Kinematic response of pipe pile embedded in fractional-order viscoelastic unsaturated soil subjected to vertically propagating seismic SH-waves.

The analytical representation of kinematic interaction between pipe pile and unsaturated soil subjected to vertical SH-waves is revisited using three-dimension continuum modelling. The fractional-order standard line solid (FSLS) model is employed in the governing equation of unsaturated soil to refine the characterization of the flow-independent viscosity of the soil skeleton. The Timoshenko beam theory is utilized to describe the horizontal dynamic behavior of pipe pile. A closed series form solution of horizontal kinematic response for a pipe pile embedded in unsaturated soils under the action of vertical SH-waves is deduced theoretically with boundary conditions of pile-soil system. The solutions of the proposed model are compared with those captured from existing solutions. Finally, the effects of physical parameters in pile-soil system on the horizontal kinematic response of pipe pile under SH-waves are evaluated with analytical examples and parametric study. The results indicate that FSLS model parameters have significant impact on the horizontal kinematic response of the pipe pile, changes in the soil saturation have a relatively slight effect on the horizontal kinematic response of the pipe pile, and the length and radii of pipe pile should be moderate rather than too large or too small to make the pipe pile play a better seismic performance. [ABSTRACT FROM AUTHOR]