Articles | Volume 11, issue 4
Nat. Hazards Earth Syst. Sci., 11, 1153–1162, 2011
Nat. Hazards Earth Syst. Sci., 11, 1153–1162, 2011

Research article 26 Apr 2011

Research article | 26 Apr 2011

Particle flow and segregation in a giant landslide event triggered by the 2008 Wenchuan earthquake, Sichuan, China

L. M. Zhang1,2, Y. Xu1,3, R. Q. Huang2, and D. S. Chang1 L. M. Zhang et al.
  • 1Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
  • 2State Key Laboratory of Geohazard Prevention and Geoenvironment Protection, Chengdu University of Technology, Chengdu, Sichuan, China
  • 3China Institute of Water Resources and Hydropower Research, Beijing, China

Abstract. During the 12 May 2008 Wenchuan earthquake, a large landslide of approximately 30 million m3 occurred at Donghekou with a particle run-out distance of over 2000 m. This paper presents fascinating particle flow and segregation characteristics in the landslide process found through field investigation of changes in the soil particle size, density, and fabric along the particle movement paths. The soil particles experienced projection, long-distance flying, sliding, and rolling. Trajectory segregation, inverse grading, and particle crushing were found in the landslide event, which contributed to the heterogeneity of the soil deposits. In the initial deposition area, particles with larger diameters appeared to have flown longer. Materials from different sources mixed, forming more uniform debris. In the run-out area, the particle flow tended to cause large particles to travel further. However, particle disintegration and crushing led to more small particles along the movement paths and the observed characteristic flow distances of very large particles did not increase with the particle diameter, which is different from observations of an idealized granular mass flow.