Large diameter rotary bored piles are a type of deep foundation used to support heavy loads in construction. These piles are drilled into the ground using rotary drilling equipment and are commonly employed when traditional shallow foundations are insufficient due to high load requirements or poor soil conditions.
1.Design Considerations:
Load Capacity: Determined by soil conditions and pile dimensions. The design needs to account for both vertical loads and lateral forces.
Pile Diameter: Typically ranges from 600 mm (24 inches) to 1500 mm (60 inches) or more. Larger diameters provide higher load capacities.
Depth: Pile length can vary based on soil strata and load requirements. Deep piles reach stable soil or rock layers.
Reinforcement: Steel reinforcement cages are used to strengthen the pile. The design and placement of these reinforcements are crucial for structural integrity.
2. Construction Process:
Site Preparation: The area is prepared, and the location of each pile is marked.
Drilling: Rotary drilling rigs are used to bore the pile hole. This involves rotating a drill bit while applying downward pressure.
Casing Installation: In some cases, temporary casing is used to prevent collapse of the borehole, especially in loose or unstable soils.
Reinforcement Placement: A steel cage is lowered into the drilled hole.
Concrete Pouring: Concrete is poured into the hole to form the pile. This can be done using a tremie pipe or other methods to ensure concrete quality and avoid contamination.
Curing: The concrete is allowed to cure and gain strength before any load is applied.