610
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
Wire line rod
Testing
section
Testing
section
Water table in measuring pipe is
fallen by being given gas pressure
Packer
Three-way
Pressure regulation
·
Distributor
Nylon tube for packer
pressurization
Pressure sensor code
Converter
Converter
Computer
Computer
Gas tube
Air valve
AQ rod
Wire line rod
Underwater connector
Packer
(Expanded state)
Underwater connector
Drainage pipe
Crystal oscillation sensor
Guide for water flow
Figure 6. Structure of new type measuring equipment of pore water pressure for sand (H-MHT).
4.3 Results and discussion
4.3.1 Estimation of pore water pressure using hyperbolic
method
The diameter of the tip part of GD-CONE is designed of thin
size because pore water pressure is needed to dissipate rapidly.
The standard method to GD-CONE continue to measure for
three hours after penetrating. The adoption value of pore water
pressure is calculated by hyperbolic method using the data
measured after three hours from penetration. In order to
accurate the adoption value, the long hour’s measurement, 38
hours, has carried out. The results of these data are shown in
Table 4. Since the results of the long hour’s measurement and
the adoption value by hyperbolic method using three hours’
measurement are almost same, the accuracy of hyperbolic
method has been confirmed.
Table 4. Application of hyperbola method for measuring result of pore
ater pressure.
w
No.
Altitude
(CDL-m)
Investigation
case
Measuring
hours(sec)
Pore water pressure
of last measuring
time (kPa)
Pore water pressure
by hyperbola
method (kPa)
1
263.47
11260
2760
2700
2
263.47
Standard
measurement
12110
2800
2702
3
264.02
Long
measurement
138917
2700
2702
4.3.2 Reliability of sealing of measurement section of GD-
CONE
Three patterns of penetration of GD-CONE, which is varied
from 30cm, 60cm to 90cm length, have carried out. The results
are shown in Figure 7. These data are almost same despite the
penetrating length. In addition, since the result of pore water
pressure is not same to the mud water pressure of the bore hole,
the seal of measuring section is regarded completely.
間隙水圧（kPa）
6000
5000
4000
3000
2000
1000
0
0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000
経過時間（sec）
1回目押し込み結果
2回目押し込み結果
3回目押し込み結果
凡例
泥水圧＝2960kPa
Note
Pushing length: 30cm
Pushing length: 60cm
Pushing length: 90cm
Mud water pressure=2,960kPa
Pore water pressure (kPa)
Time (sec)
Figure 7. Difference of test result of pore water pressure by penetrating
length.
4.3.3 Comparison examination of the results by GD-CONE
and H-MHT for Pleistocene clay
The comparative experiments used both GD-CONE and H-
MHT has been carried out in same depth, which is 170m in
depth. The results are shown in Table 5. Since these data are
almost same, the appropriate of GD-CONE and H-MHT method
for measuring equipment for great depth can be confirmed.
Table 5. Comparison between measuring result of pore water pressure
sing GD-CONE and H-MHT.
u
Measuring
method
Altitude
(CDL-m)
Pore water pressure
p
(kPa)
Excess pore water
pressure Δ
u
(kPa)
GD-CONE
172.77
2006
256
H-MHT
169.12
～
172.77
1984
257
5 CONCLUSIONS
Kansai international airport which has been constructed in the
Osaka bay far from 5km from the land area in order to solve
noise pollution has been able to take off and landing of airplane
using two runways whose length is about 4,000m. The
consolidation settlement of 2nd runway, which is related to this
paper, is almost the same like the consolidation analysis. For the
future, the management of consolidation settlement shall be
important for the operation of the airport while the
consolidation settlement will continue for long times. It is
important that the continuing study for the settlement of
Pleistocene clays using the in-situ observation data.
6 REFFERENCES
Matsumoto K., et al. 1981. Undisturbed sampling method using wire
line sampler (in Japanese). Sampling symposium.
Okumura T., et al. 1982. Soil investigation at Kansai international
airport –The investigation for great depth- (in Japanese).
Mechanization for construction
.
Andresen A. and Kolstad P. 1979. The NGI 54-mm Samplers for
Undisturbed Sampling of Clays and Representative Sampling of
Coarser Materials.
State of the Art on Current Practice of Soil
Sampling, Progressing of the International Symposium of Soil
Sampling
. Singapore. 13-21.
Lunne T., et al. 1997. Sample disturbance effect in soft low plastic
Norwegian clay.
Symposium on Recent developments in Soil and
Pavement Mechanics
. Rio de Janeiro. 81-102.
Japanese geotechnical standard (JGS 1313-2003). 2004. Method for
Measuring Pore Water Pressure using Electric Transducer (in
Japanese).
Japanese Standards for Geotechnical and
Geoenvironmental Investigation Methods –Standards and
Explanations-
. 368-376.
