Undrained shear band in water saturated granular media: A critical revisiting with numerical examples

2011 ◽  
Vol 37 (4) ◽  
pp. 353-373 ◽  
Author(s):  
Peijun Guo
Keyword(s):  
Shear Band ◽  
Granular Media ◽  
Numerical Examples ◽  
Water Saturated ◽  
Undrained Shear

Undrained Shear Band Deformation in Granular Media

1997 ◽  
Vol 123 (6) ◽  
pp. 577-585 ◽  
Author(s):  
Michael A. Mooney ◽  
Gioacchino Viggiani ◽  
Richard J. Finno
Keyword(s):  
Shear Band ◽  
Granular Media ◽  
Band Deformation ◽  
Undrained Shear

Monitoring of damage processes in cemented granular materials with acoustic emissions and seismic velocity reduction

2020 ◽  
Author(s):  
Vincent Canel ◽  
Xiaoping Jia ◽  
Michel Campillo ◽  
Ioan R. Ionescu
Keyword(s):  
Acoustic Emission ◽  
Shear Band ◽  
Sound Velocity ◽  
Granular Materials ◽  
Fracture Process ◽  
Granular Media ◽  
Acoustic Emissions ◽  
Shear Band Formation ◽  
Band Formation ◽  
Velocity Decrease

<p>Earthquakes or fault core sliding occur naturally in response to long-term deformation produced by plate tectonics. However, the way the damage or fracture process of rocks control the frictional slip is not well understood. It involves indeed materials in very different states: from granular-like materials near the shear band within the highly cracked fault core [1] to almost cohesive state in distant host rocks. To address this issue, we perform controlled laboratory experiments and new numerical simulations of damage in cemented granular materials to study the material evolution from cohesive to granular-like states under external loading. Our synthetic rocks (porous media) are made of cemented glass beads in which the packing density and the cement property (ductile or brittle) as well its content are tunable [2,3]. Two mechanical tests have been conducted: i) under oedometric load in a cylindrical cell with rigid wall; and ii) under triaxial load in a cell with elastic membrane (confined by atmospheric pressure). The fracture processes are monitored by acoustic waves, measuring the longitudinal ultrasound velocity (active detection) [4] and the acoustic emission (passive detection) [5].</p><p>More precisely, in the case (i) the fracture process is likely associated with the crack increase, spatially diffused without shear-band formation. For a rock sample cemented by a ductile bond, the damage induced by load appears likely as an anomalous deviation in the master curve of stress-strain whereas the combined acoustic detection provides a very clear evidence with an important sound velocity decrease. Upon cyclic unloading-reloading, we recover a power-law scaling of the sound velocity with the pressure similar to the law in purely granular media but with a finite velocity at vanishing pressure which depends on the residual cohesion of the damaged material. When the drop stress occurs intermittently in fractured samples cemented with brittle materials, we measure not only the sound velocity decrease but also acoustic emissions. In the case (ii) under a triaxial load, we observe the formation of shear-bands, i.e. fractures on the scale of the sample at a load much smaller than those applied in the oedometric loading (i). Again, there is a strong elastic softening (velocity decrease) [4]. Finally, we also compare these experiments with the finite-element modelling of damage and wave propagation in 2D dense cemented disk packings with various cement contents and elasto-visco-plastic properties. This numerical simulation allows to characterize the heterogeneous damage of the material at a microscopic scale.</p><p> </p><p><strong>References</strong></p><p>[1] C. Marone, Laboratory-derived friction laws and their applications to seismic faulting, Annu. Rev. Earth Planet. Sci. 26 <strong>1998</strong>, 643-696.</p><p>[2] V. Langlois, X. Jia, Acoustic probing of elastic behavior and damage in weakly cemented granular media, Phys. Rev. E 89 <strong>2014, </strong>023206.</p><p>[3] A. Hemmerle, M. Schröter, L. Goehring, A cohesive granular material with tunable elasticity, Scientific reports <strong>2016.</strong></p><p>[4] Y. Khidas, X. Jia, Probing the shear-band formation in granular media with sound waves, Phys. Rev. E 85 <strong>2012, </strong>051302.</p><p>[5] P.A. Johnson et al., Acoustic emission and microslip precursors to stick-slip failure in sheared granular media, Geophys. Res. Lett. 40 <strong>2013</strong>, 5627-5631.</p>

scholarly journals Rayleigh Waves Transformation in Liquefying Water-saturated Sands

2016 ◽  
Vol 63 (2-3) ◽  
pp. 173-190
Author(s):  
Ryszard Staroszczyk
Keyword(s):  
Rayleigh Waves ◽  
Granular Media ◽  
Ground Motions ◽  
Soil Liquefaction ◽  
Saturated Sand ◽  
Rayleigh Surface Waves ◽  
Pore Pressures ◽  
Sand Deposit ◽  
Water Saturated ◽  
Excess Pore Pressures

