Soil slope instability along a strategic road corridor in Meghalaya, north-eastern India
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ORIGINAL PAPER
Soil slope instability along a strategic road corridor in Meghalaya, north-eastern India Ravi Kumar Umrao 1 & Rajesh Singh 2 & L. K. Sharma 1 & T. N. Singh 1
Received: 25 July 2016 / Accepted: 23 May 2017 # Saudi Society for Geosciences 2017
Abstract The road widening carried out along National Highway-40, a strategic road corridor of north-eastern India, to ease the traffic snarls for geopolitical developments in the region. The newly exposed in situ soil slopes along National Highway-40 are on the verge of shear instability, and slope failures occur due to heavy earth cuttings. As a consequence, the road corridor witnesses several geotechnical failures during rainy seasons. The blasting activities initiated and propagated the soil creeps and falls resulting road blockades. Even a small rain shower is enough to undercut and uproot trees and transport boulders and surrounding earth materials up to the corridor. Besides, landslides are also prone to damage demographic areas and settling house units, thus invites for preventive measures towards hill slope management as these slopes make the highway corridor unsafe to the commuters. Therefore, the present study is aimed to investigate the stability of the hill cut soil slopes and to suggest possible stabilisation measures. The study also highlighted that steep soil slopes with high moisture content are prone to landslides mainly due to infiltration, and water flows on the slopes during high and prolonged rainfall. The highly plastic soils rich in silt and clay size particles with high moisture content cause soil/debris slide and flow. The numerical modelling of slopes using Fast Lagrangian Analysis of Continua (FLAC) codes (version 4.0) indicates failures in excavated high angle cut slopes. The re-excavation and benching of unstable slopes
* Ravi Kumar Umrao [email protected]
1
Department of Earth Sciences, Indian Institute of Technology Bombay, Mumbai 400 076, India
2
Department of Geology, University of Lucknow, Lucknow 226 007, India
with geonets or bionets or jute matting to promote vegetation growth were suggested as stabilisation measures by field investigation, laboratory studies and numerical analysis of slopes. Keywords Landslides . Meghalaya . NH-40 . Slopestability . FLAC . Factor of safety
Introduction Generally, slope failure initiates from one or a combination of factors like slope geometry, slope forming material strength, geohydrological condition, structural discontinuity, weathering, development of weak zones, lithological disturbance and heavy rainfall (Ahmad et al. 2013; Singh and Singh 1992; Singh et al. 2014; Umrao et al. 2011). In the past one decade, landslide hazards triggered by rainfall are becoming most common calamities and are responsible for the many disasters in India (Srinivasan 2013; Umrao et al. 2013). Moreover, anthropogenic interferences due to large-scale developments and ignorance towards hill slope management make hill slopes on the verge of instability. Over the past few years, many studies have been
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