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Methods of improving bearing capacity
Short answer
Bearing capacity is the soil's ability to support loads without shear failure or excessive settlement; safe bearing capacity is the ultimate capacity divided by a factor of safety. Improvement methods include compaction, drainage, soil replacement, deep compaction with sand piles, grouting, stabilization, and using deeper or wider foundations.
What do you mean by the bearing capacity of the soil? Explain the different methods of improving the bearing capacity of soil.
Bearing capacity of soil is the ability of soil to carry load from the foundation without shear failure or excessive settlement. Ultimate bearing capacity () is the pressure at which the soil fails in shear; safe bearing capacity is divided by factor of safety (usually 2.5 to 3), and also limited by permissible settlement.
Methods of improving bearing capacity
- Compaction: Rollers, rammers or vibrators raise the density of loose, granular soil in layers.
- Drainage: Lowering the water table by sumps, well points or sub-soil drains increases effective stress and strength.
- Replacement: Poor soil is excavated and replaced with compacted sand, gravel or murrum (sand cushion).
- Increasing depth and width of the foundation: A deeper and wider footing gives better capacity and reduced pressure.
- Confining the soil: Sheet piles or a ring wall keep loose soil in place.
- Sand piles and stone columns: Holes bored and filled with sand or crushed stone, compacted; raise the density of soft soil.
- Chemical treatment / grouting: Cement, lime or chemical grout injected into soil voids.
- Stabilisation: Mixing cement, lime, bitumen or fly ash with soil.
- Pre-loading and geosynthetics: Surcharge to pre-consolidate soft clay; geotextile and geogrids reinforce.
- Vibroflotation for deep compaction of sand.
- Pile foundations for transfer to a deeper stratum, if the above are not sufficient.
✓ Answer checked by Claude Opus 5.5 (high effort)
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