The Research Of The Vibration Isolation Performance Of The Fluid Saturated Porous Wave Impeding Block In Two-Dimensional Foundation

At present, the effect of various artificial vibrations on the environment is becoming more and more frequent. The problem of environmental vibration and its control in the field of soil dynamics and environmental geotechnical engineering needs to be worked out. The artificial vibration is mainly transmitted from artificial vibration source to the surrounding environment by the foundation. The surrounding environment vibration caused by the foundation is the main way of artificial vibration pollution. The wave impedance block(abbreviated to WIB), as a kind of barrier isolation measure, has given rise to a large number of scholar’s research and has obtained remarkable achievements since it was put forward. Fluid saturated porous media is a kind of two-phase materials, which interior is mesoscopic pore structure with the pore filled with liquid. The effect of two-phase mutual coupling of solid skeleton and pore fluid makes energy dissipation of the structure of saturated porous media in the process of vibration. This effect similar to damping can be used for vibration isolation. Now, there are two kinds of wave impedance block,include physical block and honeycomb, but there isn’t the situation of using fluid saturated porous media material as a WIB. Therefore, the study of vibration isolation effect of fluid saturated material WIB not only has important theoretical significance, but also will provide certain application value for practical engineering. In this paper, the research content mainly includes:1. The time-domain finite element simulation of the unsplit perfectly matched layer absorbing boundaryFoundation, as a kind of half infinite space structure, must be truncated to finite area in the process of the actual simulation calculation. At the moment, the artificial boundary conditions must be introduced to improve the accuracy of the calculation results to the uttermost and reduce the artificial boundary reflection wave. This paper selects the Perfectly Matched Layer(abbreviated as PML) absorbing boundary conditions, which has better absorbing effect of the wave. Firstly, based on second-order elastic wave equation of two-dimensional homogeneous isotropic elastic medium, a kind of unsplit PML absorbing boundary is established with the aid of auxiliary variable after Laplace and complex stretching coordinate transformation. Secondly, the time-domain finite element model in the form of displacement is given by applying Galerkin approximate technique. Finally, the effective absorbing performance of unsplit PML is verified by numerical examples.2. The parameter analysis of single phase wave impedance block’s vibration isolation effectBased on two-dimensional elastic wave theory, the limited computing area is truncated by PML. Then, the vibration isolation performance of the single-phase WIB in two-dimensional elastic foundation is calculated by combining with time-domain finite element method. After the detailed parameter analysis, the influence of the material parameters on the vibration isolation effect at foundation’s different position is studied, including the WIB’s thickness, modulus of elasticity, buried depth and so on. The result shows that appropriately increasing WIB’s thickness, elastic modulus and reducing the buried depth of the WIB can improve the vibration isolation effect.3. The parameter analysis of fluid saturated porous wave impedance block’s vibration isolation effectBased on Biot porous wave theory and combined with PML boundary condition, the vibration isolation performance of fluid saturated porous WIB is studied by using time-domain finite element method. The influence of the material parameters on the foundation’s vibration isolation is studied, including the fluid saturated porous WIB’s thickness, modulus of elasticity, buried depth, porosity and so on. The result shows that the vibration isolation effect of fluid saturated porous WIB is better than the single phase WIB, and appropriately increasing WIB’s thickness, elastic modulus and controlling the buried depth of the WIB can improve the vibration isolation effect. At the same time, we should choose the porosity of fluid saturated porous WIB as large as possible.