It is a simple ground improvement Method, where the soil is compact through external compaction effort. Soil compaction is the process of applying external energy to a loose soil to consolidate it and remove any voids from the soil and thereby improving the physical properties of the soil. If performed improperly, settlement of the soil can occur and may result in unnecessary maintenance costs or structural failure.
The Purpose of Soil Compaction :
The purpose of soil compaction is to improve its engineering properties by increasing its density to make it strong enough to resist displacement or movement under loads that may be applied to it.
Types of earth pressure, such as dams, retaining walls and highways require man-placed soil of fill. Compact the soil means it to place in the dense state. The dense state achieved through the reduction of air-voids in the soil, with less or no reduction in the water content.
Principal soil properties affected by compaction are following:
01. Improve load bearing capacity
02. Provides stability
03. Decrease Impermeability
04. Decrease future settlement of foundation
05. Soil resistance
06. Increase shear strength
07. Increase Slope Stability of embankments
08. Reduces water seepages, swelling and contraction.
Mechanism of Soil Compaction:
The process of soil compaction is simply removing the air from the voids or reducing air voids from the soil particles. By reducing the air voids, more soil can be added. Increasing the soil particles will close together more on each other causing more reduction in volume, which will result in adding more soil and hence the dry density will also increase accordingly.
Four types of basic mechanisms on which different types of compaction equipment work are:
- Impact: It is a large force acting for a very short interval of time.
- Pressure: It is a force acting on the unit contact area.
- Vibration: It is a shaking force applied on the surface
- Kneading: manipulating or Rearrangement of the soil particles.
There are many factors which affect the degree of compaction on the site. Some depend on compaction equipment and some depend on soil properties.
The Factors Affecting the Compaction Process are given below :
- Nature and type of the soil
- Water content at the time of compaction
- Site conditions e.g. type of site, weather and thickness of layer
- Compactive effort: weight and vibration.
- Contact pressure.
- Rolling speed of the equipment.