Energy dissipation in nearly saturated poroviscoelastic soil columns during quasi-static compressional excitations

This paper presents a theoretical investigation on the energy dissipation in a nearly saturated poroviscoelastic soil column under quasi-static compressional excitations. Different components of the energy dissipation are evaluated and compared. The magnitudeof fluidinduced energy dissipation is primarily a function of a normalized excitation frequency ω. For small values of ω, a drained soil column is fully relaxed and essentially behaves as a dry column with negligible pore pressure. For such a soil column, fluid-induced energy dissipation is negligible, and the total damping ratio of the column is essentially the same as that of the solid skeleton. For very high values ofω, a drained soil column is fully loaded and the excitation-generated pore pressure decreases as the fluid becomes more compressible. For such a soil column, the fluid pressure gradient only exists in a thin boundary layer near the drainage boundary, where drainage occurs and fluid induces energy dissipation, whereas the rest of the column is essentially undrained. Significant fluid-induced energy dissipation occurs for moderate values of ω because of a combination of moderate fluid pressure, pressure gradient, and fluid relative motion throughout the soil column. The effects of the boundary drainage condition, saturation, porosity, and skeleton damping ratio on fluid-induced energy dissipation are discussed.