Analysis of Rotary Vibration of Rigid Friction Pipe Pile in Unsaturated Soil

Fu-Yao Zhao,Peng Xiang,Samuele De Bartolo

doi:10.1155/2020/2807574

Abstract

Based on the mixture theory and previous work, the governing equation of the rotary vibration of rigid friction pipe pile in unsaturated soil is established. The analytical solution of this equation can be used to analyze the displacements and the complex stiffness of rotary vibration. The results show that the contribution to stiffness is as follows: solid < liquid < gas; and the contribution to rotational impedance is as follows: solid > liquid > gas. In addition, when the fluid permeability coefficient decreases, the stiffness decreases and the rotational impedance increases, but the influence is not obvious (especially the gas permeability coefficient). Four different kinds of degradation problems are also presented. Relevant conclusions can provide reference for engineering application.

Highlights

For static torsion problem of a single pile, the solution has been found in principle since SaintVenant problem in elastic mechanics had been solved [1]. ere is much valuable research even when considering the effect of soil surrounding pile
Fattah et al [5,6,7] analyzed the dynamic response of pile foundation in dry and saturated sandy soil excited by two opposite rotary machines and found that in dry soil the pile tip load decreased for all (L/d) ratios and operating frequencies
Fattah et al [8] studied load sharing and behavior of single pile embedded in unsaturated swelling soil, the results showed that the ultimate skin resistance increased to about 49% when the initial degree of saturation decreased from 90% to 70%

Summary

Equations and Solutions of Rotary Vibration of Rigid Friction Pipe Pile

Considering the symmetry of the model and assuming that all the movements are simple harmonic, the circumferential displacement of the solid phase component has the form uθ (r, t) uθeiωt and the circumferential displacement of the liquid and gas phase components relative to the solid phase component is wθ (r, t) wθeiωt and vθ (r, t) vθeiωt (uθ, wθ, and vθ are the amplitude of rotational vibration), and the rest of the components of the displacement are zero It is the Laplace operator of a central symmetric plane problem; ρ is the density of unsaturated soil:. Calculation of Complex Stiffness of Rotary Vibration of Rigid Friction Pipe Pile. Ω2πρpH where kM is the rotary stiffness of the pile body and a complex function It can be written as follows: kM kM1 + ikM2,. Since the analysis process is similar, it will not be repeated here

Degeneration Problems

Calculation Examples and Analysis

Findings

Conclusion