An agile technique that adapts to the complexity of the project and its environment.

Foundations, reinforcements, underpinning – discover the wide range of applications of micropile technology used by Soletanche Bachy.

micropiles process / procédé micropieu
Micropile technology

Micropiles are bored piles with a diameter of less than 300mm.


Micropiles are generally used for repairs to existing foundations and for reinforcing foundations of existing structures. Micropile driving and/or boring machines are light and compact, allowing work to be carried out within the existing structure.


Micropiles can also be used to carry out new construction work and retaining structures such as micro-Berlin-type wall.


Micropiles can bear both compressive and tensile loads and also be used on steep gradients (> 20° from the vertical).


The micropile is supported by a steel bar, a steel tube or an H beam, which is:

  • either sealed to the ground using a cement grout, mortar or using micro-concrete for bored micropiles.
  • or in direct contact with the ground for displacement micropiles.

What are the advantages of this technique?

Applicable to foundation works, from transmission of tensile loads to angled boreholes, repairs, reinforcements or even retaining works,

Adapts to site constraints: limited height, work from a platform, near existing structures and structures in use, etc.

Adapts to constraints linked to the nature of the ground: stability, drillability, hardness, granulometry, etc.

Soletanche Bachy’s advantages

Soletanche Bachy’s advantages

  • A large fleet of drill rigs available for work sites, some of which are electric, allowing work in confined spaces,
  • Dedicated software developed in-house,
  • A Design office capable of designing and building machines tailored to a site’s specific constraints: remote platform, linked to a structure, suspended from a crane, floating, etc.
  • Technical developments of the tool, developed internally to better meet the project’s needs and improve our projects’ performance (see – Did you know?)


Bored micropiles

Methods of execution of bored micropiles are based on the use of compact drilling machines which allow continuous drilling in direct and/or reverse circulation with a drilling fluid such as air, water, bentonite mud, polymers or cement grout. In order to optimize production, it is common for the reinforcement to comprise a hollow bar or a tube, “self-bored” using a lost tool, allowing drilling fluid and sealing grout to flow through its centre.


Displacement micropiles

In the case of displacement micropiles, the load-bearing component made of steel, iron or precast concrete may be installed by vibro-driving or driving.


When underpinning the foundations of a building, the loads may be totally or partially transferred by jacking to control the effects of differential movements over time.  The vertical deformations of micropiles are greater than those of piles of equivalent bearing capacity.

Soletanche Bachy has developed continuous and rigorous real-time monitoring of the foundation construction process to allow immediate action in the case of changes to the foundation construction conditions.


These decision-making tools assist operators in real time to correct any errors which could lead to a lower quality foundation.

Reprise en sous-œuvre / Fondation /underpinning/micropiles

Execution controls and monitoring

Did you know?

Ever more innovative and involved in the geotechnical community, Soletanche Bachy continues to develop proprietary tools and techniques and to participate in French and European standardisation.

The Hi’Drill® process

In order to be always more efficient, Soletanche Bachy has developed the Hi’Drill® process, which allows boring to be carried out more quickly thanks to the combined effects of rotation and translation of a traditional head and those of resonance of a Hi’Drill® head. This process adapts to all types of ground, from the softest to the hardest. It is particularly effective in mixed formations, including through wood and reinforced concrete.