Abstract:
Northern Pakistan is one of the world's most active and hazardous geological zones. As a result, the area has experienced multiple massive landslides throughout history, destroying infrastructure, stopping the Hunza River, and severely damaging the Karakoram highway. Despite the high frequency of large-magnitude landslides and the resulting devastation, the entire area remains understudied, owing to the difficult logistics and vast distances involved. This study investigates the slope failure along the Hunza River (HR), Village Humarri Nagar District Upper Hunza Gilgit Baltistan, Pakistan by using Limit Equilibrium Method (LEM). The slope was investigated thoroughly for its geological conditions, slope geometry, soil strength parameters and the determination of FOS using Slide Rocscience software. During the excursion, soil samples from the slope were taken for analysing geotechnical qualities, and the geometry of the slope was also assessed. The soil sample are analyzed for its strength properties, with values of moisture content (w) 1%, specific gravity (Gs) 2.64, unit weight (r) 19kN/m3 angle of internal friction(ϕ) 30 and cohesion (c) 69 kPa. The Humarri active landslide soil was classified according to the Unified Classification System (UCS) as sandy silt with group symbol of ML. The FOS of the slope was determined using LEM with the assumption of ordinary (O), Janbu (J) and Bishop (B) methods in Slide Rocscience software. The effect of Pore Water Pressure (PWP), Unit Weight, Cohesion, Angle of Internal Friction, and Overburden on FOS was calculated using a series of cases. The findings show that as cohesion and angle of internal friction increase, so does FOS; however, as unit weight and overburden of overlaying materials increase, so does FOS. Furthermore, while PWP has a positive effect to some extent, increasing it results in a considerable drop in FOS. Based on available strength parameters and simulated slide rocscience findings, it is believed that the Humarri active landslide is stable in its current state because all FOS is greater than 1.
