Secant Pile Wall (SPW)
A Secant pile wall is a type of shoring made of “hard” and “soft” pile. Hard piles are made with a weak concrete (C35 to C50) and are reinforced while the soft pile also called “female” pile are made of soft concrete (C10 to C20) and are unreinforced (except special case).
The shoring system will be formed by casting the soft piles first and then the hard piles. Hard piles will be interlocked into the soft piles with an overcut of approximately 100 to 150mm, depending on the excavation depth and on the water table level.
Common pile diameter used for this type of shoring is from 600mm to 1200mm, for an excavation depth up to 14.00m (except special case).
A secant pile wall structure offers a relatively good water tightness barrier and also prevents the ingress of loose soils in between the piles.
The typical sequence of work is as explained below:
• construction of the guide wall,
• installation of the soft piles with the use of support fluid if necessary or temporary casings,
• concreting of the soft pile,
• installation of the hard piles with the use of support fluid if necessary or temporary casings,
• lowering down of the reinforcement cage in to the hard pile,
• concreting of the hard pile and withdrawal of the temporary casing.
Notes:
Secant pile walls have limitations in term of excavation depth due to the possible risks of error in verticality. This may induce for a deep excavation a gap in between piles and therefore potentially create ingress of water and sometime fine particles of sand.
This technique offers the ability to go through underground obstruction with the help of special drilling tools.
The shoring system will be formed by casting the soft piles first and then the hard piles. Hard piles will be interlocked into the soft piles with an overcut of approximately 100 to 150mm, depending on the excavation depth and on the water table level.
Common pile diameter used for this type of shoring is from 600mm to 1200mm, for an excavation depth up to 14.00m (except special case).
A secant pile wall structure offers a relatively good water tightness barrier and also prevents the ingress of loose soils in between the piles.
The typical sequence of work is as explained below:
• construction of the guide wall,
• installation of the soft piles with the use of support fluid if necessary or temporary casings,
• concreting of the soft pile,
• installation of the hard piles with the use of support fluid if necessary or temporary casings,
• lowering down of the reinforcement cage in to the hard pile,
• concreting of the hard pile and withdrawal of the temporary casing.
Notes:
Secant pile walls have limitations in term of excavation depth due to the possible risks of error in verticality. This may induce for a deep excavation a gap in between piles and therefore potentially create ingress of water and sometime fine particles of sand.
This technique offers the ability to go through underground obstruction with the help of special drilling tools.