Mesoscopic Study On Mechanical Properties And Deformation Behavior Of Reinforced Soil Retaining Walls Under Static And Dynamic Loads

Geogrid-reinforced soil retaining walls have good technical and cost advantages,and are widely used in engineering practices such as railways,highways,and water conservancy.Exploring the mechanism of geogrid in soil is important for the design and application of reinforced soil structures.Based on the laboratory model test,a discrete element calculation model was established using particle flow code software to study the mechanical characteristics and deformation behavior of reinforced soil retaining walls during the filling process and under static and dynamic loads from the meso-level.The results can provide theoretical support for the optimization of the design of the reinforced soil retaining walls.The main research contents include:(1)In the discrete element simulation,based on the improved parallel bond contact model,the discrete element model of geogrid tensile test is established.Based on the linear contact model and the slip model,the discrete element model of soil direct shear test is established.Through the sensitivity analysis of the meso-parameters,the influence of different meso-parameters on the macroscopic results is obtained,and the meso-parameters in this study are finally determined.(2)The discrete element model of reinforced earth retaining wall is established by using the above-mentioned meso-parameters,and the strip foundation static load is applied at the top of the retaining wall,the variation of geogrid strain and tensile force during filling and the evolution of deformation of retaining wall,geogrid strain,distribution of contact force chain between particles,displacement vector of particles and internal stress field of retaining wall under static load are analyzed.The results show that the geogrid strain and tensile force increase with the increase of the filling height,and the geogrid strain mainly occurs during the filling period,with the increase of the height of the retaining wall,the maximum strain position of the geogrid moves to the right gradually,and the maximum strain of the top geogrid moves to the loading position,the earth pressure is non-linear along the direction of reinforcement laying,and the horizontal earth pressure at the geogrid position from the retaining wall stress field is small,which shows that the geogrid greatly restricts the lateral movement of soil particles.(3)After the static load is applied,the dynamic load is applied to the retaining wall,and the distribution of deformation,geogrid strain and earth pressure under the dynamic load is analyzed.The results show that the deformation of retaining wall and the earth pressure vary in a sinusoidal curve,and the deformation of retaining wall increases gradually with the increase of loading times and tends to be flat,and the deformation of retaining wall and the earth pressure are greatly affected by the amplitude of load,the dynamic response of retaining wall is studied by analyzing the distribution of contact force chain,the number of contact,the vector of particle velocity and the variation of earth pressure in a complete loading cycle.The number of particle contact changes in a sine curve,but the value decreases on the whole.With the increase and decrease of the dynamic load,the soil particles show the law of downward and upward movement,which shows that the soil particles have a tendency to return to their original position,however,irreversible deformation will occur,and the influence of the load on the earth pressure is mainly concentrated at the position of the loading plate and decreases gradually along the two sides,and the vertical earth pressure changes with the load in a sine wave curve,but the horizontal earth pressure changes slightly,it shows that the geogrid restricts the lateral movement of soil particles.