All Outputs (23)

A study of membrane correction accounting for both curvature and tension in DEM simulations of triaxial tests of sand and ballast with two alternative flexible membrane models (2024)
Journal Article
Tolomeo, M., & McDowell, G. R. (2024). A study of membrane correction accounting for both curvature and tension in DEM simulations of triaxial tests of sand and ballast with two alternative flexible membrane models. Granular Matter, 26(2), Article 47. https://doi.org/10.1007/s10035-024-01419-1

In DEM simulations of triaxial tests, modelling a flexible lateral membrane is crucial and challenging. It is essential for the correct application of a uniform lateral pressure and for an accurate measurement of sample volume. Here, we introduce a m... Read More about A study of membrane correction accounting for both curvature and tension in DEM simulations of triaxial tests of sand and ballast with two alternative flexible membrane models.

Modelling the mechanical behaviour of clay using particle-scale simulations (2024)
Journal Article
de Bono, J., & McDowell, G. (2024). Modelling the mechanical behaviour of clay using particle-scale simulations. Granular Matter, 26(2), Article 29. https://doi.org/10.1007/s10035-024-01401-x

This paper demonstrates the latest developments in particle-scale modelling of a clay. It shows that by creating an initial sample of platelets featuring aggregated stacks, excellent macroscopic behaviour is achieved. This approach is justified by ex... Read More about Modelling the mechanical behaviour of clay using particle-scale simulations.

A particle-scale analysis of unload-reload hysteresis for normally consolidated kaolin (2023)
Journal Article
de Bono, J., & McDowell, G. (2023). A particle-scale analysis of unload-reload hysteresis for normally consolidated kaolin. Applied Clay Science, 246, Article 107190. https://doi.org/10.1016/j.clay.2023.107190

The mechanical behaviour of sands and clays subject to “normal” (plastic) compression are very similar, albeit at different stress levels, despite the differences in inter-particle interactions (Hertzian normal contact forces or similar for sand) and... Read More about A particle-scale analysis of unload-reload hysteresis for normally consolidated kaolin.

DEM study of an “avatar” railway ballast with real particle shape, fabric and contact mechanics (2023)
Journal Article
Tolomeo, M., & McDowell, G. R. (2023). DEM study of an “avatar” railway ballast with real particle shape, fabric and contact mechanics. Granular Matter, 25(2), Article 32. https://doi.org/10.1007/s10035-023-01322-1

In this paper we show DEM simulations of static and cyclic large triaxial tests on a sample of railway ballast. The sample is reconstructed from X-Ray tomography images of an untested laboratory sample, recovered by impregnation with an epoxy resin.... Read More about DEM study of an “avatar” railway ballast with real particle shape, fabric and contact mechanics.

Simulating multifaceted interactions between kaolinite platelets (2022)
Journal Article
de Bono, J., & McDowell, G. (2023). Simulating multifaceted interactions between kaolinite platelets. Powder Technology, 413, Article 118062. https://doi.org/10.1016/j.powtec.2022.118062

It is well known that kaolinite platelets readily aggregate into ‘stacks’, having face-to-face contact. The traditional view of kaolin has been that the platelet faces are negatively charged and the edges are positively charged in an acidic environme... Read More about Simulating multifaceted interactions between kaolinite platelets.

Implementation of real contact behaviour in the DEM modelling of triaxial tests on railway ballast (2022)
Journal Article
Tolomeo, M., & McDowell, G. R. (2022). Implementation of real contact behaviour in the DEM modelling of triaxial tests on railway ballast. Powder Technology, 412, Article 118021. https://doi.org/10.1016/j.powtec.2022.118021

In the Discrete Element modelling of soils, the micromechanical behaviour at contacts has often been considered to have a minor influence on the macromechanical response, leaving basic theoretical models (e.g., Hertz) to describe the contact response... Read More about Implementation of real contact behaviour in the DEM modelling of triaxial tests on railway ballast.

