IMPACT OF HYDROLOGICAL AND SEISMIC FACTORS ON THE STABILITY OF A HIGHLEVEL EMBANKMENT BASED ON MARL SOIL CLASS A3 IN THE SOUTH CORRIDOR RIFAIN - HIGHWAY SECTION OF FEZ-TAZA (MOROCCO)

The A2 highway connects the west of the country to its eastern part. The section between Fez and Taza passes through the South Rifain Corridor mainly characterized by marl formations of the Miocene. The mechanical behavior of these marls leads to regular land instability phenomena which represent a high risk for linear features such as roads and the A2 highway. The impact of these land instabilities is more accentuated in the case of embankments such as kilometer point 232.900, which is the subject of this study. This point represents a serious issue despite the different reinforcement measures. In order to better understand the subsoil deformation at this point, a geotechnical campaign concerning the recognition of the subsoil and the installation of inclinometer instruments was carried out. The ground movement monitoring showed some slight movements acting deep downstream of the embankment. The two-dimensional modeling of the stability status of this embankment by GEOSTUDIO geotechnical software allowed us to simulate the events and disorders that could affect the structure. In order to understand the factors causing these ground movements, we evaluated the stability of the embankment in its static and pseudo static state and also during rainy and dry periods of the year. The obtained results show a decrease in the resistance of the soil to sliding during the rainy season, or even a possible triggering in the case of the occurrence of an earthquake, while the adoption of the recommended reinforcement structures has shown a good maintenance of the structure in this kilometer point even in the worse conditions. These structures have been adopted as comfort solutions by the highway manager