Prediction of Rainfall-Induced Slope Failure of Curved Embankments Using SEEP/W-FLAC3D Conjugate Analysis

Slopes in hilly regions often have curved profile and complex geometry, which result in complicated stress conditions that cannot be addressed in conventional two-dimensional (2D) analysis. Rainfall may further worsen the scenario to cause landslides in hilly regions. In the present study, conjugate analysis using SEEP/W and FLAC3D is employed to predict the slope failure of curved embankments under rainfall infiltration condition. Three-dimensional (3D) slope stability analysis is performed and compared with the results obtained from 2D analysis. Both 2D and 3D slope stability analysis is performed in FLAC3D, considering the phreatic surface obtained from SEEP/W after simulating the intended rainfall. Three slope profiles—straight, convex, and concave—are analyzed for a 7-day rainfall and average annual rainfall as obtained from the Regional Meteorological Center, Guwahati, and the Central Ground Water Board, Guwahati, respectively. Soil properties of the slope have been adopted from a part of the Haflong Hill in Assam, which is a landslide-prone zone. It is observed that the proposed conjugate analysis is effective in predicting rainfall-induced slope failure of curved embankments. It is further concluded that 3D slope stability analysis must be performed instead of 2D analysis in the case of curved embankments to avoid uneconomical design.