Micropiles and Midpiles for Foundations and Retaining Walls

Micropiles are small-diameter piles (diameter ≤ 300 mm) and serve as a structural element to transfer loads to greater depths and/or limit structural settlements. The reinforcement of micropiles is typically made of a steel tubular or profiled structure, while the filling material can be a cementitious mixture, cement mortar, or grout. Larger-diameter micropiles (up to 400 mm), also known as mid-piles, are usually reinforced with steel cages.

Micropile Retaining Walls: Berlin Walls

Berlin Walls are flexible support structures consisting mainly of a series of micropiles installed at regular intervals along the perimeter of the excavation to be supported. The spacing between one pile and another varies from 30 cm to 50 cm depending on the requirement. Berlin Walls are a valid alternative to traditional structures created using diaphragm walls or drilled pile walls and are suitable in the following contexts:

• The soil is not suitable for excavation or drilling of large elements due to the presence of rocky material in the form of layers or blocks.
• Boundary conditions require non-invasive interventions.
• Minimum excavation space loss is required.
• Circumstances where surface morphology, available space, and boundary conditions only allow the mobilization of smaller-sized equipment (excavation downstream of the structure is not required below the water table).