Static and Dynamic Slope Stability Assessment of a Himalayan Rock Slope

Stability of rock slope along the stretch of Badrinath National Highway (NH-58) of Garhwal Himalayas in Uttarakhand, India is very much essential to protect the infrastructure and livelihood in the area nearby. Every year this part of the slope has been facing severe landslides due to intensive rainfall causing substantial damages. The chosen area is also highly sensitive to earthquake according to Geological survey of India. Due to the severe earthquake and intensive rainfall, stability of rock mass is under continuous depletion. Rock slope in this area is highly jointed and possess a joint orientation which is highly vulnerable to seismic force. In this study, finite element slope stability analysis of this rock slope has been carried out in commercial software PHASE². As per the earthquake zonation map of India, the site is located in seismic zone V, and hence, dynamic stability of slope has been performed considering pseudo static and time-response method. Initially, the rock slope is considered to be devoid of any joints and is modeled as a continuum mass using equivalent Mohr–Coulomb shear strength criteria. In the second model, the discontinuities are applied in the continuum model by providing interface elements as joints in between the rock walls. Results from the analysis accentuate the fact that the of rock slopes is stable under high seismic force.