Geomorphological and Geotechnical Investigations of Shallow-rainfall Induced Landslides Along Murree Expressway, a Case Study of Khajut Landslide, District Rawalpindi, Pakistan

Abstract

Abstract Landslide is a recurrent environmental hazard in the hilly regions and effects the socioeconomic development in Pakistan. The study area lies in the Tehsil Murree, Western Himalayas, Pakistan. The present study deals with detailed geomorphological mapping and geotechnical investigations of shallow rainfall-induced landslide i.e., Khajut Landslide, the Murree Expressway. The extensive field survey and detailed geomorphological, geological mapping and laboratory testing was carried out. Based on field observations, geotechnical investigations and longitudinal profiling, the Khajut landslide is classified as a rotational slide. The slope angle of the Khajut landslide is > 42º. The particle size distribution analysis of soil samples of Khajut landslide indicate that the landslide body consists of coarser particles i.e., sand and gravels. The average specific gravity of the soil sample collected from the Khajut landslide range from 2.89 kg/m3. The liquid limit of Khajut landslide soil samples ranges from 14%- 19%. The plasticity chart shows that soil is inorganic silt and inorganic clays of low to medium plasticity. The plastic limit of Khajut landslide ranges from 5%- 16%. Based on these results, it is concluded that frequent, cyclic wetting & drying during heavy rainfall strongly influence the shrink & swell behavior of the soil on the studied landslide which as a result can deform soils & damage Murree Expressway and other man-made structures.