380
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Using Eqs. (5) and (6), the variation of
p
during loading in
the thin-wall oedometer tests for the test materials were
obtained. The peak friction angle
p
decreased from 49.5
to
45.8
and 39.5
to 38.5
in the range of
v
from 16.0 to 111.5
kPa for the dense (DS) and loose (LS) sands, respectively.
Using
p
,
c
and
s
for Jumunjin sand, K
0
was calculated and
compared with the measured K
0
values in Fig. 4. The
s
was
assumed equal to 26
and 17
for Jumunjin sand and glass
beads, based on the values presented by Procter and Barton
(1974) and Andrawes and El-Sohby (1973). Note that K
0
from
c
and
s
is constant as these are intrinsic soil variables.
p
produces the lowest range of K
0
values, while the upper
bound is given by
s
. It is also noticed that the K
0
values
measured during
loading follows quasi constant, while decreases in
p
is
certainly expected as indicated in Eqs. (5) and (6). From Fig. 4,
it is seen that the measured K
0
values for the loose and dense
sands are close to those calculated using
s
and
c
, respectively.
This implies that the application of
p
is likely to produce
underestimated K
0
values. For glass beads, the application of
critical state friction angle
c
produces close match to the
measured K
0
values. Similar results were observed for etched
glass beads.
5
CONCLUSION
In this paper, the values of K
0
were investigated for different
granular materials focusing on the effect of various particle
characteristics. For this purpose, laboratory tests using the thin-
wall oedometer were conducted to measure the values of K
0
under various test conditions. Sand particles, glass beads with
and without etched particle surfaces were used in the testing
program.
From the test results, it was observed that the effect of
material density on K
0
was greater in OC stress state than in NC
stress state, and in particular becomes more pronounced when
unloaded. Regarding the effect of particle shape and angularity,
the lower values of K
0
were observed from Jumunjin sand
particles than from glass beads, due to the higher angularity and
interlocking effects.
For sands, the values of the friction angle employed into the
Jaky
’
s K
0
equation to match the measured K
0
values were
different for loose and dense sands. From measured and
calculated K
0
values, it was found that the measured K
0
values
for the loose sand were close to the calculated values using the
inter-particle friction angle
s
. For dense sand, on the other
hand,
c
produced close match to the measured K
0
values. This
indicates that the application of the peak friction angle
p
is
likely to result in underestimation of K
0
. For glass beads,
calculated K
0
values using
c
were in good agreement with
measured results for both relative densities.
6
ACKNOWLEDGEMENTS
This work was supported by Basic Science Research Program
through the National Research Foundation of Korea (NRF)
grant funded by the Korea government (MEST) (No. 2011-
0030845).
7
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