Contiguous piles, also known as contiguous bored piles or CFA (Continuous Flight Auger) piles, are a type of foundation element used in civil engineering and construction. These piles are constructed using a continuous auger, and the construction process involves drilling a borehole using the auger while simultaneously filling it with concrete or grout. Contiguous piles are commonly used in various applications, including building foundations and deep excavation support.
Here are key features and uses of contiguous piles:
Construction Process:
- Continuous Auger Drilling: The process begins with drilling a borehole into the ground using a continuous flight auger. The auger is equipped with a hollow stem, allowing the soil to be removed as it drills.
- Concrete or Grout Injection: While the auger is withdrawn, concrete or grout is pumped through the hollow stem, filling the void left by the auger.
- Reinforcement: In some cases, reinforcement, such as steel bars, may be inserted into the fresh concrete to enhance the structural strength of the pile.
Key Components and Design:
- Diameter and Depth: The diameter and depth of contiguous piles can vary based on project specifications, soil conditions, and structural requirements.
- Spacing: The spacing between contiguous piles is typically determined by the structural engineer based on the load-bearing capacity of the soil and the anticipated loads on the foundation.
Advantages and Uses:
- Deep Foundations: Contiguous piles are suitable for creating deep foundations in various soil conditions, providing support for structures.
- Retaining Walls: They are often used in the construction of retaining walls, especially in situations where a continuous barrier is needed to resist lateral soil pressure.
- Reduced Noise and Vibration: The construction process of contiguous piles tends to generate less noise and vibration compared to other piling methods, making them suitable for projects in urban or sensitive areas.
- Suitable for Limited Access Sites: CFA piles can be constructed in areas with limited access because the drilling equipment can be adapted to fit into confined spaces.
Applications:
- Building Foundations: Contiguous piles are commonly used to support the foundations of buildings, especially in areas with challenging soil conditions.
- Deep Excavations: They can be employed to provide support for deep excavations, preventing soil collapse and ensuring stability during construction.
- Infrastructure Projects: Contiguous piles are utilized in various infrastructure projects, including bridges, highways, and other structures.
In summary, contiguous piles are a versatile and efficient solution for creating deep foundations and providing support in challenging soil conditions. Their construction process, which involves continuous auger drilling and simultaneous concrete or grout injection, makes them suitable for various applications, including building foundations and retaining walls. The reduced noise and vibration associated with their construction process make them advantageous in urban or sensitive environments.