AbstractThe behaviour of a water-saturated sand deposit subjected to dynamic loads induced by the propagation of Rayleigh surface waves is analysed. Cyclic shearing of the saturated sand matrix due to ground motions results in the development of excess pore pressures in the soil and its subsequent liquefaction. The phenomena of pore pressure generation and soil liquefaction are investigated within the framework of a compaction theory for saturated granular media. The results of calculations, carried out by a finite-element method, illustrate the evolution of pore pressures and the development of liquefaction zones in the soil, and show the variation of surface wave parameters with the progressive degradation of the strength of the subsoil.

scholarly journals Shear Band Formation in Granular Media as a Variational Problem

2004 ◽  
Vol 92 (21) ◽  
Author(s):  
T. Unger ◽  
J. Török ◽  
J. Kertész ◽  
D. E. Wolf
Keyword(s):  
Shear Band ◽  
Variational Problem ◽  
Granular Media ◽  
Shear Band Formation ◽  
Band Formation

scholarly journals Emergence of Shear Bands in Confined Granular Systems: Singularity of the q-Statistics

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 862 ◽  
Author(s):  
Léo Viallon-Galiner ◽  
Gaël Combe ◽  
Vincent Richefeu ◽  
Allbens Picardi Faria-Atman
Keyword(s):  
Shear Band ◽  
Granular Media ◽  
Experimental Validation ◽  
Scaling Law ◽  
Shear Bands ◽  
Percolation Cluster ◽  
Granular Systems ◽  
Original Approach ◽  
Exact Point ◽  
Confined System

The statistics of grain displacements probability distribution function (pdf) during the shear of a granular medium displays an unusual dependence with the shear increment upscaling as recently evinced (see “experimental validation of a nonextensive scaling law in confined granular media”). Basically, the pdf of grain displacements has clear nonextensive (q-Gaussian) features at small scales, but approaches to Gaussian characteristics at large shear window scales—the granulence effect. Here, we extend this analysis studying a larger system (more grains considered in the experimental setup), which exhibits a severe shear band fault during the macroscopic straining. We calculate the pdf of grain displacements and the dependency of the q-statistics with the shear increment. This analysis has shown a singular behavior of q at large scales, displaying a non-monotonic dependence with the shear increment. By means of an independent image analysis, we demonstrate that this singular non-monotonicity could be associated with the emergence of a shear band within the confined system. We show that the exact point where the q-value inverts its tendency coincides with the emergence of a giant percolation cluster along the system, caused by the shear band. We believe that this original approach using Statistical Mechanics tools to identify shear bands can be a very useful piece to solve the complex puzzle of the rheology of dense granular systems.

scholarly journals Modeling of large-deformation behaviour of marine sensitive clays and its application to submarine slope stability analysis

2016 ◽  
Vol 53 (7) ◽  
pp. 1138-1155 ◽  
Author(s):  
Rajib Dey ◽  
Bipul Hawlader ◽  
Ryan Phillips ◽  
Kenichi Soga
Keyword(s):  
Shear Strength ◽  
Shear Band ◽  
Large Scale ◽  
Critical Length ◽  
Undrained Shear Strength ◽  
Model Parameters ◽  
Submarine Landslides ◽  
Weakened Zone ◽  
Sensitive Clay ◽  
Undrained Shear

Post-slide investigations suggest that many large-scale submarine landslides occur through marine sensitive clay layers. A nonlinear mathematical model for post-peak degradation of undrained shear strength of sensitive clay is proposed based on experimental results. A method for estimation of model parameters is presented. Incorporating the model, an analytical solution is developed to examine possible mechanisms of large-scale submarine landslides. Analyses are performed for mild infinite slopes where the failure initiates from a “fully weakened zone” of soil having undrained shear strength lower than the shear stress acting parallel to the slope. The driving force, in excess of resistance, generated from the fully weakened zone is then transferred to the surrounding soil elements resulting in shear band formation due to strain-softening behaviour of sensitive clays. When the length of the fully weakened zone is greater than a critical length, catastrophic shear band propagation (self-driven without any additional external force) occurs, which could result in large-scale offshore landslides. A simple design chart is developed to calculate the critical length. Compared with a 2005 study by Puzrin and Germanovich based on a linear post-peak shear strength degradation model, the present study gives a conservative estimation of critical length for catastrophic shear band propagation.

Shear Band Patterns in Biaxially Sheared Granular Media

2009 ◽  
Author(s):  
J. Török ◽  
L. Brendel ◽  
D. E. Wolf ◽  
Masami Nakagawa ◽  
Stefan Luding
Keyword(s):  
Shear Band ◽  
Granular Media
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