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近年来,频发的地质构造活动和极端气候灾害诱发了大量堰塞坝,严重威胁上下游群众的生命财产安全。开挖泄流槽是最常用降低堰塞坝溃决风险的措施,由于时间非常急迫、交通极度瘫痪,其开挖量非常有限,因此如何利用有限的开挖量将溃坝风险降低至最小是亟待解决的问题。本文基于水土耦合冲刷机理,提出了考虑不同泄流槽方案的堰塞坝溃决机理分析方法,并应用于唐家山堰塞坝。该方法根据水力学参数和坝体抗冲刷性参数动态计算瞬时坝体冲刷率,进而分析泄流槽对溃决全过程的影响,从而自动获取最优的泄流槽设计方案。将此方法应用于唐家山堰塞坝案例发现:唐家山堰塞坝泄流槽最优设计时溃坝洪峰流量为1700m~3·s~(-1),小于实际峰值流量6500m~3·s~(-1),主要是因为增大泄流槽的纵坡率,显著增强溃坝前的冲刷并形成双洪峰,从而有效降低了溃决峰值流量。由于复合槽相对较小的水力半径限制了溃坝前的冲刷,使得临溃时水位较高,因此溃坝峰值流量比单槽大,溃坝风险降低效果不如单槽。
In recent years, frequent geological structure activities and extreme weather disasters have induced a large number of damming dams, which seriously threaten the life and property safety of the upstream and downstream people. It is the most commonly used method to reduce the risk of the dam dam failure. Due to the extreme urgency of time and the extreme traffic paralysis, the amount of excavation is very limited. Therefore, it is urgent to minimize the risk of dam failure by using a limited amount of excavation solved problem. Based on the coupling mechanism of soil and water, this paper presents a method to analyze the failure mechanism of dam bar considering different drainage channels and applies it to Tangjiashan dam. The method calculates the instantaneous dam body flushing rate dynamically according to the hydraulic parameters and the anti-erosion parameters of the dam body, and then analyzes the influence of the drain groove on the whole collapse process so as to obtain the optimum design scheme of the drain groove automatically. The application of this method to the case of Tangjiashan dam shows that the flood peak discharge of Tangjiashan barrage dam is 1700m ~ 3 · s ~ (-1), which is less than the actual peak flow of 6500m ~ 3 · s ~ (-1), mainly because of increasing the longitudinal slope of the drainage channel, significantly increasing the erosion before the dam breaching and forming a double flood peak, thus effectively reducing the peak flow rate of the collapse. Because the relatively smaller hydraulic radius of the composite trough limits the erosion before the dam breakage, the water level at the temporary collapse is higher, so the peak flow of the dam breakage is larger than that of the single trough, and the dam breakage risk reduction effect is not as good as that of the single trough.