Effect of earthquake-induced liquefaction of runout-path material on the movement of landslide.

The Donghekou landslide triggered by the 2008 Wenchuan earthquake was a typical large-scale rapid and long runout landslide. The saturated deposit material in runout path was liquefiable under the dynamic loading, which may play a key role in the hypermobility of the Donghekou landslide. The dynamic loading triaxial compression tests were performed to investigate dynamic responses of the soil samples from the runout path. The influence of variation of pore water pressure of deposit in runout path on the movement process of the landslide was investigated and analyzed by discontinuous deformation analysis (DDA). The results show that the impact loading could cause a sharp rise of the pore water pressure of the soil, but it cannot trigger liquefaction before the sample failure. Seismic loading is the main loading that causes the liquefaction of deposit material, while landquake loading has little effect on soil liquefaction. During the earthquake, liquefaction of the shallow soil (the depth was < 10 m) of deposit in the runout path was induced by the seismic loading. Thus, the shallow runout-path material and landslide debris can slide faster and farther under a significantly small friction. [ABSTRACT FROM AUTHOR]