Stress-induced anisotropy in sand under cyclic loading

Hu, Minyun; O’Sullivan, Catherine; Jardine, Richard; Jiang, Mingjing

doi:10.1007/s10035-010-0206-7

Cited by 41 publications

(12 citation statements)

References 22 publications

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“…Using micromechanics theory, they presented a link between interparticle force-displacement relationship to macroscopic stress-strain behavior. The morphological characteristics of the granular assembly (at the microscale) used in the simulations might substantially affect the predicted overall macroscopic behavior and that by taking into account the surface roughness, the numerical results are closer to the real behavior observed in laboratory tests (after Hu et al, 2010;Senetakis et al, 2013a;Yimsiri & Soga, 2000).…”

Section: Yimsiri and Soga Modelmentioning

confidence: 75%

Micromechanical Behavior of DNA‐1A Lunar Regolith Simulant in Comparison to Ottawa Sand

et al. 2019

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In this study, the micromechanical interparticle contact behavior of “De NoArtri” (DNA‐1A) grains is investigated, which is a lunar regolith simulant, using a custom‐built micromechanical loading apparatus, and the results on the DNA‐1A are compared with Ottawa sand which is a standard quartz soil. Material characterization is performed through several techniques. Based on microhardness intender and surface profiler analyses, it was found that the DNA‐1A grains had lower values of hardness and higher values of surface roughness compared to Ottawa sand grains. In normal contact micromechanical tests, the results showed that the DNA‐1A had softer behavior compared with Ottawa sand grains and that cumulative plastic displacements were observed for the DNA‐1A simulant during cyclic compression, whereas for Ottawa sand grains elastic displacements were dominant in the cyclic sequences. In tangential contact micromechanical tests, it was shown that the interparticle friction values of DNA‐1A were much greater than that of Ottawa sand grains, which was attributed to the softer contact response and greater roughness of the DNA‐1A grains. Widely used theoretical models both in normal and tangential directions were fitted to the experimental data to obtain representative parameters, which can be useful as input in numerical analyses which use the discrete element method.

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Section: Yimsiri and Soga Modelmentioning

confidence: 75%

Micromechanical Behavior of DNA‐1A Lunar Regolith Simulant in Comparison to Ottawa Sand

et al. 2019

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“…Today, the application of distinct element method in simulation of micromechanical behavior of granular soils is rapidly spreading. Substantial progress is made in DEM modeling of laboratory tests such as direct shear test [14], triaxial test [15], true triaxial test [16], cyclic triaxial test [17], cyclic loading [18], hollow cylinder torsional test [19] and oedometer consolidation test [20]. Elshamy and Zamani employed distinct element method to analyze the seismic response of shallow foundations considering soil-foundation-structure interactions.…”

Section: Distinct Element Methodsmentioning

confidence: 99%

Numerical analysis of ground improvement effects on dynamic settlement of uniform sand using DEM

Ahmadi

Sizkow

2020

SN Appl. Sci.

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Uniform fine sands are recognized as problematic soils which are highly prone to earthquake or dynamic loads effects. Cyclic and dynamic loads on such soils can destroy its structure and cause them to experience high volume change. In loose sands, volume change originated from dynamic or cyclic loadings (caused by earthquake, machineries or other similar sources) can lead to excessive settlements on the ground surface which in turn endangers the structural integrity and performance of the superstructure. As a consequence, it is important to perform soil improvements prior to putting any foundation on them. Among many known and recently developed techniques, the soil compaction (or densification) and cement injection are the widest techniques in fine sands improvement. In this research, a numerical study is employed which incorporates the distinct elements method to investigate the volume change and settlement of uniform fine sands. The results obtained numerically have been compared with those observed in a laminar shear box physical model of samples of fine sand. A surface footing is placed over the top of the specimen in the shear box which is modeled by a small rigid plate. Comparisons indicate that the applied simulation technique is suitable for the soil under study. To simulate the model and for verification purpose, Anzali sand physical and mechanical properties have been implemented. Soil particles in the discrete elements technique were modeled by spherical particles obeying the Anzali sand grain size distribution, and for the surface footing, rigid clumps of particles were used. Experiments were performed for density indices of 30-88%, and numerical simulations by the discrete elements method were performed at porosities of 0.43-0.38. The trend of dynamic settlement over the cyclic loading shows a good agreement with measured data in the laboratory. Results revealed that the improvement techniques such as compaction and cementation have a significant effect on the reduction in the final settlement under applied dynamic loads.

