Contiguous Wall Piles

Contiguous bored pile walls consist of a line of individual piles positioned at close centres.

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The piles are installed by rotating a continuous flight, hollow shaft auger into the soil to a specified depth. High strength cement grout is pumped under pressure through the hollow shaft as the auger is slowly withdrawn. Reinforcing is then installed while the cement grout is still fluid. The resulting grout column hardens and forms an auger cast pile.  

Advantages using auger cast piles include:: 

• Less noise - Auger cast piles are a drilled and pumped grouted not a driven pile, which eliminates the hammer-impact noise created by driving piles.
• No objectionable vibration - The elimination of a pile-driving hammer allows the installation of auger cast piles adjacent to existing structures without the danger of settlement or damage to existing footings or walls.
• No temporary casing required - During the installation of a dual rotary contiguous pile the earth filled auger maintains the shape for the pile hole during the drilling phase, which is then pumped with grout against the soft soils. 
• Can be installed in tight areas - The dual rotary auger  using a drive mechanism that aloows it to pile very close to adjacent structures. Thereby maximising ground floor space.
• Soil at each pile hole can be inspected - The grout that is pumped into the pile displaces the existing soil for the entire length of the pile. This displacing action makes the soil along the length available for visual inspection and testing.

Because the piles are discreet the retaining function of the wall relies upon the soil between the piles arching. Consequently they are therefore not normally appropriate for use in granular soils with a high ground water table. 

Piles are installed in a line to form a structure supporting soils and adjacent structures retained behind when excavation is required in front of the wall. These are often installed on the perimeter of the structure or where significant level changes are necessary and groundwater can also be controlled and drained as necessary. These structures can be designed to provide temporary works for a short duration and also incorporated into the permanent structure in the long term.