Assessment of Landslides Along NH 29 in the Kevüza Area, Kohima, Nagaland
By: Chang, C. Nokendangba
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Contributor(s): Ezung, Meripeni.
Publisher: Germany Springer 2021Edition: Vol.51(4), August.Description: 841-860p.Subject(s): Civil EngineeringOnline resources: Click here
In:
Indian geotechnical journalSummary: National Highway (NH) 29 is a strategic highway of India that runs from Assam to Manipur, through Nagaland. This highway, also known as the Asian Highway 1 (AH 1), connects India to the Southeast Asian countries via Myanmar. A section of the highway, located near the capital city of Kohima, was damaged by major landslides on 1st August 2018. Another landslide occurred in the same area on 4th August 2019, which totally blocked vehicular movement for nearly a month. In both instances, the area received heavy rainfall intermittently for some days preceding slope failure. Geologically, the area is made up of highly jointed and fractured Disang rocks that are composed predominantly of shales intercalated with minor beds of siltstone, and some clay pockets indicating weathering of these rocks. The slide material comprises a mixture of loose debris of shales and saturated clays. A multi-parameter study involving geotechnical, kinematic and joint analyses, slope mass rating, resistivity surveys, and remote sensing using an Unmanned Aerial Vehicle (UAV) was carried out to determine the factors responsible for the two landslide events in this area. The study finds that the soils, with low values of unconfined compressive strength, are one of the major contributors to slope failure in the area. Slope stability analyses demarcate the slopes of the study area as partially stable to highly unstable. Kinematic and joint analyses indicate that the rocks are structurally weak due to the presence of joints, which make them susceptible to wedge failure. Analyses of joints and slickensides confirm complex deformation taking place in the area. The study of satellite imagery of the study area, coupled with field evidences, indicate that the area is crossed with faults. The presence of one such fault and two confined aquifers was validated by resistivity surveys, which explains the shearing of the rocks and high degree of weathering of the country rocks. The low shear strength of the soils and saturation of other slope materials due to heavy rainfall led to the two landslides events.
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Articles Abstract Database
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School of Engineering & Technology (PG) Archieval Section | Not for loan | 2021-2022187 |
National Highway (NH) 29 is a strategic highway of India that runs from Assam to Manipur, through Nagaland. This highway, also known as the Asian Highway 1 (AH 1), connects India to the Southeast Asian countries via Myanmar. A section of the highway, located near the capital city of Kohima, was damaged by major landslides on 1st August 2018. Another landslide occurred in the same area on 4th August 2019, which totally blocked vehicular movement for nearly a month. In both instances, the area received heavy rainfall intermittently for some days preceding slope failure. Geologically, the area is made up of highly jointed and fractured Disang rocks that are composed predominantly of shales intercalated with minor beds of siltstone, and some clay pockets indicating weathering of these rocks. The slide material comprises a mixture of loose debris of shales and saturated clays. A multi-parameter study involving geotechnical, kinematic and joint analyses, slope mass rating, resistivity surveys, and remote sensing using an Unmanned Aerial Vehicle (UAV) was carried out to determine the factors responsible for the two landslide events in this area. The study finds that the soils, with low values of unconfined compressive strength, are one of the major contributors to slope failure in the area. Slope stability analyses demarcate the slopes of the study area as partially stable to highly unstable. Kinematic and joint analyses indicate that the rocks are structurally weak due to the presence of joints, which make them susceptible to wedge failure. Analyses of joints and slickensides confirm complex deformation taking place in the area. The study of satellite imagery of the study area, coupled with field evidences, indicate that the area is crossed with faults. The presence of one such fault and two confined aquifers was validated by resistivity surveys, which explains the shearing of the rocks and high degree of weathering of the country rocks. The low shear strength of the soils and saturation of other slope materials due to heavy rainfall led to the two landslides events.
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