Restricted access bored piling

Utilising the Martello Technique, large diameter piles (750/900/1050mm) are able to be constructed to depths of 40.0m to form fully reinforced piles of up to 8500kN (dependant on site specific conditions and diameters) in restricted access and low headroom conditions. 

Construction Sequence

1.Drill a short pilot hole.

2.Install a lead casing and screw into the ground.

3. Excavate soil from within the casing, utilising the Martello Technique, where the auger slides up and down the Kelly bar (which remains in situ) to remove the spoil.

4. When the depth of the boring reaches depth of the first kelly bar section (2.0m), an additional length of Kelly bar is added at ground level to advance to boring operation.

5. Add further lengths to casing in advance of the bore depth.

6. Add further lengths of sectional Kelly bar (Martello Technique) to enable the pile bore to be advanced to depth and to bring up the spoil.

7. When the bore has reached the design depth, remove auger and kelly sections to enable the pile case reinforcement to be placed and concrete the pile. 

8. Remove the temporary casing.

Fields of application

• Structures where large rigs cannot gain access.

• Strengthening foundations to existing buildings or under bridges.

• Undertaking pre-demolition piling within existing basements.

• Size of Martello rigs enable plant to be craned into existing basements and excavations.

• Drilling through obstacles (man-made and natural) 

• Drilling with polymer or bentonite where deep ground support is required 

Environmental impact 

• Low vibration and noise

• Able to form high capacity piles without the need to pre-demolish existing structures

• Removal of excavated spoil required

Technical Specifications

• Diameter: 600mm up to 1050mm

• Depths up to 40m in 3.5m of headroom

• Bearing capabilities to 8500kN

• High lateral load capacity to form secant and contiguous piled walls

Related projects for this technique

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