Application of various extensions of slope mass rating and kinematic analysis based factor of safety in the Lesser Himalayas

The Himalayan mountain ranges are well-known for dynamic geological and geotechnical conditions and often experience slope failures caused by a variety of natural and anthropogenic factors. The region is greatly affected by the instability of engineered slopes, leading to significant socio-economic impacts. The main aim of this study is to analyse the stability of twelve vulnerable road cut slopes along NH-9 from Pithoragarh to Ghat in the Lesser Himalayan terrain. By considering the geological and geotechnical complexities of the area, critical slopes were identified. The study utilised kinematic analysis to identify various modes of failures in the jointed rock mass and factor of safety (FS) against such structural failures. Additionally, several extensions of slope mass rating (SMR), such as continuous slope mass rating (CoSMR) and chinese slope mass rating (ChSMR) were applied to evaluate stability. The rock mass classification (RMC) stability scores range from 7 to 77, corresponding to completely unstable to stable class. The SMR, CoSMR and ChSMR give values of three slopes in completely unstable to unstable category. The FS aligns with the stability score ranging from 0.4 to 3.95. Findings of all applied proxies were compared to depict variability and trend among different outcomes. The spatial variations of stability score outcomes within the studied section have been depicted on the map using Geographic Information System (GIS) tool. After conducting thorough geotechnical analyses, the necessary steps to improve slope stability have been recommended. Potential challenges and future scope arising from the current study are also provided.