Vulnerability Study Of The Protection Project For The Debris Flow In Earthquake Region, Wenchuan County

Debris flow is one of the common geological disasters in mountainous area, withferocious and sudden characteristics.12May2008Wenchuan County in SichuanProvince,the magnitude8.0earthquake,gave birth to numerous landslides,avalanchesand potential adverse geological unstable slopes,debris flow for the earthquake areaand provide favorable breeding conditions. A large debris flow disaster was triggeredby a heavy rainfall in study area on August14，2010．The debris flow carried out a lotof loose sediments and the total amount is about80.5×104m3．This debris flow led toserious secondary disasters including Minjiang river was blocked,Yingxiu town wasflooded,and the213highway was interrupted，the roadbed and bridge pier of a rampbridge was destroyed, and resulted in17people missing, serious economic loss. Atpresent, the region has to build the protection project of debris flow. Due to thearea still has a lot of loose material, to ensure the construction safe and effective tocarry out, by the vulnerability assessment of debris flow in the research area protectionproject which not only can be aware of the anti disaste ability,and has importantsignificance to improve the ability of the resistance disaster.This thesis rely on the protection project of debris flow,the debris flowvulnerability assessment and prevention project grading classification as the maincontent,focus on the following aspects:First of all, through field investigation and data of the study area,analyzed thebasic conditions of geological environmental background and the formation of debrisflow area,introduces the protection project layout situation in the study area, namelythe upstream slope stability solid source engineering,in the middle of the blockadjustment Project and downstream drainage consolidation engineering,the,in thedebris flow control works now on the basis of investigation,preliminary analysis of thedamaged reasons.Secondly, according to the type of protection project, the project is divided into blockengineering and drainage engineering evaluation, blocking projects selected five the first levelindicators, they respectively are dam, damlocation conditions,debris flow and earthquake, divided into seven indicators of the first level index, respectively for the dam site engineering geologicalconditions, the dam and the channel relative position, height of dam, building materials, the debrisflow scale,frequency,rainfall and intensity of earthquake; the same to block engineering, drainageproject also for the four the first level indicators, and includes nine the secondly levelindexes, respectively for the dam of engineering geological conditions,axis and the channelaxis angle, it’s building materials,groove longitudinal slope,width,the debris flow scale, requencyand intensity of earthquake.The method of fuzzy analytic hierarchy process. First through theanalytic hierarchy process to calculate the weight of governance project vulnerability factors,thenusing fuzzy method to calculate the vulnerability index.Finally,based on the fuzzy analytic hierarchy process to obtain vunlnerabilty index ofprotection project,and to selection the BP neural network prediction model to build projectvulnerability index,and selected8projects as training samples,and the structure parametersobtained stable network,then this network select3projects for the training samples,the result arein good agreement with the actual situation.