Study on the Overtopping Breach Mechanism of Climbing-type Landslide Dams
Frequent geological activities and extreme natural disasters in Southwest China have in-duced a large number of landslide dams,making the region a high-risk area for such formations. These dams are characterized by their sudden occurrence and high danger,posing serious threats to the lives and property of people in the affected river basins. An in-depth investigation into the breaching process of climbing-type landslide dams can provide essential theoretical support for hazard prevention and mit-igation. This study focuses on the primary factors affecting the overtopping breach of climbing-type landslide dams,including soil particle gradation,backwater slope gradient,and dam crest shape. The overtopping breach evolution process of the dam was analyzed in terms of overtopping breach process,breach flow process,breach evolution process,residual dam structure,and downstream sedimenta-tion. Experimental results indicated that as the gradation of soil and rock materials became broader,the overall stability of the dam increased,the breach duration extended,and the flood peak flow de-creased. In addition,the peak occurrence was delayed,and the residual breach top width was smaller with a larger dam body volume. The sediment transport distance from the dam toe was shorter,and the sediment thickness at 1 meter from the dam toe was thinner. Conversely,a steeper backwater slope resulted in greater kinetic energy of the water flow,accelerating the breaching process. This re-sulted in a fully developed breach,an increase in flood peak flow,earlier peak occurrence,and a wider residual breach top with a smaller dam body volume. The sediment transport distance from the dam toe was longer,and sediment thickness at 1 meter from the dam toe was greater. Additionally,a larg-er width-to-depth ratio led to a higher relative breach position and a greater head difference during the erosion stage,accelerating the erosion process. This resulted in a fully developed breach,larger resid-ual breach top width,smaller total dam body volume,a longer sediment transport distance from the dam toe,and greater sediment thickness at 1 meter from the dam toe.
climbing-type landslide dambreaching processovertopping breach mechanismphysical model tests
万方数据
维普
