Research Repository

See what's under the surface


Micro mechanics of the critical state line at high stresses (2018)
Journal Article
de Bono, J. P., & McDowell, G. R. (2018). Micro mechanics of the critical state line at high stresses. Computers and Geotechnics, 98, doi:10.1016/j.compgeo.2018.02.016. ISSN 0266-352X

A critical state line is presented for a crushable numerical soil, which is parallel to the isotropic normal compression line. A previous theory for the normal compression line, which correctly predicts the slope as a function of the size-effect on p... Read More

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, doi:10.1016/j.compgeo.2018.01.010. ISSN 0266-352X

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

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), doi:10.1680/jgeot.16.P.318. ISSN 0016-8505

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

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, doi:10.1680/jgeot.17.T.007. ISSN 0016-8505

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

Particle breakage criteria in discrete-element modelling (2016)
Journal Article
de Bono, J. P., & McDowell, G. R. (in press). Particle breakage criteria in discrete-element modelling. Géotechnique, doi:10.1680/jgeot.15.P.280. ISSN 0016-8505

Previous work by the authors, using the discrete element method (DEM) has used the octahedral shear stress within a sphere together with a Weibull distribution of strengths and a size effect on average strength, to determine whether fracture occurs o... Read More

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), doi:10.1007/s10035-016-0605-5. ISSN 1434-5021

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

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, doi:10.1016/j.compgeo.2016.04.018. ISSN 0266-352X

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

On the micro mechanics of one-dimensional normal compression (2015)
Journal Article
McDowell, G. R., & de Bono, J. P. (2015). On the micro mechanics of one-dimensional normal compression. Géotechnique, 63(11), doi:10.1680/geot.12.P.041. ISSN 0016-8505

Discrete-element modelling has been used to investigate the micro mechanics of one-dimensional compression. One-dimensional compression is modelled in three dimensions using an oedometer and a large number of particles, and without the use of agglome... Read More

Discrete element modelling and cavity expansion analysis of cone penetration testing (2015)
Journal Article
Falagush, O., McDowell, G. R., Yu, H., & de Bono, J. P. (in press). Discrete element modelling and cavity expansion analysis of cone penetration testing. Granular Matter, 17(4), doi:10.1007/s10035-015-0570-4. ISSN 1434-5021

This paper uses the discrete element method (DEM) in three dimensions to simulate cone penetration testing (CPT) of granular materials in a calibration chamber. Several researchers have used different numerical techniques such as strain path methods... Read More

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, doi:10.1016/j.powtec.2015.05.043. ISSN 0032-5910

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

Discrete element modelling of creep of asphalt mixtures (2015)
Journal Article
Cai, W., McDowell, G. R., Airey, G., & de Bono, J. P. (in press). Discrete element modelling of creep of asphalt mixtures. Geomechanics and Geoengineering, 11(1), doi:10.1080/17486025.2015.1006689. ISSN 1748-6025

Creep tests on asphalt mixtures have been undertaken under four stress levels in the laboratory while the Discrete Element Model (DEM) has been used to simulate the laboratory tests. A modified Burger’s model has been used to represent the time-depen... Read More

Investigating the micro mechanics of cemented sand using DEM (2014)
Journal Article
de Bono, J. P., McDowell, G. R., & Wanatowski, D. (2015). Investigating the micro mechanics of cemented sand using DEM. International Journal for Numerical and Analytical Methods in Geomechanics, 39(6), doi:10.1002/nag.2340. ISSN 0363-9061

The discrete element method has been used to investigate the micro mechanics of cemented sand. High pressure drained triaxial tests are modelled in 3D using a flexible membrane which allows the correct deformation to develop. Simulations with up to... Read More

An insight into the yielding and normal compression of sand with irregularly-shaped particles using DEM (2014)
Journal Article
de Bono, J. P., & McDowell, G. R. (2015). An insight into the yielding and normal compression of sand with irregularly-shaped particles using DEM. Powder Technology, 271, doi:10.1016/j.powtec.2014.11.013. ISSN 0032-5910

The micro mechanics of one-dimensional and isotropic normal compression of granular soil have recently been revealed using the discrete element method. By modelling soil grains as spheres and implementing a new crushing model, the authors have previo... Read More

DEM of triaxial tests on crushable cemented sand (2014)
Journal Article
de Bono, J. P., McDowell, G. R., & Wanatowski, D. (2014). DEM of triaxial tests on crushable cemented sand. Granular Matter, 16(4), doi:10.1007/s10035-014-0502-8. ISSN 1434-5021

Using the discrete element method, triaxial simulations of cemented sand consisting of crushable particles are presented. The triaxial model used features a flexible membrane, allowing realistic deformation to occur, and cementation is modelled using... Read More

Discrete element modelling of one-dimensional compression of cemented sand (2013)
Journal Article
de Bono, J. P., & McDowell, G. R. (2014). Discrete element modelling of one-dimensional compression of cemented sand. Granular Matter, 16(1), doi:10.1007/s10035-013-0466-0. ISSN 1434-5021

It has recently been shown that the one-dimensional normal compression of sand can be modelled effectively in three-dimensions using the discrete element method, and that the slope of the compression curve (in log voids ratio–log stress space) is con... Read More

Micro mechanics of isotropic normal compression (2013)
Journal Article
McDowell, G. R., de Bono, J. P., Yue, P., & Yu, H. (2013). Micro mechanics of isotropic normal compression. Géotechnique Letters, 3(4), doi:10.1680/geolett.13.00050. ISSN 2045-2543

Discrete element modelling has been used to investigate the micro mechanics of isotropic normal compression. One-dimensional (1D) normal compression has previously been modelled in three dimensions using an oedometer and a large number of particles a... Read More

Discrete element modelling of a flexible membrane for triaxial testing of granular material at high pressures (2012)
Journal Article
testing of granular material at high pressures. Géotechnique Letters, 2(4), doi:10.1680/geolett.12.00040. ISSN 2045-2543

The discrete element method (DEM) has been used to simulate triaxial tests on a bonded material at high pressures. A key feature of the model is the use of a flexible membrane that allows the correct volumetric deformation and the true failure mode... Read More