This study investigates the effect of using floating grid-form soil improvement (FGFSI) technique which is constructed in the shallow region of a liquefied layer. Using FGFSI to mitigate liquefaction below a container yard, two dynamic centrifuge model tests were conducted using the Nankai Trough earthquake as the input motion, with the aim of assessing the countermeasure effects. One test involved no countermeasure, whereas the other used FGFSI with 5 m high grid walls and a grid spacing of 6 m or 12 m. The average container settlement without countermeasures was 0.571 m, whereas that with the 6 m grid FGFSI was 0.280 m; the settlement with countermeasures was reduced to 49% that without countermeasures. A relatively large free-field settlement of 0.308 m occurred without countermeasures. However, no liquefaction was recorded within FGFSI region because it was suppressed by the contact pressure of the container. With less space between the grid walls, there was less difference between the container and ground surface settlements.
Subjects: liquefaction, floating grid-form soil improvement, dynamic centrifuge model test, settlement
Author: Shoichi Tsukuni, Takahiro Sugano, Takahiko Masumoto, Kazuhiro Kaneda and Yoshio Hirai
Publisher: DFI, EFFC