唐家山堰塞体溃口宽度的模拟计算

Calculation of Breach Width of Tangjiashan Quake Lake

唐家山堰塞湖的溃决具有以下特点:上下双层的土体结构,水压差大,渗流严重,导流渠弯曲,颗粒不均匀,物质组成松散及坝体稳定性差等.为了寻找合适的模型用于模拟唐家山堰塞湖溃口口门的发展,本文对比分析了河岸展宽模型(Osman公式)及土石坝溃决模型(Froehlich方法和垦务局模型)的计算结果与实测溃口资料.结果表明,Osman公式的计算溃口宽与土体启动切应力的取值关系较大,而土体切应力的计算方法各异;而Froehlich方法计算的口门宽度在溃口发生的始末阶段较为吻合,而在洪峰增长过程中误差较大,垦务局方法则在溃口发展后期的计算误差较大.分析认为,两种方法在模拟计算唐家山堰塞体的溃口宽度时均不是很理想,模拟唐家山坝体的溃口尚需要更为深入的研究,以能反映其溃口的特点.

The breach of Tangjiashan Quake Lake is characterized with double-frame soil,high water pressure,serious seepage,loose materials with un-uniform sediment and unstable dam.In order to simulate the breach of Tangjiashan Quake Lake,two different ways were used to simulate the breach width based on the measured data,riverbank widening method(Osman method) and earthen dam break method(models of Froehlich and Bureau of Reclamation).Ananlysis revealed that,reach width calculated by Osman method depended on the shear stress of soil,which was difficult to determine.The result by Froehlich method agreeed well with the measured at the begining and end of the breaching process,with much more deviation when simulating the width during discharge increasing period.And the width by method of Bureau of Reclamation deviated more in the later stage.The analysis showed that,the simulation of break width of Tangjiashan Quake Lake needs more specific method,which one can reflect the characteristics of breach in Tangjiashan Quake Lake.