METHODS OF IMPROVING BEARING CAPACITY OF SOIL.
The following techniques can improve the bearing capacity of the soil.
- Increasing depth of the foundation
- Draining the soil
- Compacting the soil
- Confining the soil
- Replacing the poor soil
- Using grouting material
- Stabilizing the soil with chemicals
1. INCREASING DEPTH OF FOUNDATION
At deeper depths, the pressure on soil is higher, hence the soil is more compacted at a deeper depth. As a result, it shows a higher bearing capacity. This is applicable only for cohesionless soils such as sandy and gravelly soils. This method is not applicable if the subsoil material which grows wetter at a deeper depth. This method increases the cost of foundation.
2. DRAINING THE SOIL
Increasing the percentage of water content in soil can decreases the bearing capacity. In the case of sandy soil, bearing capacity may reduce as much as 50% due to the presence of water in the soil. Cohesion less soils can be drained by laying the porous pipes, filter medium, gentle slope, and above the pipes bed, filling sand and loose boulder. These drainage pipes subsequently should lead to the nearest well or any water body.
3. COMPACTING THE SOIL
If we compact soil using appropriate method we can improve bearing capacity, compaction increases density of soil and shear strength. So compaction also increases bearing capacity of soil. there are many methods are conducting at the site for compaction.
4. CONFINING THE SOIL
In this method, the soils are enclosed by sheet piles. This confined soil is further compacted to get more strength and bearing capacity. This method is applicable to shallow foundations.
S. REPLACING THE POOR SOIL
Remove all the poor soil and replace with sand, stone, gravel or any other hard material. In order to do this, first excavate the foundation trench of about 1.5 m deep, and then fill the hard material in layer of 30 cm.Then compact the hard material at every layer. This method is very useful for improving bearing capacity of black cotton soils.
6. USING GROUTING MATERIAL
Poor soil bearing strata is injecting by the cement grout under pressure. This method is applicable for soils where there is the presence of cracks pores, fissures.
7. STABILIZING THE SOIL WITH CHEMICALS
In this method, chemical solutions, like silicates of soda and calcium chloride is injected with pressure into the soil. These chemicals develop a compact mass along with the soil particles. This is called chemical stabilization of soil. Chemical stabilization gives additional strength to soft soils at deeper depths. This method is very costly. Chemical stabilization applied in exceptional cases for improving the bearing capacity of the soil.
Soil stabilization applicable for improving the California Bearing Ratio of soil. The other objective of soil stabilization is to improve on-site materials to create a solid and strong sub-base and base courses.
Read more : Plate load test of Soil for SBC
Founder & Admin of civilengineeringsolution.com, I am a civil engineer working as a Assistant Engineer (QA/QC).