Under reamed piles are the most and economical foundation in Black cotton soil. Under reamed piles are bored cast in situ concrete piles having bulb shaped enlargement near base. A pile having one bulb is called single under reamed pile. In its closed position, the under reamer fits inside the straight section of a pile shaft and can be expanded at the base of the pile to produce the enlarged base.

The cost advantages of under-reamed piles are due to the reduced pile shaft diameter, resulting in less concrete needed to replace the excavated material.

Under reamed piles are of two types:

Pre-cast under reamed piles

In-situ cast under reamed piles

Features:

• It is 15 to 20% cheaper than the strip footing.
• Less material required.
• Digging is normal so the work is carried out for anytime of the year.
• No back filling is required.
• Shoring is not required.
• Dewatering is not required.