Diaphragm Wall Construction (D-Wall)
Diaphragm Wall Construction, commonly known as D-Wall construction, is a specialized deep foundation technique widely used in modern infrastructure and geotechnical engineering projects. These reinforced concrete walls are constructed in the ground before excavation and act as permanent or temporary retaining structures. D-walls are especially effective in projects requiring deep excavations in congested urban areas or challenging soil conditions.
What is a Diaphragm Wall?
A diaphragm wall is a reinforced concrete wall constructed using a trench excavation method, supported by slurry (bentonite or polymer) to prevent soil collapse. Once the trench reaches the desired depth, a reinforcement cage is placed inside, and concrete is poured using the tremie method to form a continuous, strong wall.
These walls are commonly used for:
Basement construction
Metro and underground stations
Deep foundations
Cut-and-cover tunnels
Waterfront and quay walls
Diaphragm Wall Construction Process
1. Guide Wall Construction
Shallow guide walls are constructed first to ensure alignment and stability during trench excavation.
2. Trench Excavation
A hydraulic grab or trench cutter is used to excavate the soil. Bentonite or polymer slurry is circulated to support trench walls.
3. Slurry Stabilization
The slurry maintains hydrostatic pressure, preventing trench collapse and groundwater ingress.
4. Reinforcement Cage Installation
Pre-fabricated steel reinforcement cages are lowered into the trench.
5. Concrete Placement
Concrete is poured from the bottom using tremie pipes, displacing the slurry and forming a dense reinforced concrete wall.
Types of Diaphragm Walls
Panel Walls โ Constructed in panels for large projects
Secant Diaphragm Walls โ Overlapping panels for increased water tightness
Anchored Diaphragm Walls โ Supported with ground anchors
Cantilever Diaphragm Walls โ Used where excavation depth is limited
Advantages of Diaphragm Wall Construction
High structural strength and stiffness
Excellent water-tightness
Suitable for deep excavations
Minimal vibration (ideal for urban areas)
Can serve as a permanent structure
Long service life with low maintenance
Applications of Diaphragm Walls
Underground parking basements
Metro rail projects
High-rise building foundations
Bridge abutments
Dams and water retaining structures
Industrial and commercial complexes
Diaphragm Wall vs Other Retaining Systems
Compared to sheet piles or secant piles, diaphragm walls offer:
Greater depth capability
Better load-bearing capacity
Reduced noise and vibration
Superior durability and water resistance
Conclusion
Diaphragm Wall Construction (D-Wall) is a reliable and advanced foundation solution for deep excavation and structural support in complex geotechnical conditions. With its superior strength, water resistance, and adaptability, D-wall construction has become a preferred choice for major infrastructure and urban development projects.
