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Failure in Granular Materials: Macro and Micro Views
Failure is one of the most debated notions since many decades in geomechanics. On the one hand, the discrete nature of granular materials does not make it easy to define the notion from a phenomenological point of view. On the other hand, this notion is essential for civil engineers since projects have to be designed so as no failure is expected to occur. We herein consider the failure mode related to the creation of kinetic energy, without change in the control parameters. The general framework relating the existence of bursts of kinetic energy to the vanishing of the second-order work is first recalled. Then, the second-order work is investigated from a micromechanical point of view. First, a micromechanical model (micro-directional model of Nicot and Darve, 2005) is considered. The macroscopic second-order work is shown to be the sum of microscopic second-order works, defined on each contact, extended to all the existing contacts. Then, this result is generalized without referring to any constitutive model. This basic relation between both micro and macro second-order works is used to investigate the microstructural origins of the vanishing of the second-order work. Analytical relationships are first derived, highlighting the bridge between both micro and macro scales, and then numerical simulations based on a discrete element method are presented to confirm the relevance of this multiscale approach of failure.
Failure in Granular Materials: Macro and Micro Views
Failure is one of the most debated notions since many decades in geomechanics. On the one hand, the discrete nature of granular materials does not make it easy to define the notion from a phenomenological point of view. On the other hand, this notion is essential for civil engineers since projects have to be designed so as no failure is expected to occur. We herein consider the failure mode related to the creation of kinetic energy, without change in the control parameters. The general framework relating the existence of bursts of kinetic energy to the vanishing of the second-order work is first recalled. Then, the second-order work is investigated from a micromechanical point of view. First, a micromechanical model (micro-directional model of Nicot and Darve, 2005) is considered. The macroscopic second-order work is shown to be the sum of microscopic second-order works, defined on each contact, extended to all the existing contacts. Then, this result is generalized without referring to any constitutive model. This basic relation between both micro and macro second-order works is used to investigate the microstructural origins of the vanishing of the second-order work. Analytical relationships are first derived, highlighting the bridge between both micro and macro scales, and then numerical simulations based on a discrete element method are presented to confirm the relevance of this multiscale approach of failure.
Failure in Granular Materials: Macro and Micro Views
Wan, Richard (editor) / Alsaleh, Mustafa (editor) / Labuz, Joe (editor) / Nicot, F. (author) / Sibille, L. (author) / Darve, F. (author)
2011-01-01
12 pages
Article/Chapter (Book)
Electronic Resource
English
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