such as sand, are complex systems in which relatively simple building blocks (i.e. contacting particles - sand grains) behave and interact collectively and in complicated ways. These interactions produce structural evolution over a range of different spatial and temporal scales from contacting-particle interactions to intermediate (meso-) scale communication and structure formation (e.g. localised deformation such as shear bands) to longer-range pattern formation. These kinematic effects are associated with the build-up of stress and possible relaxation via structural reorganisation and particle damage. Furthermore, such particulate masses are frictional and their behaviours are dependent on the mean stress, therefore the same material can exhibit a range of mechanical behaviours, depending on the conditions, from being similar to fluids to behaving more like solids (although never being exactly either). Accurate simulation of the mechanical behaviour of granular systems is thus non-trivial and remains an open challenge. Whilst there is much theoretical and numerical research into improving these simulations, there is significantly less research into the mechanical characterisation and quantification of the micro-scale mechanics, which is necessary to support the ever-more sophisticated modelling. This research tackles the experimental challenge and, in particular, the quest for one of the holy grails of granular mechanics, namely the combined measurement of the kinematics and force transmission in real 3D materials during loading. The research has implications in terrestrial geomechanical/geotechnical engineering challenges, e.g. in optimising foundations or tunnels to mitigate risks of structural failure. There are also extra-terrestrial implications relating to the need to know/predict the mechanical behaviour of soils at lunar/Martian landing sites so as to reduce the risk of very costly landing failures.

Call for proposal

FP7-PEOPLE-2012-CIG
See other projects for this call

Coordinator

MAX IV Laboratory, Lund University
Address
Paradisgatan 5C
22100 Lund
Sweden
Activity type
Higher or Secondary Education Establishments
EU contribution
€ 100 000
Administrative Contact
Matti Ristinmaa (Prof.)