Macro And Mesoscopic Study Of Geogrid Pull-out Tests Under Static And Dynamic Loading Conditions

The interaction characteristics of the geogrid-soil interface is an important research content for exploring the reinforcement mechanism of reinforced soil structures and analyzing structural stability.Because the geogrid and the soil have different elastoplastic properties,and the interaction mechanism of the geogrid-soil interface is affected by many factors,the interaction mechanism between the geogrid and the soil is relatively complicated.The existing research results have not fully explained the geogrid The reinforcement mechanism.The existing research on the mechanism of geogrid reinforcement is mostly the research results under static load boundary conditions,and there are few reports on the research results of the interaction mechanism of the geogrid-soil interface under the dynamic load boundary conditions generated during train operation.In view of this,this paper,based on the indoor geogrid pull-out test research under static load boundary conditions,combined with discrete element numerical simulation to deeply explore the influence of static and dynamic load boundary conditions on the results of the geogrid pull-out test.The system reveals the difference The mechanism of the interface between the geogrid and the soil under load boundary conditions.The main findings are as follows:(1)Through indoor geogrid tensile test and soil direct shear test,the physical and mechanical performance indexes of geogrid and soil material are obtained.Through the indoor geogrid pull-out test under static load conditions,the influence of factors such as normal stress and fill height on the interface between the geogrid reinforcement and soil is obtained.(2)The numerical models of the geogrid tensile test and the direct shear test of the soil material were established by the particle flow software,and the discrete element simulation meso parameters of the geogrid and the soil material were calibrated through the parameter inversion method.The discrete element numerical model of the pull-out test of geogrid under static load boundary conditions is established,and the results of the indoor pull-out test and the numerical simulation results are compared and analyzed.In-depth analysis of the change law of the coordination number and porosity of the fill soil during the pulling process of the static load boundary condition,the distribution of geogrid tension,the distribution of geogrid displacement and strain,and the rotational movement of soil particles are analyzed.(3)A numerical model of the geogrid pull-out test under dynamic load boundary conditions was established,and the numerical simulation results of the pull-out forcedisplacement curve of the geogrid under different normal stresses,different fill heights,and different load frequencies were carried out.In-depth research.The relationship between the drawing force and the drawing displacement of the geogrid considering the influence of different working conditions under the dynamic load boundary conditions is analyzed.The system reveals the variation law of the coordination number and porosity of the fill during the drawing process,and the displacement and displacement of the geogrid are systematically revealed.The distribution of strain,the law of normal stress transfer,the law of rotation of soil particles,etc.The simulation results of various meso-fabrics under the two boundary conditions of static and dynamic loads are compared and analyzed.