Measuring the fabric evolution of sand – application and challenges

geotechnik ◽  
2020 ◽  
Author(s):  
Max Wiebicke ◽  
Ivo Herle ◽  
Edward Andò ◽  
Gioacchino Viggiani
Keyword(s):  
Fabric Evolution

scholarly journals The response of fabric variations to simple shear and migration recrystallization

2015 ◽  
Vol 61 (227) ◽  
pp. 537-550 ◽  
Author(s):  
Joseph H. Kennedy ◽  
Erin C. Pettit
Keyword(s):  
Thermal Activation ◽  
Nearest Neighbor ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Polar Ice ◽  
Climatic Variations ◽  
Fabric Evolution ◽  
Polar Ice Sheets ◽  
Low Levels ◽  
And Migration

AbstractThe observable microstructures in ice are the result of many dynamic and competing processes. These processes are influenced by climate variables in the firn. Layers deposited in different climate regimes may show variations in fabric which can persist deep into the ice sheet; fabric may ‘remember’ these past climate regimes. We model the evolution of fabric variations below the firn–ice transition and show that the addition of shear to compressive-stress regimes preserves the modeled fabric variations longer than compression-only regimes, because shear drives a positive feedback between crystal rotation and deformation. Even without shear, the modeled ice retains memory of the fabric variation for 200 ka in typical polar ice-sheet conditions. Our model shows that temperature affects how long the fabric variation is preserved, but only affects the strain-integrated fabric evolution profile when comparing results straddling the thermal-activation-energy threshold (∼−10°C). Even at high temperatures, migration recrystallization does not eliminate the modeled fabric’s memory under most conditions. High levels of nearest-neighbor interactions will, however, eliminate the modeled fabric’s memory more quickly than low levels of nearest-neighbor interactions. Ultimately, our model predicts that fabrics will retain memory of past climatic variations when subject to a wide variety of conditions found in polar ice sheets.

Mesoscale and macroscale kinetic energy fluxes from granular fabric evolution

2014 ◽  
Vol 89 (3) ◽  
Author(s):  
David M. Walker ◽  
Antoinette Tordesillas ◽  
Gary Froyland
Keyword(s):  
Kinetic Energy ◽  
Energy Fluxes ◽  
Fabric Evolution

A critical state sand plasticity model accounting for fabric evolution

2013 ◽  
Vol 38 (4) ◽  
pp. 370-390 ◽  
Author(s):  
Zhiwei Gao ◽  
Jidong Zhao ◽  
Xiang-Song Li ◽  
Yannis F. Dafalias
Keyword(s):  
Critical State ◽  
Plasticity Model ◽  
Fabric Evolution

scholarly journals Steady radial ice-sheet flow with fabric evolution

2006 ◽  
Vol 52 (177) ◽  
pp. 267-280 ◽  
Author(s):  
Leslie W. Morland ◽  
Ryszard Staroszczyk
Keyword(s):  
Strain Rate ◽  
Response Function ◽  
Ice Sheet ◽  
Individual Crystal ◽  
Dependent Rate ◽  
Fabric Evolution ◽  
Basal Sliding ◽  
Basal Melting ◽  
Surface Ice ◽  
Fabric Response

AbstractReorientation of individual crystal glide planes, as isotropic surface ice is deformed during its passage to depth in an ice sheet, creates a fabric and associated anisotropy. We adopt an evolving orthotropic viscous law which was developed to reflect the induced anisotropy arising from the mean rotation of crystal axes during deformation. This expresses the deviatoric stress in terms of the strain rate, strain and three structure tensors based on the principal stretch axes, and involves one fabric response function which determines the strength of the anisotropy. The initial isotropic response enters as a multiplying factor depending on a strain-rate invariant and incorporating a temperature-dependent rate factor. The fabric response function has been constructed by correlations with complete (idealized) uniaxial compression and shearing responses for both ‘cold’ and ‘warm’ ice. The possible effects of such fabric evolution are now illustrated by determining steady radially symmetric flow solutions for an ice sheet with a prescribed temperature distribution and subject to an elevation-dependent surface accumulation/ablation distribution, zero basal melting and a prescribed basal sliding law. Comparisons are made with solutions for the conventional isotropic viscous law, for a flat bed, for a bed with a single modest slope hump and for a bed with a single modest slope hollow, for both cold and warm ice.

Influence of Initial Anisotropy, Stress Path and Principal Stress Rotation on Monotonic Behavior of Clean and Mixed Sands

2020 ◽  
Vol 857 ◽  
pp. 417-430
Author(s):  
Kazem Fakharian ◽  
Farzad Kaviani Hamedani
Keyword(s):  
Principal Stress ◽  
Stress Path ◽  
Silica Sand ◽  
Large Strains ◽  
Principal Stress Rotation ◽  
Soil Behavior ◽  
Stress Rotation ◽  
Fabric Evolution ◽  
Initial Anisotropy

It is widely accepted that soil behavior is complicated taking into account soil anisotropy owing to the fact that this phenomenon arises from oriented soil fabric or structure forged in the deposition stage. In this study, a review of major findings of authors’ previous studies are presented with the main focus on soil anisotropy using extensive experimental results incuding Triaxial (TXT), Simple Shear (SSA), and Hollow Cylinder (HCA) apparatus. Effects of initial anisotropy, fabric evolution, stress path, principal stress rotation and intermediate stress state are evaluated for a crushed silica sand. In addition, the effects of Portland cement content and granulated rubber contents on anisotropic behavior of the sand are investigated. Bender elments are mounted on triaxial specimens both in vertical and horizontal directions to measure the shear wave velocity and hence maximum shear modulus at the end of consolidation as well as during shearing up to large strains at critical state condition, as an index of evaluating the fabric evolution. The effects of principal stress rotation and stress paths reveals the crucial role of soil anisotropy on the behavior of clean sand. However, adding either cement or granulated rubber to the sand has considerably decreased anisotropy.

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