Definition

A contiguous pile wall is a type of retaining wall constructed by installing a series of closely spaced piles, where the gaps between the piles are small but do not overlap. Unlike secant or tangent pile walls, contiguous pile walls leave small gaps between the piles, which can allow some soil or water to pass through. This construction method is typically used for temporary excavation support, particularly in dry soil conditions, and is effective for retaining soil in less critical applications.

Construction

The construction of a contiguous pile wall involves several key steps:

• Site Preparation: The construction site is prepared by clearing and leveling the area and setting up the necessary drilling equipment.
• Pile Installation: Piles are drilled and installed at regular intervals, with small gaps between them. The piles are usually made of reinforced concrete and are installed using bored piling techniques.
• Completion: After all piles are installed, the wall provides lateral support to the excavation. The gaps between the piles can be filled with grout or left open, depending on the project requirements.

Context of Use

Contiguous pile walls are commonly used in various geotechnical engineering applications, particularly where groundwater control is not a major concern:

• Temporary Excavation Support: Contiguous pile walls are often used to provide temporary support for excavations, particularly in dry conditions where groundwater seepage is minimal.
• Urban Construction: These walls are used in urban environments where space constraints require vertical excavation support, but complete watertightness is not essential.
• Low-Risk Retaining Structures: Contiguous pile walls are suitable for retaining soil in low-risk applications where the movement of soil or water through the gaps between piles is acceptable.
• Cost-Effective Solutions: Compared to other types of pile walls, contiguous pile walls can be a more cost-effective solution, particularly for less critical projects.

Advantages

• Cost-Effective: Contiguous pile walls are generally less expensive to construct than secant or tangent pile walls, making them suitable for projects with budget constraints.
• Speed of Construction: The construction process for contiguous pile walls is relatively quick, as there is no need for overlapping or cutting into adjacent piles.
• Suitable for Dry Conditions: These walls are particularly effective in dry soil conditions where groundwater control is not a significant concern.

Limitations

• Limited Groundwater Control: The gaps between piles can allow groundwater to seep through, making contiguous pile walls unsuitable for applications where watertightness is required.
• Less Structural Integrity: Contiguous pile walls may not provide the same level of structural strength and support as secant or tangent pile walls, particularly in challenging soil conditions.
• Potential for Soil Loss: In some cases, soil can erode or migrate through the gaps between the piles, which may require additional measures to prevent movement.

Summary

Contiguous pile walls are a practical and cost-effective solution for providing lateral support in excavations, particularly in dry soil conditions where groundwater control is not a major concern. By installing a series of closely spaced piles with small gaps between them, these walls offer a quick and economical way to retain soil during construction. However, the gaps between the piles limit the wall’s ability to control groundwater and may reduce its overall structural integrity, making contiguous pile walls best suited for low-risk or temporary applications.