藏东高原浅丘红层区泥石流发育特征及活动性研究

Research on the development characteristics and activity of debris flows in shallow hill red beds of the Eastern Tibetan Plateau

摘要:

藏东贡觉县高原浅丘红层区降雨条件有限，泥石流发生、发展主要受控于物源条件及沟道条件，属“物源控制型”泥石流。通过地质调查及统计分析的方法，详细分析了泥石流形成条件、形成机制及活动特征，得出了以下结论：流域面积<1.0 km²、沟道纵比降100‰~300‰的沟道容易发生泥石流；受构造、冻融风化及含石膏岩的影响，泥石流物源相对丰富，物源类型以坡面侵蚀为主，具有“点多面广”的分布特征，补给形式表现为“零存整取”的特征；受控于物源补给形式，泥石流形成主要包括：坡面冲刷起动→沟床汇聚堆积→揭底侵蚀3个阶段；受物质来源的影响，区内泥石流流体性质以粘性-过渡型为主，泥石流具有多期次、中低频率、单次泥石流规模较小的活动特征。

Abstract:

The rainfall conditions in the shallow hilly red layer area of Gongjue County in eastern Tibet are limited， and the occurrence and development of debris flows are mainly controlled by material source conditions and channel conditions， belonging to the “material source control type” of debris flows. Through geological investigation and statistical analysis， the conditions， mechanisms， and activity characteristics of debris flow formation were analyzed in detail. The following conclusion has been drawn： Gullies with a drainage area less than 1.0km² and a longitudinal gradient of 100‰ to 300‰ are prone to debris flows； Due to the influence of structure， freeze-thaw weathering， and gypsum containing rocks， the sources of debris flows are relatively abundant， with slope erosion as the main type of source and a distribution characteristic of “multiple points and wide areas”. The supply form is characterized by “zero storage and whole extraction”； Controlled by the form of material supply， the formation of debris flows mainly includes three stages： slope erosion initiation， gully bed accumulation， and bottom erosion； Due to the influence of material sources， the fluid properties of debris flows in the area are mainly viscous transitional， and debris flows have the characteristics of multiple periods， medium to high frequencies， and smaller scale of single debris flows.