Secant Walls

Bachy Soletanche is experienced in designing and building hard/soft, hard/firm and hard/hard secant walls using continuous flight auger techniques or segmental casings for applications of 750mm pile diameters upwards.

The development of powerful high torque drilling equipment has led to an increase in the range of ground conditions and obstructions that can be penetrated and the wall thicknesses that can be constructed. We are therefore able to install secant walls in the most challenging urban environment.

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. These alternatives are generally used where temporary works are required.

Permanent retention can be provided with all reinforced piles (hard/hard), which can be incorporated within the final structure.

Piles in a secant wall are spaced at 0.8 to 0.9 pile diameters. Primary piles are secanted by secondary piles, thus providing a closed structure to act as a barrier in water bearing soils, and to prevent the ingress of soil between the piles.

Secant piling offers minimal vibration, low noise levels and the flexibility to fit complex site boundaries to maximise land use. Secant piling also has the ability to go through underground obstructions such as steel, heavily reinforced concrete, granite and masonry, while at the same time, avoiding any risk of construction induced settlements to neighbouring structures.