Thaw-induced slope failures and stability analyses in permafrost regions of the Qinghai-Tibet Plateau,China |
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Authors: | Fujun Niu Jing Luo Zhanju Lin Jianhong Fang Minghao Liu |
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Institution: | 1.State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute,Chinese Academy of Sciences,Lanzhou,China;2.Key Laboratory of Highway Construction & Maintenance Technology in Permafrost Region, Ministry of Transport,CCCC First Highway Consultants Co., Ltd,Xi’an,China;3.University of Chinese Academy of Sciences,Beijing,China;4.Qinghai Research Institute of Transportation,Xining,China |
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Abstract: | The distribution of permafrost-related slope failures along the Qinghai-Tibet Highway from Wuddaoliang to Fenghuoshan correlates with ice content, slope gradient, and ground temperature. Slope failures are of two types. (1) Retrogressive thaw slumps result from icy permafrost being exposed by either man-induced excavation or fluvial-thermal erosion and undercutting of basal slopes. (2) Active-layer-detachment failures are caused by thaw of icy permafrost at the active layer-permafrost interface. After initial failure, active-layer-detachment failures can lead to retrogressive thaw-slumping and localized surficial landslide. Common trigger mechanisms for failure include high summer air temperatures and heavy summer precipitation. A third possible trigger mechanism for slope failure is earthquake occurrence. A geotechnical slope stability analysis was undertaken for an active-layer-detachment failure that had progressed into a retrogressive thaw slump. A safety factor (F s ) of 1.24 for the natural slope was determined using in situ tested strength parameters. However, the slope would lose stability when either the groundwater level over the permafrost table exceeded 1.42 m or seismic acceleration reached, or exceeded, 0.03?g. |
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