Seismic response of rigid cylindrical caissons embedded in inhomogeneous soil strata

This study develops a novel reference analytical elastodynamic model for the harmonic and seismic response of a rigid caisson, extending the pioneering work of Veletsos & Younan (1994) to vertically inhomogeneous soils. Both the caisson and the soil stratum are supported on a non-deformable base which is subjected to uniform horizontal motion. The solution is based on Sturm-Liouville’s theory and Helmholtz’s decomposition and makes use of the realistic simplifying assumption of universally vanishing the vertical normal stresses in the soil medium. An extensive parametric analysis in terms of horizontal soil pressures, shear force and bending moment for a soil shear modulus which increases with depth, demonstrating the effect of the type and degree of soil inhomogeneity on the caisson’s response. The findings offer an improved understanding of soil-caisson interaction mechanism in presence of inhomogeneous soils, which can be used to validate numerical models and interpret results for more complex systems.