关键词: 振动与波, 单桩, 分层饱和土, 扭转动力阻抗, 传递矩阵法

Abstract: The torsional vibration of a single pile in layered and saturated soil foundation was taken as the research object. The soil around the pile was regarded as a medium with the constitutive relation of fractional-derivative viscoelasticity. The dynamic differential equations of the soil for torsional vibration analysis were established in virtue of the dynamic equilibrium equation, viscoelastic constitutive relation and the stress-displacement relation of the soil. With a double-layered viscoelastic saturated soil foundation as an example, the influence of main mechanical parameters of the pile and the soil on torsional dynamic impedance was investigated. It is shown that the order ratio of the viscoelastic constitutive relations of lower soil layer to upper soil layer has great influence on the torsional dynamic impedance of the pile, and the influence of the ratio of shear wave velocities and the ratio of thicknesses between the two soil layers, and the influence of the ratio of moduli of the pile to the soil on the torsional dynamic impedance depends on the frequency of torsional vibration. However, the influence of these ratios is very small when the solid-liquid coupling coefficients of both soil layers are small.

Key words: vibration and wave, single pile, layered and saturated soil, torsional dynamic impedance, transfer matrix method