Research On Stress Diffusion And Deformation Characteristics Of Geogrid Reinforced Earth Retaining Wall In High-speed Railway

The internal force and form of reinforced earth retaining wall of high speed railway will change under static loads,wall gravity,rail system and dynamic load of a moving train.In this paper,a systematic research was conducted in order to understand the stress distribution and deformation characteristics of geogrid reinforced earth retaining wall of high speed railway under static and dynamic loads.The earth pressure,the stress distribution angle of reinforced soil retaining wall,the strain of the reinforcement,the horizontal deformation of the wall face and the settlement at the top of the wall were measured.The research was conducted with the use of a model test,finite element numerical simulation,as well as relying on the geogrid reinforced earth retaining wall of Qingdao-Rongcheng intercity railway.The main research contents and conclusions are as follows:(1)The model test of reinforced earth retaining wall was designed and carried out according to the similarity theory.The earth pressure distribution on a the retaining wall,the horizontal deformation of the wall face,the settlement at the top of the wall and the strain of the geogrid under static load were obtained.The test results show that the vertical earth pressure of retaining wall is a nonlinear distribution along the length of reinforcement,and the maximum value of vertical soil pressure is located in the soil near the loading position.The horizontal earth pressure at the back of the wall is a nonlinear distribution along the height of the wall.The deformation of the reinforced earth retaining wall is very small under static load,in which the maximum horizontal displacement of the wall face is 0.23mm,accounting for 0.03%of the height of the wall,and the maximum settlement at the top of the wall is 1.15mm,which is about 0.14%of the height of the wall.The strain of the reinforcement is nonlinear ditribution along its length,and the peak position of the strain of reinforcement is basically the same as the position of potential slip face of reinforced earth retaining wall predicted by method of"0.3H".The strain of reinforcement is mainly formed in the filling stage of reinforced earth retaining wall,and the external load has little effect on it.(2)The finite element model of geogrid reinforced earth retaining wall for high speed railway was designed by the use of finite element software Abaqus,and the stress distribution characteristics of reinforced soil retaining wall under static and dynamic loads were studied.The calculation results have shown that stress distribution angle of reinforced soil retaining wall is not a fixed value,but there is a range,in which the stress distribution angle of the upper part of the retaining wall is larger.The stress distribution angle decreases with the increase of the vertical spacing of the reinforcement,and increases with the increase of the length and strength of reinforcement,the external load and the speed of the train.The stress distribution angle of reinforced earth retaining wall is mainly between 38° and 70°.(3)The deformation characteristics of reinforced earth retaining wall under static and dynamic loads were studied based on the finite element model of geogrid reinforced earth retaining wall for high speed railway.The calculation results have shown that the horizontal displacement of the wall and settlement of the top of the wall increase with the increase of the vertical spacing of reinforcement,the external load and the speed of train,and decrease with the the increase of the length and strength of the reinforcement.Under the static load,the maximum value of the horizontal displacement of the wall face is located in the middle and lower part of the wall.Under dynamic loading,the maximum value of the horizontal displacement of the wall face gradually moves from the lower part of the wall to the upper part of the wall with the increase of the speed of the train.The maximum value of the settlement of the top of the wall appears at the loading place.(4)The stress distribution angle and the deformation of reinforced earth retaining wall are mainly affected by the changes of the vertical spacing of reinforcement,the external load and the speed of the train.The changes of the length and strength of reinforcement have little effect on them.