Numerical Modeling of Centrifuge Experiment on Vacuum Consolidation of Soft Clay

Abstract

AbstractThis paper presents the finite element (FE) modeling of centrifuge experiments on vacuum consolidation of soft clay deposits. FE analysis of centrifuge tests as a model scale was performed, and the comparison is made with the centrifuge tests modeled as a prototype. The effect of different material parameters namely unit weight of water and density, initial void ratio and permeability of clay at model and prototype were studied. FE analysis confirmed that the use of unit weight of pore water at 1-g as an input parameter results in an incorrect distribution of vertical effective stress. To correctly compute vertical effective stress, unit weight of water at N-g should be used. In order to model the centrifuge test exactly it would be appropriate to give the values of initial dry density, initial void ratio and the initial vertical stress corresponding to those at 1-g so that the final conditions after self-weight consolidation results in proper distribution of void ratio and other field variables. To correctly model the increase in seepage velocity with gravity in centrifuge tests, permeability must be increased by the same factor as the gravity. Four pore water pressure boundary conditions to model the vacuum pressure were analyzed through numerical runs. The numerical model at the model scale considering all factors analyzed earlier were used in modeling vacuum consolidation of soft clay. It was found that to accurately model the vacuum pressure, the vacuum pressure should be applied only at the top of the soil layer for accurate prediction of the field variables.KeywordsFinite element modelingCentrifuge testVacuum consolidationSoft clayGround improvement