In order to stabilize the deep excavations, some kind of lateral support is needed. This is to reduce and control the lateral displacements of the shoring system and to allow deep basements.

This technique of using pre-stressed anchor is relatively recent compared to other branches of special underground works. Our perfect knowledge of this technique permits the use of such anchor in almost any type of soils.

Anchors are divided in two categories, permanent and temporary anchors.

Typically, an anchor consists of three parts:

• The free length.
• The fixed length.
• The anchor head.

The typical sequence of work is as explained below:

• Drilling of the hole to the required designed depth, using casing or support fluid, water or bentonite,
• Flashing, cleaning of the shaft,
• Injection of the anchors
• Second injection of the anchor if required
• Setting up of the grout,
• Stressing of the anchor.

Anchors are designed to typically ranging from 20.0T to 120T, depending on the numbers of strands, the lengths and the soil conditions.