Anchored sheet piles

When the height of sheet piles is less than 6m, it is economical to use sheet piles which is anchored near its top. (Fig.1-b) Anchoring the sheet piles cause less penetration depth and also less moment to the sheet piles.

Well constructed anchor walls undergo less lateral deflection than braced walls and so provide a better control of back-slope subsidence. Anchor installation only requires a small excavation to allow equipment access.

Anchored walls are always pre stressed which essentially removes the slacks from the system. The anchor will maintain their load through the excavation sequence unless creep occurs.

The anchors also place the entire soil mass between the anchors and wall in compression, thus creating a very large gravity wall. (Hunt, 1986)

There are two causes of subsidence for anchor systems:

1) Caving of the anchor holes prior to grouting

2) Flow of cohesionless material into the excavation through wall opening made for anchor installation.

Another disadvantage includes possible downward movement of the wall due to the vertical component of the anchor forces.