The Character And Mechanism Study On The Debris Flow Cause By Dam-break In Gully

"5·12" Wenchuan Earthquake, a large number lake formed in the affected areas. For these formed the main lake on the river, the harm lies in the upper flooded roads, villages, towns and farmland .Lake outburst floods in turn, the downstream flood destroyed towns, villages and roads, communications and other in frastructure. The support for distributed small-scale lake trench more, although not as the main lake on the river caused large-scale disasters as, but will still lead to large-scale landslides, to their risk of the roads, villages and towns, etc., causing serious harm .This channel within the dam break cause the disaster debris flow features such as fast and large scale, it is different from the disaster caused by heavy rainfall, but the average loss is much more serious .After the earthquake in Wenchuan as conditions change in the debris flow disaster, many small watershed memory block in the earthquake-induced dam, if its outburst formed debris flow ,the formation process and mitigation measures are different from the storm debris. Therefore, the correct prediction of the earthquake debris flow disaster prediction and reduction is necessary. Through field investigation of this paper and laboratory tests, to simulate the outburst of barrier required to break the body flow.The following conclusions:(1)Such outbreaks have the confidentiality ,is not easy to detect, and the hazards is greater than that debris flow formed by landslide block the gully when Earthquake occur.(2)Dammed the main body of overtopping flood break in the form of outburst , and accompanied by two important phenomena-Scarp and Slope instability.(3)Under the limited conditions ,a fixed volume parameters and compaction , break is because the composition of the dam material's gradation characteristics(4)While D50 and CU is the characteristic value ,16 set of experiments has done ,critical break flow has decreased with the increase of Cu stabilizing trend:QB = mD₅₀C u-^0.285.(5)We experiment to study the part of the 3 groups after outburst start under different traffic breach obtained smaller breach, the launch of the larger unit discharge , because the smaller the breach, the smaller the hydraulic radius, the smaller the flow rate. However, under natural conditions, breach sizes are larger, therefore, can ignore the breach width of the impact on the unit discharge.(6)Under different stream flow observed after the break found in Dam break at the volatility curve. In this paper, dammed by differences in body composition and particle size analysis of dam-break wave two reasons.(7) In Chayuan Gully ,there three dam caused by "5·12" Wenchuan earthquake, now the dam has been part of the outburst, in the paper we calculated Chayuan Gully and Dagan Gully, after the dam break and have been analyzed experiments can be used for example calculation formula.