SANXI VILLAGE LANDSLIDE IN DUJIANGYAN, SICHUAN PROVINCE ON JULY 10, 2013

At 10:00 on July 10, 2013, a high topographic position landslide was triggered by the extremely rainfall at the Sanxi village in Dujiangyan city of Sichuan province. The landslide debris flow run-out distance is 1260m and the volume of landslide debris flow is more than 1.5 million m3. The debris destroyed the Sanxi village and caused serious fatalities. This paper is based on the field investigation and laboratory study. It summarizes the basic characteristics of Sanxi village landslide. The forming mechanism and their sliding speeds are also analyzed. Some conclusions are as follows. 1)The landslide has the high topographic-position characteristic. The sandstones from the trailing edge of Sanxi village slipped to the NE direction, then severely hit the slope, and scraped the loose materials on the high topographic slope position, and finally formed the landslide-debris flow disaster. 2)According to its movement and accumulation characteristics, the landslide can be divided into the top sliding area, the middle collision and scraping area, and the lower debris flow deposits area. 3)The direct factor of the landslide triggers is the continuously extreme rainfall weather process. The three days of rainfall in the Dujangyan city are equivalent to 44.1% of the annual average rainfall. 4)Sanxi village landslide is triggered by Wenchuan earthquake, special structural of rocks and soils, terrain conditions and the extreme rainfall events. It is controlled by the coupling effect mechanism of endogenic and exogenic geological processes. 5)The finding of this research is useful to reduce and mitigate the disaster of high topographic-position and fast speed landslide debris flow. It proposes to strengthen the research, monitoring and early warning for high topographic-position landslide due to the increase of extremely heavy rainfall events in recent years.