The Research On The Mechanism And Kinetic Characteristic Of Woqian Landslide In Qingchuan Town

On May 12 ,2008 when the earthquake occurred in Wenchuan,a long-runout landslide was directly triggered in Woqian ,a commune in Qingchuang county.It had a volume of 12 million cm and resulted in 38 victims.As this landslide had the extraordinary heavy damages and biggest affected area which lead to disastrous consequences, so for us to do, both studying the formation mechanism and moving feature of landslide to debris flow will pragmatically benefit to predict the damage range and do a better disaster prevention.This paper,which bases on a series of outdoor surveys and datum collecting and analysis,sets forth the Engineering Geology features of the Woqian landslide,and thus generalizes its geologic conceptual mode.Firstly,the landslide's configuration is divided into several parts on the basis of survey analysis.Research shows the main feature when the landslide was in process.Secondly,the formation mechanism is studyed in three aspects which are following,the relation between landslide and the crevices which arised by earthquake,the structure feature of that slope,and as well as how the earthquake impacted on it. At last,two ways,which called momentum transfer and A.E.Scheidegger's are used to analyse the process of the landslide. What's more,the results that worked out have been compared with each other.The paper has a macro-analysis of the slope's structure.It consists two units,one of which is the upper hard layer named limestone,and the other is the lower soft layer named slate.The origin area where the landslide began was formed mainly by limestone,while with some slate at the top at the same time.The limestone,of where the fissures grows,was backfilled calcites。Since the fault at Shikan went across from the back edge of the slope,the limestone in this part were easily shattered.In addition,the terrane of the original area sloped out the surface slowly,intersect with the leading direction of the landslide at small angle.The fault passed by the back edge when side edges was incised by fissures whose planes were open。Herewith,the combination of the fissure-planes on side edges ,back edge fault and the surface of the terrane presented in a unstable form, almost bordering both the steep part and the glacis when landslide started by the joint action of accumulating and inducing effects of the earthquake.Owe to this,the landslide had a higher muzzle velocity.Taking the advantage of the valley flat,land slided fast while a process of disaggregating into debris was growing and contributing into long-run landslide.The analysis was caculated in reverse direction by means of momentum transfer and A.E.Scheidegger's.A conclusion was drawed according to the comparison the two different datas.This landslide had a highest speed between 46.69m/s and 56.1m/s.With a average velocity at 35.6m/s,the whole landslide lasted for 57.1s from the very beginning to the end.