What is the main factor affecting soil consolidation in geotechnical engineering?

The principal factor affecting soil consolidation is effective stress. Consolidation refers to the process by which soils decrease in volume due to expulsion of water from the pore spaces when subjected to increased load. Effective stress, defined as the stress carried by the soil skeleton, is crucial in this process. It is determined by subtracting pore water pressure from the total stress acting on the soil. As effective stress increases, soil particles are pushed closer together, leading to a reduction in pore volume and the expulsion of water. This phenomenon is governed by the principles of fluid mechanics and soil mechanics, specifically relating to how soils behave under load and how their volume changes over time.

The other factors, while they may contribute to various soil properties and behaviors, do not directly govern the consolidation process. Capillarity influences the movement of water within soils and can affect moisture retention but is not the main driver for consolidation. The plasticity index relates to the plastic behavior and workability of soil but does not play a defining role in the consolidation mechanism. Soil color is largely irrelevant in terms of physical and mechanical properties affecting consolidation.