Dynamic disintegration processes accompanying transport of an earthquake-induced landslide

• Published in: Landslides Vol. 18; no. 3; pp. 909 - 933
• Main Authors: Gao, Ge, Meguid, Mohamed A., Chouinard, Luc E., Zhan, Weiwei
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2021; Springer Nature B.V
• Subjects: Agriculture; Boundary conditions; Civil Engineering; Coalescing; Deformation; Dilatancy; Discrete element method; Disintegration; Earth and Environmental Science; Earth Sciences; Earthquake damage; Earthquake loads; Earthquakes; Forces (mechanics); Fractal geometry; Geography; Gravity; Isotropy; Landslides; Mass; Mass distribution; Morphometry; Natural Hazards; Original Paper; P-waves; Particle size distribution; Seismic activity; Seismic response; Seismic surveys; Seismic waves; Shaking; Shear forces; Size distribution; Slopes; Statistical methods; Transport; Transport phenomena; Wave reflection; Earthquake-induced landslide; Discrete element method; Absorbing boundary condition; Dilatancy; Fragmentation
• ISSN: 1612-510X; 1612-5118
• DOI: 10.1007/s10346-020-01508-1

Aiming to understand the dynamic disintegration and transport behavior of an earthquake-induced landslide, a dynamic discrete element method has been employed to analyze the Wangjiayan landslide triggered by the 2008 Ms 8.0 Wenchuan earthquake. Absorbing boundary condition is used for the seismic wave transmission and reflection at the slope base. The numerical results show that under seismic loading, internal rock damage initiates, propagates, and coalesces progressively along the weak solid structure and subsequently leads to fragmentation and pulverization of the slope mass. This can be quantitatively interpreted with the continuously rapid increase of the damage ratio and sudden decline of growth ratio of the number of fragments after the peak seismic shaking. During emplacement evolution, fragmented deformation patterns within the translating joint-defined granular assemblies are affected by the locally high dilatancy with a simultaneous occurrence of highly energetic collisions related to the action of shearing, and this can be quantified by the enhancement of particle kinematic activities (high vibrational and rotational granular temperatures) and intense fluctuations of location-dependent global dispersive stress. In this process, slope destabilized and transports downward in a rapid pulsing motion as friction bonds are locally and continually overcome by the seismic- and gravity-induced shear forces. The joint-determined fragment network before movement initiation and the final fragmented depositions after the rapidly sheared transport have been systematically investigated by fragment statistics (fragment size distribution, fragment mass distribution, and fractal dimension) and morphometric characters (fragment shape isotropy) to offer new insights into the disintegration characteristics of the earthquake-induced catastrophic mass movements.