Static and Dynamic Slope Stability Analysis for locating Critical Slip Surface in Gangtok, Sikkim-Himalaya

Gangtok, the capital City of Sikkim suffered immensely from Slope failure problem due to complex geological setting, high intensity rainfall and seismic shaking. In the present study site-specific geophysical and geotechnical investigations have been carried out at Chandmari, a perennial sliding zone for slope stability analysis. In order to identify sliding surfaces, Newmark Displacement methods have been applied for the estimation of Factor of Safety (FOS) and lateral displacement along the sliding block. The predicted FOS at Chandmari exhibiting that the sliding blocks are unstable due to gravity sliding/water seepage and/or seismic shaking. The near surface imaging through Ground Penetrating Radar survey exhibits that the discontinuity and fractured saturated zones are present in the near and shallow subsurface strata triggering ground subsidence and slope failure necessitating systematic slope failure modelling in the terrain for adopting appropriate mitigation measures.