The Risk Assessment And Prevention Simulation Of Anxian County

Debris flow is a common disaster in the mountains of our country, which havefeatures of breakout suddenly and heavily damaged."5.12" Wenchuan earthquake in2008produced a large number of collapses, landslides, and some potential adversegeologic body, these adverse geological phenomenon provides sufficient conditionsfor the debris flow’s development, In September2008、July2009and August2010the heavy rainfall which occurred in the county of Anxian、Beichuan、Yingxiu inSichuan province,resulting the breakout of large-scale landslides. These landslidescausing serious losses and at same time hindered the reconstruction work in theseareas. Therefore, the analysis and research of debris flow activity have guidingsignificance for the prevention and mitigation work.Debris flow is a kind of complex natural phenomena. Now the study of debrisflow is mainly for the risk assessment of debris flow, because of the influencingfactors of landslides are numerous, the risk assessment results in different areas arenot the same. According to the geological changes in the environment of Anxiancounty after the earthquake, this paper uses the extension theory to evaluate debrisflow risk. First of all establish the debris flow risk assessment model based on theextension theory. Then eight debris flows were choose to research the risk assessmentby this model, and also the movement of the fluid in the debris flow will be simulatedin CFX software. According to analysis the results of evaluation and simulation, putforward a reasonable measures for the debris flow prevention. This research haspractical significance and reference value for the reconstruction of Anxian county.The specific content of this paper are as follows:(1)Research the formation conditions and distribution law of debris flow in Anxiancounty: the debris flow in Anxian county are widely distributed, but these have rulesin the distribution and the time of occurrence. First analysis the geologicalenvironmental conditions of Anxian county and the experience of the past debris flow,then research the formation and distribution rules of debris flow, this research can provide the basis for debris flow hazard assessment.(2)Establish the evaluation model and assessment the risk: according to the surveydate, establish the evaluation model based on the extension theory. In this model,9factors which affect the growth and development of debris flow were used asevaluation index. The results of evaluation are divided into low risk, moderate risk,high risk and extremely risk levels.(3)Simulation the movement of debris flow: use the CFX software to simulate thedebris flow, through the speed flow line and the pressure field to reflect the movementof debris flow; then simulate the control effect of dams. The results shows that thedams have an obvious effect to the debris flow which occurred by heavy rainfall.