无黏性土坝漫顶溃决过程及机理研究

以室内试验为技术手段,以无黏性非连续宽级配沙砾料土坝为研究对象,首次尝试采用"埋入式轻型冲蚀捕捉器"动态记录溃决过程。在上游恒定来流量30 L/s条件下,研究了洪水漫顶条件下坝体(1 m高)的冲蚀过程和溃口水力要素变化过程。明确提出了坝体溃决过程的4个阶段:即侵蚀沟形成发育阶段(下游坡面侵蚀缓慢渐进)→"多级跌坎"冲刷阶段(下游坡面冲蚀能力逐渐加大)→"瀑布状跌落水流"冲蚀阶段(坝体快速溃塌)→坝体冲蚀趋于稳定阶段。初步分析了坝体溃决的机理,揭示了冲蚀过程的非均衡性和溃口水力要素的强非恒定流特性。

Overtopping Failure Process of Cohesionless Earth Dam

Through indoor model tests,a lightweight embedded erosion capturer was used for the first time to record dynamically the breaking process of a cohesionless earth dam with broadly graded non-uniform sand-gravel.Under constant upstream incoming flow of 30L/s,the erosion process of the dam(at 1m height) and the hydraulic parameters at the breach in overtopping condition were researched.The whole dam-break process was divided into four phases:in the first phase,erosion notch formed and developed,with the downstream slope erosion proceeded slowly;in the second phase,the water fell in multilevel steps and the downstream slope erosion intensified gradually;in the third phase,the multilevel steps developed into a big waterfall and the dam broke rapidly;in the fourth phase,dam erosion slowed down and tended to be stable.Based on the test results,the failure mechanism was preliminarily analyzed,the erosion process was revealed to be unbalanced,and the hydraulic parameters at the breach were of strong unsteady flow character.This research offers technological support for people to reduce damages caused by dam-break and to apply emergent measures.