ABSTRACT
In Japan, decomposed granite soil, more popularly referred to locally as Masado, is used in large areas of land reclamation in the coastal regions. Masado is crushable and angular in morphology. It was initially considered as high-quality fill material with little risk of liquefaction. However, during the 1995 Great Hanshin-Awaji earthquake, widespread liquefaction was observed in lands reclaimed using Masado. This necessitated the determination of the liquefaction strength of this material. In the present investigation, a comprehensive experimental program consisting of a series of cyclic triaxial tests had been carried out to investigate the liquefaction strength of Port Island Masado, Shimonoseki Masado and Iwakuni Masado. The effects of relative density, confining pressure and overconsolidation ratio on the liquefaction strength were considered. Samples were prepared by dry deposition and water sedimentation methods to simulate the in-situ deposition process. It was observed that water sedimentation method produced denser samples than dry deposition method. The test results showed that liquefaction strength of samples is not affected by changes in initial relative density if Dri is less than 100%. On the other hand, the liquefaction strength was significantly improved with increase in initial density to more than Dri = 100% and through overconsolidation.
