Dynamic Consolidation Numerical Analysis Based On The Physical State Model

In this paper, aiming at the problem of saturated sand liquefaction, the cycle elastic-plastic model and the dynamic physical state model considering the physical state transformation behaviors of saturated sand are discussed further. Based on the dynamic consolidation equation the dynamics controlling equations in FEM analysis are deduced by considering the physical state model and the elastic-plastic model. Furthermore the controlling equation is expressed in space and time domains and can be used to write the FEM calculation program. After the particular solving method of dynamics consolidation analysis having been proposed, a two-dimensional program of dynamics consolidation analysis applying the physical state model and cyclic elastic-plastic model is work out which refers to the coupled reaction of liquid and solid in the saturated sand. At the same time the vertical and horizontal sin-wave, random-wave in the single direction and the coupled directions can be input into in this program. Besides it can consider the artificial viscous boundary to improve the behaviors. For the model tests of sand embankment and the sand-gravel columns improved foundations, the research results of dynamics response and consolidation analysis show that the physical state model of saturated sand can predict the transient fluctuating of the dynamics pore water press under the dynamics loading and the cycle transformation track of the effective stress path in effect stress space, which reflects the sand physical state transformation of the negative and positive dilatancy during the dynamics loading. The resident deformation during the shaking and the consolidation deformation after the earthquake can be determined. The drainage function of the sand-gravel columns, which can efficiently prevent from the pore water press increase in the upper stratum, are simulating by the numerical analysis. There is a zero pore water press zone in the reinforced domain at all times. Comparing with the testing results of the shaking table model test, the pore water pressure calculating with the cycle elastic-plastic model increases rapidly in the initial loading stage, which shows that the plastic deformation is great. However, the pore water pressure calculated by the physical state model increases slowly and is consistent with the model test results. When the viscous boundary instead of general boundary is used in the dynamics analysis, the fluctuating of pore water press and the amplification scale of acceleration can be reduced efficiently and the dynamics behavior of boundary elements is much more according with the variation principle. From the above results, the credibility and exactitude of this program has been validated.It is apparent that the physical state model of saturated sand applying in the practical engineering is accomplished firstly. For the future it can be used in the more practice and has a great deal of utility value.