DEM Simulations of Granular Soils under Undrained Triaxial Compression and  Plane Strain

Gong, Guobin

doi:10.4236/jamp.2015.38123

Cited by 7 publications

(4 citation statements)

References 12 publications

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“…The constant volume method has been shown to save computational time by eliminating complex computations in the coupled fluid DEM. The results of these studies have been shown to be logically compatible with the laboratory results [55][56].…”

Section: Simulation Of Undrained Behaviorsupporting

confidence: 80%

The role of fines content and particle size ratio on the load-bearing structure of binary granular soil: A micromechanical approach

Nia,

Bayesteh,

Khodaparast

2024

Preprint

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The particle size ratio and fines content are the most important factors influencing the behavior of binary graded granular soil. Previous studies have focused more on the effects of the fabric, particle size distribution and fines content on the macroscopic response of binary mixtures. The effect of the fines participation factor (β) on the load-bearing structure of binary graded soil and estimation of this parameter (β) from the macro and micromechanical perspectives have rarely been evaluated. The present study used a micro-mechanical approach and DEM to evaluate the global void ratio (e), intergranular void ratio (e*) and the contribution of the fines content to the load-bearing structure of binary graded soil during drained and undrained tests. The effects of the particle size ratio, fines content, initial packing density and confining pressure on β also have been evaluated. The results showed that e* is a more reliable parameter than e for interpreting the behavior of binary graded soil. In a binary graded mixture that contains coarse and fine grains, β increased non-linearly and lower values of β were obtained for denser samples. With an increase in the particle size ratio, the values of β and microscopic parameters such as the coarse-fine (C-F) particle contact decreased. The decrease in the C-F particle contact caused a decrease in β. An equation is proposed to estimate β based on the fines content and particle size ratio of the binary mixtures.

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Section: Simulation Of Undrained Behaviorsupporting

confidence: 80%

The role of fines content and particle size ratio on the load-bearing structure of binary granular soil: A micromechanical approach

Nia,

Bayesteh,

Khodaparast

2024

Preprint

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“…For uniform spheres with the same radius, e max = 0.90986, and e min = 0.35047 [40]. The current void ratio is expressed as e = u s 1 − u s (18) in which the porosity of the sample, u s , is numerically computed from the subtraction of the total volume of the cell and the total volume of the rigid spheres.…”

Section: Model Descriptionmentioning

confidence: 99%

“…Therefore, the advantage of the DEM is the ability to simulate the material microstructure and to represent directly and intrinsically the heterogeneous discrete nature of granular soils (e.g., particle shape and size distribution) [9]. DEM simulations have been conducted to replicate geotechnical testing such as the conventional monotonic triaxial test to derive the stress-strain behavior of the numerical specimen [10] and to show typical theoretical aspects such as dilatation and critical state behavior [11][12][13][14][15][16][17][18][19][20][21][22]. Most studies are based on the use of simplified sphere particle shapes to keep calculation costs as low as possible [11,14,[17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

“…DEM simulations have been conducted to replicate geotechnical testing such as the conventional monotonic triaxial test to derive the stress-strain behavior of the numerical specimen [10] and to show typical theoretical aspects such as dilatation and critical state behavior [11][12][13][14][15][16][17][18][19][20][21][22]. Most studies are based on the use of simplified sphere particle shapes to keep calculation costs as low as possible [11,14,[17][18][19][20][21][22]. On the other hand, spherical shapes can manifest excessive rolling, leading to an underestimation of the value of the friction angle as compared to real cohesionless soil [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

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Derivation of Cyclic Stiffness and Strength Degradation Curves of Sands through Discrete Element Modelling

Максимов

Tombari

2022

Modelling

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Cyclic degradation in fully saturated sands is a liquefaction phenomenon characterized by the progressive variation of the soil strength and stiffness that occurs when the soil is subjected to cyclic loading in undrained conditions. An evaluation of the relationships between the degradation of the soil properties and the number of loading cycles is essential for deriving advanced cyclic constitutive soil models. Generally, the calibration of cyclic damage models can be performed through controlled laboratory tests, such as cyclic triaxial testing. However, the undrained response of soils is dependent on several factors, such as the fabric, sample preparation, initial density, initial stress state, and stress path during loading; hence, a large number of tests would be required. On the other hand, the Discrete Element Method offers an interesting approach to simulating the complex behavior of an assembly of particles, which can be used to perform simulations of geotechnical laboratory testing. In this paper, numerical triaxial analyses of sands with different consistencies, loose and medium-dense states, were performed. First, static triaxial testing was performed to characterize the sand properties and validate the results with the literature data. Then, cyclic undrained triaxial testing was performed to investigate the impact of the number of cycles on the cyclic degradation of the soil stiffness and strength. Laws that can be used in damage soil models were derived.

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DEM studies on the effect of particle breakage on the critical state behaviours of granular soils under undrained shear conditions

et al. 2022

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A number of discrete element analyses of undrained triaxial shear tests on crushable assemblies are performed using 3-dimensional particle flow code (PFC3D). The undrained shear of the samples is simulated by assigning different velocities at the boundaries to control the constant volume of the samples during the shear. Particle breakage is studied using the octahedral shear stress breakage criterion and the fragment spawning mode satisfying an Apollonian sphere packing. The microparameters of the soils are obtained by simulating the test results reported on a Nansha calcareous sand. The effects of particle breakage and drainage condition on the critical state behaviours of the sand are intensively examined. It is found that particle breakage and drainage condition do not affect the slope of the critical state p′−q line. In the ecs−(p′cs/pa)0.7 space, the critical state line translates downward and rotates clockwise when particle breakage is considered, whilst drainage condition does not affect the critical state line. The intrinsic macro–micro correlations underlying the critical state behaviours are explored by analysing the evolution of representative micromechanical indicators such as coordination number, redundancy ratio, and fabric and force anisotropies.

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DEM Simulations of Granular Soils under Undrained Triaxial Compression and Plane Strain

Cited by 7 publications

References 12 publications

The role of fines content and particle size ratio on the load-bearing structure of binary granular soil: A micromechanical approach

The role of fines content and particle size ratio on the load-bearing structure of binary granular soil: A micromechanical approach

Derivation of Cyclic Stiffness and Strength Degradation Curves of Sands through Discrete Element Modelling

DEM studies on the effect of particle breakage on the critical state behaviours of granular soils under undrained shear conditions

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