In-Situ Test on Desaturation by Air Injection and Its Monitoring

Mitsu Okamura1,a, Masaya Takebayashi2, Katsuji Nishida3, Nao Fujii4, Motoharu Jinguji5, Takehiko Imasato6, Hideaki Yasuhara1 and Emiko Nakagawa7

1Graduate School of Science and Engineering, Ehime University, 3 Bunkyo-cho, Matsuyama, 790-8577, Japan.

2Research and Development Center, TOA Corporation, 1-3 Anzen-cho.

3Fudo Tetra Corporation, 7-2 Nihonbashi-koami-cho.

4Oriental Shiraishi Corporation, 5 Kinugaoka.

5Planning Headquarters, National Institute of Advance Industrial Science and Technology, Address, 1-3-1

6Nihonchikatansa Co. Ltd., 658-2 Hongo-cho.

7Takamatsu Port and Airport Technical Investigation Office, MLIT, 1-6-1 Bancho.


Desaturation of ground by air injection attracts considerable attention in resent years as an innovative technique for liquefaction countermeasure. Several research programs have been run in laboratories regarding related topics. This paper describes an in-situ air injection test which aimed to confirm the effectiveness of the air injection to desaturate ground and validity of observation techniques to monitor the evolution of unsaturated zone. Degree of saturation of the in-situ soil was observed using high quality undisturbed samples obtained by the ground freezing method. The degree of saturation ranged between 68% and 98%, which was low enough to almost double the liquefaction resistance of the soil at the site. 3D electric resistivity tomography technique was found to be effective to detect evaluation of the desaturated zone.

Keywords: Degree of saturation; desaturation; liquefaction; electric resistivity; tomography.

     Back to TOC