Consolidation and Creep of Saturated Clayey Soils

The soil mass containing saturated layers and interacting with the foundation of the structure is referred to as a saturated base. In these bases, pore pressure resistance is invariably produced under the action of an external load. This pore pressure dissipates, its rate of dissipation depending on numerous factors, including the rheological properties of soil skeleton, coefficient of permeability and compressibility of pore water, dimensions of the soil mass being consolidated and so forth. In view of these, the temporal behaviour of saturated bases is governed, on the one hand, by consolidation and, on the other, by creep of the soil skeleton. Differentiation of the process of soil consolidation into consolidation due to seepage and secondary consolidation is merely formal. Secondary consolidation is related to strain under compressive consolidation, which has been observed in laboratory experiments to grow proportionately with the logarithm of time after almost total dissipation of pore pressure. However, many researchers seem to forget that the rate of deformation of the skeleton during secondary consolidation is very small; the skeleton encounters no resistance from pore water and its deformation can increase at almost negligible pore pressure gradients. In other words, the mutual penetration of soil skeleton and pore water at negligibly small rates produces no significant pressure gradient.