01.Under Reamed Piles:

The Solution for Expansive Soils

Under Reamed (UR) Piles are a specialized type of bored, cast-in-situ concrete pile designed primarily to provide a robust and reliable foundation in challenging ground conditions, particularly in areas with expansive soils like black cotton soil.

How They Work

The core feature of an Under Reamed Pile is its enlarged base bulb (or multiple bulbs) created at the bottom of the bore. This bulb is formed using a special tool called a reamer before the concrete is poured.

The pile functions in two critical ways:

• 1. Anchorage: The enlarged bulb acts as an anchor below the zone of seasonal moisture variation (the active zone). When expansive soil swells due to moisture, it grips the vertical shaft but cannot lift the pile because the bulb is locked into the non-expansive, deeper stratum.
• 2. Bearing Capacity: The bulb significantly increases the bearing area, distributing the structure's load over a much larger surface, thereby enhancing the overall load-carrying capacity of the foundation.

Key Advantages

• • Counteracts Swell and Shrink: The most significant advantage is their ability to resist the forces of uplift and heaving caused by the volume changes in expansive and cohesive soils, protecting the structure from differential settlement.
• • Increased Load Capacity: They offer higher compression and tension (uplift) capacity compared to a plain straight-shaft pile of the same diameter and depth.
• • Cost-Effective: Often a more economical foundation choice than deep straight-shaft piles or rafts when dealing with moderate to high expansive soil risks.

Under Reamed Piles are the geotechnical engineer's choice for providing stability and long-term durability in unpredictable sub-surface environments.