Study on Buckling Behavior of Tapered Friction Piles in Soft Soils with Linear Shaft Friction

Abstract

The buckling instability of long slender piles in soft soils is a key consideration in geoengineering design. By considering both the linear shaft friction and linear lateral stiffness of the soft soil, the buckling behaviors of a tapered friction pile embedded in heterogeneous soil are extensively studied. This study establishes and validates an analytical model to formulate the equilibrium equations and boundary conditions and then numerically solves the boundary value problem to obtain the critical buckling load and buckling shape by using software Matlab. The effects of boundary conditions, tapered ratio, stiffness ratio, friction ratio, lateral stiffness, and shaft friction on the buckling behavior of the friction pile are extensively explored. This study demonstrates that the buckling load decreases with the increase of friction ratio of the linear shaft friction. There exists an optimal tapered ratio corresponding to the maximum dimensionless buckling load in the tapered friction pile with linear shaft friction. The result means that the linear shaft friction should be considered in designing the tapered friction piles in heterogeneous soils. The results also have potential applications in the fields of growing of tree roots in soils, moving of slender rods in viscous fluids, penetrating of fine rods in soft elastomers, etc.