The national standard implementing Eurocode 7 for deep foundations, NF P94-262, defines four types of micropiles: type I and II (gravity fill), type III IGU (post grouting single stage) and type IV IRS (post grouting multi stage).
However, the performance of type III micropiles is clearly the most variable in terms of axial friction, since they are highly dependent on the waiting time between filling the grout sheath and injecting a second pressurised grout into the borehole.
This article concerns a new type of micropile proposed by Soletanche Bachy, called a single-stage immediate post grouting (ISU – Injection de Serrage Unitaire) micropile, which eliminates that waiting time and improves the resistance of the grouted micropiles. This new process is particularly effective combined with self-drilling and Hi’Drill® techniques.
This innovation is the subject of Specific Specifications, initially validated by Bureau Veritas, then assessed and validated by Ifsttar and Cerema. Finally, we should add that this process recently received the VINCI innovation award in the Greater Paris region in the “processes and techniques” category.
Want to find out more? Read the attached article