Abstract
Pile buckling is infrequent, but sometimes it can occur in slender piles (i.e., micropiles) driven into soils with soft layers and/or voids. Buckling analysis of piles becomes more complex if the pile is surrounded by multi-layered soil. In this case, the well-known Timoshenko’s solution for pile buckling is of no use because it refers to single-layered soils. A variational approach for buckling analysis of piles in multi-layered soils is herein proposed. The proposed method allows for the estimation of the critical buckling load of piles in any multi-layered soil and for any boundary condition, provided that the distribution of the soil coefficient of the subgrade reaction is available. An eigenvalue-eigenvector problem is defined, where each eigenvector is the set of coefficients of a Fourier series describing the second-order displaced shape of the pile, and the related buckling load is the eigenvalue, thus obtaining the effective buckling load as the minimum eigenvalue. Besides the pile deformed shape, the stiffness distribution in the multi-layered soil is also described through a Fourier series. The Rayleigh–Ritz direct method is used to identify the Fourier development coefficients describing the pile deformation. For validation, buckling analysis results were compared with those obtained from an experimental test and a finite element analysis available in the literature, which confirmed this method’s reliability.
Highlights
The design problem of pile buckling is not usually faced in civil engineering practice because its occurrence is infrequent
This study shows how pile buckling can be an issue when slender piles pass through cavities or very soft soils, especially peaty soils, even if some silty sands and normally consolidated clays can be soft enough to allow for buckling of the slender piles driven in them (Section 3.1)
A similar consideration can be made regarding the number of coefficients of the Fourier series of the step function describing the distribution of the soil stiffness K(x)
Summary
The design problem of pile buckling is not usually faced in civil engineering practice because its occurrence is infrequent. This problem is becoming more important with the increasing use of micropiles, especially for retrofit interventions, and elastic buckling of micropiles surrounded by soft soils is possible and is worth investigating. Different approaches have been adopted for studying pile buckling. Timoshenko and Gere [3] proposed a variational approach to study the elastic buckling of a bar on an elastic foundation, hinged at its ends and axially loaded on top. Timoshenko’s study’s conclusion is similar to the Engesser formula for calculating the buckling load of an elastically embedded beam
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
