关键词: 特大型泥石流;成灾特征;形成机理;曾达沟泥石流;四川省;

Abstract: At 22:45 on June 27, 2019, a large debris flow event occurred in Zengda Gully, Jinchuan County, Sichuan Province, with a drainage area of 125.53 km2. About 1.2 million m3 of solid matter was washed out and the economic loss reached to RMB 151 million Yuan. This research mainly adopts methods such as field survey, remote sensing interpretation and indoor experiment. According to the basic conditions of source material, topography, water source, etc., the disaster characteristics, formation and evolution process, dynamic and static characteristic parameters, and the development trend of future disasters were analyzed. Results were as follows: this event was a sparse debris flow caused by both the previous rainfall and the induced rainfall, with density of 1.60 ~ 1.78 g/cm3 and peak discharge rate of 442 m3/s. This debris flow event can be divided into three process stages: the instability of the landslide in the source area of Longgu Gully led to the occurrence of debris flow in the branch ditch firstly, then the scale expanded with the branch gully material merging into the main gully, and finally the material slowed down and stopped in the sedimentation area of the main gully. The combination of ‘Forecast and Prevention dependent on Masses’ system and engineering measures played an important role in the avoidance of debris flow disasters, which can provide reference for the early warning and avoidance of related geological disasters in the future.

Key words: super-large debris flow；disaster characteristics; formation mechanism; Zengda Gully debris flow; Sichuan Province