HOW TO IMPROVE BEARING CAPACITY OF SOIL?

Techniques Used to Improve the Carrying Capacity of Soil

The following techniques can be used to improve the carrying capacity of the soil as per the site conditions.

  • increasing depth of foundation
  • soil removal
  • compacting the soil
  • liming of soil
  • replace bad soil
  • grouting material used
  • stabilizing soil with chemicals

How to improve the carrying capacity of soil

1. Increasing depth of foundation

At deeper depths, the pressure of greater load on the soil is greater; So the soil is compacted at greater depth. As a result it shows high bearing capacity. This is applicable only for sandy and gravelly soils. This method of improving the bearing capacity of the soil is not applicable if the subsoil becomes wet as the depth increases. This method has limited use as the weight and cost of the foundation increase with the increase in depth.

2. Soil extraction

With an increase in the percentage of water content in the soil, the bearing capacity decreases. In case of sandy soil, the bearing capacity may be reduced by 50% due to the presence of water content. Cohesive soils (ie sandy and gravelly soils) can be drained by laying a porous pipe on a gentle slope over a bed of sand and filling the trenches over the pipe with loose boulders. These trenches should later be led to the nearest well or any water body.

3. compacting the soil

If we compact the soil using suitable method, its density and shear strength will increase. As a result, the carrying capacity of the soil also increases. There are several methods of compacting the soil on the site. Some of them are mentioned below.

  • By spreading broken stones, gravel or sand and then ramming it thoroughly into the bottom of the trenches.
  • Using roller suitable as per soil type to move at specified speed.
  • Br Moving a concrete pile or wood pile and removing the pile and then filling the holes with sand or concrete.

4. Liming the Soil

In this method, the soil is surrounded with the help of a pile of sheets. This liming soil is further compacted to obtain greater strength. This method is applicable for shallow foundations.

5. Replacing Bad Soil

In this method poor soil is first removed and then the gap is filled with better material like sand, stone, gravel or any other hard material. To do this, first dig a foundation trench about 1.5 m deep, and then fill with hard material in steps of 30 cm. Then compress the hard material at each level. This method is useful for foundation in black cotton soil.

6. Using the Grouting Material

This method is applicable for those soils where there are pores, cracks or crevices etc. under the foundation. In this method, the bearing level of poor soil is hardened by injecting cement grout under pressure, as it removes any cracks or pores or fissures etc. For proper distribution of cement grout, the ground is bored and perforated pipe is introduced for forcing. grout

7. Stabilizing Soil with Chemicals

This method of improving the bearing capacity of the soil is expensive and is applicable in exceptional cases. In this method, chemical solutions such as silicates of soda and calcium chloride are injected under pressure into the soil. These chemicals form a gel-like structure with the soil particles and develop a denser mass. This is called chemical stabilization of soil and is used to give added strength to soft soils at deep depths.


Er. Mukesh Kumar

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Er. Mukesh Kumar is Editor in Chief and Co-Funder at ProCivilEngineer.com Civil Engineering Website. Mukesh Kumar is a Bachelor in Civil Engineering From MIT. He has work experience in Highway Construction, Bridge Construction, Railway Steel Girder work, Under box culvert construction, Retaining wall construction. He was a lecturer in a Engineering college for more than 6 years.