Types Of Deep-Cut River Valley And Engineering Geological Partition In The Middle Reaches Of Jinsha River

The deep-cut valley area in the middle reaches of the Jinsha River is located in the west of the Yunnan-Guizhou Plateau,with rugged terrain,majestic mountains,steep bank slopes,and deep valleys.This paper takes the deep-cut valley area in the middle reaches of the Jinsha River(Shigu Town of Lijiang City,Yunnan Province to Panzhihua of Sichuan Province)as the research scope.Based on the collection of previous research results,topographic maps of the study area,satellite images,and existing works and engineering cases,the topographic features of the deep-cut valley area in the middle reaches of the Jinsha River were analyzed.The basic types of deep-cut valleys and their topographic features in the study area are summarized.The engineering geological features of each section of the study area were systematically analyzed.Seven evaluation factors,such as topography,deep valley type,stratigraphic lithology,geological hazards,geological structure,earthquake,and topographic variation field,were selected to establish a segmented evaluation index system for engineering geology in the deep cut valley of the middle reaches of the Jinsha River.The thesis adopts GIS-based spatial analysis function and analytic hierarchy process as the evaluation method.Using the spatial analysis function of Arc GIS 10.2 software,an engineering geological zoning evaluation was conducted in the study area,and the zoning evaluation results were analyzed.The main research progress achieved are as follows:(1)The topographic features of the deep-cut valley in the middle reaches of the Jinsha River are analyzed.The Shigu Town-Shitian Bay section of the study area is a high mountain and a deep gorge section of Zhongshan.The bank slope is steep,the terrain is undulating and the river valley is deep;the section of Shitianwan-Dong'an Village is the broad valley of Zhongshan.The shape of the river valley is mostly "U" shape,the bottom of the valley is wide and gentle,and the cutting depth of the valley is relatively low.The Shigu Town-Shitian Bay section is high mountain,middle mountain and basin area.The cutting depth of the river valley is large.The slope of the bank slope is large,and the shape of the river valley is mostly "V" shape.(2)Summarize the main types and basic characteristics of the deep-cut valley in the middle reaches of the Jinsha River.Based on the topography,the types of the deep-cut valley in the middle reaches of the Jinsha River are divided into five categories: A,B,C,D,and wide-valley.(3)Established an evaluation index system for engineering geological zoning in the deep-cut valley area of the middle reaches of the Jinsha River.The topography and topography,deep-cut valley type,stratigraphic lithology,geological hazards,geological structure,earthquakes,and topographic change fields were selected as evaluation indicators,and a GIS-based analytic hierarchy process evaluation model was constructed,and the weights were calculated using expert scoring method.The heavy weight is the deep-cut valley type,topography and stratum lithology index,followed by geological disasters,geological structure and other indicators.(4)According to the constructed engineering geological evaluation model,the engineering geological evaluation was carried out in the research area.The engineering geological environment in the deep-cut valley area of the middle reaches of the Jinsha River has significant zoning and segmentation characteristics.The engineering geological conditions of the Shigu Town-Shitian Bay section are complex.The engineering geological conditions show better and worse areas are larger.The areas with good engineering geological conditions are widely distributed,and are mainly located in the area from Sanjiangkou to Ahai and Rodler to Jinan Bridge.Areas with poor engineering geological conditions are also widely distributed,mainly located in the area from Ahai to Rodler,Jinan Bridge to Shitian Bay.The engineering geological conditions from Shitian Bay to Dong'an Village are generally good.The engineering geological conditions of the Dongan Village-Panzhihua deep-cut canyon section are generally average.The lithology of the exposed stratum is mostly soft rock or softer rock,with weak weathering and erosion resistance,and more frequent geological disasters.