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Secant pile wall	Contiguous bored pile wall
EXCAVATION SUPPORT Amplus installs embedded pile walls to form retaining walls in soils and soft rocks. The walls can be free standing cantilever, propped or anchored. Secant pile walls comprise a row of interlocking piles, 350mm to 900mm in diameter,with 'soft' cementitous piles between 'hard' reinforced concrete piles. Contiguous bored pile retaining walls have a nominal gap between piles. When the ground conditions are appropriate this type of wall offers an efficient embedded pile system. Ground anchors can be utilised to tie back an embedded pile wall system or used independently to stabilise soil or rock slopes. Temporary or permanent anchors can be installed according to project requirements. Grouting of the ground is undertaken to stabilise, consolidate or limit groundwater ingress.

More Information on Basement & Slope Retention

Contiguous pile wall - typical diameters and spacing

 

Diameter mm	Spacing mm
350 450 600 750	400 600 750 900

 

Secondary hard/soft secant pile wall - typical diameters and spacing

 

Diameter mm		Spacing mm
Primary	Secondary
450 600 750	450 600 750	600 900 1000

 Note:  The gap between the primary or structural piles should not exceed 40% of the diameter of the soft piles

 

Typical applications of embedded retaining walls

(ICE Specification for Piling and Embedded Retaining Walls)

 

Wall Type	Typical height range		Groundwater control		Typical vertically
	Cantilever	Propped	Temp.	Perm.
Sheet pile wall	To 5m	4 - 15m	Yes	No	1:75
Combination wall	To 10m	5 - 20m	Yes	No	n/a
King post	To 4m	4 - 20m	No	No	n/a
Contiguous	To 5m	4 - 20m	No	No	1:75
Hard/soft secant	To 5m	4 - 20m1	Yes2	No	1:75
Hard/hard secant	To 6m	4 - 25m	Yes	Yes	1:200
Diaphragm wall	To 8m	5 - 30m	Yes	Yes	1:75

 

Notes:

1.  The depth to which hard/soft pile walls can provide water resistance is restricted by 

     the construction tolerances of the boring rig and the groundwater pressure to be

     resisted.  This type of wall is most commonly used to resist groundwater flow to

     maximum depths of approximately 6m.

 

2.  The long term resistance of the soft elements of hard/soft secant pile walls to

     groundwater flow has not been proven and will vary according to the soft mix design. 

     It is recommended that long term water resistance is provided for by additional works

     such as reinforced concrete lining walls which transfer the groundwater load into the

     hard elements.

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