Definition

A pile wall is a type of retaining wall constructed by driving or drilling a series of vertical piles into the ground to form a continuous barrier that supports soil or water. Pile walls are used in various geotechnical and structural engineering applications to provide lateral earth support for deep excavations, prevent soil erosion, and control groundwater flow. Depending on the project requirements, different types of pile walls can be used, including contiguous pile walls, tangent pile walls, and secant pile walls.

Types of Pile Walls

There are several types of pile walls, each with specific construction methods and applications:

• Contiguous Pile Wall: Consists of piles installed with small gaps between them, suitable for temporary support in dry conditions where groundwater control is not critical.
• Tangent Pile Wall: Involves piles installed with their edges just touching each other, creating a continuous wall with minimal gaps, used for retaining soil in various conditions.
• Secant Pile Wall: Constructed with overlapping piles, providing a nearly watertight barrier that is effective for deep excavations and groundwater control.

Construction

The construction of a pile wall typically involves the following steps:

• Site Preparation: The construction site is cleared and leveled, and drilling or driving equipment is set up.
• Pile Installation: Piles are installed vertically at regular intervals using bored or driven piling techniques. The type of pile and installation method depends on the soil conditions and the specific type of pile wall being constructed.
• Reinforcement: Piles are often reinforced with steel bars or cages and filled with concrete to enhance their load-bearing capacity.
• Completion: After the piles are installed, any gaps between them may be filled with grout or shotcrete to improve the wall’s integrity, especially in tangent and secant pile walls.

Context of Use

Pile walls are commonly used in various geotechnical and structural engineering applications, including:

• Deep Excavations: Pile walls provide essential lateral support for deep excavations, preventing soil movement and ensuring the stability of adjacent structures.
• Retaining Structures: Used to retain soil and prevent erosion, pile walls are effective in both temporary and permanent retaining structures.
• Water Control: Secant pile walls, in particular, are used to control groundwater flow, making them ideal for use in below-ground structures such as basements and tunnels.
• Urban Construction: Pile walls are widely used in urban environments where space is limited and construction must minimize disruption to surrounding structures.

Advantages

• Versatility: Pile walls can be constructed in a wide range of soil conditions and are adaptable to various project requirements.
• Effective Lateral Support: Pile walls provide strong lateral support, making them suitable for deep and challenging excavations.
• Groundwater Control: Secant and tangent pile walls can be designed to control groundwater flow, reducing the risk of seepage in excavations.

Limitations

• Cost: Pile walls can be more expensive than other types of retaining walls due to the need for precise drilling and high-quality materials.
• Construction Time: The installation of pile walls can be time-consuming, particularly for secant pile walls that require overlapping and cutting into adjacent piles.
• Environmental Impact: The construction of pile walls, especially driven piles, can generate noise and vibration, which may impact nearby structures and the environment.

Summary

Pile walls are a versatile and effective solution for providing lateral earth support in various geotechnical and structural applications. By installing a series of vertical piles, these walls can retain soil, control groundwater, and provide stability for deep excavations and retaining structures. While pile walls offer significant advantages in terms of strength and adaptability, they also come with higher costs and construction complexity, requiring careful planning and execution to ensure their effectiveness and minimize environmental impact.