Viscous-Spring Dynamic Artifical Boundary For Saturated Porous Media

For the dynamic analysis of some important complex structures such as high-rise, high dam, nuclear power station and so on, the wave propagation from structure into infinite foundation should be considered.The saturated porous media is general existed in the nature, for example, the saturated soil, which is made up of solid skeleton and pore liquid fluid medium. If the dynamic interacting between the previous two part is concerned, using the saturated soil theory analyzing is more appropriate and scientific than using the single medium analyzing. As the complex of the saturated porous media theory and the difficulties of the disposing in mathematics, the analytic solution of saturated porous medium dynamic response is topical the simple boundary condition. To the complex geometry and the near field hererogeneous and nonlinear condition, numerical method is the effective mean. In the dynamic finite element analysis of saturated porous media in whole space or half-space, a finite model numerical method is usually selected for computing. To reflect unrestricted region energy radiation effect, it is necessary to input the supposed artificial boundary and computing method. The artificial boundary disposing means and computing means is largely influenced the computing accuracy. As the decoupling of time and position, explicit finite element combining local artificial method is proper to the previous complex near field wave-motion problem's solving.In the dissertation, a kind of new calculation formulation of viscous-spring boundary is proposed. Based on the constitutive equations of saturated porous media, this paper adopts the superimposing of plane wave and scattered wave in far field to simulate the propagation of the outgoing waves, and applies experimental parameter to decay of outgoing waves and multi-transmitting characteristics. By applying springs and damps on the artificial boundary, the energy absorbing function of the infinite domain beyond the ABC is realized.Numerical example indicate that the proposed viscous-spring artificial boundary enjoy good accuracy and good stability.Numerical example indicate that the accuracy and good stability of the proposed viscous-spring artificial boundary is higher than that of existing viscous boundaries, viscous-spring boundaries, the first-order transmitting boundary.The analysis of the saturated porous medium tunnel dynamic response indicates that the combination method of the explicit finite element method and the viscous-spring boundary is effective.