What is the difference between soil settlement and soil consolidation?

Soil Settlement and Soil Consolidation are two different concepts in geotechnical engineering that describe the behavior of soil under load.

1. Soil Settlement: Soil settlement refers to the downward movement of the ground surface due to changes in the stresses within the soil. This can occur due to a variety of reasons such as an increase in load on the soil (for example, construction of a new building), loss of support from below (for example, due to erosion or decay of organic material), or changes in soil structure (for example, due to drying and shrinking of clay soils). Soil settlement can occur rapidly or over a long period of time, and can cause damage to structures if not properly managed.

2. Soil Consolidation: Soil consolidation, on the other hand, is a specific type of settlement that occurs in fine-grained soils (like clay) due to expulsion of water from the soil pores. When a load is applied to such soils, the increase in pressure causes water to be squeezed out over time, resulting in a decrease in the volume of the soil. This process is usually slow and can take years to complete. The amount of consolidation is dependent on the properties of the soil, the magnitude of the load, and the time for which the load is applied.

In summary, while all soil consolidation is a form of settlement, not all soil settlement is due to consolidation. Other mechanisms like compaction, shear deformation, or collapse settlement can also cause the soil to settle.