Mechanism of formation of wiggly compaction bands in porous sandstone: 2. Numerical simulation using discrete element method
- 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
- Stanford Univ., CA (United States). Dept. of Geological and Environmental Sciences
- Nanjing Univ. (China). Suzhou High-Tech Inst. and School of Earth Sciences and Engineering
- Nanjing Univ. (China). School of Earth Sciences and Engineering
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.
- Research Organization:
- Stanford Univ., CA (United States)
- Sponsoring Organization:
- USDOE; National Natural Science Foundation of China (NSFC)
- Grant/Contract Number:
- FG02-04ER15588; 41230636; 41302216; BK20130377
- OSTI ID:
- 1469105
- Alternate ID(s):
- OSTI ID: 1402378
- Journal Information:
- Journal of Geophysical Research. Solid Earth, Vol. 120, Issue 12; ISSN 2169-9313
- Publisher:
- American Geophysical UnionCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Some considerations on the use of numerical methods to simulate past landslides and possible new failures: the case of the recent Xinmo landslide (Sichuan, China)
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journal | February 2018 |
Multiscale modeling and analysis of compaction bands in high-porosity sandstones
|
journal | May 2017 |
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