Reproduction experiment of liquefaction strength characteristic of hard diluvial sand layer and verification by distinct element method

In general, the very dense ground such as diluvial sand was not examined for the liquefaction potential. However, due to the increase of maximum acceleration in seismic design force, the seismic evaluation of the hard diluvial sand is sometimes required for the design of important structures. It has been confirmed that the frozen sample of the diluvial sand has different liquefaction characteristics from liquefiable sand material in laboratory tests. Under undrained cyclic shear loading, the shear strain increases. On the other hand the excess pore water pressure does not increase very much sometimes. This characteristics is considered to be due in part to the solidification force between soil particles, called the aging effects. In this study, to understand the liquefaction characteristics of the solidified sand that is a model of the hard diluvial sand, we conducted liquefaction strength tests of cement mixed specimens. In addition, the analysis by the distinct element method is used to simulate the shear plane development. As a result, it was found that the shear strain increases when the released solidification points are localized. (author)