Site-specific geological and geotechnical investigation of a debris landslide along unstable road cut slopes in the Himalayan region, India

Abstract

The present research work investigates the slope instability along NH-05 near Jhakri, Himachal Pradesh, India. Initially, field investigation has been conducted to study the slope morphometry and characteristics. The studied landslides trends along NW–SE direction with height 27.26 m from the road surface and at an angle of 63° vertically post failure. Parameters responsible for slope stability such as particle size distribution, Atterberg Limit and shear strength parameters were collected through direct shear plot using soil samples collected from field. The results reveal that the soil coarse to fine loamy with no surface vegetation long the landslide areas. The absence of vegetation exposes the soil for erosion during high monsoon rainfall. Based on the shear test results the value of c and Phi is 10.28 kPa and 18.8°. 2 D limit equilibrium model has been used using Rocscience software for slope stability assessment. LEM model reveals a safety factor value 0.43 which is less than the value considered for stale slopes. Re-enforced bench slope with soil nailing has been suggested as a suitable stabilization measure with a FOS value of 1.2 which reveals the slope can be stabilized with the mentioned approach.