What is the primary factor causing soil consolidation?

The primary factor causing soil consolidation is the drainage of water from the voids within the soil structure. When a load is applied to saturated soil, the soil particles are compressed, and the water that fills the spaces (or voids) between these particles is expelled. This process reduces the volume of the soil, leading to consolidation.

The expulsion of water affects the soil’s effective stress, allowing the soil particles to come closer together, therefore increasing the strength and stability of the soil over time as the excess pore water pressure decreases. While increased pore water pressure and air escape might be relevant during the initial stages of loading, it is the drainage of water from the voids that ultimately leads to the long-term consolidation settlement in saturated soils. Temperature variations have limited direct effect on the consolidation process compared to the mechanical aspects of pore water movement.