Answer:

Primary Consolidation

Primary Consolidation is the reduction in volume of soil mass caused by the application of a sustained load to the mass and due to the adjustment of the internal structure of the soil mass. It is a time-dependent phenomenon that occurs when a load is applied to a saturated soil. The load causes the water in the soil to be squeezed out, and the soil particles to pack together more tightly, resulting in a decrease in volume.

Factors affecting Primary Consolidation

The amount of primary consolidation that occurs depends on several factors, including the following:

1. Soil Type: The type of soil plays a significant role in determining the amount of consolidation that occurs. Fine-grained soils, such as clays and silts, are more susceptible to consolidation than coarse-grained soils, such as sand and gravel.

2. Load History: The load history of the soil mass is also a critical factor. If the soil has been previously loaded, it may have already undergone some consolidation, which can affect the amount of consolidation that occurs under a new load.

3. Load Magnitude: The magnitude of the load is also an important factor. Higher loads will cause more consolidation, while lower loads will cause less.

4. Time: The length of time the load is applied is also significant. Longer periods of loading will cause more consolidation than shorter periods.

Primary Consolidation Settlement

The settlement that occurs due to primary consolidation is called primary consolidation settlement. It is calculated using the following equation:

∆H = (Cc * H * log10(t2/t1))

Where ∆H is the primary consolidation settlement, Cc is the compression index of the soil, H is the thickness of the soil layer, t1 is the time at which the load is applied, and t2 is the time at which the settlement is measured.

Secondary Consolidation

After the primary consolidation is complete, there may still be some settlement that occurs over time. This settlement is called secondary consolidation and is caused by the rearrangement of soil particles due to changes in stress conditions. Secondary consolidation typically occurs over a much longer time period than primary consolidation and can continue for years or even decades after the load is applied.

Conclusion

In conclusion, primary consolidation is the reduction in volume of soil mass caused by the application of a sustained load to the mass and due to the adjustment of the internal structure of the soil mass. It is a time-dependent phenomenon that depends on several factors, including soil type, load history, load magnitude, and time. Primary consolidation settlement can be calculated using the primary consolidation settlement equation. After primary consolidation is complete, there may still be some settlement that occurs due to secondary consolidation, which is caused by the rearrangement of soil particles over time.