BIOT’S CONSOLIDATION ANALYSIS FOR CYLINDRICAL SOIL-SAMPLE BASED ON HANSBO’S FLOW1)

Some clay permeability tests show that the flow of the pore water in clays may depart from the Darcy law under the condition of the lower hydraulic gradient. In order to investigate the influence of the non-Darcy behavior of flow on the consolidation process, the Hansbo equation is introduced to describe the flow in cylindrical soil samples and the Biot consolidation equation under axisymmetric conditions is modified. The numerical analysis is performed by using the Crank--Nicolson finite difference method. The proposed method is validated by comparing the analytical solution of the axisymmetric Biot’s consolidation equation with the Darcy flow. Then the influence of the Hansbo’s flow parameters on the consolidation process of the cylindrical soil sample is investigated. The numerical results show that the Hansbo’s flow delays the consolidation process of the saturated clay compared with the Darcy flow. At the early stage of consolidation, the Mandel-Cryer effect becomes more significant with the increase of the Hansbo’s flow parameters. In other words, the peak value of the pore water pressure will increase, and the reaching of its peak will also be delayed. Similarly, the delaying phenomenon of the pore water pressure dissipation is also more obvious in the later stage of consolidation. However, the Hansbo’s flow has little effect on the displacement in the cylindrical soil.