Piled Retaining Walls

Piled retaining walls are mainly used in excavations to retain soil, sand and water. With the addition of concrete beams, they can form the foundations, and single piles can also be used as footings. It is beneficial to install piled retaining walls before excavation of adjacent buildings and structures begins. This is so that the buildings will be protected from damage or collapse.

Piled retaining walls employ bored piling techniques - normally called CFA or rotary. These provide special advantages where available working space dictates that basement excavation faces be vertical. Both methods offer technically effective, and cost efficient means of retaining the sides of bulk excavations, even in water bearing strata.

When used in permanent works, piled retaining walls can also be designed to accommodate vertical loads. Construction of both methods is the same as for foundation bearing piles. Contiguous walls are constructed with small gaps between adjacent piles. The size of this space is determined by the nature of the soils.

Secant piled walls are constructed so that space is left between alternate 'female' piles for the subsequent construction of 'male' piles. Construction of 'male' piles involves boring through the concrete in the 'female' piles in order to key 'male' piles between them. The male pile is the one where steel reinforcement cages are installed, though in some cases the female piles are also reinforced.

Secant piled walls can either be true hard/hard, hard/intermediate (firm), or hard/soft, depending on design requirements. Hard refers to structural concrete and firm or soft is usually a weaker grout mix.

Contiguous Piled Retaining Wall

A contiguous pile wall is formed by closely spacing bored piles, so that they form a retaining wall, usually before excavation of a building or structure begins. The piles are created by concrete injection and a shotcrete finish may be sprayed over the wall to create a flat surface.

Continuous Flight Auger (CFA)

Our auger drill rigs are used to drill holes, which do not require the insertion of steel casings. We inject a concrete mixture into the hole as the auger is withdrawn, and this forms a pile. Using this system we can speed up the process and produce a cost effective solution, for the construction of small to medium size piled retaining walls.

Helical Piling

Any structure can suffer from movement or subsidence. This can be caused due to clay shrinkage, tree root growth etc. Cracking can appear in buildings or structures, and on occasion, cause failure of a structure.

Accubeam piling and underpinning offer a range of piled retaining wall solutions. We utilise a combination of helical pile and masonry reinforcement technology, to stabilise and restore the integrity of structures and create a piled retaining wall. The versatility of the system, allows it to be used where other retaining wall solutions, would be too expensive and disruptive or where access isn’t possible for larger piling rigs.

Our mini piling, underpinning and retaining wall services are ideal for commercial structures, housing repair and retaining wall stabilisation. Used in conjunction with a helical beaming system, the helical pile is used as a standard pile and beam method.