Case study of a full-scale load test of a piled raft with an interposed layer for a nuclear storage facility

The ICEDA nuclear waste storage facility is being constructed near Lyon, France. It is founded on a thick clay deposit using settlement-reducing piles as soil improvement, making it the first nuclear installation in France employing this technique. The high safety requirements of the project, combined with the use of an innovative system based on piles disconnected from the foundation, have necessitated detailed studies of the soil–structure behaviour. In addition to an extensive ground investigation, a full-scale in situ test was carried out over a period of 6 months. This paper presents some of the experience gained from the project, focusing on the findings from the full-scale test compared with a class A prediction. It illustrates the difficulty in choosing soil parameters that are representative of the soil formation as a whole, and the value that the full-scale test had in the design for ICEDA.