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“…The DEM enables us to accurately model the irregular shaped particles, particle breakage and the evolution of fabric anisotropy [31][32][33][34][35][36]. DEM can also examine the mechanical behaviour of a granular assembly consisting of a collection of arbitrarily shaped discrete particles subjected to quasi-static and dynamic conditions [37,38]. In DEM, the interaction between discrete particles can be considered as a dynamic process based on a time-stepping algorithm with an explicit finite difference scheme.…”

Section: Numerical Modelling Using the Discrete Element Methodsmentioning

confidence: 99%

A study of the geogrid–subballast interface via experimental evaluation and discrete element modelling

2017

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A study of the geogrid-subballast interface via experimental evaluation and A study of the geogrid-subballast interface via experimental evaluation and discrete element modelling discrete element modelling Abstract Abstract This paper presents a study of the interface of geogrid reinforced subballast through a series of largescale direct shear tests and discrete element modelling. Direct shear tests were carried out for subballast with and without geogrid inclusions under varying normal stresses of σ n = 6.7 to 45 kPa. Numerical modelling with three-dimensional discrete element method (DEM) was used to study the shear behaviour of the interface of subballast reinforced by geogrids. In this study, groups of 25-50 spherical balls are clumped together in appropriate sizes to simulate angular subballast grains, while the geogrid is modelled by bonding small spheres together to form the desired grid geometry and apertures. The calculated results of the shear stress ratio versus shear strain show a good agreement with the experimental data, indicating that the DEM model can capture the interface behaviour of subballast reinforced by geogrids. A micromechanical analysis has also been carried out to examine how the contact force distributions and fabric anisotropy evolve during shearing. This study shows that the shear strength of the interface is governed by the geogrid characteristics (i.e. their geometry and opening apertures). Of the three types of geogrid tested, triaxial geogrid (triangular apertures) exhibits higher interface shear strength than the biaxial geogrids; and this is believed due to multi-directional load distribution of the triaxial geogrid. ABSTRACTThis paper presents a study of the interface of geogrid reinforced subballast through a series of large-scale direct shear tests and discrete element modelling. Direct shear tests were carried out for subballast with and without geogrid inclusions under varying normal stresses of ߪ = 6.7 kPa to 45 kPa. Numerical modelling with three-dimensional discrete element method (DEM) was used to study the shear behaviour of the interface of subballast reinforced by geogrids.In this study, groups of 25-50 spherical balls are clumped together in appropriate sizes to simulate angular subballast grains, while the geogrid is modelled by bonding small spheres together to form the desired grid geometry and apertures. The calculated results of the shear stress ratio versus shear strain show a good agreement with the experimental data, indicating that the DEM model can capture the interface behaviour of subballast reinforced by geogrids. A micromechanical analysis has also been carried out to examine how the contact force distributions and fabric anisotropy evolve during shearing. This study shows that the shear strength of the interface is governed by the geogrid characteristics (i.e. their geometry and opening apertures). Of the three types of geogrid tested, triaxial geogrid (triangular apertures) exhibits higher interface shear strength than the biaxial geogrids; and thi...

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Stress-induced anisotropy in sand under cyclic loading

Cited by 41 publications

References 22 publications

Micromechanical Behavior of DNA‐1A Lunar Regolith Simulant in Comparison to Ottawa Sand

Micromechanical Behavior of DNA‐1A Lunar Regolith Simulant in Comparison to Ottawa Sand

Numerical analysis of ground improvement effects on dynamic settlement of uniform sand using DEM

A study of the geogrid–subballast interface via experimental evaluation and discrete element modelling

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