Disaster-causing mechanism of Yongguang landslide under Minxian-Zhangxian Ms6.6 Earthquake

The Minxian-Zhangxian MS6.6 earthquake induced a large number of loess landslides and collapses on July 22, 2013. Based on the field borehole survey, soil sampling and surface wave investigation, the topography and distribution of soil layers of the west Yongguang loess landslide are identified. Moreover, the liquefaction probability of the landslide loess is proven through dynamic triaxial liquefaction tests. The dynamic response characteristics and stability influence factors of the landslide under strong earthquake effect are analyzed combining the dynamic finite element method and the strength reduction method. The results show that the water content increases and shear strength decreases at the loess on the slope surface because of heavy rain before the earthquake, and tensile stress and liquefaction occur in the surface of loess slope, which causes the collapse instantaneously and long sliding distance.