377
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Effect of Particle Characteristics on K
0
Behavior for Granular Materials
Effet des Caractéristiques Particulaires sur le Comportement des Matériaux Granulaires K
0
Junhwan Lee
Professor, School of Civil and Env. Eng., Yonsei University, Seoul, Korea
Dongyu Park
Ph.D. candidate, School of Civil and Env. Eng., Yonsei University, Seoul, Korea
Doohyun Kyung
Ph.D. candidate, School of Civil and Env. Eng., Yonsei University, Seoul, Korea
Dongyoel Lee
Graduate Research Assistant, School of Civil and Env. Eng., Yonsei University, Seoul, Korea
ABSTRACT:
The Jaky’s K
0
equation is commonly used for the estimation of K
0
in practice, which is given as a function of the
internal friction angle of soils. As the friction angle is a state-dependent variable, uncertain aspect still exists regarding the value of to
be adopted for the Jaky’s K
0
equation. In this study, the application of the Jaky’s K
0
equation for granular materials is investigated
with focus on the effect of particle characteristics, which are related to strength, on K
0
behavior. Particle shape and angularity of
particles are considered for the investigation of K
0
behavior. Experimental testing program is established to measure K
0
under various
mechanical and physical conditions of test materials. Sand particles and spherically shpaed glass beads with and without etched
particle surfaces are employed into the experimental testing program.
RÉSUMÉ: L'équation K
0
de Jaky est couramment utilisée pour l'estimation de K
0
en pratique, ce qui est donnée en fonction de l’angle
de frottement interne du sol. Comme l’angle de frottement est une variable dépendant de l'état, l'aspect incertain existe enc
ore au sujet
de la valeur qui sera adoptée pour l'équation K
0
de Jaky. Dans cette étude, l’application de l'équation K
0
de Jaky pour les matériaux
granulaires est étudiée, en particulier par rapport à l'effet des caractéristiques des particules, qui sont liés à la résistance sur le
comportement de K
0
. La forme et l'angularité des particules sont considérées comme des enquêtes sur le comportement de K
0
. Le
programme d'essais expérimentaux est prévu pour mesurer le K
0
dans différentes conditions mécaniques et physiques des matériaux
d'essai. Les particules de sable et de billes de verre en forme sphérique avec et sans surfaces des particules gravées sont utilisées dans
le programme d'essai expérimental.
KEYWORDS: coefficient of lateral earth pressure, granular materials, internal friction angle, thin wall oedometer test
1
INTRODUCTION
In-situ stresses are important state soil variables that are
necessary for geotechnical analysis and design. The Jaky
’
s K
0
equation (Jaky 1944) is commonly used in practice to evaluate
K
0
based on the internal friction angle of soils. In fact, it was
analytically derived assuming equilibrium condition for a sand
pile with the statically admissible stress state. From the analysis
using various assumptions on the stress distribution, it was
confirmed that the Jaky
’
s K
0
equation is valid and sufficiently
accurate for general geotechnical purposes (Michalowski 2005).
According to the Jaky
’
s K
0
equation, K
0
is given as a sole
function of the friction angle of soils, while K
0
itself represents
the state soil variable that defines the geostatic stress state
before failure.
The friction angle of soils can be differently defined.
Common definition adopted in geotechnical engineering
includes the peak, critical state, and dilatancy friction angles.
The peak friction angle
p
corresponds to the maximum peak
strength, and is composed of the critical state friction angle
c
and the dilatancy friction angle
p
. The dilatancy friction angle
p
is state-dependent varying as a function of the confining
stress and relative density. The critical state friction angle
c
is
an intrinsic soil variable that is dependent only on the inherent
soil characteristics such as mineralogy, particle shape, and
angularity. From the Jaky
’
s K
0
equation, the highest and lowest
K
0
values would be obtained from the critical state friction
angle
c
and the peak friction angle
p
, respectively.
In this study, the application of the Jaky
’
s K
0
equation for
granular materials is investigated focusing on the effect of
various particle characteristics such as particle shape, surface
roughness, and relative density on the
-K
0
correlation. The
variation of K
0
calculated using different types of friction angles
is analyzed. For this purpose, an experimental testing program
is established to measure K
0
under various soil and stress
conditions. The tested granular assemblies include natural sand
particles and spherical glass beads with and without etched
particle surfaces.
2
CORRELATION OF K
0
Jaky (1944, 1948) presented the well-known K
0
equation based
on the stress analysis of a geometrically symmetric sand wedge,
assuming a limit stress state. K
0
is defined as a function of the
internal friction angle
of soils as given by:
sin 1
sin
3
2 1
)
sin 1(
0
K
(1)
Where
= internal frictional angle of soils. Eq. (1) can be
further simplified as a form that has been a norm in current
practice, given as follows:
sin 1
0
K
(2)
It is indicated that the denser the sand, the higher the
,
resulting in lower K
0
values. The effect of stress history on K
0
is
significant. K
0
for overconsolidated (OC) condition is greater
than for normally consolidated (NC) condition (Wroth 1973). In
order to reflect the effect of stress history on K
0
, modifications
into Eq. (2) have been proposed in a form of:
Effect of Particle characteristics on K
0
Behavior for Granular Materials
Effet des caractéristiques particulaires sur le comportement des matériaux granulaires K
0
Lee J., Park D., Kyung D., Lee D.
School of Civil and Env. Eng., Yonsei University, Seoul, Korea
