REMOTE SENSING INVESTIGATION AND FORMATION MECHANISM ON WULIPO LANDSLIDE OF JULY 10, 2013 IN SANXI VILLAGE,DUJIANGYAN,SICHUAN PROVINCE

At 10:30 AM on July 10, 2013, a large-scale landslide occurred at Wulipo Sanxi Village, Zhongxing Town of Dujiangyan City in Sichuan province. The rock mass of about 264104m3 rushed down and destroyed 11 village houses that are 500m beneath the landslide rock mass in 2minutes, killed 44 people and buried 117 people, as well as damaged many rural houses. This paper interprets the environment conditions and the deformation characteristics at pre-landsliding and the characteristics at post-landsliding, using 3-stage remote sensing images. Meanwhile, the lithology, attitude of rocks and cracks of the landslide are surveyed utilizing UAV images, geomorphological mapping and field investigation. Based on these results, this paper analyzes the formation mechanism and failure mode of Wulipo landslide. Results show that under effective combination of good freeing conditions and structural surface, Wulipo landslide is triggered by heavy precipitation. By the effect of continuous heavy precipitation, the sliding rock mass is separated from the bed rock, slides towards freeing direction along the sliding surface under the pressure of dynamic water. After crossing the 36-meter high scarp at the front edge, the movement mode of the landslide becomes landslip-collapse movement. The landslide mass is accelerated instantly and breaks into pieces, and forms high speed debris flow. In this process, the floods transfer the landslide-debris flow further into mud-rock flow and cause the chain disaster of landslide-debris flow-mud rock flow. The movement and damage mode of the landslide are typical and deserve further research.