Numerical study on the active vibration isolation by wave impeding block in saturated soils under vertical loading

Dynamic response in a saturated porous medium (i.e. two-phased medium) is significantly different from the commonly assumed single-phased elastic medium in vibration analyses. To investigate the ground vibration isolation by wave impeding block (WIB) in saturated layered soils under vertical loading, an improved three-dimensional (3D) boundary element model is established for analyzing the soil-foundation-WIB interaction problem. The equations of boundary element method (BEM) for saturated and layered soils were deduced using fundamental solution (Green's function) based on thin layer method (TLM), in order to account for the lamination characteristics of the ground. The vibration screening effectiveness of WIB with different thicknesses, equivalent diameters, shear module and embedded depths were systematically investigated and the results were compared with those in a single-phased elastic soil. The results show that the WIB can effectively reduce the vibration amplitude in the saturated ground and its effectiveness increases with increasing shear modulus, equivalent diameter, thickness, and decreasing embedded depth of the WIB. In addition, a significant amplification of the vibration is observed in the saturated soil when the dimensionless embedded depth is larger than or the dimensionless thickness is smaller than a threshold value.