On the role of pore pressure in dynamic instabilities of saturated model granular materials

Nguyen, Thi Thu Tra; Doanh, T.; Bot, Alain Le; Dalmas, Davy

doi:10.1007/s10035-019-0915-5

Cited by 7 publications

(8 citation statements)

References 67 publications

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“…2. Moreover, we obtained identical results 50 (not presented here) for all the tested confining pressures ranging from 50 to 500 kPa. From all the collected high-resolution measurements (cf.…”

Section: Stick-slip Motions Under Triaxial Compressionsupporting

confidence: 80%

High-temporal-resolution quasideterministic dynamics of granular stick-slip

Nguyen

Doanh

Bot

et al. 2021

Sci Rep

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We report high-temporal-resolution observations of the spontaneous instability of model granular materials under isotropic and triaxial compression in fully drained conditions during laboratory tests representative of earthquakes. Unlike in natural granular materials, in the model granular materials, during the first stage of the tests, i.e., isotropic compression, a series of local collapses of various amplitudes occurs under random triggering cell pressures. During the second stage, i.e., shearing under triaxial compression, the model granular samples exhibit very large quasiperiodic stick-slip motions at random deviatoric triggering stresses. These motions are responsible for very large stress drops that are described by power laws and are accurate over more than 3 decades in logarithmic space. Then, we identify the quasideterministic nature of these stick-slip events, assuming that they are fully controlled by the cell pressure and solid fraction. Finally, we discuss the potential mechanisms that could explain these intriguing behaviors and the possible links with natural earthquakes.

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Section: Stick-slip Motions Under Triaxial Compressionsupporting

confidence: 80%

High-temporal-resolution quasideterministic dynamics of granular stick-slip

Nguyen

Doanh

Bot

et al. 2021

Sci Rep

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“…The stick-slip phenomenon, manifested as strong fluctuations of stress and volumetric strain, was not detected in DEM calculations despite several additional runs with an increase/decrease of the spheres number and a reduction of both the grain size and the wall stiffness. To our knowledge, the phenomenon was not detected in any DEM simulations for spherical particles yet [63,64]. There is a suggestion that the stick-slip appears in reality due to physicochemical reactions at grain contacts [63].…”

Section: Calibration Of the Dem Modelmentioning

confidence: 68%

Contact force network evolution in active earth pressure state of granular materials: photo-elastic tests and DEM

et al. 2020

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The paper deals with a quasi-static behaviour of cohesion-less granular material in active earth pressure state. Photo-elastic model tests on a rigid wall, translating out of the granular material, are analyzed. Grain crushing tests are used to estimate the range of contact forces during the model tests. Substitute granular material (low optical sensitivity glass granules) is employed. The focus is on the evolution of contact force network with deformation of granular material. The model tests are simulated using the discrete element method (DEM) to compare physical and numerical full-field force network structure and the maximum/minimum stress level. The same model geometry, loading scheme and grain size distribution, as in the model tests, are accepted in DEM simulations, although only a single layer of grains is modelled. DEM model correctly predicts the overall structure of the force network and its characteristic features, including localization. It also gives the stress level close to the experimental one and properly identifies the areas of phase transitions.

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“…Instead of having a usual continuous increase of solid fraction with increasing internal effective stress 18 of real granular media such as natural sands 14 , the isotropic drained compression creates irregular stick-slip-like events termed as isotropic local collapses , 16 , 19 in a sawtooth behaviour in Fig. 1 , beginning from 20 kPa up to an unexpected full destruction of the granular structure at 212 kPa.…”

Section: Resultsmentioning

confidence: 99%

“…The internal stress of the saturated granular structure is greatly reduced by U , according to the Terzaghi effective stress principle, = - U 18 . The last event has a vanishing internal stress accompanied by an exceptionally large incremental axial strain of 19.2% and a jump in solid fraction of 0.018 in one single step in less than 1 s, moving I toward a higher value of about 10 ; hence the dynamic isotropic liquefaction for the slip phase 16 , crossing the jamming transition 21 and the dynamic consolidation for the stick phase 19 . Note the consistent positive delay of pore pressure outburst for all instability events, indicating a surprising counter-intuitive coupled response with systematic constant time delay 22 between the solid and liquid phases for a fully saturated two-phase mixture (Fig.…”

Section: Resultsmentioning

confidence: 99%

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An acoustic signature of extreme failure on model granular materials

Nguyen

Doanh

Bot

et al. 2022

Sci Rep

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Unexpectedly, granular materials can fail, the structure even destroyed, spontaneously in simple isotropic compression with stick-slip-like frictional behaviour. This extreme behaviour is conceptually impossible for saturated two-phase assembly in classical granular physics. Furthermore, the triggering mechanisms of these laboratory events remain mysterious, as in natural earthquakes. Here, we report a new interpretation of these failures in under-explored isotropic compression using the time-frequency analysis of Cauchy continuous wavelet transform of acoustic emissions and multiphysics numerical simulations. Wavelet transformation techniques can give insights into the temporal evolution of the state of granular materials en route to failure and offer a plausible explanation of the distinctive hearing sound of the stick-slip phenomenon. We also extend the traditional statistical seismic Gutenberg–Richter power-law behaviour for hypothetical biggest earthquakes based on the mechanisms of stick-slip frictional instability, using very large artificial isotropic labquakes and the ultimate unpredictable liquefaction failure.

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On the role of pore pressure in dynamic instabilities of saturated model granular materials

Cited by 7 publications

References 67 publications

High-temporal-resolution quasideterministic dynamics of granular stick-slip

High-temporal-resolution quasideterministic dynamics of granular stick-slip

Contact force network evolution in active earth pressure state of granular materials: photo-elastic tests and DEM

An acoustic signature of extreme failure on model granular materials

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