Evidence of dilatant and non-dilatant damage processes in oolitic iron ore: P-wave velocity and acoustic emission analyses | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Evidence of dilatant and non-dilatant damage processes in oolitic iron ore: P-wave velocity and acoustic emission analyses

Type de publication:

Journal Article

Source:

Geophysical Journal International, Volume 177, Ticket 3, p.1343-1356 (2009)

ISBN:

0956-540X

Numéro d'accès:

ISI:000266025200040

URL:

http://onlinelibrary.wiley.com/doi/10.1111/j.1365-246X.2008.04017.x/abstract

Mots-clés:

UMR 7154 ; Dynamique des Fluides Géologiques ; Geomechanics; Microstructures; Defects; Elasticity and anelasticity; Acoustic properties; Fractures and faults

Résumé:

Uniaxial and triaxial compression experiments were performed on oolitic iron ores to investigate damage processes. Most of these experiments included four indirect measurements of damage evolution, that is, P-wave velocity and maximum amplitude received during pulse transmission experiments, elastic properties (apparent Young's modulus and apparent Poisson's ratio) and acoustic emission (AE) monitoring. The mechanical behaviour deduced from strain measurements is dilatant for some samples and non-dilatant for the other samples. However, variations in elastic properties indicate damage processes for all samples. AE source mechanism analysis shows two different microscopic damage processes: (1) for dilatant rock, the development of axial extensive microcracks as well as their interaction and coalescence lead to the formation of shear macroscopic discontinuities; (2) for non-dilatant oolitic iron ore, both compressive and shear micromechanisms take place and interact with macroscopic fractures. A particular consistency between the four types of measurements employed was observed.

Notes:

Wassermann, J. Senfaute, G. Amitrano, D. Homand, F.