Assessing the Impact of Water Saturation on Planar and Wedge Stability: Limit Equilibrium Modelling with RocPlane and SWedge

ABSTRACT The National Highway 06 connecting the Indian states of Assam and Meghalaya has witnessed several unfortunate and devastating events of landslides and rockfall hazards. For evaluating the stability of the road cut slopes, the determination of their modes of failure is crucial. In this study, an assessment of the instability of a heavily jointed rock slope located along this highway, between the Sonapur tunnel and Malidor bridge, has been conducted using kinematic analysis and the limit equilibrium method. For stability analysis, the properties of the slope material and joint planes have been evaluated by field investigation and laboratory testing of rock samples. Planar and wedge failure modes predicted by kinematic analysis using Dips have been efficiently validated using the limit equilibrium method, with RocPlane and SWedge, respectively. The results of the analyses have revealed that the slope is highly susceptible to the corresponding modes of failure. Sensitivity analyses have been done in wedge analyses to show the effect of the percentage increment of filled water in the joint planes on stability. For planar sliding, the effect of tension crack has been taken into consideration, and sensitivity analyses have been done to show the impact of water content variation in tension crack and sliding plane on the factor of safety.