Himalayan Geology, Vol. 43 (1A), 2022, pp. 51-60, Printed in India
Assessment of slope instability using Kinematic analysis and Finite Element Modelling in the Main Central Thrust zone, Bhagirathi Valley, NW Himalaya
MEENAKSHI DEVI1,2, VIKRAM GUPTA1*, AMBAR SOLANKI1, KRIPAMOY SARKAR2
1Wadia Institute of Himalayan Geology, Dehradun, 248001, India,
2Indian Institute of Technology (Indian School of Mines), Dhanbad-826004, India
*Email (Corresponding author): vgupta@wihg.res.in / vgupta_wihg@yahoo.com
Abstract: The slopes in and around the Main Central Thrust (MCT) zone, Bhagirathi valley, Uttarakhand, demarcate the evidence of subsidence by way of ground subsidence, cracks in the buildings, and tilting of trees. Owing to the rugged topography of the area and weak rock structures, numerous difficulties arise in the construction and maintenance of infrastructure and engineering projects. The area is characterised by unfavourable geological and geomorphological conditions, therefore, there is a need to identify weak zones that are susceptible to further deformation and failure. The paper deals with the stability assessment of the slopes of the Natin, Bhatwari, and Kyarak villages, which fall in the MCT zone. Towards this, kinematic, static, and dynamic analyses have been carried out using the Shear Strength Reduction technique and time-acceleration history of Uttarkashi earthquake 1991, in Phase2 version 9.0 software. The results show the deformation in terms of total displacement and maximum shear strain. Accordingly, the Kyarak village was found to be most susceptible with the Strength Reduction Factor of 1.12 under dry - static conditions and 1.11 under wet- static conditions, whereas the dynamic analysis depicts the Bhatwari village to be most susceptible to ground vibrations with the total displacement of 90 mm.
Keywords: Landslides, Finite element modelling, NW Himalaya, Bhagirathi valley
