DEM Numerical Simulation And Soil Arching Effect Evolution Of Geosynthetic Reinforced Pile Support Embankments

At present,China is in a period of high-speed development.Highway and highspeed railway have great technical needs for Pile-supported embankment.Pilesupported embankment has obvious advantages,it can effectively control the settlement and lateral deformation of foundation,can quickly fill construction,greatly shorten the construction period.Soil arching effect is the main working mechanism of pilesupported embankment and there are many models at present.However,it is not enough to pay attention to the evolution of soil arching effect with the process of soil subsidence between piles,nor to the coupling relationship between tension membrane effect and soil arching effect.A series of model tests of reinforced pile-supported embankment were carried out by using the multi-functional geotechnical model test box made by our research group.The particle displacement of embankment is monitored by particle image velocimetry technology,and the vertical loads between piles and soil are recorded by self-made three-point load meter.The deformation modes and the degree of soil arching effect under reinforced and unreinforced conditions are compared and analyzed.When reinforced,the triangular expanding mode and tower-shaped elevation pattern will be changed into concentric ellipse expansion pattern,and the equal settlement pattern will be changed into concentric circle equal settlement pattern,which reveals the development process of soil arching effect of the two models along with soil subsidence between piles.The effects of model test data on embankment height,pile net spacing,reinforced height and stiffness are discussed respectively.It is revealed that with the increase of embankment height,the deformation mode is gradually transformed from concentric ellipse expansion pattern to concentric circle equal settlement pattern.The critical filling height is 1.5 times the net distance between piles,but when concentric circle equal settlement pattern is formed,The height of equal settlement surface is only 0.67 times the pile net spacing,the double effects of reinforcement on soil arching effect are revealed.On the one hand,reinforcement reduces differential settlement,resulting in the reduction of soil arching effect.On the other hand,the reinforcement changes the deformation mode,forming a "concentric circle" multi-arch,and provides a stable arch foot for this multi-arch form.The first aspect is dominant under the condition of low embankment reinforcement,and the second aspect is dominant under the condition of weak reinforced high embankment.The influence of the height of reinforced material on the deformation mode of soil arch and the load-sharing ratio of soil arch effect is limited.Based on the discrete element numerical simulation of geosynthetic reinforced pile support embankment,the development of soil arch structure of geosynthetic reinforced pile support embankment is analyzed from the point of view of force chain.The numerical simulation is used to validate the model test results.The concentric ellipse expansion pattern and the concentric circle equal settlement pattern are unified.