LIQUEFACTION OF EMBANKMENTS ON SANDY SOIL AND THE OPTIMUM COUNTERMEASURE AGAINST THE LIQUEFACTION

Abstract

Shaking table tests for 12 different cases are performed to invertigate the behavior of embankments resting on liquefiable sand grounds in a model box, and to compare the effectiveness of several methods of countermeasures in mitigating earthquake induced liquefaction phenomena. The countermeasures employed here are installation of sheet-pile walls, gravel drains, sand compaction piles, and pipe piles. The dimensions of the transparent model box are 194cm long, 44cm wide, and 60cm deep. Saturated sand grounds are prepared for the tests to have a relative density of about 30% by water sedimentation method, and 15cm high embankments are constructed on the model frounds. 12 pore water pressure transducers, 4 accelerometers, and 2 LVDTs are installed throughout the model set-ups to monitor the response of the ground as well as the embankmens. The shaking table, whose size is 2m×2m, is excited from 0.1g up to 0.4g. Sand compaction piles are found to be the most effective in mitigating the liquefaction damages among the methtods applied in the model tests, even if all the methods are proven to be effective tool in preventing the occurrence of liquefaction at normal range of excitations. Further, the optimum location of each countermeasure is also determined in this study.