Experimental Study On Silt Allow Elevation Of Xiaolangdi Hub

Xiao LangDi is the last one water gap reservoir which has more regulated ability before downstream of Yellow River;it can produce advantage for flood prevent and sediment reducing.The sediment concentration is high and the amount of sediment is large in Yellow River.When XiaoLangDi hydro-junction was put to use from 1999 to April 2014,sediment accumulation at reservoir region has become severely more and more;Owing to the influence of sediment accumulation,many problems will occur such as inlet will be blocked up,gate will be difficult to turn on or turn off and so on.As development of sediment accumulation,vertex of delta will push on to be more close to dam and with the increasing of silt elevation,it will create inlet be blocked up when sedimentation advance to the dam.Opening the inlet,sedimentation will clog the hole and the hole maybe full of no flow or no flow in a short time when silt elevation which before the bottom outlet of intake exceeds the permissible.This will has negative influence on engineering benefit and safe working.Therefore,in order to ensure the reservoir operate safely and engineering benefits play normally,it is necessary for us to start a test about the allow silt elevation values of Xiao LangDi.In this paper,we use Xiao LangDi Reservoir as the research object,build a physical model of muddy water which is normality of the Reservoir area.On the base of validate it's similarity,choose the characteristic level of water which is 210 m as it's control requirement,review the maximum allowed elevation at the present stage with the short duration who's elevation is 183.5m and 187.0m and sustained duration who's elevation is 187.0m as the program respectively.Carry out some tests of different gate relative opening of desilting tunnel for the maximum allowable of Silt elevation values.Come up with the operation scheme of relative opening of desilting tunnel,which has the minimum water yield discarded and meet the demand of dragged silt by analyzing of the result.The results showed that:(1)When the deposition achieved 183.5m or 187.0m under this circumstance which the operating water level is 210 m before the dam,it is effectively to open the desilting tunnel at that time and then there have no clog in the desilting tunnel.The allows elevation values can still use 187.0m for Xiaolangdi water control project based on operating condition of metal structures and equipment;(2)For the 187.0m allow silt elevation values,when open the desilting tunnel to discharge water then use the degree of relative opening which the value is 0.15 of the 1st flushing hole and the 2st flushing hole,and the other flushing hole's is 0.18,it could achieve the best desired effect and minimum amount of water required to discard under the premise of guaranteed power generation benefit,unit water required is 24.48 m3/t in this condition.