Question

What is the reduction in volume of soil primarily due to squeezing out of water from the voids called?
1. Creep
2. Primary consolidation
3. Plastic flow
4. Secondary consolidation

Answer 1

Correct Answer - Option 2 : Primary consolidation

Explanation:

Compressibility:

It is defined as a gradual decrease in the volume in the soil due to the application of load on soil mass. It is basically two types:

1. Compaction or Initial compression
2. Consolidation

Consolidation is further two types;

1. Primary consolidation
2. Secondary consolidation

Compaction:

It is an instantaneous process that occurs immediately after loading and is due to compression and expulsion of pore air.

Primary Consolidation:

• It begins when the soil reaches full saturation (after the expulsion of pore air) and remains saturated for the entire process of primary consolidation.
• It takes place due to the expulsion of pore water and completes when the expulsion of pore water stops.

Secondary Consolidation:

It starts after completion of primary consolidation if the load is constant and volume change is recorded with the passage of time, without expulsion of pore water then volume change is due to plastic readjustment of soil solids and it is termed as secondary consolidation.