Analysis Of Two-Dimensional Biot’s Consolidation With Hansbo’s Flow

There will be a large deviation when we use traditional multi-dimensional consolidation theory with Darcy’s law to get the predicted consolidation and settlement compared with the measured values sometimes. One important reason is the pore water flow in these soils does not confirm Darcy’s law. Therefore, the widely-used Hansbo’s equation which could describe the characteristic of the flow for soft clay is applied to dimensional,linear and flexible consolidation theory of Biot, and the new FEM consolidation equation is established. The related calculation program is designed by using the computer language of Fortran 90. Compared with the computational results for one dimensional consolidation theory, the effectiveness of the calculation program is verified. Finally, by analyzing some examples in numerical with the computational program, the influences of consolidation and Mandel effects in different seepage parameters of Hansbo’s flow and the foundation thickness is discussed, and some conclusions can be arrived as follow:(1) By analyzing the Biot’s consolidation problems in the natural foundation of soft clay, the behavior of non-Darcian flow can reduce the rate of dissipation of pore water pressure effectively; for the soil with linear and elastic deformations, the rate of consolidation and sedimentation could be reduced. The dissipation rate of the pore water pressure and the consolidation rate of the soil will decrease with the increasing of the seepage parameters m or il for Hansbo’s flow and the the foundation thickness, in result of the decreasing of the degree of consolidation, namely the rate of seepage consolidation would be slower.(2) After considering the characteristics of non-Darcian flow, there would be some significant changes for the vertical displacement of ground surface. The larger the seepage parameters m or il for Hansbo’s flow, the smaller the surface subsidence occurred settlement section, the larger the value of surface uplift occurred swell section.(3) Whether considering the characteristics of non-Darcian flow or not, there would be a phenomenon that the pore pressure will decrease after the first increase in the early stage of consolidation, which is called Mandel effects.With the increasing of the ground depth, the occurrence time of Mandel effects would be put off, and the duration would be extended. In addition, for the problems considering the characteristics of non-Darcian flow, with the increasing of the seepage parameters m or il for Hansbo’s flow, the occurrence time of Mandel effects would be put off, the duration would be extended, and the peak pore pressure would be larger.