ProfessorCatherineO'Sullivan

My research considers discrete element analysis and the micro-mechanics of granular materials.  My full list of publications is available here or at my google scholar page.

JOSE SALOMON

2022 - present

YOHEI NAKAMICHI

Oct 2021 - present

tara Sassel

Oct 2018 - present

DR. peter adesina

PhD 2022, Imperial College London

The Effects of Particle Shape and Sample Grading on the Behaviour of Granular Materials 

DR.Tokio Morimoto

PhD 2022, Imperial College London

Particle-scale numerical simulation of the thermal behaviour of granular materials

DR.DEYUN Liu

PhD 2022, Imperial College London

Investigating the mechanical behaviour of gap-graded soils: from micro to macro 

DR. Sara Bandera

PhD 2021, Imperial College London

Fundamental analysis of the Influence of structure on clay behaviour

DR. Hoang Nguyen

PhD 2021, Imperial College Londont

Micromechanics of shear wave propagation and non-linear stiffness of granular materials

DR. CHRIS KNIGHT

PhD 2019, Imperial College Londont

Fluid flow and drag in polydisperse granular materials subject to laminar seepage flow

DR. MASAHIDE OTSUBO

PhD 2017, Imperial College London

Particle scale analysis of soil stiffness and elastic wave propagation

DR. KENICHI KAWANO 

MPhil, 2017, Imperial College London

Numerical evaluation of internal erosion due to seepage flow

DR. HOWARD TAYLOR 

PhD 2016, Imperial College London

Assessing the potential for suffusion in sands using x-ray micro-CT images

DR. Thomas Shire

PhD 2014 Imperial College London

Micromechanical study of suffusion in soils

DR. xin huang

PhD 2014 Imperial College London and University of Hong Kong (Joint PhD)

Exploring critical-state behaviour using DEM

DR.John O'Donovan

PhD 2014 Imperial College London

Discrete element simulations of wave propagation in soil

DR. Aine Ni Bhreasail

PhD 2013 Imperial College London

Micro computed tomography to study micro mechanics of permafrost

Dr. CHIN-KANG SHEN

A micro-mechanical investigation of drained simple shear tests on dense sand using discrete element simulations

PhD 2012, Imperial College London

Dr Joana Fonseca

The evolution of morphology and fabric of a sand during shearing

PhD, 2011, Imperial College London

Dr. LOK YEE GERALDINE CHEUNG

Micromechanics of sand production in oil wells

PhD 2010, University of London

Dr. IGNAZIO CAVARRETTA

The influence of particle characteristics on the engineering behaviour of granular materials

PhD  2009, University of London

DR. Daniel Barretto

Numerical and experimental investigation in to the behaviour of granular amterials under generalised stress states.

PhD 2009, University of London

Dr. Liang Cui

Developing a Virtual Test Environment for Granular Materials Using
Discrete Element Modelling

PhD 2006, University College Dublin

• In June 2018 Catherine delivered a special lecture to the Japanese Geotechnical Society entitled " A particle scale perspective on internal erosion and filter design.  Her presentation slides"  are here.
• Catherine delivered a presentation on the use of DEM to advance understanding of load:deformation response at the Institute of Industrial Science at the University of Tokyo in June 2018.  Her presentation slides are  here.
• Catherine presented some of her recent research at the 2018 Pre-Rakine Seminar.  Her presentation slides are here.
• Catherine participated in the 25th meeting of the ICOLD European Working Group on Internal Erosion in Sept 2017.  Her presentation slides are here.
• Catherine participated in the 25th meeting of the ICOLD European Working Group on Internal Erosion in Sept 2017.  Her presentation slides are here.
• In October 2016 Catherine participated in a 1 day Doctoral School on DEM held in conjunction with the GEO-RAMP RISE project. The presentation was titled Developing robust DEM models to simulate element tests
• Catherine visited Japan in May 2016 and delivered a presentation at IMS Chibu entitled Underpinning Empiricism with Particulate Soil Mechanics.
• Catherine gave the 2015 BGA Geotechnique lecture on Nov 17 2015. A pdf of the presentation is available.

MicroCT Image of Sand Illustrating Individual Particles and Voids (PhD Howard Taylor 2016)

 Micro-computed tomography (microCT) allows us to  image real materials and observe their particle-scale kinematics.

