Characterization of reconsolidation volumetric strain of liquefied sand and validation by centrifuge model tests

The results of consolidation tests under K₀ condition and cyclic triaxial tests on Fujian sand at a given relative density are introduced, and the mechanism of the liquefaction-induced volumetric strain is revealed, which is composed of the re-sedimentation and the re-consolidation processes. The re-sedimentation is closely related to the cyclic shear strain history, especially that after liquefaction, and the more the accumulated shear strain ratio is, the more the re-sedimentation volumetric is. Besides, the re-consolidation behavior is significantly affected by the previous consolidation history and cyclic stress history, and the post-liquefaction reconsolidation will follow the trend of the previous normal consolidation curve, and the compression index is larger than that of the normal consolidation curve under the same conditions. A post-liquefaction volumetric strain model accounting for both the consolidation and cyclic shear strain histories is proposed, which treats the re-sedimentation as part of the re-consolidation by introducing the concept of assumed initial stress, and the estimation methods for re-compression index and the assumed initial stress are recommended accordingly. Then dynamic centrifuge model tests are performed, and the consolidation settlement and liquefaction responses are monitored, whereupon the mechanisms of liquefaction-induced volumetric strain are observed at the model scale, and the proposed model for post-liquefaction settlement estimation is preliminarily validated.