黄土高原淤地坝溃损条件下坝地侵蚀机理及溃口水流特征

Erosion Mechanism of Dam Lands and Flow Characteristics of Dam-Break Under Warping-Dam-Break Conditions in the Loess Plateau

研究淤地坝溃损条件下的坝地侵蚀机理及水沙过程对于淤地坝的建设和后期管护具有重大意义。基于文献调研和实地调查分析,发现淤地坝溃损后的坝地侵蚀主要受坝地土体性质、坝地形成特征及淤地坝溃损模式影响,坝地侵蚀造沟模式可概括为“淤地坝溃损→溯源侵蚀→冲刷下切→沟壁坍塌→水沙混合流”;以山西省吕梁市离石区马槽里#2骨干坝为例,通过数值计算不同淤地工况下淤地坝溃损时的溃口流量过程和水位过程得知,淤地坝溃损条件下的水沙过程受库区的淤地情况显著变化,且坝地具有削峰落沙的作用。

The study of water-sediment processes and dam-land-erosion mechanisms under warping-dam-break conditions is of great significance for the construction and later management of warping dams in the Loess Plateau.Based on the literature research and field investigation,this paper identified the main causes of dam-land-erosion under warping-dam-break conditions,including the nature of the dam soil,the formation characteristics of the dam and the check dam break mode.It proposed that the process of dam erosions and gully erosions after warping dam failures was as follows:“warping dam failure→retrogressive erosion→scouring and undercutting→collapse of gully walls→mixed flow of water and sand”.Taking the~#2 main dam in Macaoli of Lishi District in Lvliang City,Shanxi Province as an example,the numerical calculation results indicate that the water-sand process under the condition of warping dam failures was significantly changed by the siltation of the reservoir areas,and the dam lands have the role of shaving peaks and sinking sands.