Impact of land instability on road infrastructure in the Southern Central Rif (Case of PK 144 on regional road 408 - Taounate, Morocco)

Resumen

The study area belongs to the external structural unit of the Moroccan Rif, and more precisely within the southern Central Rif (Mesorif domain), which is considered a transition zone between two major units: the Prérif to the south and the Internal Rif to the north. Indeed, these areas are characterized by a high susceptibility to slope instability, under the influence of several factors, the main ones being: the predominance of soft rocks, rugged terrain with steep slopes, aggressive climate, strong fluvial erosion..., as well as land use practices, deforestation, and road construction. Slope instability negatively affects the populations’ properties, and infrastructure, particularly roads and associated engineering structures (bridges, culverts, etc.). In this study, we will address this issue by presenting a typical case of instability phenomena in the southern Central Rif, on regional road 408 at kilometer point 144, which is affected by surface dynamics and semi-deep erosion combining subsidence and landslide at an average speed of 30.7 cm between 2016 and 2021. In order to achieve the objectives of this work, a scientific methodology has been adopted, based on field research (temporal monitoring of the sliding movement using iron bars), laboratory analyses to determine the soil characteristics, and the use of geotechnical studies that have carried out deep boreholes down to the bedrock.