239
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
1
Comparison of the geotechnical properties of pumice sand from Japan and New
Zealand
Comparaison des propriétés géotechniques de sables de pierre ponce du Japon et de Nouvelle-
Zélande
N. Kikkawa
National Institute of Occupational Safety and Health, Japan
M. J. Pender & R. P. Orense
University of Auckland, New Zealand
ABSTRACT: The geotechnical properties of pumice sands from Japan and New Zealand are compared. Both of these materials are
characterised by the presence of particles that are easily crushed against a hard surface under fingernail pressure. The paper gives
data on the changes in particle size distribution before and after hydrostatic compression and drained triaxial shear. It is apparent from
the results of drained triaxial compression tests that the shear stress continues to climb with increasing shear strain, so that there is not
a well-defined friction angle. However, the mobilised friction angle reaches quite large values when the mean principal effective
stress is in the range of a few hundred kPa, but decreases as the mean principal effective stress increases further. A particularly
interesting feature of the drained shear behaviour of the materials is that with a sufficiently large confining pressure they tend to
deform in one-dimensional compression. In general terms, the properties of these two materials of different origin are quite similar.
RESUME: On compare les propriétés géotechniques de sables de pierre ponce provenant du Japon et de Nouvelle-Zélande. Ces deux
types de matériaux sont caractérisés par la présence de particules qui sont facilement écrasées contre une surface dure sous la pression
de l'ongle. Des données sont fournies sur les modifications de distribution granulométrique des particules avant et après compression
hydrostatique et cisaillement triaxial drainé. Il ressort des résultats d'essais de compression triaxiale drainée que la contrai nte de
cisaillement continue d'augmenter avec l'augmentation de la déformation de cisaillement, de telle sorte qu'il n'y a pas
d’
angle de
frottement bien défini. Toutefois, l'angle de frottement mobilisé atteint des valeurs très élevées lorsque la contrainte effective
principale moyenne est de l'ordre de quelques centaines de kPa, mais diminue à mesure que la contrainte effective principale moyenne
continue de croître. Une caractéristique particulièrement intéressante du comportement en cisaillement drainé de ces matériaux est
qu'avec une pression de confinement suffisamment élevée, ils ont tendance à se déformer en compression unidimensionnelle. De
manière générale, les propriétés de ces deux matériaux
d’origines différentes
sont tout à fait similaires.
KEYWORDS: pumice, particle crushing, shear strength mobilisation, lateral strain during drained shear
MOTS CLES : pierre ponce, écrasement de particules, mobilisation du cisaillement, déformation latérale en cisaillement drainé
1 INTRODUCTION
Pumice sands derived from volcanic activity are found in Japan
and New Zealand. Both of these materials are characterised by
the presence of particles that are easily crushed against a hard
surface under fingernail pressure. In this paper we compare the
geotechnical properties of these materials. The composition of
both pumice sands is dominated by silica and aluminium oxide.
Pumice deposits are found in several areas in New Zealand.
They originated from a series of volcanic eruptions centred in
the Taupo and Rotorua regions of the central North Island.
Although they do not cover wide areas, their concentration in
river valleys and flood plains means they tend to coincide with
areas of considerable human activity and development. Thus,
they are frequently encountered in engineering projects and
their evaluation is a matter of considerable geotechnical interest.
Further information about the properties of New Zealand
pumice sand are given by Wesley et al (1999), Pender et al
(2006) and Naotaka et al (2011).
The Japanese pumice used in this study was sampled from
the Kanoya-city located on the Osumi-peninsula in the Southern
Kyushu.
Individual particles are not solid but have internal voids.
This is the reason for the low unit weights presented in Table 1.
The particle density is not well-defined because of the internal
voids, hence only typical values are given in Table 1.
2 STRESS-STRAIN-STRENGTH BEHAVIOUR
The first comparison is given in Figure 1 where the change in
volume of dry pumice sand specimens under hydrostatic
compression is plotted. It is apparent that the Japanese pumice
undergoes considerably more volume change than the NZ
material; this may be a consequence of the different particle size
range of the two samples, as shown in Figure 5, and the well-
sorted size distribution of the Japanese pumice.
Figure 2 presents the deviator stress
–
axial strain plots for
conventional drained triaxial tests on specimens of the sand
after consolidation under hydrostatic pressure. Figure 3 has the
volume change behaviour of these specimens; note that the de-
Table 1. Physical properties of the pumice sands used in this study.
Grain
size
Typical
particle
density
Minimum
dry unit
weight
Maximum
dry unit
weight
Test dry
unit
weight
d
s
dmin
dmax
d
mm kg/m
3
kN/m
3
kN/m
3
kN/m
3
NZ pumice 0.05
~1.18 2340
5.65
6.95 5.42
~ 5.87
Japanese
pumice
0.15
~ 0.30 2489
4.34
6.41 5.70
~ 5.77
Kikkaw N.
Pender M.J., Orense R.P.
