A method for characterizing the deformation localization in granular materials using the relative particle motion

Lu, Dechun; Dong, Hongyu; Lin, Qingtao; Guo, Cheng; Gao, Zhiwei; Du, Xiuli

doi:10.1016/j.compgeo.2023.105262

Cited by 2 publications

(3 citation statements)

References 48 publications

(32 reference statements)

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“…These local strains are measured at the scale of the Voronoi cells surrounding each grain after the generation of a Voronoi tessellation, as described in Materials and Methods . Prior work has used a combination of grain rotations, relative displacements, angular velocity, coordination numbers, and local void ratios to identify shear bands ( 38 , 50 – 54 ). Here, we identified shear bands using local deviatoric strains, ϵ dev , consistent with recent work ( 47 ) and confirmed to identify similar regions, albeit in dilative shear bands, to those obtained based on enhanced grain rotations, angular velocities, reduced coordination numbers, and reduced void ratios ( 53 ).…”

Section: Resultsmentioning

confidence: 99%

“…Detailed discrete element method (DEM) simulations, recently applied to “digital twins” or direct replicas of physical specimens, have also quantified force chains and principal stress rotations in shear bands ( 47 – 49 ). Recent experiments employing XRCT, and accompanying numerical simulations, have also advanced a variety of methods for identifying shear bands based on grain rotations, relative displacements, angular velocity, particle contact (or coordination) numbers, and local void ratios ( 50 – 54 ). Furthermore, recent theoretical and numerical studies have highlighted the importance of the distinct mechanical responses (stresses, strains, and length scales) in and out of shear bands and have begun to incorporate shear band features into constitutive frameworks such as the double-scale approach ( 55 – 57 ).…”

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confidence: 99%

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Assessing continuum plasticity postulates with grain stress and local strain measurements in triaxially compressed sand

Hurley

Shahin

Kuwik

et al. 2023

Proc. Natl. Acad. Sci. U.S.A.

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Critical state and continuum plasticity theories have been used in research and engineering practice in soil and rock mechanics for decades. These theories rely on postulated relationships between material stresses and strains. Some classical postulates include coaxiality between stress and strain rates, stress–dilatancy relationships, and kinematic assumptions in shear bands. Although numerical and experimental data have quantified the strains and grain kinematics in such experiments, little data quantifying grain stresses are available. Here, we report the first-known grain stress and local strain measurements in triaxial compression tests on synthetic quartz sands using synchrotron X-ray tomography and 3D X-ray diffraction. We use these data to examine the micromechanics of shear banding, with a focus on coaxiality, stress-dilatancy, and kinematics within bands. Our results indicate the following: 1) elevated deviatoric stress, strain, and stress ratios in shear bands throughout experiments; 2) coaxial principal compressive stresses and strains throughout samples; 3) significant contraction along shear bands; 4) vanishing volumetric strain but nonvanishing stress fluctuations throughout samples at all stages of deformation. Our results provide some of the first-known in situ stress and strain measurements able to aid in critically evaluating postulates employed in continuum plasticity and strain localization theories for sands.

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Assessing continuum plasticity postulates with grain stress and local strain measurements in triaxially compressed sand

Hurley

Shahin

Kuwik

et al. 2023

Proc. Natl. Acad. Sci. U.S.A.

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“…Trapdoor tests [3][4][5][6] have been frequently used to study the ground deformation modes, where attention is mainly placed on the evolution of earth pressure. The ground settlement is not monitored.…”

Section: Introductionmentioning

confidence: 99%

Experimental Research on the Settlement Feature of Two Ground Deformation Modes Induced by Tunnelling

Lin

Guo

et al. 2023

Mathematics

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Two ground deformation modes, i.e., the arching mode and collapsing mode, may be caused by tunnel excavation. However, the development of the ground deformation corresponding to the two modes is unclear. A piece of a model test facility is designed to study the ground settlement induced by tunnel excavation. Tunnel excavation is realized by decreasing the area of the model tunnel. Two model tests with different soil cohesion are conducted, and the two ground deformation modes form in the two tests, respectively. The former mode is observed at higher soil cohesion while the latter is found to develop at lower soil cohesion. Whether the failure surface develops to the ground surface or not is the most significant difference between the two ground deformation modes. In the two modes, the failure surface occurs at the position where the ground settlement contours distribute densely, and the shape of the failure surface can be described by the semi-oval for both modes. Meanwhile, for both the arching mode and the collapsing mode, Gaussian curves can reasonably describe the ground settlement troughs before the ground surface settlement becomes stable or increases sharply, and distribution of the trough width parameter is similar.

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A method for characterizing the deformation localization in granular materials using the relative particle motion

Cited by 2 publications

References 48 publications

Assessing continuum plasticity postulates with grain stress and local strain measurements in triaxially compressed sand

Assessing continuum plasticity postulates with grain stress and local strain measurements in triaxially compressed sand

Experimental Research on the Settlement Feature of Two Ground Deformation Modes Induced by Tunnelling

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