Research On Deformation Mechanism And Failure Mode Of Large-area High Embankment On Weak Slope Foundation

Due to the weak surface soil and the presence of ground slope in the high embankment on slope weak foundation,there may be excessive vertical settlement and lateral displacement under the embankment weight and train load.Improper treatment may cause the embankment slope to be slumped and unstable.,lateral deformation is too large,uneven settlement of the road and other problems.The key to solving this problem is to deeply understand the deformation mechanism and instability failure mode of high embankment on slope weak foundation.For this reason,this paper relies on the high embankment of weak slope foundation in Pingnan Station of Quzhou-Ningde Railway Station,through a combination of theoretical analysis and numerical simulation,studing the deformation mechanism and failure of high embankment on slope weak foundation,and the deformation control method is given.The main findings are as follows:(1)Based on the elasticity theory of concentrated loads acting on the surface of a semi-infinite body,an approximate formula for the additional stress in the ground caused by embankments on slopes is deduced,and its distribution pattern is given.(2)For embankments on slope weak foundation,the larger the fill layer thickness,the greater the deformation of the filling body during the filling process.The increase of fill layer thickness will increase the deformation amplitude of the rock foundation of the slope,and the fill layer thickness of the slope rock foundation should not be too large.The increase in fill height will reduce the stability of the fill slope and change its potential slip surface position.When the fill height is small,the potential sliding surface is located on the soft foundation of the slope,and when the fill height is larger,the potential sliding surface is located in the filling body.(3)The maximum horizontal displacement of high embankment on slope weak foundation generally occurs in the lower part of the embankment to the foot of the slope.The maximum vertical settlement occurs on the surface of the embankment and the soft foundation,and the vertical uplift occurs at the surface of the soft slope at the foot of the slope;The failure mode is mainly the arc-shaped sliding of the embankment or the linear-arc compound sliding of the surface of the soft ground and the interior of the embankment.(4)The influence of geometric and mechanical parameters of slope weak foundation on the deformation and stability of high fill embankment was discussed by numerical simulation methods.The deformation of the fill slope increases with the increase of the slope of the soft foundation,but the magnitude of the change is small.The impact of the elastic modulus,internal friction angle,and cohesion of the soft foundation on the deformation of the embankment is from sensitive to insensitive.The thickness and elastic modulus of soft foundation have little effect on the stability of high embankment,but its slope,internal friction angle and cohesion force have a significant effect.The influence of internal friction angle and cohesion on embankment stability exists the threshold which from yes to no.(5)The effects of different geogrids layout on the deformation and stability of high embankment on slope weak foundation are analyzed.Geogrids can reduce embankment deformation and significantly increase its stability.The postive effect of the geogrids on the settlement is better than geogrids on the horizontal deformation.For the highembankment on slope weak foundation,the effect of long geogrids is significantly better than that of short geogrids.For high embankment on slope rock foundation,combined geogrids of long and short has more significant effect on improving the stability of embankment.(6)The influences of different slopes,heights,and other methods on the prebuilt steps of the slope are discussed for the effect of the deformation and stability of the high embankment by numerical simulation methods.The steps is beneficial to reduce the lateral deformation during embankment filling,and can significantly increase the stability of the embankment on slope weak foundation;for this supporting project,the slope of the steps can be taken as 1:10 and the height should be taken as 0.8m.The research results in the deformation mechanism,failure mode and deformation control methods of high embankment on slope weak foundation can provide guidance and reference for similar projects and have theoretical significance and engineering value.