Centrifugal Model Tests on Soil Behavior During Preload Removal from Ground Improved with Vertical Drains

Vertical drain method with preloading is one of the typical soft ground improvement technologies. When a preload is removed before completion of the required consolidation period due to a limitation of construction process, it is important to predict a residual settlement in advance. To improve the prediction of deformation after removing the preload, a series of centrifugal model tests simulating the preloading work was conducted. The experiment showed that when the preload is removed from a ground in insufficient consolidation with vertical drains, recompression occurs after expansion due to unloading. Since the recompression is caused corresponding to the change of a strain rate, the isotache concept can be applied to evaluate the residual settlement.