992
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
micromechanics of geomaterials. This discipline owes much of
its success to the Discrete Element Method (DEM), introduced
in the 1970s by Cundall & Strack (1970). DEM’s dominance in
micromechanical analysis remains unsurpassed, with all but a
few datasets at the particle scale arising from DEM simulations
(
e.g
., Cundall 1989, Oda & Iwashita 2000, Thornton & Zhang
2006, Anthony 2007, Tordesillas 2007, Zhu
et al.
2007, just to
mention a few). As pertinently enunciated by Sibille & Froiio
(2007): ‘
This has led to the paradox of micromechanics of
granular materials as a science based almost entirely on
“virtual evidence”
’.
On the experimental side, the past few years have witnessed
some major advances, possibly heralding a new era in
micromechanics of geomaterials. Measurements of contact
forces, contacts and grain kinematics in 2D idealized assemblies
of photoelastic discs have been achieved and analyzed (see the
work of Behringer and co-workers,
e.g
., Kondic
et al.
2012).
Experimental 3D measurements on natural geomaterials are
becoming possible at ever-increasing spatial resolution, and
researchers are facing an unprecedented opportunity to integrate
r complement these measurements with data from DEM
simulations to probe the rheology of geomaterials, just as
Terzaghi envisioned – from observations of behavior of
individual particles.
o
Experimental access to information at the micro scale allows
us to answer existing questions as well as to discover new
mechanisms operating across the spatial scales, from the
particle to the bulk. Of course, this new capability poses new
challenges to modeling. Measurements at the small scale have
an important role in revealing the physical origins of
phenomena observed at the macro scale. However, rational
theories are required to underpin this physics in terms of
predictive tools, with numerical computations that extend the
theoretical work, and allow for analysis of geomaterials with all
their complexities, variabilities and uncertainties. While it is
beyond any doubt that we can gain much from a more accurate
description of these features at the finer scales, a fundamental
issue (and the key challenge for the years to come) is to develop
models capable of integrating information at multiple scales.
This ambitious objective should be kept in mind as the
background for the papers discussed in this report.
Table 1. List of papers belonging to this session.
keywords
Authors
Country
Title
lab testing, sand, x-ray CT, compaction
Otani J.
et al.
Japan
France
Microscopic observation on compacted
sandy soil using micro-focus X-ray CT
lab testing, sand, x-ray CT, strain
localization
Andò E.
et al.
France
Sweden
Grain-scale experimental investigation
of shear banding in sand
lab testing, clay, micrographs, creep,
consolidation
Yigit I. & Cinicioglu S.F.
Turkey
A look into time dependent behaviour
of clays at macro and micro scale
lab testing, clay, chemical modification,
soil improvement
Minder P. & Puzrin A.M.
Switzerland
Microstructural changes leading to
chemically enhanced drainage
DEM, contact model, methane hydrates Jiang M.J.
et al.
China
A Simplified Contact Model for Sandy
Grains Cemented with Methane Hydrate
DEM, trapdoor, gravity flow, tunnel
Kikkawa N.
et al.
Japan
New Zealand
Three dimensional discrete element
simulation of trapdoor unloading and
gravity flow of sandy granular material
DEM, small strain, shear wave velocity
Ning Z. & Evans T.M.
USA
Discrete Element Method Study of
Shear Wave Propagation in Granular
Soil
DEM, computational fluid mechanics,
dense phase flow
Tomac I. & Gutierrez M.
USA Particulate Modeling of Sand Slurry
Flow Retardation
analytical, effective stress equation
Shao L.T.
et al.
China
Uniform effective stress equation for
soil mechanics
analytical, granular materials, crushing,
abrasion, poly-disperse mixtures,
compaction
Caicedo B.
et al.
Colombia
USA
Modelling crushing of granular
materials as a poly-disperse mixture
FEM, multi-scale modeling, wellbore
damage
Khoa H.D.V.
et al.
Norway
Macro- and micro-FE modelling of
wellbore damage due to drilling and
coring processes
lab testing, sand, plane strain, high
pressure, methane hydrates
Hyodo M.
et al.
Japan
Shear strength and deformation of
methane hydrate bearing sand with fines
Lattice Boltzmann Method, relative
permeability, petroleum geomechanics
Pak A. & Sheikh B.
Iran
Study of relative permeability variation
during unsteady flow in saturated
reservoir rock using Lattice Boltzmann
method
lab testing, compacted soil, shear
strength, constant water content, direct
shear test
Heitor A.
et al.
Australia
Behaviour of a compacted silty sand
under constant water content shearing
lab testing, unsaturated soils, resilient
modulus, thermo-hydro-mechanics
Zhou C. & Ng C.W.W.
Hong Kong
Experimental study of resilient modulus
of unsaturated soil at different
temperatures
