TBM breakthrough into a secant piling reception shaft. In tunnelling projects where a Tunnel Boring Machine (TBM) breakthrough occurs into a reception shaft supported by secant piling or Diaphragm walling, the inclusion of a soft eye within the structure facilitates a smoother breakthrough for the TBM. Secant piling provides structural support to the shaft by creating a continuous wall of interlocking piles, which helps to stabilise the surrounding soil or rock. The soft eye acts as a predetermi

Secant Pile wall A Secant Piled Wall is a retaining wall constructed for ground retention prior to excavation. The wall is formed by constructing alternating primary (female) and secondary (male) piles where the secondary piles partially cut into either side of the primary piles in order to form a continuous impervious structure. Secant walls are frequently used to as an alternative to Diaphragm walls where obstructions are anticipated, or in urban basement projects where space is limited. In co