Piling is a foundation-building technique that transfers a building’s weight to deeper soil. It’s an effective construction method for sites where ground conditions prevent the construction of shallow foundations and is also used to reinforcing existing foundations.
We use specialised drilling rigs to work in domestic spaces where headroom and access are limited, as well as commercial projects such as basements. These rigs are much less disruptive and noisy than traditional construction methods.
CFA (Continuous Flight Auger) Piling
CFA piles are a quick and economical solution for load bearing piles in most ground conditions. Also known as drilled displacement piles, they are also commonly used for excavation support (tangent or secant pile walls).
Piles are formed using an auger with a hollow stem bored into the ground to the required design depth. Concrete is pumped through the hollow stem whilst the auger is being slowly extracted forming a shaft of concrete to the ground surface into which a reinforcing cage can be inserted. This is done under controlled pressure and volume monitored by on-board rig telemetry.
This method is ideal for construction in noise sensitive areas as it generates very low levels of vibration compared with other piling methods. It is also a suitable solution for projects with low headroom conditions or where piles are to be constructed in water bearing strata. It is also the preferred method for constructing tangent and secant pile walls as it allows greater productivity rates than other piling techniques.
SFA (Sectional Flight Auger) Piling
Piles are drilled into the ground using CFA rigs (sometimes known as auger displacement rigs). This is a quick, economical and quiet method of piling which is particularly suitable for inner city projects due to the low levels of vibration, noise pollution and disruption to adjacent buildings.
Upon reaching the design depth, concrete or grout is pumped through the hollow stem of the continuous flight auger whilst it is slowly withdrawn from the hole. The resulting pile is then immediately reinforced with a steel cage.
CFA piles are a popular and highly versatile solution for both residential and commercial developments as they can be used in most soil conditions including dense sand, clay or low-grade rock. Designed to meet a wide range of load requirements, they are particularly well suited for applications where heave is a concern or to provide a deep foundation in a limited space. They can also be used in conjunction with a retaining wall to reduce the risk of movement.
Retaining Walls
Retaining walls are structures that are used to bound soils that would otherwise slide down a slope. They’re essential in the creation of sunken patios, walkout basements and any hardscape with an abrupt separation in ground elevation. They’re also indispensable for parks and public gardens where they act as retainers for plants, statues and decorative landscaping elements.
Restrained earth walls, also known as mechanically stabilized earth (MSE) walls, use layers of geogrid to reinforce soil into a cohesive mass that resists differential settlement. This construction technique is often employed in locations where a piling retaining wall wouldn’t be suitable due to vibration or noise concerns.
Bored pile retaining walls are constructed using a series of bored piles that are either interlocking or installed next to each other (contiguous). This construction method is typically employed in scenarios where the structural performance of a conventional piling retaining wall is required, but a vibration-free operation is preferred. This solution is most commonly employed in soft soils where a traditional piling retaining wall wouldn’t be feasible.
