Stability Analysis Of Typical Loess High Slope In The Moving South Project Of National Highway 310

In China,the loess area is vast and widely distributed in northern China.With the large-scale construction of infrastructure in China,high-grade highway and railway have high requirements for linearity,so the construction of highway and railway in northern loess area will form a large number of deep cutting slopes and high fill embankment slopes.In the process of design and construction of loess high slope,if it is not handled properly,slope instability may occur,resulting in disaster accidents.In this paper,based on the National Highway 310 Luosanjie to Sanmenxia West Section of the New Southward Moving Project,the physical and mechanical properties of loess along the highway and the dynamic test research under traffic load are studied.The Geo Studio series software is used to simulate the construction process of deep cutting slope excavation and high fill embankment layered filling,and the construction process is analyzed.This dissertation analysis the change of stress and deformation and the stability of slops during construction.The main work and achievements of this paper are as follows:(1)The physical and mechanical properties of loess,including particle size distribution,liquid plastic limit,optimal moisture content and maximum dry density,permeability coefficient,shear strength index are tested by indoor geotechnical test,which provides a powerful reference for the construction of the National Highway 310 New Southward Moving Project,and also provides basic data for loess slope stability calculation and numerical simulation analysis.(2)GDS dynamic triaxial test system is used to study the axial deformation,dynamic stress-strain relationship and its variation of loess under traffic load.The results show that with the increase of vibration frequency,the axial cumulative deformation decreases,the modulus of resilience increases,the area of hysteresis loop decreases and the damping ratio decreases.With the increase of cyclic stress ratio,the axial cumulative deformation increases obviously,and the area of hysteresis loop and the damping ratio of loess increase.With the increase of the number of cycles,the hysteresis loop gradually moves to the right,but the movement amplitude gradually decreases.(3)In this paper,the finite element analysis software Geo Studio is used to simulate the stress and deformation of the loess deep cutting slope during the construction process,and the simplified Bishop method is used to analyze the stability of the typical loess deep cutting slope during the construction process.The results show that the maximum horizontal displacement is 0.28 meters,appearing at the foot of the slope,and increasing with the increase of excavation times;the settlement value of the top of the slope is only 0.06 meters;the bottom of the slope will uplift during the excavation,with the increase of excavation times,the uplift displacement of slope bottom first increases and then decreases,and the maximum displacement of the bottom of the slope uplift reaches 0.55 meters,which occurs after the completion of the third excavation,while the slope is fully excavated after the end of the excavation,the slope bottom uplift displacement is 0.15 meters.The slope safety factors under normal and earthquake conditions are 1.171 and 1.045 respectively,which are slightly less than the corresponding code requirements.(4)Numerical simulation analysis and stability calculation of layered filling construction for high fill embankment slope of Loess Slope Subgrade are carried out.The results show that the horizontal displacement of the top of the embankment slope is very small,and it mainly occurs downward settlement,the settlement is only0.039meters;after the embankment is fully filled,the horizontal displacement and vertical displacement are 0.165 meters and 0.55 meters respectively.The simplified Bishop method is used to calculate the safety factor of each layer of embankment after filling,which is between 1.437 ～ 2.201 in normal condition and 1.159 ～ 1.917 in earthquake condition,indicating that the slope is stable in the process of layered filling construction.