| The Zemuhe fault zone is located in turning parts on east boundary of the sichuan-yunnan rhombic block,in the southeast margin of the qinghai-tibet plateau,which is a large left-lateral strike-slip and inheritance active faults.Because of its special tectonic,strong crustal deformation and fault activities,it has the characteristics of complicated geological conditions,strong earthquake activities,and secondary Geohazard seriously.To provide scientific basis for Geohazard prevention,engineering construction plans and fracture Geohazard research in urban that locate in Zehemu fault zone.In this paper Dajin fault that the biggest activity in secondary fracture as an example,by remote sensing,field investigation and scientific analysis,to explore the activities characteristics of fracture and its control effect on Geoenvironment,fault Geohazard space distribution rule and long-time activity and the effect geological,the following results:(1)The effect on controlling Geoenvironment of Zemuhe fault zone.(1)the new tectonic movement and seismic control effects: The Zemuhe fault zones strongly inherit left-lateral strike-slip movement as a regional modern crustal activity,which control the regional tectonic activity and formation distribution of earthquake,become the Zemuhe earthquake activity belt.(2)the topography control effects: Through the rise,fall and warped movement by fault zone as the link,which created three kinds of different fault block unit,mean uplift block mountain,rift valley and pull-apart basin.(3)paleogeography sedimentary environment control effect: Belt or subsidence block formation new sediments that complex and changeful,loose weak.Fault blocks uplift by denudation forming loose zone of weathering,erosion,which provide source material for a variety of Geohazard and conditions.(4)control surface drainage pattern and geothermal migration effects: Fracture hub tilted movement,which change the surface water system by a pattern of four elephants landform,through the fault zone formed deep geothermal field migration towards the surface,circulation channels,constitute a strong enrichment of groundwater runoff belt.(5)the geological evolution control effects: the Zemuhe fault zone by influencing the regional Geoenvironment evolution,result in massive earthquake secondary Geohazard,and intensifying the surface process of evolution,finally driven by seismic tectonic uplift and faulted depression,the surface Geohazard process-driven erosion and deposition,the two interaction decided to existing geomorphic evolution.(2)Dajin fault geological hazard control effect:(1)The development characteristics of Geohazard: It has obvious fracture control characteristic,which provide a material structure and geomorphic conditions for Geohazard development by intensifying Geoenvironmental degradation,thus affecting Geohazard boundary characteristics,deformation failure process and evolution stage,so it's the dominant factor control of Geohazard.(2)The distribution of Geohazard: Fracture Geohazard time-space effect,namely control spatial distribution and a long time activity of Geohazard.8 space effect: fault distance effect(strip),intensity effect(attenuation),west plate effect,slope structure effect(weak),drainage effect(linear distribution),micro topography effect(elevation,slope,slope type),the tectonic stress field effect(main sliding vertical),stratigraphic tendentiousness(centralized fault fracture zone).8 time characteristics,namely Geohazard long-term activity: collapse Geohazard s which have complex activity,periodicity and extensibility,debris flow Geohazard which have activity,high frequency,erosion,deposition and sustainable.(3)Dajin fault hazard effect: the Zenuhe fault activities have an effect on Geohazard formation mechanism,geological hazard pattern and the effect of Geohazard chain.(1)Geohazard pattern: according to the differences geological conditions,slope dynamic response characteristics and failure forms,its divided into rock avalanche,debris,debris slope flow 3 kinds of collapse,the ancient earthquake,shatter,accumulation 3 kind of landslide,high slope,valleys rainstorm 2 kind of debris flow,three kinds of total collapse,landslide and debris flow,8 sub-types,15 small classes.(2)fracture-formative mechanism: The Zemuhe fault zone play a role in decision and control construction activities on the regional geological background and Geohazard pattern.Fracture formed evolution process proved material structure and terrain,Geoenvironment continued to deteriorate under strong earthquake dominant,the accumulative deformation of earthquake triggering effect significantly,especially in late near weak earthquake frequent continuous disturbance,the extreme coupling effect of rainfall infiltration,frequent strong human engineering activities,become the root cause of the Geohazard.(3)fracture Geohazard chain effect: Fault zone has a good Geohazard chain effect;its type can be divided into single ditch,main ditch and compound 3 kinds of 10 classes.Motivating factor is earthquake and rainfall,the evolution process is landslide(collapse)?debris flow?pluvial fan(turbidity),damage characteristics include human wealth damage+engineering damage+ environmental degradation.Geohazard chain evolution model is summarized as follows: Geoenvironment breeds?glacier movement and qionghai lake deposition ? sedimentary seismic rupture zone and ancient landslide formation?post-earthquake Geohazard strongly development?earthquake Geohazard chain recession 5 stages of evolution.Fault zone Geohazard chain effect have an extension of time and strong space,large type and size,and complex environment mechanism,must form a long-term,systematic and comprehensive,real-time integrated.The disaster effects of the Longmen Mountain and Zemuhe fault are similar and different,the former will gradually transition or transform to the latter.Therefore,this paper can provide a reference for the scientific research on the prevention and control of earthquake disasters in Wenchuan Earthquake stricken area. |
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