Study On The Stability Of The Bank Slope Of The Mainstream Of The Nujiang River

Lushui County which belong to the Lisu Autonomous prefecture of Nujiang located in the west of Yunnan Province.Because of the tectonic environment of the Lushui Conunty is in a strong collision and extrusion,geomorphic features of the area are high mountains and steep slopes,crisscrossing of faults,fragile geological environment,frequently and harmful geological disasters.The main stream of the Nujiang River across the county from north to south,and the bank slope of the river is the high frequency area of geological hazard.There are a large number of residents on both sides of the Nujiang River.The right bank of Nujiang River is built with S228 and S230 provincial roads.And there are many rural roads on the left bank of the river.These characteristics told above make the area easy to suffer from the geological hazard which threaten personal safety such as collapse,landslide,debris flow and so on.Based on the 1:50000 detailed investigation project of geological hazards in Lushui County,the paper makes a study on the characteristics and stability analysis of the slope in Lushui section of Nujiang River.This paper studies the basic geological conditions of the area,such as the humanistic environment,natural geography,meteorology and hydrology,stratum lithology and human economic engineering activities.The structural types of the bank slope,the failure mechanism of typical collapse and landslide,and the stability of the typical bank are analyzed.With the powerful spatial analysis function of the GIS software,the Application of information method and the Analsis Hierarchy Process(AHP)is used to study on stability zoning in the Lushui section of Nuujiang River.(1)The basic geological conditions of the study area are analyzed,such as natural geographical features,meteorological and hydrological characteristics,topography and geomorphology and so on.Based on the preliminary division about the structural types of bank slope in the study area,the stability analysis is carried out for the typical bank.At the same time,the development characteristics and formation mechanism of the typical collapse and landslide in the study area are analyzed in detail.(2)Study on the system about stability estimation of the bank slope,the paper respectively expound the information method,the Analysis Hierarchy Process(AHP)and evaluation methods.According to the relevant principles of the evaluation index,combined with the actual situation of field investigation,the eight factor which are elevation,gradient,aspect,geological engineering petrofabric,structural buffer zone,fluvial process,slope shape,climate and human activities are the evaluation indexs of the study area.(3)Setting up the evaluation model in researched region through the information method and analytic hierarchy process.Using the Spatial analysis and attribute evaluation by ArcGis software,that Partition on bank slope stability of Lushui period in Nujiang River.We can analyzed that,different stability areas has roughly similar proportion.However,it has different proportion in local bank slope stability by the result of these two evaluation methods.(4)Comparing to the divisional chart of slope stability in two different methods,then get the researched region divisional chart of slope stability.The stability of the research region is divided into four levels.Furthermore,analyzing the bank slope stability which in the research region.The highest stability area accounted for 16.60%;the high stability area accounted for 33.56%;the low stability area accounted for 21.59%;the lower stability area accounted for 28.24%.