Modelling real particle shape in DEM: a comparison of two methods with application to railway ballast (2022)
Journal Article
Tolomeo, M., & McDowell, G. R. (2022). Modelling real particle shape in DEM: a comparison of two methods with application to railway ballast. International Journal of Rock Mechanics and Mining Sciences, 159, Article 105221. https://doi.org/10.1016/j.ijrmms.2022.105221

Two different methods for the modelling of real particle shape in 3D DEM simulations are assessed in this paper. The first method uses overlapping spheres (clumps), while the second uses a block defined as a closed and convex polyhedron. The two meth... Read More about Modelling real particle shape in DEM: a comparison of two methods with application to railway ballast.

Discrete element modelling of normal compression of clay (2022)
Journal Article
de Bono, J. P., & McDowell, G. R. (2022). Discrete element modelling of normal compression of clay. Journal of the Mechanics and Physics of Solids, 162, Article 104847. https://doi.org/10.1016/j.jmps.2022.104847

The discrete element method (DEM) has only rarely been used to simulate clay, due to difficulties in modelling clay particle shape and capturing the various particle interactions. This paper presents a new approach to simulate clay in three dimension... Read More about Discrete element modelling of normal compression of clay.

Some important aspects of modelling clay platelet interactions using DEM (2021)
Journal Article
de Bono, J. P., & McDowell, G. R. (2022). Some important aspects of modelling clay platelet interactions using DEM. Powder Technology, 398, Article 117056. https://doi.org/10.1016/j.powtec.2021.117056

The discrete element method (DEM) is a popular tool for simulating soils, however it has rarely been used for modelling clays. This is despite the behaviour of clays being much less well understood compared to sands. This paper aims to increase the u... Read More about Some important aspects of modelling clay platelet interactions using DEM.

Relating Hydraulic Conductivity to Particle Size Using DEM (2020)
Journal Article
McDowell, G., & de Bono, J. (2021). Relating Hydraulic Conductivity to Particle Size Using DEM. International Journal of Geomechanics, 21(1), Article 0602003. https://doi.org/10.1061/%28asce%29gm.1943-5622.0001670

For over 100 years it has been accepted that the permeability or hydraulic conductivity of a soil is controlled by the size of pores through which the fluid flows, and that this pore size should be a function of particle sizes. All well-known formula... Read More about Relating Hydraulic Conductivity to Particle Size Using DEM.

Discrete element modelling of two-layered ballast in a box test (2020)
Journal Article
Li, H., & Mcdowell, G. (2020). Discrete element modelling of two-layered ballast in a box test. Granular Matter, 22, Article 76. https://doi.org/10.1007/s10035-020-01046-6

It has been recently reported that ballast comprising differently graded layers helps to reduce track settlement. The main goal of this paper is to provide micro mechanical insight about how the differently layered ballasts reduce the settlement by e... Read More about Discrete element modelling of two-layered ballast in a box test.

A new abrasive wear model for railway ballast (2020)
Journal Article
De Bono, J., Li, H., & McDowell, G. (2020). A new abrasive wear model for railway ballast. Soils and Foundations, 60(3), 714-721. https://doi.org/10.1016/j.sandf.2020.05.001

A new method to model the abrasion of granular particles using the discrete element method is demonstrated in this paper. This new, simple method is based on a classical theory of abrasive wear, relating the volume of solid lost to the frictional wor... Read More about A new abrasive wear model for railway ballast.

The effects of particle shape on the yielding behaviour of crushable sand (2020)
Journal Article
De Bono, J., & Mcdowell, G. (2020). The effects of particle shape on the yielding behaviour of crushable sand. Soils and Foundations, 60(2), 520-532. https://doi.org/10.1016/j.sandf.2020.04.001

Discrete element method simulations are used to investigate the effects of particle shape on the plastic behaviour of sand. This is achieved by using four different shapes of crushable particles. The behaviours of the different particles when subject... Read More about The effects of particle shape on the yielding behaviour of crushable sand.

