A catastrophic landslide in Hsiankai (Liugui District, Kaohsiung City) was induced by 2009 Morakot Typhoon. Many house and inhibits were buried by the landslide debris, causing many victims. The volume of the landslide debris was about 1 million m3. The geometry of the landslide is wide in the source and deposit zones,and narrow in the transportation zone. By using a granular discrete element simulation model, our result shows that the whole block doesn’t slide down simultaneously. Instead, the sliding starts from the bottom of the block, then moves upward. In the source area, debris falls toward a center, and then rushes through a narrow passage, the transportation
zone. When the debris reaches the deposit zonedue to collision-induced energy dissipation, the velocity of
the landslide debris decreases rapidly, and the friction coefficient increases. Therefore, the debris spreads out at the deposit area. Most of the debris deposits on the toe of the slope, and few of the debris slides into the Launong River.The duration of the landslide is about 120 seconds. The maximum velocity of the landslide debris is 40m/sec.
Key Words : Granular, Discrete Element, Hsiankai, PFC 3D.