Cast In Place, Sheet Piles or Diaphragm Walls
Techniques are available to provide temporary and permanent retaining walls which allow deep excavations (including adjacent to existing structures) to be carried out safely and in dry conditions, these include secant (piles interlock), contiguous ( a small gaps between the piles), sheet piles or diaphragm walls.
Walls can either be cantilevered or propped by a number of techniques including ground anchors and generally require the installation of a capping beam.
Diaphragm walls are constructed as permanent walls which reduce the width of construction and working space needed when compared to a solution that has both a temporary ground support and permanent works within. Diaphragm walls can also be used to support vertical loads.
Walls are constructed using specialist equipment, constructed in panels, often under fluid support and then reinforced and concreted.
Piled Retaining Walls (Contiguous or Secant)
In dry stable soils, contiguous bored pile walls can be constructed. This type of wall is a series of piles, with intervening gaps, to provide an effective retention solution. Where soils are saturated and water tightness is a requirement secant walls using either bentonite cement materials (soft) or weaker concrete (firm) are used in combination with reinforced concrete (hard) piles . Permanent retention can be provided with all reinforced piles (hard/hard) which can be incorporated within the final structure.
Steel Sheet Piling
Sheet piles can be designed to retain temporary and permanent excavations and can be constructed with or without propping as necessary. Piles can be installed using driven, or vibrationless techniques.