Torsional Vibration Characteristics of A Belled Pile Considering the Construction Disturbance Effect

Based on the plane strain model, the torsional vibration of a belled pile is theoretically investigated considering the construction disturbance effect. First, in view of the cross-sectional characteristics of the belled pile and the radial inhomogeneity of the surrounding soil caused by construction disturbance, the belled pile is divided into finite sections along the longitudinal direction, and the surrounding soil is divided into finite annular zones along the radial direction. The pile and soil vibration governing equations are established, respectively. Then, the soil governing equations of each zone are solved one by one through the shear complex stiffness transfer model to obtain the shear complex stiffness at the pile-soil interface, which is substituted into the governing equation of the pile. The displacement impedance function at the belled pile head is obtained in the frequency domain by virtue of the Laplace transform and impedance function transfer method, and further the amplitude-frequency response function of the twist angle at the belled pile head is obtained. Finally, the influence of bottom-expanding section parameters and construction disturbance effect on the complex impedance and amplitude-frequency of the twist angle at the pile head are analyzed in the low frequency range utilizing parametric analysis.