ANALYSIS OF RADIAL ELASTIC VISCO-PLASTIC CONSOLIDATION FOR IDEAL SAND-DRAINED GROUND BASED ON HANSBO'S FLOW

The traditional sand drain consolidation theory does not consider the significant rheological properties of soft clay and the non-Darcy characteristics of flow, which often leads to a large deviation between the calculated results and the observations. In order to further investigate the consolidation mechanism of sand drain ground in soft clay area, the nonlinear deformation of soil and the non-Darcy characteristics of flow were described by introducing uniform hardening (UH) constitutive model considering time effect and Hansbo's flow model, respectively. The consolidation equation of sand drain ground under the Barron's free strain assumption was modified without consideration of the well resistance and smear effect, and its numerical solutions were obtained by using the implicit finite difference method. The validity of the proposed method was verified by comparison with Berry's explicit numerical solutions. Based on that, the influence of soil viscosity and Hansbo's flow parameters on the nonlinear consolidation process of sand drain ground was analyzed. The numerical results showed that the viscosity of soft clay caused an increase in the pore pressure near the boundary of the influence zone of the sand filled drainage well at the early stage of consolidation, and the phenomenon became more obvious with the increase of viscosity. Meanwhile, Hansbo's flow enhanced the phenomenon of increased pore water pressure. However, at the middle and late stages of consolidation, the viscosity of the soil and the non-Darcy behaviour of the flow would delay the overall dissipation of pore water pressure in the ground with sand drains.