Under-Reamed Piles Foundation was provided in the area where black cotton soil could cause structural instability. Many times, the soils undergo volumetric changes due to moisture variation underneath the ground surface. This expansion and shrinkage can cause distress which is very dangerous and critical as far as the bearing of the foundation is concerned. The fact is that Under Reamed Piles are considered as the safest and economical foundation for such black cotton soils or expansive soils.
Based on the Function the Piles are Classified as
- End Bearing Piles
- Friction Piles
- Compaction Piles
- Tension Piles
- Anchor Piles
- Fender Piles
- Batter Piles
- Sheet Piles
Based on the Materials and Composition of the Piles are classified as
- Concrete Piles
- Timber Piles
- Steel Piles
- Composite Piles
- Sand piles
Concrete piles are further divided into three. They are precast concrete pile, cast-in-situ concrete pile and prestressed concrete piles. The Under-Reamed Pile is the type of cast-in-situ concrete pile.
Uses of the under-reamed pile
Under-Reamed Piles are widely used for different types of soils such as sandy soils, clayey soils and also expansive soils.
- To avoid the undesirable effect of seasonal moisture changes in expansive soils such as black cotton soils.
- To reach hard strata.
- To obtain adequate capacity for downward, upward, lateral loads and moments.
- To take the foundations below the scour level.
- They have also been found useful for factory buildings and machine foundations.
- Under-Reamed Piles are also used under situations, where the vibration and noise caused during the construction of piles, are to be avoided.
Advantages of under reamed pile:
- It decreases the vertical settlement and also differential settlement.
- It is used when soil tends to swell and shrink due to moisture variation or expansive nature of the soil.
- Provision of under-reams or bulbs has the advantage of increasing the bearing and uplift capacities.
Disadvantages of under reamed pile:
- At a depth, where nature of soil varies with a climatic condition, Under-Reamed Piles are not suitable for waterlogged soil, as they take load by friction.
- These piles need strict quality control and regular supervision during the construction.
- Most of the times, Under Reamed Piles, are driven manually with a hand-operated machine. Hence maintaining plumb of the pile is very essential, because if they are not in plumb whole load transfer mechanism would change.