Analysis of hydraulic washing granule mass and discharging_ water flow of trench in Tangjiashan Barrier Lake | 唐家山堰塞坝散粒堆积体开槽泄流的冲刷过程分析

Chinese. 为避免溃堤形成洪峰危害下游，对唐家山堰塞湖进行开槽泄流，并预测泄流槽的冲刷演变和下泄洪峰流量及出现时间，以便提出一种分析方法，对今后震后堰塞湖抢险工程起到指导作用。依据唐家山堰塞坝的土性条件、开槽断面，以及不同粒径散粒体的冲刷运动特性，确定堰塞坝不同粒径松散体的冲刷起动流速和冲刷速度。基于堰塞湖区产流和库水位曲线，应用宽顶堰流基本理论，综合考虑土性材料冲刷性能与堰流之间的相互关系，进行了开槽泄流、水流计算、冲刷下切、库水位确定的迭代计算分析。合理确定了唐家山堰塞坝不同土层随着泄流变化的冲刷速率和泄流槽断面的变化；计算得到2008-06-10 T 12:00下泄最大洪峰流量为6 601 m3/s，与实际洪峰流量基本一致。提出了一种预测堰塞体开槽泄流下切冲刷分析及洪峰形成时间和确定最大洪峰流量的简化方法。

English. An analysis method was applied to guide the emergency work of barrier lake after earthquake in future, to avoid the flood peak caused by bursting to damage downstream, form the Tangjiashan Barrier Lake for slotting discharge, and forecast the discharge groove of scour evolution and the release of the peak flow and the time. Based on the soil properties, section of trench and washing movement characteristics of slide slope mass composing of different size particles, the start-up velocity and scouring velocity were determined by the results of washing experiment. According to producing flow and hydrograph in barrier lake area and the relationship between the scouring character of soil and weir flow, the iteration calculation of slotting discharge, hydraulic calculation, hydraulic washing and the determination of water were carried out by the theory of broad crest weir flow. The scouring development of discharging water channel and the occurrence of flood peak time and its maximum flux can be predicted by the iteration calculation. For Tangjiashan Barrier Lake, the maximum discharge flow equals to 6 601 m3/s at 12:00 on June 10th, 2008. The result is consistent with the facts. The article comes up a simplified method to predict the slotting discharge analysis and to determine the formation time and the flow of the flood peak.