1547
Proceedings of the 18
th
International Conference on Soil Mechanics and Geotechnical Engineering, Paris 2013
A method of suppressing liquefaction using a solidification material and tension
stiffeners
Étude de base sur les méthodes de résistance à la liquéfaction, en utilisant des matériaux
précontraints
Nakamichi M., Sato K.
Fukuoka University
ABSTRACT: The Great Eastern Japan Earthquake occurred on March 11, 2011 and caused significant liquefaction damage. This
obviously occurred in the Tohoku region, especially the Kanto region, but has also been a serious problem in the Tokyo bay coast
landfilled area and inland areas. Therefore, this research focuses on popular cement solidification methods with the addition of short
fibers. These are expected to increase the apparent cohesion. The effects of these additives are investigated herein. This paper reports
on the results of basic research conducted and whether these techniques lead to suppression of liquefaction related to the duration of
earthquakes.
RÉSUMÉ : Suite à la catastrophe du 11 mars 2011, le Japon fait face à des dégâts liés à la liquéfaction des sols d’une ampleur sans
précédent. Ce phénomène est devenu un problème d’une grande gravité dans la région de Tohoku évidemment, mais également dans
celle du Kantô, et notamment sur les terre-pleins de la baie de Tokyo, ainsi qu’à l’intérieur des terres. Dans cette étude, nous avons
analysé l’évolution de la force d’adhésion de l’apparence des matériaux précontraints, ainsi que le processus de solidification du
ciment dans les méthodes de résistances à la liquéfaction. Nous présenterons les résultats de cette étude pour comprendre comment
ces méthodes peuvent être corrélées à la résistance à la liquéfaction, contre les mouvements sismiques.
KEYWORDS: suppression of liquefaction, cohesion, frequency
1 INTRODUCTION
Japan is one of the most earthquake prone countries in the
world. Japan is affected by various damaging phenomena, such
as liquefaction during earthquakes (Yasuda, 2011). The Great
Eastern Japan Earthquake, which occurred in 2011, lead to
significant earthquake motions, tsunami, liquefaction, fire and
nuclear accidents. These hazards occurred very extensively
across the region. For that reason, it caused unparalleled
damage and costs. The average duration of the earthquake
ground motions that have occurred in the past in Japan was 60
seconds. However, during the Great Eastern Japan Earthquake,
the ground motion duration was 150 seconds (Sasaki, 2012).
The time period of this earthquake duration was found to lead to
significant liquefaction damage. The potential for huge
earthquake occurrences in Japan is a significant concern.
Damage caused by this type of earthquake is assumed to be
more than the Great Eastern Japan Earthquake. The influence
and equivalent earthquake durations of these earthquakes are
estimated to be longer due to concurrence of plural earthquakes.
Similar long duration earthquakes are more likely to occur in
the future. Accordingly, it is necessary for methods of
suppression of liquefaction to be considered for these longer
earthquake durations. Therefore, this research focuses on
cement solidification, which is used as a liquefaction
countermeasure and inhibition of shear deformation by
additional short fibers. The apparent cohesion is thought to
increase by inhibition of shear deformation. In addition, this
paper reports on the results of basic research conducted on
whether these techniques lead to suppression of liquefaction
related to the duration of earthquakes.
2 TESTING PROCEDURE
2.1
Purpose of this study
This study involves the investigation of liquefaction
mechanisms using a cement solidification material and tension
stiffeners. The work has concentrated on gaining an
understanding of the shear behavior of the cement admixture
material. Furthermore, investigation of types of solidification
material and different amounts of solidification material were
also investigated. In addition, short fiber admixtures were
included in the same investigation. The improved soils with
added cement solidification and short fibers were tested using
cyclic shear tests at different frequencies, to reveal the influence
of duration of earthquakes.
2.2
The materials used during this study
Toyoura sand was used for the soil samples. Ordinary Portland
cement and recycled Bassanite from waste plasterboard was
used for the solidifying material. PVA fiber, with an average
length of 12.0 mm was used for the tension stiffener. The fiber
is a polyvinyl alcohol fiber, made by Kuraray Co., Ltd.
2.3
Method of preparing specimens
Specimens were prepared with a target dry density of 1.489
g/m
3
, equivalent to a relative density of 60% of Toyoura sand
(irrespective of the presence or absence of additional cement
solidification material). Specimens were prepared using the
moist tamping method. The additional additives were blended
separately outside of the specimen and mixed at various
percentages to the absolute dry mass of Toyoura sand.
Regulation of the water content was set to 10% after mixing of
Une méthode de prévention de la liquéfaction par cimentation et précontrainte
