Probabilistic assessment of Paglajhora landslide using SLOPE/W

Abstract

This paper reports stability analysis of the dynamic and recurrent Paglajhora landslide which is situated in the upper subpart of the Shiva Khola basin in the Kurseong region of Darjeeling Himalayas in the state of West Bengal, India. The height of the affected slope is approximately 1540 m, having two porches with fluctuating slope variations. The lower portion frequently fails and causes blockage of roads damaging the NH-55 highway and cutting the Kalimpong region from other parts of the country. The problem of slope failure is further adverse due to various geological features, steep slopes, rugged topography and intense monsoonal rainfall. The study area is divided into two major lithotectonic units, the Higher Himalayan Crystalline Sequence (HHCS) and the Lesser Himalayan Sequence (LHS), separated by major ductile shear zone known as the Main Central Thrust. Parametric analysis of the slope with variation in slope height and slope angle has been performed using SLOPE/W software. The resulting change in the factor of safety is calculated. The analysis would help in understanding the possible failure scenarios of the landslide area, and effective measures could be taken to reduce the risk. © Springer Nature Singapore Pte Ltd. 2021.