Model Test and Corresponding Simulation on Compressive Characteristics of Soilbags

Abstract

It is known that response acceleration of superstructure supported by spread foundation will decrease due to the rocking of the footing when subjected to earthquake loading, which makes it possible to reduce the cross section of the pier supporting the superstructure. However, supporting ground of a spread foundation should have enough bearing capacity. Therefore, when a spread foundation is constructed on soft ground, it should be improved by replacement of gravel or ground improvement method to increase the bearing capacity. The authors have already proposed a foundation by replacing the soft ground beneath a footing with soilbags. It is wellknown that soilbags will receive much larger compressive force than filled material only. Thus, it is expected that soilbags will withstand large load beneath the footing even during earthquake. In verifying the effectiveness of the proposed foundations, the compressive characteristics of soilbags is crucial. Therefore, in this study, a compression test on soilbags was conducted and the compressive characteristics of soilbags was carefully investigated. Moreover, numerical simulation of the compression test was carried out and the mechanism of compression deformation of soilbags was examined. The calculated results coincided almost exactly with the experimental results. The calculated results also showed that vertical stress was largely shared by the centre part of soilbags, where restraint effect of a bag was more prominent.

<b>Development of Spread Foundation Composed of Micropiles and Soilbags to Reduce Seismic Response of Structures</b>

“…The rigidities of springs in between the soilbag and the ground, the soilbag and the micropiles, the ground and the micropiles were set to sufficiently large values. The compression rigidity of the soilbag was set to the secant gradient of compression stressthe compression strain curve of the soilbags obtained from the previous compression test on the soilbag [11]. Nonlinearity of the Tohoku silica layer was expressed in the model using multispring and GHE-S model together.…”