Stability Analysis Of High Earth-filled Slopes For Airport Construction On Saturated Loess

With the enhancement of China’s comprehensive national strength,the importance and investment in the construction of transportation infrastructure are increasing,and the construction of airports has entered a prosperous period.A large number of new highfilling airports have broken through the accumulation of historical experience,and it is difficult to obtain design basis from engineering examples and specifications,which has brought great troubles to engineering construction.There are many successful cases of high-fill projects,but some lessons are also learned from partial or overall failures.Recently,an airport with a maximum slope height of 200 m is planned to be built in the collapsible loess area in the northwestern part of China.A slope failure occurred during the construction process in the vicinity of this airport in the near past.The cause of the failure is related to the impact of groundwater.It is imperative to study the undrained stability of rapid earth-fill project on saturated loess foundation with high groundwater level.There is still a lack of the broad consensus on the selection of undrained strength parameters and analysis methods in Chinses geotechnical engineering society.The method commonly used in Chinese geotechnical engineering society is based on Mohr-Coulomb total stress strength parameters(Method C),which is quite different from the methods used in foreign countries,including the undrained analysis method using the Mohr-Coulomb effective stress strength parameters(Method A)and the method using consolidated undrained shear strength parameters(Method B).Firstly,this paper systematically compared three undrained stability analysis methods and their strength parameters us ed worldwide.Then,the finite element limit analysis method,the limit equilibrium method and the elastoplastic finite element method are used to perform undrained stability analysis for some simple examples and the practical high-fill engineering case,using the Mohr-Coulomb yield criterion and the Modified CamClay Model.The research results highlighted that it is necessary to use the undrained analysis methods(Method A or Method B)for this problem.The conventional stability analysis method(Method C)mostly overestimates the factor of safety of earth-fills on the saturated foundation soils,which will have a huge impact on some engineering designs.Besides,for the three numerical methods,the limit equilibrium method can basically meet the requirem ents of engineering accuracy,but the calculation results are quite discrete.The elastoplastic finite element method using the Modified Cam-Clay Model can accurately calculate the displacement,and the finite element limit analysis method can give a strict envelope of the factor of safety by calculating the upper and lower bound solutions.Both of them have the significance of popularization in the geotechnical engineering society.