The Brittle-Ductile Transition in Porous Limestone: Failure Mode, Constitutive Modeling of Inelastic Deformation and Strain Localization

Research output: Contribution to journalArticle

Abstract

Understanding of the mechanics of the brittle-ductile transition (BDT) in porous limestone is significantly more challenging than for sandstone because of the lack of consistent acoustic emission activity in limestone, meaning that one must rely on alternative techniques. In this paper, we investigate systematically the failure modes in Indiana limestone using X-ray microComputed Tomography imaging (μCT) and Digital Volume Correlation (DVC). Our new mechanical data show that the envelope for the onset of shear-enhanced compaction can be well approximated by an elliptical cap. The DVC analysis revealed the development of shear bands through the BDT, but no evidence of compaction bands. The shear band angles were between 29° and 46° with respect to the maximum principal stress. Compiling these new results with published data on Purbeck and Leitha limestones, we showed that inelastic compaction in each of these dual porosity allochemical limestones was in a good agreement with the normality condition, as defined in plasticity theory. Comparison of the observed failure modes with predictions based on bifurcation analysis showed that the shear band angles are consistently smaller than the theoretical predictions.

Details

Authors
  • Patrick Baud
  • Stephen Hall
  • Michael J. Heap
  • Yuntao Ji
  • Teng fong Wong
Organisations
External organisations
  • University of Strasbourg
  • Utrecht University
  • Chinese University of Hong Kong
  • Institute of Geology and Geophysics, Chinese Academy of Sciences
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Geology

Keywords

  • carbonates, dual porosity, plasticity theory, shear bands
Original languageEnglish
Article numbere2020JB021602
JournalJournal of Geophysical Research: Solid Earth
Volume126
Issue number5
Publication statusPublished - 2021 May
Publication categoryResearch
Peer-reviewedYes