Risk chart for identification of potential landslide due to the presence of residual soil
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Risk chart for identification of potential landslide due to the presence of residual soil Arunava Ray1 · R. E. S. Chaitanya Kumar1 · Rajesh Rai1 · Suprakash Gupta1 Received: 10 August 2018 / Accepted: 22 June 2020 © Springer Nature B.V. 2020
Abstract The incidence of slope failure involving residual soils in the Himalayan Region has increased in recent times. The prevalence of subtropical climatic zone has led to rampant weathering of varying degrees, resulting in the occurrence of residual soil over the bedrock. The study aims to give an overview of residual soil and its effect on the overall stability of the slope. Finite element-based numerical simulations have been performed utilising the results form field visits, laboratory experiments and detailed literature survey, and a landslide risk chart has been proposed. The results indicate the significance of considering the residual soil layer while performing stability analysis. A substantial decline in the factor of safety (FOS) was observed with an increase in the depth of soil layer up to 4 m, and a further reduction in FOS is not observed beyond this depth. Simulation results also indicate limited possibilities of the presence of a thick layer of residual soil on slopes greater than 45°, which is also established through field study. The overall stability of a slope depends on the critical combination of slope inclination, slope height and depth of residual soil layer. The proposed risk chart can be utilised for quick identification of vulnerable slope profiles, thereby indicating priorities for landslide risk management. Keywords Himalayan region · Residual soil · Risk chart · Numerical simulation · Factor of safety
* Rajesh Rai [email protected] Arunava Ray [email protected] R. E. S. Chaitanya Kumar [email protected] Suprakash Gupta [email protected] 1
Department of Mining Engineering, IIT (BHU), Varanasi, Uttar Pradesh 221005, India
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Natural Hazards
1 Introduction The Himalayas are generally considered as one of the most seismically active mountain chains in the world (Gerrard 1994; Singh 2009). Owing to the presence of a delicate ecosystem, which is characterised by fragile geological setting with contemporary crustal adjustments, unfavourable hydro-geological conditions, varying topology and heavy precipitation along with ever-increasing anthropogenic activities make the Himalayas highly susceptible to large-scale mass erosion and landslides (Bhambri et al. 2017; Gupta 2009; Hasegawa et al. 2009). There are a considerable number of human settlements in this region, which constantly lives under the threat of slope failures. Excluding the snow-covered area, landslides generally affect about 14% area of the Indian landmass (www.gsi.gov.in). The first key step to mitigate this natural calamity is to rapidly assess the stability of the hills in the Himalayan region (HR). Thus, the vulnerable profiles can be identified, and necessary precautionary measures can be adopted. Modera
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