Vol16 No.9: 2110-2125
【Title】Characteristicsof grain size distributionand the shear strength analysis of Chenjiaba long runout coseismic landslide
【Author】GETAHUN Ephrem; QI Sheng-wen; GUO Song-feng; ZOU Yu1,2,3; LIANG Ning1,2,3
【Addresses】1 Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Chaoyang District, Beijing 100029, China; 2 Institute of Earth Science, Chinese Academy of Sciences, Beijing 100029, China; 3 University of Chinese Academy of Sciences, Beijing 100049, China; 4 Arba Minch University, Department of Geology, P. O. Box 21, Arba Minch 00251, Ethiopia
【Corresponding author】QI Sheng-wen
【Citation】Getahun E, Qi SW, Guo SF, et al. (2019) Characteristics of grain size distribution and the shear strength analysis of Chenjiaba long runout coseismic landslide. Journal of Mountain Science 16(9). https://doi.org/10.1007/s11629-019-5535-3
【Abstract】Study on the grain size distribution characteristics and the frictional strength behavior of the slide deposits are helpful to disclose the landslide runout process and understand the mechanism of a long runout landslide.We performed grain size distribution analysis on samples collected from Chenjiaba landslide induced by Wenchuan earthquake. The grain size distribution of samples from the landslide sections quantitatively depicts a gradual coarsening upward grading from shear zone to the top section. Then a multistage - multiphase ring shearing approach was used to determine a comparative shear strength behavior of samples from each landslide section. In this method, a sample was sheared continuously for large displacement and fast rate on different normal stress conditions. The multiphase shear mode with a maximum of 105 mm/min rate has allowed observing the qualitative change and patterns of the frictional resistance behaviors of soils under different normal stresses. The results of coefficient of friction values under multiphase shear mode have shown substantial post peak shear weakening behaviors after large shear displacement that can be narrated with long runout processes. The shear strength test results indicate that the shear zone samples have developed higher friction angle values compared to overlying section samples, on the last phase of shear process, which may be very important to understand the braking mechanism of a long runout landslide.
【Keywords】Grain size distribution; Long runout; Landslide; Multistage-Multiphase; Ring Shear