Torsional Wave in Finite Length Intact Pile
Liu Dongjia(1),Zhou An(2),Liu Yuzhou(1)
(1 School of Resources and Environmental Engineering,Hefei University of Technol ogy, Hefei 230009, China)
(2 School of Civil and Architecture Engineering,Hefei University of Technology, Hefei 230009, China)

Abstract: Torsional wave in a pile subjected to an impact torque at the head is analytically investigated. The pile is assumed to be a homogeneous elastic finite bar, and soil-pile interaction is considered. The transfer function and pulse response of the soil-pile system of torsional vibration are derived by direct and inverse Laplace transforms respectively, and the frequency response function, frequency-domain and time-domain expressions for the torsional vibration velocity at the pile head are obtained, the torsional wave in the pile is compared with the longitudinal one. The torsional wave characteristics of friction pile, free pile and pile embedded in rock are found out. The parametric research and t he presented formula show that attenuation of torsional wave in the pile depends on the following three ratios—ratio of soil shear wave velocity to pile torsional wave velocity, ratio of pile length to diameter, and ratio of density of the soil to density of the pile.
Keywords: soil dynamics, pile, torsional wave, dynamic testing of pile.