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DOI	10.5194/tcd-9-3617-2015
	A new methodology to simulate subglacial deformation of water saturated granular material
	Damsgaard A.; Egholm D.L.; Piotrowski J.A.; Tulaczyk S.; Larsen N.K.; Brædstrup C.F.
发表日期	2015
ISSN	19940432
卷号	9 期号:4
英文摘要	The dynamics of glaciers are to a large degree governed by processes operating at the ice-bed interface, and one of the primary mechanisms of glacier flow over soft unconsolidated sediments is subglacial deformation. However, it has proven difficult to constrain the mechanical response of subglacial sediment to the shear stress of an overriding glacier. In this study, we present a new methodology designed to simulate subglacial deformation using a coupled numerical model for computational experiments on grain-fluid mixtures. The granular phase is simulated on a per-grain basis by the discrete element method. The pore water is modeled as a compressible Newtonian fluid without inertia. The numerical approach allows close monitoring of the internal behavior under a range of conditions. The rheology of a water-saturated granular bed may include both plastic and rate-dependent dilatant hardening or weakening components, depending on the rate of deformation, the material state, clay mineral content, and the hydrological properties of the material. The influence of the fluid phase is negligible when relatively permeable sediment is deformed. However, by reducing the local permeability, fast deformation can cause variations in the pore-fluid pressure. The pressure variations weaken or strengthen the granular phase, and in turn influence the distribution of shear strain with depth. In permeable sediments the strain distribution is governed by the grain-size distribution and effective normal stress and is typically on the order of tens of centimeters. Significant dilatant strengthening in impermeable sediments causes deformation to focus at the hydrologically more stable ice-bed interface, and results in a very shallow cm-to-mm deformational depth. The amount of strengthening felt by the glacier depends on the hydraulic conductivity at the ice-bed interface. Grain-fluid feedbacks can cause complex material properties that vary over time, and which may be of importance for glacier stick-slip behavior. © Author(s) 2015.
学科领域	clay mineral; deformation mechanism; discrete element method; glacier dynamics; glacier flow; granular medium; hydraulic conductivity; Newtonian fluid; numerical model; permeability; pore pressure; porewater; rheology; saturation; shear strain; shear stress; subglacial environment
语种	英语
scopus关键词	clay mineral; deformation mechanism; discrete element method; glacier dynamics; glacier flow; granular medium; hydraulic conductivity; Newtonian fluid; numerical model; permeability; pore pressure; porewater; rheology; saturation; shear strain; shear stress; subglacial environment
来源期刊	Cryosphere Discussions
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/119859
作者单位	Department of Geoscience, Aarhus University, Aarhus C, Denmark; Department of Earth and Planetary Sciences, University of California, Santa Cruz, CA 95064, United States; Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen K, 1350, Denmark
推荐引用方式 GB/T 7714	Damsgaard A.,Egholm D.L.,Piotrowski J.A.,et al. A new methodology to simulate subglacial deformation of water saturated granular material[J],2015,9(4).
APA	Damsgaard A.,Egholm D.L.,Piotrowski J.A.,Tulaczyk S.,Larsen N.K.,&Brædstrup C.F..(2015).A new methodology to simulate subglacial deformation of water saturated granular material.Cryosphere Discussions,9(4).
MLA	Damsgaard A.,et al."A new methodology to simulate subglacial deformation of water saturated granular material".Cryosphere Discussions 9.4(2015).