Earthen works

The objective of these surveys was to estimate the resistance to duct erosion of the watertight masks of the dikes reinforced with core drill holes.

Core drillings were therefore carried out in the watertight masks of the "invariant" and "Plan Rhône" dikes, with the taking of intact samples and laboratory tests.

The core drilling was carried out over the entire height of the alluvium borehole, to obtain all the samples intact under PVC sheathing. The samples taken were sent to the Sol Solution laboratory for identification and mechanical tests. At the end of the work, these boreholes were completely filled in with clay balls.

The location, depth and inclination of the boreholes were determined in such a way as to take a sample that was as representative as possible of the core of the watertight mask while having as little impact as possible on the watertight mask.

The frequency was 1 borehole every 500 m approximately.