Cyclic Bi-Axial Tests on Assembly of Metal Rods Under Constant-Volume Condition to Study Re-Liquefaction Behavior

Abstract

As a part of fundamental studies on re-liquefaction behavior of sandy soils, cyclic bi-axial tests on assembly of aluminum rods having circular cross section were conducted under constant-volume condition, while focusing on the effects of strain amplitude during the previous liquefaction stage. By conducting image analyses on the specimen photos, possible changes in the local void conditions were evaluated and discussed. As a result, with increase in the maximum double amplitude vertical strain from 2.0 to 7.5% during the previous liquefaction stage, decrease in the re-liquefaction resistance was observed, which was consistent with results from past relevant studies on sands. Formation of locally loosened zone was observed during the liquefaction stage up to the double amplitude vertical strain of 7.5%, which may have affected the decrease in the subsequent re-liquefaction resistance. These zones were partly re-formed during the re-liquefaction stage. By the liquefaction history that was followed by re-consolidation, homogenization was observed in terms of the change of local void ratio. In addition to overall densification, such change may be regarded as one of the factors that would cause increase in the re-liquefaction resistance, as observed in the tests with liquefaction stages up to the double amplitude vertical strain of 2.0 and 5.0%.