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Title: Mechanism of formation of wiggly compaction bands in porous sandstone: 2. Numerical simulation using discrete element method

Wiggly compaction bands in porous aeolian s andstone vary from chevron shape to wavy shape to nearly straight. In some outcrops these variations occur along a single band. Here, a bonded close-packed discrete element model is used to investigate what mechanical properties control the formation of wiggly compaction bands (CBs). To simulate the volumetric yielding failure of porous sandstone, a discrete element shrinks when the force state of one of its bonds reaches the yielding cap defined by the failure force and the aspect ratio (k) of the yielding ellipse. A Matlab code “MatDEM 3D” has been developed on the basis of this enhanced discrete element method. Mechanical parameters of elements are chosen according to the elastic properties and the strengths of porous sandstone. In numerical simulations, the failure angle between the band segment and maximum principle stress decreases from 90° to approximately 45° as k increases from 0.5 to 2, and compaction bands vary from straight to chevron shape. With increasing strain, subsequent compaction occurs inside or beside compacted elements, which leads to further compaction and thickening of bands. The simulations indicate that a greater yielding stress promotes chevron CBs, and a greater cement strength promotes straight CBs. Combinedmore » with the microscopic analysis introduced in the companion paper, we conclude that the shape of wiggly CBs is controlled by the mechanical properties of sandstone, including the aspect ratio of the yielding ellipse, the cri tical yielding stress, and the cement strength, w hich are d etermined primarily by petrophysical attributes, e.g., grain sorting, porosity, and cementation.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. Nanjing Univ. (China). Suzhou High-Tech Inst. and School of Earth Sciences and Engineering; Stanford Univ., CA (United States). Dept. of Geological and Environmental Sciences
  2. Stanford Univ., CA (United States). Dept. of Geological and Environmental Sciences
  3. Nanjing Univ. (China). Suzhou High-Tech Inst. and School of Earth Sciences and Engineering
  4. Nanjing Univ. (China). School of Earth Sciences and Engineering
Publication Date:
Grant/Contract Number:
FG02-04ER15588; 41230636; 41302216; BK20130377
Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Solid Earth
Additional Journal Information:
Journal Volume: 120; Journal Issue: 12; Journal ID: ISSN 2169-9313
Publisher:
American Geophysical Union
Research Org:
Stanford Univ., CA (United States)
Sponsoring Org:
USDOE; National Natural Science Foundation of China (NNSFC)
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; wiggly compaction band; discrete element method; yielding cap; failure angle; porous sandstone
OSTI Identifier:
1469105
Alternate Identifier(s):
OSTI ID: 1402378

Liu, Chun, Pollard, David D., Gu, Kai, and Shi, Bin. Mechanism of formation of wiggly compaction bands in porous sandstone: 2. Numerical simulation using discrete element method. United States: N. p., Web. doi:10.1002/2015JB012374.
Liu, Chun, Pollard, David D., Gu, Kai, & Shi, Bin. Mechanism of formation of wiggly compaction bands in porous sandstone: 2. Numerical simulation using discrete element method. United States. doi:10.1002/2015JB012374.
Liu, Chun, Pollard, David D., Gu, Kai, and Shi, Bin. 2015. "Mechanism of formation of wiggly compaction bands in porous sandstone: 2. Numerical simulation using discrete element method". United States. doi:10.1002/2015JB012374. https://www.osti.gov/servlets/purl/1469105.
@article{osti_1469105,
title = {Mechanism of formation of wiggly compaction bands in porous sandstone: 2. Numerical simulation using discrete element method},
author = {Liu, Chun and Pollard, David D. and Gu, Kai and Shi, Bin},
abstractNote = {Wiggly compaction bands in porous aeolian s andstone vary from chevron shape to wavy shape to nearly straight. In some outcrops these variations occur along a single band. Here, a bonded close-packed discrete element model is used to investigate what mechanical properties control the formation of wiggly compaction bands (CBs). To simulate the volumetric yielding failure of porous sandstone, a discrete element shrinks when the force state of one of its bonds reaches the yielding cap defined by the failure force and the aspect ratio (k) of the yielding ellipse. A Matlab code “MatDEM3D” has been developed on the basis of this enhanced discrete element method. Mechanical parameters of elements are chosen according to the elastic properties and the strengths of porous sandstone. In numerical simulations, the failure angle between the band segment and maximum principle stress decreases from 90° to approximately 45° as k increases from 0.5 to 2, and compaction bands vary from straight to chevron shape. With increasing strain, subsequent compaction occurs inside or beside compacted elements, which leads to further compaction and thickening of bands. The simulations indicate that a greater yielding stress promotes chevron CBs, and a greater cement strength promotes straight CBs. Combined with the microscopic analysis introduced in the companion paper, we conclude that the shape of wiggly CBs is controlled by the mechanical properties of sandstone, including the aspect ratio of the yielding ellipse, the cri tical yielding stress, and the cement strength, w hich are d etermined primarily by petrophysical attributes, e.g., grain sorting, porosity, and cementation.},
doi = {10.1002/2015JB012374},
journal = {Journal of Geophysical Research. Solid Earth},
number = 12,
volume = 120,
place = {United States},
year = {2015},
month = {11}
}