Finite-Element Analysis of Helical Piers in Frozen Ground

Abstract

This paper presents a study of the behavior of helical pier foundations in frozen ground. The scope of the work presented includes developing finite-element analysis (FEA) models that simulate the stress-strain relationships in the pier and in the surrounding frozen soil. The paper also presents the results of the analysis models developed. The FEA computer program ANSYS is used to perform the computations that include three phases: The first phase is related to the instantaneous stability of piers in frozen or thawed soil under applied design loads. The second phase is related to the analysis of the pier strength during installation into frozen ground when the piers need to withstand installation torque and axial loads. The third phase is related to the long-term stability and critical loads of piers owing to creep in frozen soil. The most important finding of the analysis is that the load is not distributed into the frozen ground equally by the helixes of a multi-helix pier; instead, the bottom helix transfers most of the load.