TUNNELS - GEOLOGY

In 1882, the geology of the Pas-de-Calais region was investigated in c onnection with a Channel crossing project. After an historical review of these surveys, this Paper describes subsequent exploratory work car ried out after the submission and study by means of the geostatic meth od. It then looks into the geological data, stressing the presence of Chalk Marl which was the subject of additional studies. A description of the geotechnical characteristics and the tectonics of the site is f ollowed by a section on the choice of the alignment based upon these d ata. The Paper concludes with a detailed description of the geological follow-up studies carried out during the works.