What is the Consolidation of Soil?- Types & Process

What is the Consolidation of Soil?

Consolidation is the process by which soil particles are packed more closely together under the action of static load. It is a natural process and its take a long time. It is a two-stage process.

Types of Consolidation

  1. Primary Consolidation 
  2. Secondary Consolidation

Primary Consolidation

It is an instantaneous process of reducing the volume of voids due to the expulsion of air voids when the degree of saturation is S <1.

Secondary Consolidation

It is a time-dependent process of reducing the volume f voids due to plastic readjustment of soil solids.

What is the Consolidation of Soil?- Types & Process

Process of Consolidation In Soil

To understand the process of consolidation let us assume we have a ground which is fully saturated that means water is present at the top surface, middle and bottom. Now we build a building over the ground.

When t = 0

Now there are additional stresses on the soil. Before building the structure there is only effective stress in the soil.

Due to these additional stresses, there is the development of pore water pressure which is equal to additional stresses.

The total building load is taken by only water, soil particle will not take any load. At this condition, effective stress is zero.

Effective stress = Total stress – Pore water pressure

What is the Consolidation of Soil?- Types & Process

Where

Δσ = stress

Δu = pore water pressure

Δσ̅ = effective stress

t  =  time

When 0 > t < ∞

As time passes the water try to drain out, very first it will drain out from top surface then bottom and at last from the middle. Now there is no water to generate pore water pressure.

As the water draining out pore water pressure get reduce. As shown in the graph at the top and bottom pore water pressure is zero but in the middle, there is some pore water pressure.

At this condition, effective stress at top and bottom is more but in the middle, it is less as shown in the graph.

What is the Consolidation of Soil?- Types & Process

When t > ∞

In actual noting is greater than infinite but it is just only to show. At this condition water present in the middle layer completely drained out, now the primary consolidation is complete.

Now soil particles start taking the load. At this condition pore, water pressure is zero because there is no water at the top, bottom and in the middle layer.

At this condition, effective stress is equal to total stress that means the total load is taken by only soil particles. Now the process of secondary consolidation starts.

What is the Consolidation of Soil?- Types & Process

I hope now you understood what is soil consolidation. If you found this article informative, please be sure to share it with your friends.

Thanks!

Also, read

Difference Between Compaction And Consolidation

What is the Purpose of Providing Foundation?

Types of Foundation and Footing and Their Uses

Leave a Comment

More in Geo. Technical Engineering
9-Causes of Settlement of Foundation
9-Causes of Settlement of Foundation

Causes of Settlement of Foundation When the soil beneath the...

Close