Effective Cut Slope of Rock Slope Along NH-44

Development of national highways in the hilly terrain plays a vital role in the economic development of the country. Landslides or instability of the slopes is more common in the developing hilly terrain due to unscientific cutting of the toe of rock slope for the construction or widening of roads and/or bridges. The NH-44 in the Jaintia Hills district (Meghalaya, India) connecting Malidor to Sonapur (approx. 30 km), have experienced many landslide events causing huge loss of life and property. The two locations along the NH-44 are considered and different cut sections of slopes were studied to support the further extension of the NH-44. Kinematic analysis reveals that the possible type of failures such as wedge failure, planar failure and toppling failure occurs at the selected locations. The stability assessment of in situ rock slope and different cut slope sections were investigated to determine the effective cut slope. Potentially unsafe in situ slopes/different cut slopes were identified using PHASE², which is a finite element method, based on shear strength reduction technique. The unstable slopes were further stabilized with the installation of shotcrete and bolt. A parametric study has been done to understand the stability of rock slope under various bolting conditions.