关键词: 泥石流; 工程地质特征; 成因机制; 乐山市; 大渡河;

Abstract: Debris flow has the characteristics of complicated formation process, strong outbreak and great destructive power.Finding out the engineering geological characteristics of the debris flow, analyzing its disaster status and predicting its potential development trend are of great significance to the prevention and control of debris flows.Taking the debris flow in Zhangcungou, Jinhekou District, Leshan City, on the east bank of the Dadu River as an example, the terrain and geomorphic conditions, channel conditions, rock and soil conditions, material sources conditions, water source conditions, erosion and deposition characteristics and deposit characteristics of the debris flow were investigated.The geomorphology, material sources characteristics, accumulation area characteristics and other factors were analyzed in detail.Combining with historical remote sensing image data, the cause mechanism of the debris flow in Zhangcungou was comprehensively analyzed, and its development trend was predicted.The results show that:(1) The steep slope banks of the valley, the large longitudinal gradient of the channel bed, the large catchment area, the concentrated rainfall, and flowing water in the channel all the year around provide topography and water source conditions for the formation of the debris flow.(2) The slopes on both sides of the middle and lower reaches of the ditch are of poor stability, and there are often unstable slopes, landslides and other unfavorable geological phenomena, which are the main supply sections of debris flow sources.(3) The Zhangcungou debris flow ditch is still a “Young” debris flow ditch, which is still in its formation stage.Under the control of the topography and geological environment conditions in the area, in the future, a stronger debris flow may erupt again under the action of heavy rainfall and heavy rain.The research results can provide a certain reference for the prevention and control of similar debris flows.

Key words: debris flow; engineering geological condition; formation mechanism; Leshan City; Dadu River;