Slope stability issues of Bukula Landslide in Raghuganga Hydropower Project

Abstract

Slope stability concerns hold global significance among researchers, professionals, and academicians. Despite various research studies, geological and geotechnical investigations on landslides, there is still a lack of proper and comprehensive landslide hazard study, accurate data acquisition, and effective monitoring mechanism in Nepal. The objective of this present study is to identify the type of failure, causes and effects of landslide and possible mitigation measures of Bukula Landslide located within Raghuganga Hydropower Project in Myagdi. This landslide is a large-scale landslide that spans over 500 meters with vertical relief exceeding 300 m. Based on visual inspection, wedge, toppling, and buckling failures prevail within the landslide. The bedrock is thinly foliated and moderately jointed, while 3 m long tension cracks are observed along the foot trail across the landslide area, indicating that the slope is unstable. Notably, buckling failures are common in highly jointed bedrock with low RQD. Likewise, sheared zones/weak zones were observed within the landslide area. The geological survey, kinematic analysis and numerical simulations of the hillslope revealed that Bukula landslide was triggered by sheared rock mass and river toe cutting. To mitigate the problems caused by the landslide, proper support structure installation and drainage system design are necessary.