竹林关大柴沟大型泥石流的形成机理与发展趋势

通过对陕西省丹凤县竹林关镇大柴沟泥石流进行现场勘查分析,总结了泥石流的孕灾背景,揭示了泥石流的典型特征和基本物理力学参数,在此基础上,分别从泥石流的物质来源、形成环境、诱发条件等三大条件分析了泥石流的形成机理,归纳了大柴沟泥石流具有典型的滑坡激发性、周期暴发性、强烈致灾性等特点,对泥石流的危险性进行了现状分析和预测评价。结果表明:软硬相间的岩层和强烈的构造运动是造成岩体变形破碎的主要原因,为泥石流提供了丰富的物源,垂直高差较大、沟道狭窄为泥石流提供了良好的孕灾环境,百年一遇的暴雨是大柴沟泥石流形成的诱发条件,同时受暴雨影响,沟内产生多处浅表层滑坡堵塞沟道,为泥石流聚集了能量,以至形成规模更大、破坏性更强的泥石流。研究过程采用了实测计算与经验公式估算相结合的多种方法进行对比研究,也充分验证了经验公式的适用性。

Formation Mechanism and Development Trend of the Large-scale Debris Flow in Zhulinguan Town

According to on-site survey and analysis on the Dachaigou debris flow in Zhulinguan Town,Danfeng County in Shaanxi Province,disaster-breeding background of the debris flow is summed up,and the typical characteristics and basic physical and mechanical parameters of the debris flow are revealed.On this basis,the formation mechanism of the debris flow is analyzed from 3 aspects as material source,formation environment and induced conditions.The typical characteristics of the debris flow such as landslide triggered,periodic outbreak and strong hazard are summarized and the risk of debris flow is analyzed and predicted.Soft and hard rock layers and strong tectonic movement,as the main reasons for the deformation of the rock mass and rock breaking provided rich provenance for the Dachaigou debris flow,and the relatively great vertical elevation difference and narrow channel created useful disaster-breeding environment for it.Once-in-a-century rainstorm induced the debris flow and the plugged channel by many shallow surface landslides gathered more energy for it,which therefore became larger and more destructive.Comparative study is conducted by methods of binding actual measuring calculation and empirical formula estimation,and the applicability of the empirical formula is fully verified.