The Study On The Characteristics And Disaster Mechanism Of Debris-flow In Wenchuan Area

China is a country with a vast territory,mountains aspect,complex geological structure.Loose Quaternary deposits are significant rich in China,and belongs to the monsoon climate,adequate water,debris flow is not only widely distributed,but also frequent activities as well as diverse models for debris flows make negative contribution to human activities and agricultural production in mountains area.The Debris flow disasters occurred frequently after"5.12"Wenchuan earthquake.Earthquake debris flow source is abundant,channel longitudinal slope.Explosive debris flows has a dramatic factors such as hidden strong and great damage.On 12th August 2010,Ying xiu district which is located in Sichuan province wenchuan county began to rainfall,rain intensity increased until 14th august,approximately 163mm rainfall pattern lead to the explosive large-scale debris flow disaster,out of the source of total solids up to 80.5×10~4m~3,of which about 40×10~4m~3 source into the Minjiang River and blocked off the river,resulting in Ying Xiu Zhen District submerged,and burying of the national highway G213 400m,17 people missing,the economic losses heavy.This essay will evaluate debris flow formation conditions in hongchun ditch,fundamental factors as well as forming mechanism,the establishment of"814"toon debris flow multi-point blocking the collapse bench geological model,determine the formation of large earthquake debris flow key simulation parameters,combined with the digital elevation model(DEM),the FLO-2D two-dimensional numerical model was established.Using FLO-2D software repeat"8.14"toon ditch debris flow process.The simulation results with the actual survey results were validated and obtain the key parameters of debris flow motion:thickness of debris flow,debris flow velocity in the whole process,the pressure of debris flow,the mudslides rushed height and blocked by debris flow coefficient in the whole process.In FLO-2D in the simulation of debris flow deposits covered ditch toon Gan Xi Pu ditch,Da Shui ditch,Xin Dian Zi ditch,alluvial fan,formed in Mizoguchi block Minjiang;big ditch and Xindianzi ditch thickness of 0~6m,Gan Xi Pu Gou thickness 0~8m thick main channel Mizoguchi is 6~10m,10~20m.thick alluvial fan of Gan Xi Pu Gou into the main channel debris flow velocity is the whole hump shaped,flow speed from 0m/s↗5.6m/s↘1.8m/s↗11.9m/s↘3.8m/s;Gan Xi PU Gou River joins the main channel the maximum impact pressure is 33.15kpa,the maximum drop height 6.96m;Gan Xi into the shop the main channel of debris flow coefficient maximum value reached 2.40,close to the serious congestion,with debris flow superimposed here,the formation of burst damage,blockage coefficient decreases sharply,resulting in debris flow velocity and flow geometry amplification.In-depth analysis of hongchun ditch debris flow disaster mechanism of large debris flow prevention and control work has certain guidance and reference.