Taiwan/US/Japan　WS

Recent Development of PS Logging in Japan

Yoshi 　 Iwasaki

Geo-Research Inst., Osaka

台湾・美國・日本 /Taiwan ・ US ・ Japan Workshop on Liquefaction

November 3-4, 2003, Hsinchu, Taiwan

Kitsunezaki invented suspension PS-logging system

Borehole pick

In loose and soft ground, it is difficult to perform logging by borehole pick.

Development of Suspension System

Liquid moves with surrounding ground.

If the pick up is the same density as the liquid

Suspension sensor detects shear wave in liquid.

Shear Wave Source

S-wave

Pressure increase

decrease

Electromagnetic hammer

Tube waves

Source does not always work as designed. Hammer action may induce some volume change.

Compression/Expansion in all direction induces tube waves.

To cut tube wave, balloon was inserted between source and sensor.

Sensor

Balloon filter

Source

Patent　• Kitsunezaki obtained Japanese Patent on Suspension

PS-logging. He does not ask to pay royalty but to open the PS-velocity dat

a to be disclosed insisting the geological data should be open to everybody.

• OYO insisted the patent is invalid.

Under sea logging for Kansai airport

Diver was sent down to the bottom of the sea to strike wooden plate by sledge hammer.

Experimental Study by Port and Harbor Research Institute

Kansai Air port

phase ○ ▼ ●travel time(msec) 25.8 26.4 26.3velocity(m/ sec) 38.7 37.8 38.1

Cross Correlation

0 5 10 15 20 25 30 35 40

- 20

- 10

0

10

20time=26.5msec

Cro

ss C

orr

ela

tion

Time shift(msec)

Cross　Correlation between 6m(N) and 7m(N)

3.9m Cartridge

Receiver Section5.4m

d=15cm15x7=105cm

1.05mIsolation joint

2.1m for monopole

3.3m for upper dipole3.45m for lower dipole

4.95m

Transmitter Section

Dia=9.2cm

Schlumberger

Automatic Velocity Determination

Waves fromMonopole source

Shear wave velocity is smaller than Fluid wave

Waves from monopole source

Shear wave velocity is larger than fluid wave.

Waves from dipole source

PS-logging at Kobe

1700m in depth

Vs, Vp(km/ sec) Poisson'sRatio

Depth(m)

Granite

Pleistocene

Holocene

(Quaternary)

PS-loggingat Kobe

Vs, Vp(km/ sec) Poisson'sDensity

Conclusion

• Suspension type PS-logging tool has been invented and used widely to measure PS-velocity in geotechnical engineering for shallow depth.

• Schlumberger has further developed the system to process automatic velocity determination and for deeper application.

• The same system as Schlumberger may be developed for shallow and smaller diameter in near future.