Secant & Contiguous Pile Walls

Secant and contiguous pile walls are specialized deep foundation systems used for earth retention, basement construction, and excavation support. These pile wall systems provide both structural support and water-tight barriers, making them essential for urban construction projects with limited space and challenging ground conditions.

SECANT PILE WALLS

Secant pile walls are constructed by installing interlocking reinforced concrete piles in a specific sequence to create a continuous, impermeable barrier. The construction process involves:

• Primary Piles: Unreinforced or lightly reinforced piles installed first at designated spacing
• Secondary Piles: Fully reinforced piles drilled to partially intersect (cut into) the primary piles after they achieve initial set
• Interlocking: The overlap creates a continuous wall with no gaps, providing excellent water-tightness
• Structural Capacity: Secondary piles provide the main structural resistance to earth and water pressures

Types of Secant Pile Walls:

• Hard-Soft Secant: Primary piles are unreinforced; secondary piles are reinforced
• Hard-Hard Secant: Both primary and secondary piles are reinforced (higher capacity)
• Hard-Firm Secant: Primary piles use low-strength concrete for easier cutting

CONTIGUOUS PILE WALLS

Contiguous pile walls consist of bored piles installed in a row with minimal gaps (typically 100-150mm) between pile circumferences. Key characteristics include:

• Construction: Piles are drilled and constructed individually with small spacing between them
• Structural Function: Provides lateral support through pile-to-pile soil arching
• Gap Management: Gaps can be filled with shotcrete, gunite, or reinforced concrete facing
• Applications: Suitable for non-water-bearing soils or when groundwater control is provided separately
• Cost-Effective: More economical than secant walls when water-tightness is not critical

APPLICATIONS & ADVANTAGES

VFT specializes in both secant and contiguous pile wall systems for:

• Deep basement excavations for high-rise buildings
• Underground car parks and metro stations
• Bridge abutments and underpasses
• Permanent retaining structures
• Temporary works for tunnel portals
• Marine structures and waterfront developments

Our expertise in pile wall design and construction ensures safe, efficient excavation support tailored to specific soil conditions, water table levels, and project constraints. With advanced drilling equipment and experienced engineering teams, VFT delivers pile wall solutions that meet the highest standards of quality, safety, and performance.