• In his doctoral research Dr. Howard Taylor used MicroCT to consider filters.  Taylor et al.(2015)  describe how to identify individual voids from microCT images of sand.  In a later contribution Taylor et al. (2016) compared geometric and hydraulic constrictions.
• The doctoral research of Dr. Joana Fonseca considered the mechanical behaviour of a locked sand.  During this research we quantified the soil fabric (Fonseca et al. 2013a and Fonseca et al. 2013b) and also particle morphology (Fonseca et al. 2012).
• Ni Bhreasail et al. (2012) looked at the development of cracks in frozen soil. 
• Fonseca et al. (2014) applied microCT to look at internally unstable soils that are susceptible to internal erosion.

DEM models are highly idealized and so it is important to verify these models as well as to establish their limitations and this has been a key research theme.

Direct shear test: comparison of physical tests and DEM simulation (Cui and O'Sullivan, 2016)

•  O'Sullivan et al. (2002) and  O'Sullivan et al. (2004)  considered uniform spheres and disks and compared experiments and DEM simulations.
• Again directly comparing DEM simulations and experiments, the large strain behaviour of random assemblies of spheres was considered for the direct shear test (Cui and O'Sullivan, 2006) , triaxial tests  (Cui et al., 2007; Cui et al. 2008; O'Sullivan and Cui, 2008) and the simple shear apparatus (Bernhardt et al. 2016). 
• An EPSRC funded project in collaboration with the University of Bristol (EP/G064954/1) considered small strain stiffness and wave propagation (O'Donovan et al. 2016).
• Validation and calibration differ:  Cheung et al. (2013)   calibrated a DEM model to capture the response of reservoir sandstones, while Hanley et al. (2011) explored optimization strategies to achieve effective calibration.
• Research into the DEM method itself has considered time integration (O'Sullivan and Bray, 2004; Otsubo et al 2017) and accuracy (Hanley and O'Sullivan, 2017).  Huang et al.(2014a) , Huang et al.(2014b) and Lopera Perez (2016) consider best practice in running DEM simulations.

Combined experimental and DEM analysis of surface roughness effects on stiffness (PhD Otsubo, 2017)

• The doctoral research of Dr. Masahide Otsubo looked at the influence of roughness on stiffness using DEM and experimental approaches.  In collaboration with the University of Bristol, Otsubo et al. (2015) examined the influence of surface roughness on small strain stiffness experimentally.  This contribution was followed by a DEM-based consideration of surface roughness effects in Otsubo et al. (2016).   Otsubo et al. (2016) examined the influence of both stress level and packing density on the dynamic response of granular materials.
• In collaboration with the University of Bristol, an EPSRC funded study (grant  EP/G064954/1)  focussed on the particle-scale mechanisms of shear wave propagation, focussing on bender element test interpretation. The initial publications from this study focussed on two-dimensional systems (O'Donovan et al. 2012) and (Marketos and O'Sullivan 2013).  O'Donovan et al. 2015a and O'Donovan et al. 2015b considered stiffness and wave propagation in three dimensions for an ideal, lattice material. Comparison of the numerical model and experimental results is given in O'Donovan et al. 2014.

EPSRC grant EP/D50631X/1 funded the doctoral research of Dr. Daniel Barreto.  As summarized in Barreto and O'Sullivan (2012) and further developed in O'Sullivan et al. (2013), a key outcome from this study is the demonstration that the sensitivity of soil strength to the intermediate principal stress ratio is a consequence of the way in which the force chains of highly stressed particles buckle under the three dimensional stress state. 

Developing this line of research, we have considered how the intermediate principal stress influences the position of the critical state line (Huang et al. 2014a).  Huang et al. (2014b) used DEM to show the applicability of the state parameter as a predictor of soil behaviour in a three-dimensional stress state.

Also considering large-strain behaviour Hanley et al. 2015 considered particle crushing in compression and shear.

• Knight et. al (2020) uses fully resolved DEM-CFD (immersed boundary method) to critically appraise the drag force models currently used in resolved DEM-CFD simulations in geomechanics.
• Shire and O'Sullivan (2017) used a network model to assess base-filter combinations. Shire and O'Sullivan (2016) discuss the link between the constriction size distribution and the particle size distribution in sand.  O'Sullivan et al. (2015) consider how to identify these constrictions.  Taylor et al. (2018) consider both constriction size and spacing using DEM and microCT.
• Taylor et al. (2017) and Taylor et al.(2016) applied computational fluid dynamics to pore topology data from microCT to study the fundamentals of sand permeability.
• Shire et al. (2016) and Shire et al. (2014) consider the stress distribution in gap-graded soils to give insight into internal erosion in dams and embankments.  Complementary research using microCT is described in Fonseca et al.(2014).