Secondary consolidation is also known as secondary compression.

Secondary consolidation, also known as secondary compression, is a phenomenon that occurs in the soil after primary consolidation has taken place. It is a slow process that continues for an extended period of time after the primary consolidation is complete. Secondary consolidation is caused by the rearrangement and reorientation of soil particles under an applied load.

Primary consolidation vs Secondary consolidation:

Primary consolidation is the initial settlement that occurs in saturated soils due to the expulsion of water from the void spaces between soil particles. It is a rapid process that occurs immediately after the load is applied. The primary consolidation settlement is mainly dependent on the compressibility characteristics of the soil.

Secondary consolidation, on the other hand, is a gradual process that occurs over a longer period of time. It is caused by the realignment and reorganization of soil particles as they adjust to the applied load. During secondary consolidation, the soil continues to settle, albeit at a much slower rate compared to primary consolidation. The settlement during secondary consolidation is primarily due to the expulsion of water from the clay particles and the compression of the soil structure.

Significance of secondary consolidation:

Secondary consolidation is an important consideration in geotechnical engineering as it can significantly affect the long-term settlement of structures built on compressible soils. It is particularly relevant for clayey soils, which are known for their high compressibility and potential for secondary consolidation. The magnitude and rate of secondary consolidation depend on various factors such as the soil type, stress history, and permeability of the soil.

Conclusion:

Secondary consolidation, also known as secondary compression, is a slow process that occurs after primary consolidation in saturated soils. It is caused by the rearrangement and reorientation of soil particles under an applied load. Understanding and accounting for secondary consolidation is crucial for predicting the long-term settlement behavior of structures built on compressible soils.