INSTALATION METHODS
We specialise in cast-in-situ concrete and grout piling. The methods described can be used to construct single bearing piles, pile groups or retaining walls. Using our expertise we can choose the optimum instalation method and piling rig to suit the ground conditions, pile diameter and depth, and the access and constraints of the site. We offer a range of installation techniques:
Rotary Bored piles are drilled using temporary outer casings to support upper unstable and water bearing soils. They are then drilled open hole to the pile design founding level. The drilling method involves incrementally adding augers, or repeated raising and lowering a drilling tool on a kelly bar, into the pile bore. Where the ground cannot be sealed with casings, or bored dry, then a temporary drilling fluid such as bentonite or polymer drilling aides are used. Upon completion of drilling the augers are removed, the pile bore is cleaned, a reinforcement cage is installed and the pile is concreted. The rotary bored piling method can be adapted using special casing shoes and drilling tools to bore through obstructions, such as existing piles, or boring through natural rocks.
Continuous Flight Auger (CFA) piles are drilled using a hollow stemmed single length of “continuous” flighted auger, that is drilled to the required depth normally in one pass. As the auger is rotated out of the ground, concrete is pumped through the hollow stem of the auger to fill the void created. Upon completion of the concreting a reinforcement cage is plunged into the concrete. The boring head on the auger can be modified to suit a range of soil and rock conditions. Larger rigs are fitted with instrumentation to monitor the pile construction and provide quality control records.
Segmental Flight Auger (SFA) piles are similar to the CFA method but the auger is added segmentally to achieve the design depth. It is often used to install piles in unstable soils where access is limited and only a mini piling rig can be deployed.
