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Ground anchor2023-11-23T12:00:23+01:00

Project Description

An essential system for the stability of your structures.

Soletanche Bachy uses ground anchors for the construction or repair of structures, mainly, but not exclusively, for support of excavation works.

What is a ground anchor ?

A ground anchor is a system capable of transmitting a tensile load into a competent stratum, drawing support from the structure to be anchored.
Ground anchors are commonly used to prevent deformation of a retaining wall after excavation. In such case, anchors are installed through the retaining structure during the excavation phase. Earthworks are resumed once these anchors have been tensioned.

A ground anchor is therefore always carefully treated, as it contributes to structural stability.

An anchor comprises three parts:

  • The head, transmitting the anchor force to the structure via a bearing plate
  • a free length of tendon, from the head to the near extremity of the bond length,
  • a bond length, which is the length of tendon through which the tensile force is transmitted to the surrounding ground through a bond grout.

An anchor is called “temporary” if it is to be used for a limited period of time, generally during construction of the structure. A “permanent” anchor is a ground anchor lasting more than two years or, more generally, a component required for the entire lifetime of the structure.

Two types of ground anchors

Passive

This type of anchor does not usually have a free length. Generally speaking, the anchor consists of a steel bar or is sometimes made of composite material.  A passive anchor is only tensioned by the structure itself applying load to it.

Vue coupe d'un tirant d'ancrage

Active

This type of anchor has a free length and a bond length.  The armature is usually made of steel cables, pre-tensioned to reduce the displacement of the structure.

Each anchor is protected against corrosion to prevent any impact on the system. This is defined based on two main criteria: the lifespan of the anchor and the aggressiveness of the environment.

A wide range of applications for ground anchors

Temporary and permanent retaining walls

Diaphragm walls – Sheet piling – Retaining walls – Underpinning curtain – Berlin-type walls and similar.

Transmission of tensile loads

Anchoring of slabs below the water table – Pre-stressing of piles working in traction – Anchoring of narrow structures (pylons, tower buildings, chimneys, etc.) – Transmission of tension for rigging lines (suspension bridges, pylons, etc.).

Anchorage – Nailing

zStabilisation of slopes and landslides (cracked rocks, cliffs, scree areas) – Consolidation of tunnels – Blocks of penstocks.

Miscellaneous

Transmission of pressure on vaults – Post-stressing of structures – Dam stability improvement.

What are the advantages of this technique?

Applies to a wide range of ground conditions

Compatible with numerous small diameter drilling techniques

A retaining structure can be stabilised by one or several levels of ground anchors

Permanent lifespan of anchors (subject to regular monitoring)

Environmental benefits

  • Low-carbon concrete and grout, thanks to our solution EXEGY by Soletanche Bachy.
  • Electric equipment, to reduce our fuel consumption.
  • Designs optimized by our engineering departments, enabling us to offer variants that reduce the amount of materials used.

Implementation

Soletanche Bachy’s advantages

Perfect knowledge of the system and its uses

International experience in various soil conditions and situations

Each anchor is considered as a sensitive structure, and is therefore carefully followed

Execution controls and monitoring

  • Properties and composition of the cement grout,
  • Continuous monitoring of all stages of production, from boring to commissioning of the ground anchor
  • Tensioning phase of every active anchor is checked by one of our Design offices before commissioning.

Did you know?

  • Soletanche Bachy created the Repetitive Selective Grouting which increase significantly the capacity of ground anchors. This innovation was inspired from the Father of “Tube a Manchettes” device, Ernest Ischy.
  • The capacity of an active anchor may vary from a few dozen kiloNewtons to more than 15,000 kN
  • Very high-capacity ground anchors are often used to improve the stability of dams. Our record was established in 2014 at Wanapum Dam in the United States (Washington State) with the installation of 35 pre-stressed ground anchors. Each of these comprising 61 metallic wires at a depth of 80m.

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