Stability Assessment of a Soil Slope in Meghalaya, North-Eastern India

Landslides are a common occurrence in hill slopes in the seismically active north eastern part of India. The soil slopes are highly vulnerable to failure due to heavy earth cuttings, rainfall and blasting activities during road construction. When landslides occur in transportation corridors running along hill slopes, there is the risk of huge loss to lives and property. In addition, the communication through these networks could be brought to a standstill during such catastrophes, resulting in considerable amount of time and resources expended in restoration of traffic and causing huge inconvenience to commuters. In this scenario, the need arises for a proper investigation on failure mechanisms of hill cut soil slopes and to envisage on appropriate mitigation measures. In the present study, stability analysis is carried out of in situ soil slopes newly exposed during a road widening along National Highway-40, a strategic road corridor in Meghalaya. The analysis consists of a limit equilibrium approach wherein the slope has been modelled using in situ soil conditions. The factors of safety of the slope against sliding failure have been calculated and the critical slip surface has been found by limit equilibrium analysis. The results of numerical modelling using the commercially available software SLOPE/W indicate unstable slopes potentially vulnerable to failure under adverse conditions. Necessary mitigation measures that need to be taken have been suggested based on the vulnerability condition of the slope.