Study On Characteristics And Stability Of Operating Freeway Common Landslides On Southernmountain Area Of Guizhou Province

Landslides are the most common and most serious geological hazards in the construction of freeways in southern Guizhou Province,and they are also the biggest potential hazard during the operation period of freeways.The landslide types in the southern region of Guizhou Province is rich and worth to be investigated in detail.The analysis of their types,development patterns,background and stability is of great significance for the construction and safe operation of freeways in Guizhou Province.This paper investigates and studies tens of landslide that occurred on 9 expressway section,including the Banba-Jiangdi expressway section,the Duyun-Xinzhai expressway section,Congjiang-Yixing expressway section,Shuikou-Rongjiang expressway section,Guiyang-Duyun expressway section,Mawei-Jiaou expressway section,Zhengning-Shengjingguan expressway section,Liupanshui-Liuzhi expressway section and Kaili-Yangjia expressway section.base on huge landslide data,author systematically summarizes the background and analyzes the development types and the deformation characteristics of operating freeways in the southern area of Guizhou Province,then proposes the numerical simulation method of landslide with existed supporting structures in the operating freeway.The RK9 landslide of Kaiyang freeway are used as typical example for numerical simulation analysis and evaluation.Firstly,author analyzed and studied the development background of operating freeway landslides in southern Guizhou Province and draw the following conclusions: The landslides are mainly distributed in the elevations of 500m-2000 m,mainly occurred at middle and low mountain terrains.Landslide disasters mainly distribute in the Permian and Triassic layers covered by Quaternary residual stratum.Rainfall is the key factor that trigger the landslides.About 92% of landslides occur after heavy rainstorms or continuous heavy rainfall.Therefore,rainfall is the main cause of landslides in the southern Guizhou Province,and it is also the main reason for the long-term weakening of slopes.human being activity is also the important factor of landslide happened in the freeway.Due to factors such as cut slopes,unreasonable construction methods nad construction processes,unsuitable protecting project design,the stress state of valley slope are strongly changed,which leads to a large number of slides disaster after opening to traffic.Secondly,based on the geological survey results,the most common landslides in the southern Guizhou operating freeway are classified by material composition into five category,including accumulative formation landslides,landfill landslides,landslides of fractured rocks,bedrock landslides,and soil-rock maxed landslides.Other classification method is based on the relative positions of the landslides and the freeway,using this method,operating freeway landslides in the southern mountain area of Guizhou Province can be divided into Subgrade slope landslides,Landslide of cutting slope,landslides in tunnel front.Different types of landslides have different characteristics and deformation process.The study found that the accumulative formation landslide are mainly the Quaternary residual strata and are mostly shallow and medium-sized landslides;Landfill landslides mainly occured in the filling embankment sections with the slip surfaces lie in the fill inside or the original ground.this type of landslide are often difficult to management during the operation of freeway.bedrock landslides often occur when there are interbedded layers of soft and hard rocks.And the landslides in tunnel front become more and more common and cannot be ignored.The landslide occur in the southern Guizhou province highways that have opened to traffic are mainly artificial slope of high-steep cut and landfill subgrades.this kind of slope is often have some retaining structures but still slip in the long-term impaction.Based on the investigation of the background and development characteristics of highway landslides,this paper proposing a numerical simulation method of the operating highway landslide with early retaining structure,takes the RK9 landslide of Guizhou Kaiyang Expressway as an typical example to verify the practicality of numerical simulation technique.