Vol.:(0123456789) Natural Hazards https://doi.org/10.1007/s11069-020-04175-6 1 3 ORIGINAL PAPER Geotechnical assessment of cut slopes in the landslide‑prone Himalayas: rock mass characterization and simulation approach Tariq Siddique 1  · M. E. A. Mondal 1  · S. P. Pradhan 2  · M. Salman 1  · M. Sohel 1 Received: 16 March 2020 / Accepted: 9 July 2020 © Springer Nature B.V. 2020 Abstract The roadway networks serve as arteries for the ongoing socio-economic activities within the Himalayan region. The perilous conditions of geologically active and fragile terrain are sustained threats to various disasters, including landslides. Large numbers of casualties and fatal incidence associated with landslides are being reported every year. The stability of road cut slopes is a crucial component for safer mobility and transportation activities. To attain a hassle-free and hazard-resilient design along the critical transportation route, a schematic and rigorous geotechnical investigation has been undermined. The present case study was undertaken to envisage cut slope stability and optimal designing of engineered slopes along the national highway-94 (NH-94) from Rishikesh to New Tehri, Garhwal Himalaya, India. The major issues associated with road cut slope failures are getting high- lighted. Various rock mass classifcation systems including rock mass rating (RMR), slope mass rating (SMR) and its extensions, geological strength index, and Q Slope method were used to determine the prevailing stability. Stable slope angle without any reinforcement are suggested for the diferent probability of failure. Failure pattern was also assessed by applying kinematic analysis. Modifed RMR for slopes is suggested by adjusting the ori- entation factor by using kinematic feasibility. Numerical simulation technique was also applied to determine safety factor. Exponential relationships are derived among Q Slope, SMR, and strength reduction factor. The guidelines to improve safety in terms of landslides are also suggested by considering the outcomes obtained by diferent methods. Keywords Slope stability · Slope mass rating · Q Slope · Numerical simulation · Himalaya * Tariq Siddique tariqsiddiqueiitr@gmail.com; tariq.gl@amu.ac.in 1 Department of Geology, Aligarh Muslim University, Aligarh 202002, India 2 Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee 247667, India