Estimation of reliquefaction considering from soil element tests

抄録

Because of water drainage, liquefied sand becomes denser after liquefaction. Therefore, such sand is not expected to liquefy again. However, repeated ground liquefaction has been reported from several earthquake events. We have considered some reasons for frequent reliquefaction: (1) the upper ground remains in a loose condition after liquefaction and (2) increased pore water pressure remains during subsequent earthquake events. This study investigated reliquefaction mechanisms using triaxial tests with bender elements (BE) and local small strain measurements (LSS) to explore other reasons for reliquefaction. The experimentally obtained results demonstrate that initial shear modulus G0 is insensitive to specimens with shear and liquefaction histories, although the liquefaction strength varies considerably according to the stress and liquefaction histories. The LSS test results indicate that the elastic strain region of sand shrinks according to the liquefaction history while maintaining almost unchanged G0. Furthermore, the sand particle orientation was evaluated from 2D images obtained using optical digital microscopy.