scholarly journals Grain roughness effect on the critical state line of crushable sands

2021 ◽  
Author(s):  
Jiangtao Lei ◽  
◽  
Marcos Arroyo ◽  
Matteo Ciantia ◽  
Ningning Zhang ◽  
...  
Keyword(s):  
Granular Materials ◽  
Critical State ◽  
Roughness Effect ◽  
Dem Simulation ◽  
Dem Model ◽  
Grain Roughness

A recently proposed DEM model for materials with rough crushable grains (Zhang et al. 2021; Ciantia et al. 2015; Otsubo et al. 2017) is here employed to examine the effect of contact roughness on the critical state line, a property of granular materials which is a) fundamental for the evaluation of liquefaction risk and liquefied responses and b) easily accessible through DEM simulation (Ciantia et al. 2019).

Micro-Deformation Mechanism of Granular Materials under Different Boundary Conditions Based on DEM Simulation

2012 ◽  
Vol 170-173 ◽  
pp. 3361-3366
Author(s):  
Zhao Xia Tong ◽  
Min Zhou ◽  
Yang Ping Yao
Keyword(s):  
Boundary Condition ◽  
Granular Materials ◽  
Biaxial Compression ◽  
Special Focus ◽  
Particle Rotation ◽  
Axis Orientation ◽  
Dem Simulation ◽  
Steel Bars ◽  
Strain Relationship ◽  
Micro Deformation

Series of biaxial compression simulations are carried out to investigate the effects of boundary condition on the deformation of granular materials by using DEM. The parameters used in DEM are validated by the biaxial compression experiments on elliptical steel bars. The effects of boundary condition on the stress-strain relationship are analyzed. And special focus are put in the analysis of particle displacement, particle rotation, void distribution, particle long axis orientation and contact force with the development of deformation.

scholarly journals A 3D DEM Model for Air Sparging Technology in the Saturated Granular Soils

2022 ◽  
Vol 9 ◽  
Author(s):  
Kai Wu ◽  
Zan Li ◽  
Zhibin Liu ◽  
Songyu Liu
Keyword(s):  
Three Dimensional ◽  
Element Model ◽  
Discrete Element ◽  
Solid Particles ◽  
Air Sparging ◽  
Dem Simulation ◽  
Drag Forces ◽  
Novel Approach ◽  
Element Simulation ◽  
Dem Model

This work provides a three-dimensional discrete element simulation (DEM) model to study the air sparging technology. The simulations have taken into account the multi-phases of bubble (gas) - fluid (water) - soil (solid) particles. Bubbles are treated as discrete individual particles, with buoyancy and drag forces applied to bubbles and soil particles. The trajectory of each discrete bubble particle can be tracked using the discrete element model. It is found that the diffusion of the whole bubble is inverted conical though the motion behavior of a single bubble particle is random. Furthermore, the distribution of the radius of influence (ROI) is not uniform. The bubbles become more concentrated as in the center of the inverted cone. The number of bubbles dissipated from the water surface is normally distributed. The DEM simulation is a novel approach to studying air sparging technology that can provide us a deeper insight into bubble migration at the microscopic level.

scholarly journals Prediction of Shear Localisation in Granular Materials based on a Critical State Non-coaxial Model

2019 ◽  
Vol 92 ◽  
pp. 16006 ◽  
Author(s):  
Hansini Mallikarachchi ◽  
Kenichi Soga
Keyword(s):  
Granular Materials ◽  
Plane Strain ◽  
Critical State ◽  
Progressive Failure ◽  
Shear Bands ◽  
State Parameter ◽  
Biaxial Compression ◽  
Compression Tests ◽  
Principal Axes ◽  
Shear Localisation

Experimental evidence indicates that the shear localisation acts as a precursor to the failure in biaxial compression tests of granular materials. Once formed they are persistent and lead to progressive failure of most geotechnical structures. It is generally accepted that the primary mode of deformation within these shear bands is simple shear which is accompanied by rotation of principal axes. Hence, the conventional plasticity theories based on the assumption of coaxility is not sufficient to describe the behaviour within those shear bands. This paper highlights the influence of the non-coaxility on the initiation and orientation of shear bands in both drained and undrained sand. The con-coaxial plasticity theory is integrated into a critical state constitutive model enriched with the state parameter concept. The model is capable of taking account of the variation of lode angle under plane strain condition. Numerical plane strain biaxial compression tests are conducted to observe the effect of non-coaxility on shear localisation. Bifurcation criteria based on the acoustic tensor are checked to predict the onset and inclination of the shear band. Predictions from the non-coaxial model are compared with those of coaxial model. The influence of the initial void ratio for the formation of shear bands is explored. Results are compared qualitatively with experimental observations.

Sign in / Sign up

Export Citation Format

Share Document