宁夏贺兰山区郑官沟水石流发育特征与形成机理研究

Research on Development Characteristics and Mechanism of the Zhengguangou Debris Flow in Helan Mountain of Ningxia

通过对宁夏贺兰山区郑官沟泥石流的现场勘查与室内试验,总结了泥石流形成的地质环境条件,分析了泥石流的产流汇流机理和地形条件,并在此基础上计算了泥石流的运动学、动力学特征值,并对其危险度进行了定量评价。结果表明,郑官沟泥石流的平均容重为1.73t/m^3,应属于水石流;泥石流启动的临界坡度为tanθ≥0.29,或=16°;泥石流流通区平均流速为4.08m/s;泥石流流量为98.14m^3/s;一次泥石流最大冲出量为2.38×10~4 m^3;郑官沟泥石流的危险度为0.397,属中危险度泥石流沟。

Basing on the field exploration and laboratory experiment on the Zhengguangou debris flow in Helan mountain of Ningxia,the geo-environmental background of the debris flow formation has been summarized in this paper,the terrain trigger condition and run-off generation and accumulation mechanism have been analyzed.On the basis above,the characteristics values of kinematics and dynamics have been calculated,and the risk degree has been assessed further.The result indicates that the Zhengguangou debris flow should be a turbulent debris flow,with the mean density of 1.73 t/m^3 and the triggered critical slope of 16°（or tanθ≥0.29）.Besides,through the calculation of mean flow velocity（4.08 m/s）,flow（98.14 m^3/s）,single maximum flow volume（2.38×10~4 m^3）and other factors,the Zhengguangou debris flow could be considered as moderately dangerous,with the risk degree of 0.397.