Continuous Flight Auger Piling at Tesco / McCarthy and Stone in Aylesbury

 

Having in the past negotiated and prepared contract documents for many piling companies, I was very interested in the works next to Tesco in Aylesbury. They have sold part of the car park for McCarthy and Stone to build retirement apartments. The piling rig was in full swing when I last visited the store. I recognised the works as continuous flight auger piling and found this explanation from P J Edwards and Co on their website.

CFA piles are formed by drilling a continuous flight auger into the ground. The sides of the hole are supported at all times by the soil filled auger, eliminating the need for temporary casing or support fluids.

Upon reaching the required depth, concrete is pumped down the hollow stem as the auger is steadily withdrawn. Reinforcement is placed immediately after withdrawal of the auger and into the fluid concrete.

CFA piles are drilled in diameters up to 1200mm and to depths of up to 41.0 metres.

The CFA pile is essentially a non-displacement bored pile. Hence, there is little risk of damage to adjacent foundations or underground utilities from ground displacement or densification of loose sands, as can occur with displacement piles.

Another advantage is that CFA piles are installed with little vibration or noise. Should problems occur during pile construction, it is relatively simple to re-drill and install the pile at the same location, thereby eliminating the need to redesign the pile group or the pile caps.

The use of on-board computers provides the piling contractor and the client with excellent information on the strength of the soil bored and the pile construction in the form of a computer generated log.

Most importantly CFA piling is very fast and therefore the most economic way to install piles today.