Through the field investigation and analysis on the Sanyanyu and Luojiayu valley debris flow happened in Zhouqu county, Gansu province on August 8? 2010, the paper thought that the sudden strong rainfall, the alpine gorge landform and the rich loose deposits are the three basic conditions which caused the debris flow disaster. The disaster characteristics included three aspects. Firstly, the drainage channel was occupied excessively by the building in stack area, so the flood discharge capacity is insufficient. Secondly, the step by step failure of the natural rock fill dam and artificial blocking dam in transportation zone caused a "domino effect" type of damage. Thirdly, the debris flow blocked Bailong river and formed barrier lake. It submerged county and aggravated the debris flow disaster. Zhouqu debris flow disaster is very typical and rare, hence, it is meaningful to reveal its disaster characteristics for the post-disaster treatment.%通过对甘肃省舟曲县三眼峪沟和罗家峪沟"8.8"特大暴雨型泥石流的调查分析,认为突发性强降雨、高山峡谷地貌和丰富松散堆积物是该泥石流灾害发生的3个成因特征.就致灾特征而言,涉及到承灾对象,包括3个方面,首先是堆积区高密度建筑的挤占造成行洪能力不足,致使出谷口后的面状泥石流再次汇集,引起泥石流流量集中和过流断面不足,破坏性增强;其次是流通区天然堆石坝和拦挡坝受泥石流冲压和冲击,逐级溃坝后造成"多米诺骨牌效应"式的毁坏;第三是泥石流堵塞白龙江形成堰塞湖,造成城区淹没,加重了灾害.舟曲泥石流灾害非常具有典型性,在国内外属罕见,揭示其致灾特征对于灾后治理意义重大.
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