堰塞湖溃决人工结构体滞洪效果实验研究

摘要

汶川地震后唐家山、小岗剑等堰寒湖的应急处置中都采用了开挖泄流槽这一措施,但出现了溃决流量超过了下游城镇防洪标准的危险情景.为控制堰塞湖排泄洪水超过下游区域的防护能力,排泄后期在泄流槽中加入人工结构体可能是一种有效的措施.通过室内模型实验,在泄流槽排泄后期抛投不同型式的人工结构体进行流量调控,包括四面体实体结构、四面体实体结构串、四面体实心框架结构和四面体实心框架结构串4种型式.通过抛投人工结构体与未抛投人工结构体的对比实验,发现:1.前者比后者溃决洪峰流量减小了26.6%～61.7%,说明人工结构体在控制溃决洪峰流量方面有显著效果;2.通过流量综合分析,提出人工结构式优选次序为:四面体实心框架结构串、四面体实体结构串、四面体实心框架结构、四面体实体结构;3.从残留体高度上看,未抛投人工结构体的坝体残留高度为原始坝高的1/3,堰塞体后部基本上是冲刷到底,而抛投了人工结构体的坝体残留高度为原始坝高的1/2,说明人工结构体控制堰塞坝下切侵蚀方面有较显著的效果.且从制作工序、制作时间和制作成本三方面,探讨了四面体实体和四面体实心框架结构的适用性,在施工条件许可的情况下,使用四面体实心框架结构更为理想.%Barrier lake is a very common geo-hazard in mountain area and open channel can be usually utilized to cope with the dammed lake emergency response, such as Tangjiashan and Xiaogangjian dammed lake after Wenchuan earthquake. But the released discharge in these cases may exceed the standard of flood control of the cities downstream, which can be still cause severe disaster to the people downstream. Indoor flume model experiments, in which such four different treatments is used as single tetrahedral solid structure ( TSS), chain of TSS, single tetrahedral frame structure (TFS), and chain of TFS, are conducted to study the effect of tetrahedral structure on controlling the outburst discharge. Some conclusions can be drawn as follows: ( 1 ) when artificial tetrahedral structure is used in the tests, the peak discharge can be effectively reduced by 26.6％ ～ 61.7％, ie, tetrahedral structure may have effect on controlling the peak discharge; (2) the preference order of these four structures could be: chain of TFS - chain of TSS - TFS - TSS; (3) the dam body with artificial structures remains half the original height,whereas it remains only one third without tetrahedral structures, which makes it clear that tetrahedral structures are effective in controlling downward erosion of dam body. In addition, the application of TSS and TFS is also discussed under different conditions of making process, time and cost, and if possible, linked TFS has more priorities.