A contiguous bored pile wall is a retaining wall consisting of concrete bored piles installed in a linear configuration with a minimum spacing of 150mm between consecutive piles installed as a retaining structure.
What is a contiguous bored piled wall?
A contiguous bored pile wall is a retaining wall formed using CFA, Cased CFA (CSP), SFA or rotary bored piling techniques consisting of a row of unconnected piles cast-in-situ with a nominal gap between consecutive piles.
They are flexible in shape and design compared to diaphragm retaining walls and offer a significant lateral strength advantage compared to that of sheet piled walls.
Contiguous bored piled walls are typically installed within dry and cohesive soils, the wall is not watertight and the soil between individual piles is exposed during excavation. Reinforced mesh and spray concrete can be applied as a lining to secure the exposed soil.
A capping beam is installed to form a continuous homogeneous retaining structure that can incorporate ground anchors or temporary propping to provide additional lateral support. Depending on ground conditions walls can be installed as cantilever or a propped cantilever wall.
Key capabilities
- Rig loadings: 6–140 tonnes
- Pile diameter: 300–1,200mm to depth of 32m using CFA techniques
- Pile diameter: 300 – 2,100mm to a depth of 65m using rotary bored piling techniques
What are the advantages of Contiguous Piled Walls?
- More cost effective than diaphragm walls
- Greater flexibility in terms of geometry
- Individual piles pile can provide both lateral support and bearing capacity
- Piles can be installed within challenging ground conditions using rotary techniques
- Suited to city centre to support excavations within congested sites
- The design of continuous walls considers adjacent structures and utilities
Common Uses
- Construction of basements or cellars
- Inserting substructures close to an existing structure
- Slope stabilisation
- Excavation support
- Bridge abutment
