【摘要】 为了分析堰塞坝的溃决过程与机理,进行了堰塞坝漫顶溃决试验。结合堰塞坝的溃口扩展和溃决流量过程,将漫顶溃决过程分为最初的缓慢侵蚀阶段和之后的快速侵蚀阶段。在这个过程中,溃口在纵向上的扩展以陡坎侵蚀的方式推进,而横向上的扩展由土体坍滑失稳引起。坝体漫顶破坏属于冲刷破坏。通过分析陡坎后退过程、冲刷过程及其机理,认为冲刷过程包括土粒间剪切和孤粒搬运两个过程,土粒间剪切为搬运过程提供孤粒,而搬运过程为土粒间剪切提供作用空间。颗粒间剪切发生后,细颗粒随即被搬运,而粗颗粒多在溃口表层形成"拟混凝土"结构,阻碍陡坎下蚀。快速侵蚀阶段,随着流速、流量的增加,"拟混凝土"结构遭到破坏,溃口进一步发展。更多还原

【Abstract】 In order to analyze the outburst process and its mechanism of a barrier dam,the authors carried out overtopping outburst experiment of the barrier dam.Combined with the development of the breach and outburst discharge,the overtopping outburst is divided into two processes: slow-erosion process ahead and quick-erosion process later.During these processes,the breach in the longitudinal way develops in the means of headcut erosion,while in the cross way through soil mass collapse.Overtopping outburst is a kind of erosion failure.By analyzing the process and mechanism of the headcut development and soil erosion,people can find that the erosion process includes the inter-particle shearing failure and particle transportation process.the inter-particle failure provides particles for transportation,and the particle transportation process produces an operation room for the inter-particle shearing failure.After the inter-particle shearing failure,the fine particles are carried away at once,and the coarse particles settle down on the surface of the breach and form "near-concrete" structure,preventing the headcut from incising vertically.During the quick-erosion process,with the increase of velocity and discharge,the "near-concrete" structure is destroyed,leading to the second development of breach.更多还原