Piled Walls

Piled Walls
Soldier Pile Walls

Soldier Pile Walls may consist of preformed elements installed into pre-drilled holes, or reinforced concrete cast-in-place piles. In either case, soldier piles are positioned at typically 1.5 - 2.4 metre spacing and in-situ sprayed concrete infill panels or other forms of lagging are subsequently installed. Soldiers may be cantilevered or restrained by soil anchors, which are progressively installed along with the infill lagging, as the excavation proceeds.

Contiguous Pile Walls

This non-waterproof form of site retention is constructed utilising cast-in-place piling techniques (typically CFA piles) to form a row of closely spaced abutting piles. These piles are used for retaining adjacent structures and for lateral ground support to excavations in ground conditions of all kinds above the water table.

Pile diameters typically range from 400mm to 900mm and may be either in a cantilevered or anchored form. In situations where vibration or noise generated by driving piles is unacceptable, this form of retention piling has a distinct advantage.

Secant Pile Wall

Offering a superior level of water tightness to contiguous pile walls, secant pile walls comprise interlocking primary and secondary CFA or Bored piles. Secant pile walls are generally specified for excavations in granular material below the water table where soil loss between the piles would pose significant construction problems. Because of cold joints between adjacent piles, some leakage may occur with secant pile walls and this should be catered for within the overall basement design.

There are two types of Secant pile walls; hard / soft or hard / hard. In either case, primary (unreinforced) piles are installed first followed by secondary reinforced piles. Fully cased or double rotary CFA methods can also be used to improve verticality tolerances, though there are limitations on diameter and depth using these systems.

Sheet Piling Walls

Interlocking steel sheet piles come in a wide range of sections to suit applications ranging from simple trench support, to marine walls and cofferdams. Sheet piling is used for both temporary and permanent structures. The interlocking clutches enable the sheets to form a continuous wall. The sheets may be extracted for re-use. Installation is normally by impact or vibratory hammers, depending upon soil conditions. Guide frames or walls assist installation and accurate alignment.

Special care must be exercised in keeping piles vertical and in-line whilst interlocking and driving. This is particularly important where the closure of the sheet walling is required.