On the packing and crushing of granular materials (2018)
Journal Article
de Bono, J. P., & McDowell, G. R. (2020). On the packing and crushing of granular materials. International Journal of Solids and Structures, 187, 133-140. https://doi.org/10.1016/j.ijsolstr.2018.07.011

This paper is a study of the dependence of the volume of voids in a granular material on the particle size distribution. It has previously been proposed that the volume of voids is proportional to the volume of the smallest particles. In a particle s... Read More about On the packing and crushing of granular materials.

On the micro mechanics of yielding and hardening of crushable granular soils (2018)
Journal Article
de Bono, J. P., & McDowell, G. R. (2018). On the micro mechanics of yielding and hardening of crushable granular soils. Computers and Geotechnics, 97, https://doi.org/10.1016/j.compgeo.2018.01.010

Stress path tests are used to investigate the yield surface of a crushable numerical soil. Triaxial samples with isotropic and anisotropic stress histories are examined to determine the nature of the yield surface and to establish what governs yield.... Read More about On the micro mechanics of yielding and hardening of crushable granular soils.

Micro mechanics of drained and undrained shearing of compacted and overconsolidated crushable sand (2017)
Journal Article
de Bono, J. P., & McDowell, G. R. (2018). Micro mechanics of drained and undrained shearing of compacted and overconsolidated crushable sand. Géotechnique, 68(7), 575-589. https://doi.org/10.1680/jgeot.16.P.318

A numerical crushable soil sample has been created using the previously published McDowell and de Bono (2013) model and subjected to a range of stress paths. Compacted sand simulations are performed using conventional triaxial stress paths, constant... Read More about Micro mechanics of drained and undrained shearing of compacted and overconsolidated crushable sand.

Validation of the log e–log σ normal compression law using particle strength data (2017)
Journal Article
de Bono, J. P., & McDowell, G. R. (in press). Validation of the log e–log σ normal compression law using particle strength data. Géotechnique, https://doi.org/10.1680/jgeot.17.T.007

This note is a study of experimental data on particle strength and normal compression, to establish whether the recently proposed normal compression law by McDowell and de Bono (2013) is supported and confirmed. A number of different sands are examin... Read More about Validation of the log e–log σ normal compression law using particle strength data.

Investigating the effects of particle shape on normal compression and overconsolidation using DEM (2016)
Journal Article
de Bono, J. P., & McDowell, G. R. (in press). Investigating the effects of particle shape on normal compression and overconsolidation using DEM. Granular Matter, 18(3), https://doi.org/10.1007/s10035-016-0605-5

Discrete element modelling of normal compression has been simulated on a sample of breakable two-ball clumps and compared to that of spheres. In both cases the size effect on strength is assumed to be that of real silica sand. The slopes of the norma... Read More about Investigating the effects of particle shape on normal compression and overconsolidation using DEM.

The fractal micro mechanics of normal compression (2016)
Journal Article
de Bono, J. P., & McDowell, G. R. (2016). The fractal micro mechanics of normal compression. Computers and Geotechnics, 78, 11-24. https://doi.org/10.1016/j.compgeo.2016.04.018

The fundamental fractal micro mechanics of normal compression of granular materials is studied using DEM. This paper examines the emergence of a finite fractal bounded by two particle sizes as stress increases, and the evolution of various definition... Read More about The fractal micro mechanics of normal compression.

Micro mechanics of critical states for isotropically overconsolidated sand (2015)
Journal Article
McDowell, G. R., Yue, P., & de Bono, J. P. (2015). Micro mechanics of critical states for isotropically overconsolidated sand. Powder Technology, 283, https://doi.org/10.1016/j.powtec.2015.05.043

The discrete element method has been used to investigate the micro mechanics of shearing to a critical state on the loose and dense sides of critical. Isotropic compression has previously been modelled in 3D using a large number of particles and with... Read More about Micro mechanics of critical states for isotropically overconsolidated sand.