Hill Slope Stability Examination Along Lower Tons Valley, Garhwal Himalayas, India

The present research details the remote sensing, geotechnical and seismic aspects of hill slopes in Lower Tons river valley, Garhwal Himalaya, India. The region is a part of Lesser Himalaya and holds religious and strategic importance. The studied span has been a site of slope failures in the past. The remote sensing investigation was used to characterize the geomorphological and hydrological attributes of the area. This information was used to delineate vulnerable locations. Along the road stretch of about 80 km, 80 tests were conducted to ascertain the soil particle distribution and plasticity indices; and 33 tests for shear strength properties. Using the geotechnical parameters, numerical simulation was conducted for two slopes of angle, 40 degrees and 50 degrees, with a consistent height of 50 m. Most of the slopes were stable at an angle of 40 degrees, however, 30.30% (FEM) and 24.24% (FDM) of the analysed slopes failed for the steeper slope. Eventually, the pseudo-static analysis was done. The inclusion of seismicity increased the incidences of slope failure by 33.33% and 39.39% for the slope with an inclination of 40 degrees and 50 degrees, respectively. Afterwards, the slopes were optimized for their critical angle as a function of the safety factor.