Time effect of vertically loaded pile groups partially embedded in multilayered cross-anisotropic fractional viscoelastic saturated soils.

This paper investigates the time-varying mechanical performance of partially embedded pile groups subjected to vertical loads in multilayered cross-anisotropic fractional viscoelastic saturated soils. Piles are considered as one-dimensional compression bars and the stiffness matrix of a single pile and the global stiffness matrix of partially embedded pile groups are obtained by the finite element method. Based on the boundary element method, the soil stiffness matrix is deduced by expanding the extended precise integration solution. Then, the solution for partially embedded pile groups in multilayered fractional viscoelastic saturated soils is derived by employing the boundary element-finite element coupling method. Comparisons with existing solutions and an ABAQUS model prove the correctness of the proposed method. Numerical analyses are carried out to evaluate the influences of fractional derivative order, free length, pile spacing, pile-soil stiffness ratio as well as soil stratification on the time effect of partially embedded pile groups under vertical loads. [ABSTRACT FROM AUTHOR]