Terrassements sur terrains marneux sensibles aux glissements : cas des terrains et remblais autoroutiers entre Oued Amlil et Taza (Rif, Maroc)

In north of Morocco, between Oued Amlil and Taza, the Fes-Oujda highway alignment crosses the Rif's overlap front of the thrust covering the Middle Atlas. This Prerif and South Rif corridor area has a lithology dominated by Upper Miocene's marls. These are affected by many ravines and a multitude of recent landslides. Orographic and hydrologic conditions require the construction of embankments. Some excavated materials are reused in fillings. The cuttings are dug in materials with bad characteristics. So the earthmoving slopes have a risk of instability and some moved during or after earthworks. The geotechnical recognitions in this zone reveal cohesive soils of the GTR's classes A2, A3, A4. These soils are very plastic with evolutionary behaviour and very sensitive under the effect of water and thus to the weather conditions. Many technical solutions as the multitude of parades and the draining systems are built enough to stabilise earthmoving. These technical solutions have practically doubled the cost of the highway realization, which puts the relevance of the road alignment choice