Geotechnical investigations of mass movements in Djounde, Lainde and Ouro-Hala (Cameroon)

Mass movements constitute a major geohazard in the Djoundé, Laïndé and Ouro-Hala (DLOH) area of northern Cameroon, where slope instability controls remain poorly documented. This study characterizes geotechnical properties of soils and rocks and identifies mechanisms governing slope instability for hazard assessment and mitigation. Field investigations included seven soil pits (90–130 cm deep, ~ 50 cm diameter) and three rock samples (~ 10 kg each). Laboratory analyses comprised grain-size distribution, Atterberg limits, Proctor compaction, California Bearing Ratio (CBR), and Micro-Deval and Los Angeles abrasion tests. Soils are predominantly coarse-grained, with gravel contents of 44–96%, sand 13–30%, and silt 9–12%, indicating poor grading and high heterogeneity. Liquid limits range from 33.2 to 51.7% and plasticity indices from 12.5 to 21%, reflecting low to moderate plasticity. CBR values (40–54%) indicate good bearing capacity but limited predictive value for slope failure. Rock samples show low Micro-Deval (1.6–2.0%) and Los Angeles (17.9–18.1%) values, indicating high resistance to abrasion, although field observations reveal weathering and fracturing. Results indicate instability is controlled by poorly graded soils, high porosity, weathered volcanic rocks, and moisture variations. Findings support Rockfalls hazard assessment and risk reduction in tropical mountainous environments and provide a basis for sustainable infrastructure planning and engineering design in the region study area.