562
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
although the identical permeable capability for the individual
Pleistocene sand gravel layers was applied, the calculated
results of excess pore water pressure could show the difference
with the stress level. The calculated excess pore water pressure
–
time relations for two foundation models are shown in Fig. 6
together with the measured results for the representative
Pleistocene sand gravel layers at the monitoring point 1. It is
noteworthy that the excess pore water pressure in the upper
(Ds3) and lower (Ds10) Pleistocene sand gravel layers is
increased but the one of the middle layer (Ds6) is not increased
due to the construction of the 2
nd
phase island. The long-term
settlement associated with the phenomenon of propagation of
excess pore water pressure is another serious problem for KIX.
When the excess pore water pressure increases or the
dissipation of excess pore water pressure is hindered due to the
construction of the 2
nd
phase island, the settlement is also
retarded or slight upheaval can happen (see Fig.7). It is also
found that the calculated performance at the monitoring point 1
shows a good match for two foundation models by applying the
concept of
“
standard hydraulic gradient
”
and can also well
describe the whole process of deformation.
6 CONCLUSIONS
The long-term deformation of the reclaimed Pleistocene
foundation of the offshore twin airport was numerically
evaluated through the elasto-viscoplastic finite element analyses
considering the concepts of
“
mass permeability
”
and
“
standard
hydraulic gradient
”
for the Pleistocene sand gravel layers. The
concept of
“
mass permeability
”
was evaluated as the
representative permeable capacity of sand gravel layers of KIX.
The representative permeable capacity of sand gravel layers was
applied to the geologically genuine foundation model by
introducing the concept of
“
standard hydraulic gradient
”
for the
coupled stress-flow analysis. The concept of mass permeability
for the sand gravel layers was found to well function to assess
the process of excess pore water pressure generation/
dissipation/propagation and long-term settlement in the
reclaimed foundations of KIX. The concept of standard
hydraulic gradient was also found to well reproduce the
representative permeable capacity by comparing the calculated
results for two foundation models. The validity and objectivity
of the proposed concepts will be investigated by applying them
to the additional review sections including the monitoring
points S2 or S3 shown in Fig. 2.
7 REFERENCES
Itoh, Y., Takemura, K., Kawabata, D., Tanaka, Y. and Nakaseko, K.
2001. Quaternary Tectonic Warping and Strata Formation in the
Southern Osaka Basin Inferred from Reflection Seismic
Interpretation and Borehole Sequences,
Journal of Asian Earth
Science
, 20, 45-58.
Kitada, N., Inoue, N., Takemura, K., Fukada, K. and Emura, T. 2011.
Subsurface Structure Model Around Kansai Airport According to
Re- Interpretation of Borehole Data based on Result of KIX18-1
Core.
International Symposium on Advances in Ground Technology
and Geo-Information, IS-AGTG,
137-142.
Mimura, M. and Jang, W.Y. 2004. Description of time-dependent
behavior of quasi-overconsolidated Osaka Pleistocene clays using
elasto-viscoplastic finite element analyses,
Soils and Foundations
,
44(4), 41-52.
Mimura, M. and Jang, W.Y. 2005a. Verification of the Elasto-
viscoplastic Approach Assessing the Long-term Deformation of the
Quasi-overconsolidated Pleistocene Clay Deposits,
Soils and
Foundations
, 45(1), 37-49.
Mimura, M. and Jang, W.Y. 2005b. Long-term Settlement of the
Pleistocene Deposits due to Construction of KIA,
Proceedings of
the Symposium on Geotechnical Aspects of Kansai International
Airport
, , 77-85.
Mimura, M. and Jeon, B.G. 2011. Numerical Assessment for the
Behavior of the Pleistocene Marine Foundations Due to
Construction of the 1
st
Phase Island of Kansai International Airport,
Soils and Foundations
, 51(6), 1115-1128.
Mimura, M., Takeda, K., Yamamoto, K., Fujiwara, T. and Jang, W.Y.
2003.
Long-term settlement of the reclaimed quasi-
overconsolidated Pleistocene clay deposits in Osaka Bay,
Soils and
Foundations
43(6), 141-153.
Ds10
0
50
100
150
200
250
300
350
400
Elapsed time(years)
0
10
20
30
40
50
60
Representative foundation
Measured
Geologically genuine foundation
Ds3
0
50
100
150
200
250
300
350
400
Excess pore water pressure(kPa)
Completion of 2
phase island
nd
Start of 2
phase island
nd
Ds6
0
50
100
150
200
250
300
350
400
Figure 6. Comparison of measured and calculated excess pore
water pressure with time for the representative Pleistocene sand
gravel layers
Ma6
0
20
40
60
80
100
120
140
Elapsed time(years)
0
10
20
30
40
50
60
160
Representative foundation
Measured
Geologically genuine foundation
Settlement(m)
Completion of 2
phase island
nd
Start of 2
phase island
nd
Ma10
0
20
40
60
80
100
120
140
Ma12
0
20
40
60
80
100
120
140
160
180
200
Figure 7. Comparison of measured and calculated settlement with time
for the representative Pleistocene clay layers
