Stability analysis and modeling of the Widikum landslide (North-West Cameroon) using FLAC 2D software

This study aims to analyzes, models the Widikum landslide using FLAC 2D software and propose suitable remediable solutions. Both field and laboratory work have been conducted on five studied landslide materials in the localities of Keunom Tiben, Ogwei Tiben, Ofen Tiben, Numba, and Fifty One, respectively. Field analysis consisted of determining the height, length, width, and dip angle of the scars caused by the landslide, while laboratory tests included water content, particle size distribution, Atterberg limits, triaxial test, and oedometer compressibility test. The studied materials’ water content ranges between 15.1% and 47.4%, is porous (44%–58%), and is plastic (14.8%–29.3%). They are inherently susceptible to failure. Furthermore, the comparatively weak friction angle spans from 5.68° to 32.13°, while the cohesiveness is quite low, ranging from 10 kPa to 45 kPa. Additionally, the Keunom Tiben, Ogwei Tiben, Ofen Tiben, Numba, and Fifty One sites had safety factor values ranging between 0.115 and 2.318 for different values of the water table height and exhibit significant critical stability states in various field conditions. The comparison of the results with those of limit equilibrium approaches demonstrated that the absolute variations of safety factor range between 8.21% and 56.51%. The numerical simulation results provided different trends of variations of effective stresses within slopes, while the estimation of soil displacements reached 3 m. The application of reinforcement elements resulted in an increase in the safety factor from 0.873 to 1.115, from 0.807 to 1.381, from 0.381 to 0.76, from 0.697 to 1.295, and from 0.279 to 0.416 for the slopes of Keunom Tiben, Ogwei Tiben, Ofen Tiben, Numba, and Fifty One, and this corresponds to an improvement in the safety factor of 27.72%, 71.13%, 103.41%, 85.80%, and 49.10%, respectively.