Title: Strain localization and elastic-plastic coupling during deformation of porous sandstone

Abstract

In this paper, results of axisymmetric compression tests on weak, porous Castlegate Sandstone (Cretaceous, Utah, USA), covering a range of dilational and compactional behaviors, are examined for localization behavior. Assuming isotropy, bulk and shear moduli evolve as increasing functions of mean stress and Mises equivalent shear stress respectively, and as decreasing functions of work-conjugate plastic strains. Acoustic emissions events located during testing show onset of localization and permit calculation of observed shear and low-angle compaction localization zones, or bands, as localization commences. Total strain measured experimentally partitions into: A) elastic strain with constant moduli, B) elastic strain due to stress dependence of moduli, C) elastic strain due to moduli degradation with increasing plastic strain, and D) plastic strain. The third term is the elastic-plastic coupling strain, and though often ignored, contributes significantly to pre-failure total strain for brittle and transitional tests. Constitutive parameters and localization predictions derived from experiments are compared to theoretical predictions. In the brittle regime, predictions of band angles (angle between band normal and maximum compression) demonstrate good agreement with observed shear band angles. Compaction localization was observed in the transitional regime in between shear localization and spatially pervasive compaction, over a small range of mean stresses.more » Finally, in contrast with predictions, detailed acoustic emissions analyses in this regime show low angle, compaction-dominated but shear-enhanced, localization.« less

Authors:

Dewers, Thomas A. ^[1]; Issen, Kathleen A. ^[2]; Holcomb, David J. ^[1]; Olsson, William A. ^[1]; Ingraham, Mathew D. ^[1]

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+ Show Author Affiliations

1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Geomechanics Dept.
2. Clarkson Univ., Potsdam, NY (United States). Mechanical and Aeronautical Engineering

Publication Date:

Tue Sep 12 00:00:00 EDT 2017

Research Org.:

Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Clarkson Univ., Potsdam, NY (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)

OSTI Identifier:

1464178

Alternate Identifier(s):

OSTI ID: 1549990

Report Number(s):

SAND-2014-19086J
Journal ID: ISSN 1365-1609; 540700

Grant/Contract Number:  

NA0003525; SC0006883; EAR-0711346; NA-0003525

Resource Type:

Accepted Manuscript

Journal Name:

International Journal of Rock Mechanics and Mining Sciences

Additional Journal Information:

Journal Volume: 98; Journal ID: ISSN 1365-1609

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

15 GEOTHERMAL ENERGY; 36 MATERIALS SCIENCE; 42 ENGINEERING; localization theory; bifurcation; sandstone; experimental rock; mechanics