Thin-layer method for dynamic impedance of isolated foundation with cushions and its parameter analysis

Based on the semi-infinite elastic foundation model, the dynamic impedance solution of the isolated foundation with cushions in layered soils is deduced by introducing the thin-layer method. The proposed method is verified by the viscoelastic boundary finite element model. A systematic parameter analysis is carried out for the horizontal and rocking dynamic impedances of the isolated foundation with cushions. The calculated results by the model show that within the range of 0~10 Hz, the thickness of the cushions and the number of piles have obvious effects on the rocking impedances: the greater the thickness of the cushions, the smaller the rocking impedance of the isolated foundation with cushions; the more the piles, the greater the rocking impedance of the isolated foundation with cushions. In addition, under the same conditions, the greater the pile length, the greater the real part of the swing impedance of the cushion isolation foundation. The shear wave velocity of the cushion has a certain influence on the horizontal and rocking impedances of the foundation. The proposed method is suitable for analyzing the dynamic characteristics of the isolated foundation with cushions under earthquake loads.