Design Of Low Embankment Height In Oasis-desert Area Of Xinjiang

Low embankment has been widely used in developed countries.Attempts have also been made in parts of the country where the terrain is relatively flat.The low embankment has the advantages of reducing the land occupation rate,saving the earthwork,reducing the scale of the project,saving the investment and coordinating with the surrounding landscape in the design of the embankment.The Xinjiang Uygur Autonomous region is located in the northwestern border region of China,With the rapid development of highway construction,the problems of affecting the natural ecological environment and occupying land and cultivated land have gradually become prominent.Especially in the construction of high grade and high standard trunk roads,the high embankment has increased significantly,seriously destroying the original vegetation and water system.Causes soil erosion and debris flow and other geological disasters.Therefore,it is of great significance to design the height of embankment reasonably,reduce the scale of construction land,protect the natural environment and realize the coordinated development of environment and economy.In Xinjiang oasis desert area,because of its special geographical environment,low embankments can be generally adopted when designing highways,and the determination of low embankment height is the key technology to be solved in low embankment design.At present,there are still some unreasonable phenomena in the height design of the main road in the oasis desert area of Xinjiang.The design height of embankment in Xinjiang desert oasis area is very different because of different geographical environment under the division of three levels of natural regionalization.Therefore,it is necessary to study the reasonable height of low embankment in oasis desert area,and find out the main factors that affect the height of embankment in the aspect of technology and geographical environment.This paper relies on the project of “study on rational height of roadbed of trunk highway in oasis desert area of Xinjiang",Through field test and numerical simulation,finite element simulation of low gravel embankment of Sansha Expressway is carried out,aiming at different embankment height,different base thickness,different base course elastic modulus and different surface thickness.The characteristics of low embankment engineering were analyzed with different elastic modulus.The main contents and results are as follows:(1)Based on the collection and analysis of field data,this paper summarizes the embankment disasters,geological conditions of typical sections,the height range of subgrade fill,the existing problems of roadbed and the solutions to the problems of roadbed under the three-level natural regionalization in oasis-desert region of Xinjiang.(2)In this paper,the oasis desert area is classified into desert area,Gobi area and plain area according to the type of roadbed,the reasonable height range of highway embankment in desert area,Gobi area,plain area and the main controlling factors affecting embankment height are analyzed.Aiming at the special geographical environment of desert area,this paper puts forward that in the edge and hinterland of Taklimakan Desert and Guerbantunguta Desert,the roadbed is constructed by using eolian sand,and the quality of eolian sand is analyzed according to the field measured data.Determine whether subgrade fillers can be made.(3)Based on the sandy gravel section of Sanchakou-Shache Expressway in the desert and oasis area of Xinjiang,the finite element model of low embankment of sandy gravel soil is established by using ABAQUS finite element software,and the different embankment height,different embankment modulus and different base course thickness are analyzed in this paper.The engineering characteristics of low embankment under six working conditions: different base modulus,different surface thickness and different surface modulus.(4)In this paper,the relationship between the dynamic stress of subgrade and the depth of roadbed is analyzed by finite element method,and the dynamic stress and height of embankment,the thickness of surface layer,the modulus of surface layer,the thickness of subgrade,and the thickness of subgrade are analyzed by finite element method.The relationship between the modulus of the base is analyzed by finite element method,and the technical measures to reduce the height of the embankment are obtained.(5)In this paper,the influence of the thickness of the surface layer,the modulus of the surface layer,the thickness of the base course,the modulus of the base course on the working depth of the roadbed and the relationship between the height of the embankment and the working depth of the embankment are obtained by finite element analysis.(6)In this paper,the finite element model in chapter 3 is verified by the field soil dynamic stress test,and the comparison curve between the field measured data and the calculated result of the finite element model is obtained.It is proved that the measured value is in good agreement with the calculated value of the finite element,and the error is less than 10%.The error is analyzed.