Horizontal dynamic response of pile in unsaturated soil considering its construction disturbance effect

Considering the effect of construction disturbance, the horizontal dynamic response of pile embedded in unsaturated soil is investigated when the pile is subjected to time-harmonic horizontal loading and vertical loading. In order to consider this problem, this paper subdivides the inhomogeneous region of pile surrounding soil into a series of sub-zones whose displacements and stresses at the fictitious interface are derived by means of continuous conditions and 3D continuum model. Then, the governing equations of pile are established by using linear elastic Timoshenko beam. Utilizing the Laplace transform and transfer matrix method, the analytical solutions of the dynamic impedance of soil and the horizontal dynamic impedance of pile head are derived. To verify the rationality and accuracy of the present solutions, the computed results are compared with those obtained from existing solutions. Through parametric study method, the influence of construction disturbance range and degree on the horizontal dynamic impedance of pile head is investigated within the low-frequency range concerned in dynamic pile foundation design. The main results show that the variations in the shear modulus and width of boundary zone of pile surrounding soil owing to relaxation effect or compaction effect have a significant influence on the horizontal dynamic response of pile head.