Analysis On Dam Blocked By Debris Flow And Dam-break In Kezi River Of Xinjiang

In 1966,1998 and 1999,the debris flow broke out and blocked the river way in Kezi river of Xingjiang. The debris flow formed a natural debris flow dam, and then it was broken to become a flood of dam-break and caused a enormous economic loss. At present, the hidden trouble of blocking is not solved, once blocking and dam-break happened again, it will pose a serious threat to the hydraulic engineering of downstream and people's life and property. In this paper, we studied with the fact of blocking and dam-break in Kezi river of Xingjiang. We discussed the effect of dam blocking principle and dam-break process and hoped to offer valuable reference for prediction and treatment of debris flow disaster.Through the way of collecting the data of debris flow in the Kezi River, processing and analyzing them, we got the storage curve, the amount of accumulation in debris flow and the physical parameters of the materials in blocking dam. Through the investigation, it was found in analysis that the direction of the debris flow which in the export of the ditch was an important condition of blocking dam.We used the method of completing the square to analyze scales of debris flow in different conditions of the rainfall intensity. The results showed that the scale of debris flow in the Qiaerayigeer ditch was increased with increase of rainfall intensity. When the rainfall intensity increased from 5mm/h to 10mm/h, the volume of accumulation would increased from 890,000 m3 to 1,500,000 m3.Consquently, when there was a rainfall intensity of regional precipitation which was more than 5mm/h in the debris flow, the debris flow would enter into the main river and possibly became a certain scale of the debris flow dam. If the debris flow was less than 207 m3/s, and the regional rainfall intensity was greater than 5mm/h, at the same time, the debris flow entered directly into the main river, and then the possibility of occurrence of dam blocking would be greater.According to the simulation analysis of dam breaking of the debris flow in 1966, 1999, we concluded that the erosive ratio could confirm patulous export with the gradual dam-break model which could be reasonably practicable to predict and analysis the flood of the the breaking dam. According to the analysis of the debris flow dam-break flood, it's reasonable to use small periods of time and take the flow coefficient which is 0.322.The prediction of the different height of debris flow blocking dam indicates: when the the dam height of blocking is less than 10m, and the flow of the river way is less than 1062.49 m3/s,it will affect the downstream a little. When the dam height is greater than 10m, the flux is greater than 1062.49m3/s, it will possibly affect the downstream a lot.In order to minish the damages which caused by the debris flow dam-break, we advise to strengthen the monitoring of the transformation of the landform in the export of debris flow ditch, monitor the precipitation of the upstream debris flow field when the flux is smaller in the Kezi River in the summer. If the condition is permitted, we take measures of digging a diversion trench to change the directions of debris flow, prevent the debris flow from swarming directly into the main river and avoid hazard of blocking dam.