Probabilistic analysis of slope in Amiyan landslide area, Uttarakhand

Abstract

This paper reports stability analysis of active and recurrent Amiyan landslide at Kathgodam in Uttarakhand State, India. The height of the affected slope is approximately 501 m, having two terraces with varying slope inclinations. Lower bench, above the basement, always fails and leads failure paths for others. The problem of slide is further adverse due to fluctuation in water level or Gaula river, which is passing along the slope masses. These rocks mainly belong to Siwalik system suffered by many structural disturbances. The stability assessment of the area is very critical to avoid and manage further damage to surrounding agricultural land as well as population along the river. The slopes' failures increase the siltation, reduce carrying capacity of the river with time and further increase the water level on the bank of the slope. The slope was simulated using two modelling methods, namely limit equilibrium method and finite element method. Results indicate that the stress is mostly confined in the terrace above the basement in all the cases, where the factor of safety is almost unity. The probability of failure estimated between 13.1% and 16.9% using probabilistic slope stability analysis. The results of numerical simulations matched with field observations.