| Yuzixi River Basin is located in the middle of the city of Sichuan Province,Aba,Wenchuan County,Midwest.It belongs to middle and high mountain gorge landscape,river development in the area,serious erosion of bank slope and complicated geological environment.The Maowen fault zone traverses the study area,with strong tectonic activity and frequent seismicity.The study area is located near the epicenter of the Wenchuan earthquake.Due to the Wenchuan earthquake,a large amount of landslide occurred in the area,and a large number of slopes are caused by the aftershocks and rainfall.A serious threat to life and property of the people.Therefore,the study of mountain geological disaster chain has in-depth theoretical value and practical significance.In this paper,through the remote sensing interpretation and field geological survey of Yuzixi Basin.Combined with ARCGIS software,statistical analysis and other research methods,geological disasters Yuzixi watershed characteristics and development process chain conducted in-depth research.The main research results are as follows:According to remote sensing interpretation and field survey,found that the study area developed landslide 75,collapsed 419,debris flow 57,a large number of geological disasters along the river and its trench distribution.Yingxiu-Gengda section area,located between Beichuan-Yingxiu fault and Maowen fault.Lithology is mainly "Pengguan rock",is a major growth area of geological disasters,collapse hazard continuous distribution,causing 70% of road along the canal were destroyed;In the west of Gengda,the development of geological disasters is reduced.The Wenchuan earthquake landslide is divided into shock-slip and slip-slip type,mainly distributed along the water system,elevation of 1500 ~ 2000 m,slope of 30 ~ 60 °,mainly distributed on the sunny slope;The collapse of the disaster is divided into shock type,erosion type and erosion type,in the spatial distribution of the main along the river and the distribution of both sides of the valley,slope of 40 ~ 70 °,and slope height of less than 200 m on the steep slopes,mainly to large and medium-sized collapse,the main movement characteristics of the Rolling Stones after sliding instability are sliding,projectile,jumping and rolling;The debris flow disaster is divided into slope type debris flow and valley debris flow,mainly by the rainfall and the post-earthquake loose source control,with high frequency of outbreak,large scale,destructive and so on.Through field investigation,combined with Arcgis software for DEM and remote sensing image data analysis,factors Affecting the geological hazards in the study area in terms of slope,elevation,river morphology,distance to the fault zone,tectonic position,the ramp structure,earthquakes,rainfall and human engineering activities,etc.Through field investigation and analysis,formation and evolution process of slope failure after the earthquake,the study area is divided into four stages: original slope deformation,the slope fractured,the surface potential structure is formed,shattered rock instability.The investigation and analysis,summarized landslide hazard mechanism is formed shatter-sliding overall dispersion and shattering collapse slip;Mechanism of formation collapse hazard shatter-skid,shatter-dumping type,shatter-faulting formula shatter-shattering buckling formula and-collapsing the formula;Debris flow disaster formation mechanism for the post-earthquake debris flow anomalies,micro-topography watershed mutation,channel blocking effect,critical precipitation conditions change and rainfall infiltration conditions change.According to the information collection and on-site investigation,analyzes the main features of geological disasters in the study area as the main chain of predisposing factors for the earthquake and rainfall,geological disasters and the number of full multi-type,special valley landforms,landslides highest level of activity;Conditions for the formation of ecological fragile geological environment,rock slope shattered a lot of development,short-term heavy rainfall in some areas,with the conditions and characteristics of blocking the river.The study area is divided into geological hazards chain forming mode earthquake disaster damage directly induced slump-chain and heavy rain,disaster-induced chain under the combined effects of the earthquake.Analysis of a typical geological disasters Nanhuaping collapse upstream group and Xiaojiagou debris flow disaster chain formation.This paper analyzes the collapse of the collapse group in the upper reaches of Nanhuaping,the development characteristics of the dam,the formation conditions of the collapse,the mechanism of formation and the process of movement and the environmental impact of the barrier event.The division of debris flow in Xiaojiagou,loose solid source characteristics,debris flow causes,the formation mechanism and the movement process,the environmental effects of blocking the river after the analysis. |
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